gui-cs.Terminal.Gui/Terminal.Gui/Views/TextView.cs

#nullable enable

// TextView.cs: multi-line text editing
using System.Diagnostics;
using System.Globalization;
using System.Runtime.CompilerServices;
using System.Text.Json.Serialization;
using Terminal.Gui.Resources;

namespace Terminal.Gui;

/// <summary>
///     Represents a single row/column within the <see cref="TextView"/>. Includes the glyph and the
///     foreground/background colors.
/// </summary>
[DebuggerDisplay ("{ColorSchemeDebuggerDisplay}")]
public class RuneCell : IEquatable<RuneCell>
{
    /// <summary>The <see cref="Terminal.Gui.ColorScheme"/> color sets to draw the glyph with.</summary>
    [JsonConverter (typeof (ColorSchemeJsonConverter))]
    public ColorScheme? ColorScheme { get; set; }

    /// <summary>The glyph to draw.</summary>
    [JsonConverter (typeof (RuneJsonConverter))]
    public Rune Rune { get; set; }

    private string ColorSchemeDebuggerDisplay => ToString ();

    /// <summary>Indicates whether the current object is equal to another object of the same type.</summary>
    /// <param name="other">An object to compare with this object.</param>
    /// <returns>
    ///     <see langword="true"/> if the current object is equal to the <paramref name="other"/> parameter; otherwise,
    ///     <see langword="false"/>.
    /// </returns>
    public bool Equals (RuneCell? other) { return other is { } && Rune.Equals (other.Rune) && ColorScheme == other.ColorScheme; }

    /// <summary>Returns a string that represents the current object.</summary>
    /// <returns>A string that represents the current object.</returns>
    public override string ToString ()
    {
        string colorSchemeStr = ColorScheme?.ToString () ?? "null";

        return $"U+{Rune.Value:X4} '{Rune.ToString ()}'; {colorSchemeStr}";
    }
}

internal class TextModel
{
    private List<List<RuneCell>> _lines = new ();
    private (Point startPointToFind, Point currentPointToFind, bool found) _toFind;

    /// <summary>The number of text lines in the model</summary>
    public int Count => _lines.Count;

    public string? FilePath { get; set; }

    /// <summary>Adds a line to the model at the specified position.</summary>
    /// <param name="pos">Line number where the line will be inserted.</param>
    /// <param name="cells">The line of text and color, as a List of RuneCell.</param>
    public void AddLine (int pos, List<RuneCell> cells) { _lines.Insert (pos, cells); }

    public bool CloseFile ()
    {
        if (FilePath is null)
        {
            throw new ArgumentNullException (nameof (FilePath));
        }

        FilePath = null;
        _lines = new List<List<RuneCell>> ();

        return true;
    }

    public List<List<RuneCell>> GetAllLines () { return _lines; }

    /// <summary>Returns the specified line as a List of Rune</summary>
    /// <returns>The line.</returns>
    /// <param name="line">Line number to retrieve.</param>
    public List<RuneCell> GetLine (int line)
    {
        if (_lines.Count > 0)
        {
            if (line < Count)
            {
                return _lines [line];
            }

            return _lines [Count - 1];
        }

        _lines.Add (new List<RuneCell> ());

        return _lines [0];
    }

    /// <summary>Returns the maximum line length of the visible lines.</summary>
    /// <param name="first">The first line.</param>
    /// <param name="last">The last line.</param>
    /// <param name="tabWidth">The tab width.</param>
    public int GetMaxVisibleLine (int first, int last, int tabWidth)
    {
        var maxLength = 0;
        last = last < _lines.Count ? last : _lines.Count;

        for (int i = first; i < last; i++)
        {
            List<RuneCell> line = GetLine (i);
            int tabSum = line.Sum (c => c.Rune.Value == '\t' ? Math.Max (tabWidth - 1, 0) : 0);
            int l = line.Count + tabSum;

            if (l > maxLength)
            {
                maxLength = l;
            }
        }

        return maxLength;
    }

    public event EventHandler? LinesLoaded;

    public bool LoadFile (string file)
    {
        FilePath = file ?? throw new ArgumentNullException (nameof (file));

        using (FileStream stream = File.OpenRead (file))
        {
            LoadStream (stream);

            return true;
        }
    }

    public void LoadListRuneCells (List<List<RuneCell>> cellsList, ColorScheme? colorScheme)
    {
        _lines = cellsList;
        SetColorSchemes (colorScheme);
        OnLinesLoaded ();
    }

    public void LoadRuneCells (List<RuneCell> cells, ColorScheme? colorScheme)
    {
        _lines = ToRuneCells (cells);
        SetColorSchemes (colorScheme);
        OnLinesLoaded ();
    }

    public void LoadStream (Stream input)
    {
        if (input is null)
        {
            throw new ArgumentNullException (nameof (input));
        }

        _lines = new List<List<RuneCell>> ();
        var buff = new BufferedStream (input);
        int v;
        List<byte> line = new ();
        var wasNewLine = false;

        while ((v = buff.ReadByte ()) != -1)
        {
            if (v == 13)
            {
                continue;
            }

            if (v == 10)
            {
                Append (line);
                line.Clear ();
                wasNewLine = true;

                continue;
            }

            line.Add ((byte)v);
            wasNewLine = false;
        }

        if (line.Count > 0 || wasNewLine)
        {
            Append (line);
        }

        buff.Dispose ();

        OnLinesLoaded ();
    }

    public void LoadString (string content)
    {
        _lines = StringToLinesOfRuneCells (content);

        OnLinesLoaded ();
    }

    /// <summary>Removes the line at the specified position</summary>
    /// <param name="pos">Position.</param>
    public void RemoveLine (int pos)
    {
        if (_lines.Count > 0)
        {
            if (_lines.Count == 1 && _lines [0].Count == 0)
            {
                return;
            }

            _lines.RemoveAt (pos);
        }
    }

    public void ReplaceLine (int pos, List<RuneCell> runes)
    {
        if (_lines.Count > 0 && pos < _lines.Count)
        {
            _lines [pos] = new List<RuneCell> (runes);
        }
        else if (_lines.Count == 0 || (_lines.Count > 0 && pos >= _lines.Count))
        {
            _lines.Add (runes);
        }
    }

    // Splits a string into a List that contains a List<RuneCell> for each line
    public static List<List<RuneCell>> StringToLinesOfRuneCells (string content, ColorScheme? colorScheme = null)
    {
        List<RuneCell> cells = content.EnumerateRunes ()
                                      .Select (x => new RuneCell { Rune = x, ColorScheme = colorScheme })
                                      .ToList ();

        return SplitNewLines (cells);
    }

    /// <summary>Converts the string into a <see cref="List{RuneCell}"/>.</summary>
    /// <param name="str">The string to convert.</param>
    /// <param name="colorScheme">The <see cref="ColorScheme"/> to use.</param>
    /// <returns></returns>
    public static List<RuneCell> ToRuneCellList (string str, ColorScheme? colorScheme = null)
    {
        List<RuneCell> cells = new ();

        foreach (Rune rune in str.EnumerateRunes ())
        {
            cells.Add (new RuneCell { Rune = rune, ColorScheme = colorScheme });
        }

        return cells;
    }

    public override string ToString ()
    {
        var sb = new StringBuilder ();

        for (var i = 0; i < _lines.Count; i++)
        {
            sb.Append (ToString (_lines [i]));

            if (i + 1 < _lines.Count)
            {
                sb.AppendLine ();
            }
        }

        return sb.ToString ();
    }

    /// <summary>Converts a <see cref="RuneCell"/> generic collection into a string.</summary>
    /// <param name="cells">The enumerable cell to convert.</param>
    /// <returns></returns>
    public static string ToString (IEnumerable<RuneCell> cells)
    {
        var str = string.Empty;

        foreach (RuneCell cell in cells)
        {
            str += cell.Rune.ToString ();
        }

        return str;
    }

    public (int col, int row)? WordBackward (int fromCol, int fromRow)
    {
        if (fromRow == 0 && fromCol == 0)
        {
            return null;
        }

        int col = Math.Max (fromCol - 1, 0);
        int row = fromRow;

        try
        {
            RuneCell? cell = RuneAt (col, row);
            Rune rune;

            if (cell is { })
            {
                rune = cell.Rune;
            }
            else
            {
                if (col > 0)
                {
                    return (col, row);
                }

                if (col == 0 && row > 0)
                {
                    row--;
                    List<RuneCell> line = GetLine (row);

                    return (line.Count, row);
                }

                return null;
            }

            RuneType runeType = GetRuneType (rune);

            int lastValidCol = IsSameRuneType (rune, runeType) && (Rune.IsLetterOrDigit (rune) || Rune.IsPunctuation (rune) || Rune.IsSymbol (rune))
                                   ? col
                                   : -1;

            void ProcMovePrev (ref int nCol, ref int nRow, Rune nRune)
            {
                if (Rune.IsWhiteSpace (nRune))
                {
                    while (MovePrev (ref nCol, ref nRow, out nRune))
                    {
                        if (Rune.IsLetterOrDigit (nRune) || Rune.IsPunctuation (nRune) || Rune.IsSymbol (nRune))
                        {
                            lastValidCol = nCol;

                            if (runeType == RuneType.IsWhiteSpace || runeType == RuneType.IsUnknow)
                            {
                                runeType = GetRuneType (nRune);
                            }

                            break;
                        }
                    }

                    if (nRow != fromRow && (Rune.IsLetterOrDigit (nRune) || Rune.IsPunctuation (nRune) || Rune.IsSymbol (nRune)))
                    {
                        if (lastValidCol > -1)
                        {
                            nCol = lastValidCol;
                        }

                        return;
                    }

                    while (MovePrev (ref nCol, ref nRow, out nRune))
                    {
                        if (!Rune.IsLetterOrDigit (nRune) && !Rune.IsPunctuation (nRune) && !Rune.IsSymbol (nRune))
                        {
                            break;
                        }

                        if (nRow != fromRow)
                        {
                            break;
                        }

                        lastValidCol =
                            (IsSameRuneType (nRune, runeType) && Rune.IsLetterOrDigit (nRune)) || Rune.IsPunctuation (nRune) || Rune.IsSymbol (nRune)
                                ? nCol
                                : lastValidCol;
                    }

                    if (lastValidCol > -1)
                    {
                        nCol = lastValidCol;
                        nRow = fromRow;
                    }
                }
                else
                {
                    if (!MovePrev (ref nCol, ref nRow, out nRune))
                    {
                        return;
                    }

                    List<RuneCell> line = GetLine (nRow);

                    if (nCol == 0
                        && nRow == fromRow
                        && (Rune.IsLetterOrDigit (line [0].Rune) || Rune.IsPunctuation (line [0].Rune) || Rune.IsSymbol (line [0].Rune)))
                    {
                        return;
                    }

                    lastValidCol =
                        (IsSameRuneType (nRune, runeType) && Rune.IsLetterOrDigit (nRune)) || Rune.IsPunctuation (nRune) || Rune.IsSymbol (nRune)
                            ? nCol
                            : lastValidCol;

                    if (lastValidCol > -1 && Rune.IsWhiteSpace (nRune))
                    {
                        nCol = lastValidCol;

                        return;
                    }

                    if (fromRow != nRow)
                    {
                        nCol = line.Count;

                        return;
                    }

                    ProcMovePrev (ref nCol, ref nRow, nRune);
                }
            }

            ProcMovePrev (ref col, ref row, rune);

            if (fromCol != col || fromRow != row)
            {
                return (col, row);
            }

            return null;
        }
        catch (Exception)
        {
            return null;
        }
    }

    public (int col, int row)? WordForward (int fromCol, int fromRow)
    {
        if (fromRow == _lines.Count - 1 && fromCol == GetLine (_lines.Count - 1).Count)
        {
            return null;
        }

        int col = fromCol;
        int row = fromRow;

        try
        {
            Rune rune = RuneAt (col, row).Rune;
            RuneType runeType = GetRuneType (rune);

            int lastValidCol = IsSameRuneType (rune, runeType) && (Rune.IsLetterOrDigit (rune) || Rune.IsPunctuation (rune) || Rune.IsSymbol (rune))
                                   ? col
                                   : -1;

            void ProcMoveNext (ref int nCol, ref int nRow, Rune nRune)
            {
                if (Rune.IsWhiteSpace (nRune))
                {
                    while (MoveNext (ref nCol, ref nRow, out nRune))
                    {
                        if (Rune.IsLetterOrDigit (nRune) || Rune.IsPunctuation (nRune) || Rune.IsSymbol (nRune))
                        {
                            lastValidCol = nCol;

                            return;
                        }
                    }

                    if (nRow != fromRow && (Rune.IsLetterOrDigit (nRune) || Rune.IsPunctuation (nRune) || Rune.IsSymbol (nRune)))
                    {
                        if (lastValidCol > -1)
                        {
                            nCol = lastValidCol;
                        }

                        return;
                    }

                    while (MoveNext (ref nCol, ref nRow, out nRune))
                    {
                        if (!Rune.IsLetterOrDigit (nRune) && !Rune.IsPunctuation (nRune) && !Rune.IsSymbol (nRune))
                        {
                            break;
                        }

                        if (nRow != fromRow)
                        {
                            break;
                        }

                        lastValidCol =
                            (IsSameRuneType (nRune, runeType) && Rune.IsLetterOrDigit (nRune)) || Rune.IsPunctuation (nRune) || Rune.IsSymbol (nRune)
                                ? nCol
                                : lastValidCol;
                    }

                    if (lastValidCol > -1)
                    {
                        nCol = lastValidCol;
                        nRow = fromRow;
                    }
                }
                else
                {
                    if (!MoveNext (ref nCol, ref nRow, out nRune))
                    {
                        return;
                    }

                    if (!IsSameRuneType (nRune, runeType) && !Rune.IsWhiteSpace (nRune))
                    {
                        return;
                    }

                    List<RuneCell> line = GetLine (nRow);

                    if (nCol == line.Count
                        && nRow == fromRow
                        && (Rune.IsLetterOrDigit (line [0].Rune) || Rune.IsPunctuation (line [0].Rune) || Rune.IsSymbol (line [0].Rune)))
                    {
                        return;
                    }

                    lastValidCol =
                        (IsSameRuneType (nRune, runeType) && Rune.IsLetterOrDigit (nRune)) || Rune.IsPunctuation (nRune) || Rune.IsSymbol (nRune)
                            ? nCol
                            : lastValidCol;

                    if (fromRow != nRow)
                    {
                        nCol = 0;

                        return;
                    }

                    ProcMoveNext (ref nCol, ref nRow, nRune);
                }
            }

            ProcMoveNext (ref col, ref row, rune);

            if (fromCol != col || fromRow != row)
            {
                return (col, row);
            }

            return null;
        }
        catch (Exception)
        {
            return null;
        }
    }

    internal static int CalculateLeftColumn (List<RuneCell> t, int start, int end, int width, int tabWidth = 0)
    {
        List<Rune> runes = new ();

        foreach (RuneCell cell in t)
        {
            runes.Add (cell.Rune);
        }

        return CalculateLeftColumn (runes, start, end, width, tabWidth);
    }

    // Returns the left column in a range of the string.
    internal static int CalculateLeftColumn (List<Rune> t, int start, int end, int width, int tabWidth = 0)
    {
        if (t is null || t.Count == 0)
        {
            return 0;
        }

        var size = 0;
        int tcount = end > t.Count - 1 ? t.Count - 1 : end;
        var col = 0;

        for (int i = tcount; i >= 0; i--)
        {
            Rune rune = t [i];
            size += rune.GetColumns ();

            if (rune.Value == '\t')
            {
                size += tabWidth + 1;
            }

            if (size > width)
            {
                if (col + width == end)
                {
                    col++;
                }

                break;
            }

            if ((end < t.Count && col > 0 && start < end && col == start) || end - col == width - 1)
            {
                break;
            }

            col = i;
        }

        return col;
    }

    internal static (int size, int length) DisplaySize (
        List<RuneCell> t,
        int start = -1,
        int end = -1,
        bool checkNextRune = true,
        int tabWidth = 0
    )
    {
        List<Rune> runes = new ();

        foreach (RuneCell cell in t)
        {
            runes.Add (cell.Rune);
        }

        return DisplaySize (runes, start, end, checkNextRune, tabWidth);
    }

    // Returns the size and length in a range of the string.
    internal static (int size, int length) DisplaySize (
        List<Rune> t,
        int start = -1,
        int end = -1,
        bool checkNextRune = true,
        int tabWidth = 0
    )
    {
        if (t is null || t.Count == 0)
        {
            return (0, 0);
        }

        var size = 0;
        var len = 0;

        int tcount = end == -1 ? t.Count :
                     end > t.Count ? t.Count : end;
        int i = start == -1 ? 0 : start;

        for (; i < tcount; i++)
        {
            Rune rune = t [i];
            size += rune.GetColumns ();
            len += rune.GetEncodingLength (Encoding.Unicode);

            if (rune.Value == '\t')
            {
                size += tabWidth + 1;
                len += tabWidth - 1;
            }

            if (checkNextRune && i == tcount - 1 && t.Count > tcount && IsWideRune (t [i + 1], tabWidth, out int s, out int l))
            {
                size += s;
                len += l;
            }
        }

        bool IsWideRune (Rune r, int tWidth, out int s, out int l)
        {
            s = r.GetColumns ();
            l = r.GetEncodingLength ();

            if (r.Value == '\t')
            {
                s += tWidth + 1;
                l += tWidth - 1;
            }

            return s > 1;
        }

        return (size, len);
    }

    internal (Point current, bool found) FindNextText (
        string text,
        out bool gaveFullTurn,
        bool matchCase = false,
        bool matchWholeWord = false
    )
    {
        if (text is null || _lines.Count == 0)
        {
            gaveFullTurn = false;

            return (Point.Empty, false);
        }

        if (_toFind.found)
        {
            _toFind.currentPointToFind.X++;
        }

        (Point current, bool found) foundPos = GetFoundNextTextPoint (
                                                                      text,
                                                                      _lines.Count,
                                                                      matchCase,
                                                                      matchWholeWord,
                                                                      _toFind.currentPointToFind
                                                                     );

        if (!foundPos.found && _toFind.currentPointToFind != _toFind.startPointToFind)
        {
            foundPos = GetFoundNextTextPoint (
                                              text,
                                              _toFind.startPointToFind.Y + 1,
                                              matchCase,
                                              matchWholeWord,
                                              Point.Empty
                                             );
        }

        gaveFullTurn = ApplyToFind (foundPos);

        return foundPos;
    }

    internal (Point current, bool found) FindPreviousText (
        string text,
        out bool gaveFullTurn,
        bool matchCase = false,
        bool matchWholeWord = false
    )
    {
        if (text is null || _lines.Count == 0)
        {
            gaveFullTurn = false;

            return (Point.Empty, false);
        }

        if (_toFind.found)
        {
            _toFind.currentPointToFind.X++;
        }

        int linesCount = _toFind.currentPointToFind.IsEmpty ? _lines.Count - 1 : _toFind.currentPointToFind.Y;

        (Point current, bool found) foundPos = GetFoundPreviousTextPoint (
                                                                          text,
                                                                          linesCount,
                                                                          matchCase,
                                                                          matchWholeWord,
                                                                          _toFind.currentPointToFind
                                                                         );

        if (!foundPos.found && _toFind.currentPointToFind != _toFind.startPointToFind)
        {
            foundPos = GetFoundPreviousTextPoint (
                                                  text,
                                                  _lines.Count - 1,
                                                  matchCase,
                                                  matchWholeWord,
                                                  new Point (_lines [_lines.Count - 1].Count, _lines.Count)
                                                 );
        }

        gaveFullTurn = ApplyToFind (foundPos);

        return foundPos;
    }

    internal static int GetColFromX (List<RuneCell> t, int start, int x, int tabWidth = 0)
    {
        List<Rune> runes = new ();

        foreach (RuneCell cell in t)
        {
            runes.Add (cell.Rune);
        }

        return GetColFromX (runes, start, x, tabWidth);
    }

    internal static int GetColFromX (List<Rune> t, int start, int x, int tabWidth = 0)
    {
        if (x < 0)
        {
            return x;
        }

        int size = start;
        int pX = x + start;

        for (int i = start; i < t.Count; i++)
        {
            Rune r = t [i];
            size += r.GetColumns ();

            if (r.Value == '\t')
            {
                size += tabWidth + 1;
            }

            if (i == pX || size > pX)
            {
                return i - start;
            }
        }

        return t.Count - start;
    }

    internal (Point current, bool found) ReplaceAllText (
        string text,
        bool matchCase = false,
        bool matchWholeWord = false,
        string? textToReplace = null
    )
    {
        var found = false;
        var pos = Point.Empty;

        for (var i = 0; i < _lines.Count; i++)
        {
            List<RuneCell> x = _lines [i];
            string txt = GetText (x);
            string matchText = !matchCase ? text.ToUpper () : text;
            int col = txt.IndexOf (matchText);

            while (col > -1)
            {
                if (matchWholeWord && !MatchWholeWord (txt, matchText, col))
                {
                    if (col + 1 > txt.Length)
                    {
                        break;
                    }

                    col = txt.IndexOf (matchText, col + 1);

                    continue;
                }

                if (col > -1)
                {
                    if (!found)
                    {
                        found = true;
                    }

                    _lines [i] = ToRuneCellList (ReplaceText (x, textToReplace!, matchText, col));
                    x = _lines [i];
                    txt = GetText (x);
                    pos = new Point (col, i);
                    col += textToReplace!.Length - matchText.Length;
                }

                if (col < 0 || col + 1 > txt.Length)
                {
                    break;
                }

                col = txt.IndexOf (matchText, col + 1);
            }
        }

        string GetText (List<RuneCell> x)
        {
            string txt = ToString (x);

            if (!matchCase)
            {
                txt = txt.ToUpper ();
            }

            return txt;
        }

        return (pos, found);
    }

    /// <summary>Redefine column and line tracking.</summary>
    /// <param name="point">Contains the column and line.</param>
    internal void ResetContinuousFind (Point point)
    {
        _toFind.startPointToFind = _toFind.currentPointToFind = point;
        _toFind.found = false;
    }

    internal static bool SetCol (ref int col, int width, int cols)
    {
        if (col + cols <= width)
        {
            col += cols;

            return true;
        }

        return false;
    }

    // Turns the string into cells, this does not split the 
    // contents on a newline if it is present.
    internal static List<RuneCell> StringToRuneCells (string str, ColorScheme? colorScheme = null)
    {
        List<RuneCell> cells = new ();

        foreach (Rune rune in str.ToRunes ())
        {
            cells.Add (new RuneCell { Rune = rune, ColorScheme = colorScheme });
        }

        return cells;
    }

    internal static List<RuneCell> ToRuneCells (IEnumerable<Rune> runes, ColorScheme? colorScheme = null)
    {
        List<RuneCell> cells = new ();

        foreach (Rune rune in runes)
        {
            cells.Add (new RuneCell { Rune = rune, ColorScheme = colorScheme });
        }

        return cells;
    }

    private void Append (List<byte> line)
    {
        var str = StringExtensions.ToString (line.ToArray ());
        _lines.Add (StringToRuneCells (str));
    }

    private bool ApplyToFind ((Point current, bool found) foundPos)
    {
        var gaveFullTurn = false;

        if (foundPos.found)
        {
            _toFind.currentPointToFind = foundPos.current;

            if (_toFind.found && _toFind.currentPointToFind == _toFind.startPointToFind)
            {
                gaveFullTurn = true;
            }

            if (!_toFind.found)
            {
                _toFind.startPointToFind = _toFind.currentPointToFind = foundPos.current;
                _toFind.found = foundPos.found;
            }
        }

        return gaveFullTurn;
    }

    private (Point current, bool found) GetFoundNextTextPoint (
        string text,
        int linesCount,
        bool matchCase,
        bool matchWholeWord,
        Point start
    )
    {
        for (int i = start.Y; i < linesCount; i++)
        {
            List<RuneCell> x = _lines [i];
            string txt = ToString (x);

            if (!matchCase)
            {
                txt = txt.ToUpper ();
            }

            string matchText = !matchCase ? text.ToUpper () : text;
            int col = txt.IndexOf (matchText, Math.Min (start.X, txt.Length));

            if (col > -1 && matchWholeWord && !MatchWholeWord (txt, matchText, col))
            {
                continue;
            }

            if (col > -1 && ((i == start.Y && col >= start.X) || i > start.Y) && txt.Contains (matchText))
            {
                return (new Point (col, i), true);
            }

            if (col == -1 && start.X > 0)
            {
                start.X = 0;
            }
        }

        return (Point.Empty, false);
    }

    private (Point current, bool found) GetFoundPreviousTextPoint (
        string text,
        int linesCount,
        bool matchCase,
        bool matchWholeWord,
        Point start
    )
    {
        for (int i = linesCount; i >= 0; i--)
        {
            List<RuneCell> x = _lines [i];
            string txt = ToString (x);

            if (!matchCase)
            {
                txt = txt.ToUpper ();
            }

            if (start.Y != i)
            {
                start.X = Math.Max (x.Count - 1, 0);
            }

            string matchText = !matchCase ? text.ToUpper () : text;
            int col = txt.LastIndexOf (matchText, _toFind.found ? start.X - 1 : start.X);

            if (col > -1 && matchWholeWord && !MatchWholeWord (txt, matchText, col))
            {
                continue;
            }

            if (col > -1 && ((i <= linesCount && col <= start.X) || i < start.Y) && txt.Contains (matchText))
            {
                return (new Point (col, i), true);
            }
        }

        return (Point.Empty, false);
    }

    private RuneType GetRuneType (Rune rune)
    {
        if (Rune.IsSymbol (rune))
        {
            return RuneType.IsSymbol;
        }

        if (Rune.IsWhiteSpace (rune))
        {
            return RuneType.IsWhiteSpace;
        }

        if (Rune.IsLetterOrDigit (rune))
        {
            return RuneType.IsLetterOrDigit;
        }

        if (Rune.IsPunctuation (rune))
        {
            return RuneType.IsPunctuation;
        }

        return RuneType.IsUnknow;
    }

    private bool IsSameRuneType (Rune newRune, RuneType runeType)
    {
        RuneType rt = GetRuneType (newRune);

        return rt == runeType;
    }

    private bool MatchWholeWord (string source, string matchText, int index = 0)
    {
        if (string.IsNullOrEmpty (source) || string.IsNullOrEmpty (matchText))
        {
            return false;
        }

        string txt = matchText.Trim ();
        int start = index > 0 ? index - 1 : 0;
        int end = index + txt.Length;

        if ((start == 0 || Rune.IsWhiteSpace ((Rune)source [start])) && (end == source.Length || Rune.IsWhiteSpace ((Rune)source [end])))
        {
            return true;
        }

        return false;
    }

    private bool MoveNext (ref int col, ref int row, out Rune rune)
    {
        List<RuneCell> line = GetLine (row);

        if (col + 1 < line.Count)
        {
            col++;
            rune = line [col].Rune;

            if (col + 1 == line.Count && !Rune.IsLetterOrDigit (rune) && !Rune.IsWhiteSpace (line [col - 1].Rune))
            {
                col++;
            }

            return true;
        }

        if (col + 1 == line.Count)
        {
            col++;
        }

        while (row + 1 < Count)
        {
            col = 0;
            row++;
            line = GetLine (row);

            if (line.Count > 0)
            {
                rune = line [0].Rune;

                return true;
            }
        }

        rune = default (Rune);

        return false;
    }

    private bool MovePrev (ref int col, ref int row, out Rune rune)
    {
        List<RuneCell> line = GetLine (row);

        if (col > 0)
        {
            col--;
            rune = line [col].Rune;

            return true;
        }

        if (row == 0)
        {
            rune = default (Rune);

            return false;
        }

        while (row > 0)
        {
            row--;
            line = GetLine (row);
            col = line.Count - 1;

            if (col >= 0)
            {
                rune = line [col].Rune;

                return true;
            }
        }

        rune = default (Rune);

        return false;
    }

    private void OnLinesLoaded () { LinesLoaded?.Invoke (this, EventArgs.Empty); }

    private string ReplaceText (List<RuneCell> source, string textToReplace, string matchText, int col)
    {
        string origTxt = ToString (source);
        (_, int len) = DisplaySize (source, 0, col, false);
        (_, int len2) = DisplaySize (source, col, col + matchText.Length, false);
        (_, int len3) = DisplaySize (source, col + matchText.Length, origTxt.GetRuneCount (), false);

        return origTxt [..len] + textToReplace + origTxt.Substring (len + len2, len3);
    }

    private RuneCell RuneAt (int col, int row)
    {
        List<RuneCell> line = GetLine (row);

        if (line.Count > 0)
        {
            return line [col > line.Count - 1 ? line.Count - 1 : col];
        }

        return default (RuneCell)!;
    }

    private void SetColorSchemes (ColorScheme? colorScheme)
    {
        foreach (List<RuneCell> line in _lines)
        {
            foreach (RuneCell cell in line)
            {
                cell.ColorScheme ??= colorScheme;
            }
        }
    }

    private static List<List<RuneCell>> SplitNewLines (List<RuneCell> cells)
    {
        List<List<RuneCell>> lines = new ();
        int start = 0, i = 0;
        var hasCR = false;

        // ASCII code 13 = Carriage Return.
        // ASCII code 10 = Line Feed.
        for (; i < cells.Count; i++)
        {
            if (cells [i].Rune.Value == 13)
            {
                hasCR = true;

                continue;
            }

            if (cells [i].Rune.Value == 10)
            {
                if (i - start > 0)
                {
                    lines.Add (cells.GetRange (start, hasCR ? i - 1 - start : i - start));
                }
                else
                {
                    lines.Add (StringToRuneCells (string.Empty));
                }

                start = i + 1;
                hasCR = false;
            }
        }

        if (i - start >= 0)
        {
            lines.Add (cells.GetRange (start, i - start));
        }

        return lines;
    }

    private static List<List<RuneCell>> ToRuneCells (List<RuneCell> cells) { return SplitNewLines (cells); }

    private enum RuneType
    {
        IsSymbol,
        IsWhiteSpace,
        IsLetterOrDigit,
        IsPunctuation,
        IsUnknow
    }
}

internal partial class HistoryText
{
    public enum LineStatus
    {
        Original,
        Replaced,
        Removed,
        Added
    }

    private readonly List<HistoryTextItem> _historyTextItems = new ();
    private int _idxHistoryText = -1;
    private string? _originalText;
    public bool HasHistoryChanges => _idxHistoryText > -1;
    public bool IsFromHistory { get; private set; }

    public void Add (List<List<RuneCell>> lines, Point curPos, LineStatus lineStatus = LineStatus.Original)
    {
        if (lineStatus == LineStatus.Original && _historyTextItems.Count > 0 && _historyTextItems.Last ().LineStatus == LineStatus.Original)
        {
            return;
        }

        if (lineStatus == LineStatus.Replaced && _historyTextItems.Count > 0 && _historyTextItems.Last ().LineStatus == LineStatus.Replaced)
        {
            return;
        }

        if (_historyTextItems.Count == 0 && lineStatus != LineStatus.Original)
        {
            throw new ArgumentException ("The first item must be the original.");
        }

        if (_idxHistoryText >= 0 && _idxHistoryText + 1 < _historyTextItems.Count)
        {
            _historyTextItems.RemoveRange (
                                           _idxHistoryText + 1,
                                           _historyTextItems.Count - _idxHistoryText - 1
                                          );
        }

        _historyTextItems.Add (new HistoryTextItem (lines, curPos, lineStatus));
        _idxHistoryText++;
    }

    public event EventHandler<HistoryTextItem>? ChangeText;

    public void Clear (string text)
    {
        _historyTextItems.Clear ();
        _idxHistoryText = -1;
        _originalText = text;
        OnChangeText (null);
    }

    public bool IsDirty (string text) { return _originalText != text; }

    public void Redo ()
    {
        if (_historyTextItems?.Count > 0 && _idxHistoryText < _historyTextItems.Count - 1)
        {
            IsFromHistory = true;

            _idxHistoryText++;

            var historyTextItem = new HistoryTextItem (_historyTextItems [_idxHistoryText]) { IsUndoing = false };

            ProcessChanges (ref historyTextItem);

            IsFromHistory = false;
        }
    }

    public void ReplaceLast (List<List<RuneCell>> lines, Point curPos, LineStatus lineStatus)
    {
        HistoryTextItem? found = _historyTextItems.FindLast (x => x.LineStatus == lineStatus);

        if (found is { })
        {
            found.Lines = lines;
            found.CursorPosition = curPos;
        }
    }

    public void Undo ()
    {
        if (_historyTextItems?.Count > 0 && _idxHistoryText > 0)
        {
            IsFromHistory = true;

            _idxHistoryText--;

            var historyTextItem = new HistoryTextItem (_historyTextItems [_idxHistoryText]) { IsUndoing = true };

            ProcessChanges (ref historyTextItem);

            IsFromHistory = false;
        }
    }

    private void OnChangeText (HistoryTextItem? lines) { ChangeText?.Invoke (this, lines!); }

    private void ProcessChanges (ref HistoryTextItem historyTextItem)
    {
        if (historyTextItem.IsUndoing)
        {
            if (_idxHistoryText - 1 > -1
                && (_historyTextItems [_idxHistoryText - 1].LineStatus == LineStatus.Added
                    || _historyTextItems [_idxHistoryText - 1].LineStatus == LineStatus.Removed
                    || (historyTextItem.LineStatus == LineStatus.Replaced && _historyTextItems [_idxHistoryText - 1].LineStatus == LineStatus.Original)))
            {
                _idxHistoryText--;

                while (_historyTextItems [_idxHistoryText].LineStatus == LineStatus.Added
                       && _historyTextItems [_idxHistoryText - 1].LineStatus == LineStatus.Removed)
                {
                    _idxHistoryText--;
                }

                historyTextItem = new HistoryTextItem (_historyTextItems [_idxHistoryText]);
                historyTextItem.IsUndoing = true;
                historyTextItem.FinalCursorPosition = historyTextItem.CursorPosition;
            }

            if (historyTextItem.LineStatus == LineStatus.Removed && _historyTextItems [_idxHistoryText + 1].LineStatus == LineStatus.Added)
            {
                historyTextItem.RemovedOnAdded =
                    new HistoryTextItem (_historyTextItems [_idxHistoryText + 1]);
            }

            if ((historyTextItem.LineStatus == LineStatus.Added && _historyTextItems [_idxHistoryText - 1].LineStatus == LineStatus.Original)
                || (historyTextItem.LineStatus == LineStatus.Removed && _historyTextItems [_idxHistoryText - 1].LineStatus == LineStatus.Original)
                || (historyTextItem.LineStatus == LineStatus.Added && _historyTextItems [_idxHistoryText - 1].LineStatus == LineStatus.Removed))
            {
                if (!historyTextItem.Lines [0]
                                    .SequenceEqual (_historyTextItems [_idxHistoryText - 1].Lines [0])
                    && historyTextItem.CursorPosition == _historyTextItems [_idxHistoryText - 1].CursorPosition)
                {
                    historyTextItem.Lines [0] =
                        new List<RuneCell> (_historyTextItems [_idxHistoryText - 1].Lines [0]);
                }

                if (historyTextItem.LineStatus == LineStatus.Added && _historyTextItems [_idxHistoryText - 1].LineStatus == LineStatus.Removed)
                {
                    historyTextItem.FinalCursorPosition =
                        _historyTextItems [_idxHistoryText - 2].CursorPosition;
                }
                else
                {
                    historyTextItem.FinalCursorPosition =
                        _historyTextItems [_idxHistoryText - 1].CursorPosition;
                }
            }
            else
            {
                historyTextItem.FinalCursorPosition = historyTextItem.CursorPosition;
            }

            OnChangeText (historyTextItem);

            while (_historyTextItems [_idxHistoryText].LineStatus == LineStatus.Removed
                   || _historyTextItems [_idxHistoryText].LineStatus == LineStatus.Added)
            {
                _idxHistoryText--;
            }
        }
        else if (!historyTextItem.IsUndoing)
        {
            if (_idxHistoryText + 1 < _historyTextItems.Count
                && (historyTextItem.LineStatus == LineStatus.Original
                    || _historyTextItems [_idxHistoryText + 1].LineStatus == LineStatus.Added
                    || _historyTextItems [_idxHistoryText + 1].LineStatus == LineStatus.Removed))
            {
                _idxHistoryText++;
                historyTextItem = new HistoryTextItem (_historyTextItems [_idxHistoryText]);
                historyTextItem.IsUndoing = false;
                historyTextItem.FinalCursorPosition = historyTextItem.CursorPosition;
            }

            if (historyTextItem.LineStatus == LineStatus.Added && _historyTextItems [_idxHistoryText - 1].LineStatus == LineStatus.Removed)
            {
                historyTextItem.RemovedOnAdded =
                    new HistoryTextItem (_historyTextItems [_idxHistoryText - 1]);
            }

            if ((historyTextItem.LineStatus == LineStatus.Removed && _historyTextItems [_idxHistoryText + 1].LineStatus == LineStatus.Replaced)
                || (historyTextItem.LineStatus == LineStatus.Removed && _historyTextItems [_idxHistoryText + 1].LineStatus == LineStatus.Original)
                || (historyTextItem.LineStatus == LineStatus.Added && _historyTextItems [_idxHistoryText + 1].LineStatus == LineStatus.Replaced))
            {
                if (historyTextItem.LineStatus == LineStatus.Removed
                    && !historyTextItem.Lines [0]
                                       .SequenceEqual (_historyTextItems [_idxHistoryText + 1].Lines [0]))
                {
                    historyTextItem.Lines [0] =
                        new List<RuneCell> (_historyTextItems [_idxHistoryText + 1].Lines [0]);
                }

                historyTextItem.FinalCursorPosition =
                    _historyTextItems [_idxHistoryText + 1].CursorPosition;
            }
            else
            {
                historyTextItem.FinalCursorPosition = historyTextItem.CursorPosition;
            }

            OnChangeText (historyTextItem);

            while (_historyTextItems [_idxHistoryText].LineStatus == LineStatus.Removed
                   || _historyTextItems [_idxHistoryText].LineStatus == LineStatus.Added)
            {
                _idxHistoryText++;
            }
        }
    }
}

internal class WordWrapManager
{
    private int _frameWidth;
    private bool _isWrapModelRefreshing;
    private List<WrappedLine> _wrappedModelLines = new ();
    public WordWrapManager (TextModel model) { Model = model; }
    public TextModel Model { get; private set; }

    public void AddLine (int row, int col)
    {
        int modelRow = GetModelLineFromWrappedLines (row);
        int modelCol = GetModelColFromWrappedLines (row, col);
        List<RuneCell> line = GetCurrentLine (modelRow);
        int restCount = line.Count - modelCol;
        List<RuneCell> rest = line.GetRange (modelCol, restCount);
        line.RemoveRange (modelCol, restCount);
        Model.AddLine (modelRow + 1, rest);
        _isWrapModelRefreshing = true;
        WrapModel (_frameWidth, out _, out _, out _, out _, modelRow + 1);
        _isWrapModelRefreshing = false;
    }

    public int GetModelColFromWrappedLines (int line, int col)
    {
        if (_wrappedModelLines?.Count == 0)
        {
            return 0;
        }

        int modelLine = GetModelLineFromWrappedLines (line);
        int firstLine = _wrappedModelLines.IndexOf (r => r.ModelLine == modelLine);
        var modelCol = 0;

        for (int i = firstLine; i <= Math.Min (line, _wrappedModelLines!.Count - 1); i++)
        {
            WrappedLine wLine = _wrappedModelLines [i];

            if (i < line)
            {
                modelCol += wLine.ColWidth;
            }
            else
            {
                modelCol += col;
            }
        }

        return modelCol;
    }

    public int GetModelLineFromWrappedLines (int line)
    {
        return _wrappedModelLines.Count > 0
                   ? _wrappedModelLines [Math.Min (
                                                   line,
                                                   _wrappedModelLines.Count - 1
                                                  )].ModelLine
                   : 0;
    }

    public int GetWrappedLineColWidth (int line, int col, WordWrapManager wrapManager)
    {
        if (_wrappedModelLines?.Count == 0)
        {
            return 0;
        }

        List<WrappedLine> wModelLines = wrapManager._wrappedModelLines;
        int modelLine = GetModelLineFromWrappedLines (line);
        int firstLine = _wrappedModelLines.IndexOf (r => r.ModelLine == modelLine);
        var modelCol = 0;
        var colWidthOffset = 0;
        int i = firstLine;

        while (modelCol < col)
        {
            WrappedLine wLine = _wrappedModelLines! [i];
            WrappedLine wLineToCompare = wModelLines [i];

            if (wLine.ModelLine != modelLine || wLineToCompare.ModelLine != modelLine)
            {
                break;
            }

            modelCol += Math.Max (wLine.ColWidth, wLineToCompare.ColWidth);
            colWidthOffset += wLine.ColWidth - wLineToCompare.ColWidth;

            if (modelCol > col)
            {
                modelCol += col - modelCol;
            }

            i++;
        }

        return modelCol - colWidthOffset;
    }

    public bool Insert (int row, int col, RuneCell cell)
    {
        List<RuneCell> line = GetCurrentLine (GetModelLineFromWrappedLines (row));
        line.Insert (GetModelColFromWrappedLines (row, col), cell);

        if (line.Count > _frameWidth)
        {
            return true;
        }

        return false;
    }

    public bool RemoveAt (int row, int col)
    {
        int modelRow = GetModelLineFromWrappedLines (row);
        List<RuneCell> line = GetCurrentLine (modelRow);
        int modelCol = GetModelColFromWrappedLines (row, col);

        if (modelCol > line.Count)
        {
            Model.RemoveLine (modelRow);
            RemoveAt (row, 0);

            return false;
        }

        if (modelCol < line.Count)
        {
            line.RemoveAt (modelCol);
        }

        if (line.Count > _frameWidth || (row + 1 < _wrappedModelLines.Count && _wrappedModelLines [row + 1].ModelLine == modelRow))
        {
            return true;
        }

        return false;
    }

    public bool RemoveLine (int row, int col, out bool lineRemoved, bool forward = true)
    {
        lineRemoved = false;
        int modelRow = GetModelLineFromWrappedLines (row);
        List<RuneCell> line = GetCurrentLine (modelRow);
        int modelCol = GetModelColFromWrappedLines (row, col);

        if (modelCol == 0 && line.Count == 0)
        {
            Model.RemoveLine (modelRow);

            return false;
        }

        if (modelCol < line.Count)
        {
            if (forward)
            {
                line.RemoveAt (modelCol);

                return true;
            }

            if (modelCol - 1 > -1)
            {
                line.RemoveAt (modelCol - 1);

                return true;
            }
        }

        lineRemoved = true;

        if (forward)
        {
            if (modelRow + 1 == Model.Count)
            {
                return false;
            }

            List<RuneCell> nextLine = Model.GetLine (modelRow + 1);
            line.AddRange (nextLine);
            Model.RemoveLine (modelRow + 1);

            if (line.Count > _frameWidth)
            {
                return true;
            }
        }
        else
        {
            if (modelRow == 0)
            {
                return false;
            }

            List<RuneCell> prevLine = Model.GetLine (modelRow - 1);
            prevLine.AddRange (line);
            Model.RemoveLine (modelRow);

            if (prevLine.Count > _frameWidth)
            {
                return true;
            }
        }

        return false;
    }

    public bool RemoveRange (int row, int index, int count)
    {
        int modelRow = GetModelLineFromWrappedLines (row);
        List<RuneCell> line = GetCurrentLine (modelRow);
        int modelCol = GetModelColFromWrappedLines (row, index);

        try
        {
            line.RemoveRange (modelCol, count);
        }
        catch (Exception)
        {
            return false;
        }

        return true;
    }

    public List<List<RuneCell>> ToListRune (List<string> textList)
    {
        List<List<RuneCell>> runesList = new ();

        foreach (string text in textList)
        {
            runesList.Add (TextModel.ToRuneCellList (text));
        }

        return runesList;
    }

    public void UpdateModel (
        TextModel model,
        out int nRow,
        out int nCol,
        out int nStartRow,
        out int nStartCol,
        int row,
        int col,
        int startRow,
        int startCol,
        bool preserveTrailingSpaces
    )
    {
        _isWrapModelRefreshing = true;
        Model = model;

        WrapModel (
                   _frameWidth,
                   out nRow,
                   out nCol,
                   out nStartRow,
                   out nStartCol,
                   row,
                   col,
                   startRow,
                   startCol,
                   0,
                   preserveTrailingSpaces
                  );
        _isWrapModelRefreshing = false;
    }

    public TextModel WrapModel (
        int width,
        out int nRow,
        out int nCol,
        out int nStartRow,
        out int nStartCol,
        int row = 0,
        int col = 0,
        int startRow = 0,
        int startCol = 0,
        int tabWidth = 0,
        bool preserveTrailingSpaces = true
    )
    {
        _frameWidth = width;

        int modelRow = _isWrapModelRefreshing ? row : GetModelLineFromWrappedLines (row);
        int modelCol = _isWrapModelRefreshing ? col : GetModelColFromWrappedLines (row, col);
        int modelStartRow = _isWrapModelRefreshing ? startRow : GetModelLineFromWrappedLines (startRow);

        int modelStartCol =
            _isWrapModelRefreshing ? startCol : GetModelColFromWrappedLines (startRow, startCol);
        var wrappedModel = new TextModel ();
        var lines = 0;
        nRow = 0;
        nCol = 0;
        nStartRow = 0;
        nStartCol = 0;
        bool isRowAndColSetted = row == 0 && col == 0;
        bool isStartRowAndColSetted = startRow == 0 && startCol == 0;
        List<WrappedLine> wModelLines = new ();

        for (var i = 0; i < Model.Count; i++)
        {
            List<RuneCell> line = Model.GetLine (i);

            List<List<RuneCell>> wrappedLines = ToListRune (
                                                            TextFormatter.Format (
                                                                                  TextModel.ToString (line),
                                                                                  width,
                                                                                  TextAlignment.Left,
                                                                                  true,
                                                                                  preserveTrailingSpaces,
                                                                                  tabWidth
                                                                                 )
                                                           );
            var sumColWidth = 0;

            for (var j = 0; j < wrappedLines.Count; j++)
            {
                List<RuneCell> wrapLine = wrappedLines [j];

                if (!isRowAndColSetted && modelRow == i)
                {
                    if (nCol + wrapLine.Count <= modelCol)
                    {
                        nCol += wrapLine.Count;
                        nRow = lines;

                        if (nCol == modelCol)
                        {
                            nCol = wrapLine.Count;
                            isRowAndColSetted = true;
                        }
                        else if (j == wrappedLines.Count - 1)
                        {
                            nCol = wrapLine.Count - j + modelCol - nCol;
                            isRowAndColSetted = true;
                        }
                    }
                    else
                    {
                        int offset = nCol + wrapLine.Count - modelCol;
                        nCol = wrapLine.Count - offset;
                        nRow = lines;
                        isRowAndColSetted = true;
                    }
                }

                if (!isStartRowAndColSetted && modelStartRow == i)
                {
                    if (nStartCol + wrapLine.Count <= modelStartCol)
                    {
                        nStartCol += wrapLine.Count;
                        nStartRow = lines;

                        if (nStartCol == modelStartCol)
                        {
                            nStartCol = wrapLine.Count;
                            isStartRowAndColSetted = true;
                        }
                        else if (j == wrappedLines.Count - 1)
                        {
                            nStartCol = wrapLine.Count - j + modelStartCol - nStartCol;
                            isStartRowAndColSetted = true;
                        }
                    }
                    else
                    {
                        int offset = nStartCol + wrapLine.Count - modelStartCol;
                        nStartCol = wrapLine.Count - offset;
                        nStartRow = lines;
                        isStartRowAndColSetted = true;
                    }
                }

                for (int k = j; k < wrapLine.Count; k++)
                {
                    wrapLine [k].ColorScheme = line [k].ColorScheme;
                }

                wrappedModel.AddLine (lines, wrapLine);
                sumColWidth += wrapLine.Count;

                var wrappedLine = new WrappedLine
                {
                    ModelLine = i, Row = lines, RowIndex = j, ColWidth = wrapLine.Count
                };
                wModelLines.Add (wrappedLine);
                lines++;
            }
        }

        _wrappedModelLines = wModelLines;

        return wrappedModel;
    }

    private List<RuneCell> GetCurrentLine (int row) { return Model.GetLine (row); }

    private class WrappedLine
    {
        public int ColWidth;
        public int ModelLine;
        public int Row;
        public int RowIndex;
    }
}

/// <summary>Multi-line text editing <see cref="View"/>.</summary>
/// <remarks>
///     <para>
///         <see cref="TextView"/> provides a multi-line text editor. Users interact with it with the standard Windows,
///         Mac, and Linux (Emacs) commands.
///     </para>
///     <list type="table">
///         <listheader>
///             <term>Shortcut</term> <description>Action performed</description>
///         </listheader>
///         <item>
///             <term>Left cursor, Control-b</term> <description>Moves the editing point left.</description>
///         </item>
///         <item>
///             <term>Right cursor, Control-f</term> <description>Moves the editing point right.</description>
///         </item>
///         <item>
///             <term>Alt-b</term> <description>Moves one word back.</description>
///         </item>
///         <item>
///             <term>Alt-f</term> <description>Moves one word forward.</description>
///         </item>
///         <item>
///             <term>Up cursor, Control-p</term> <description>Moves the editing point one line up.</description>
///         </item>
///         <item>
///             <term>Down cursor, Control-n</term> <description>Moves the editing point one line down</description>
///         </item>
///         <item>
///             <term>Home key, Control-a</term> <description>Moves the cursor to the beginning of the line.</description>
///         </item>
///         <item>
///             <term>End key, Control-e</term> <description>Moves the cursor to the end of the line.</description>
///         </item>
///         <item>
///             <term>Control-Home</term> <description>Scrolls to the first line and moves the cursor there.</description>
///         </item>
///         <item>
///             <term>Control-End</term> <description>Scrolls to the last line and moves the cursor there.</description>
///         </item>
///         <item>
///             <term>Delete, Control-d</term> <description>Deletes the character in front of the cursor.</description>
///         </item>
///         <item>
///             <term>Backspace</term> <description>Deletes the character behind the cursor.</description>
///         </item>
///         <item>
///             <term>Control-k</term>
///             <description>
///                 Deletes the text until the end of the line and replaces the kill buffer with the deleted text.
///                 You can paste this text in a different place by using Control-y.
///             </description>
///         </item>
///         <item>
///             <term>Control-y</term>
///             <description>Pastes the content of the kill ring into the current position.</description>
///         </item>
///         <item>
///             <term>Alt-d</term>
///             <description>
///                 Deletes the word above the cursor and adds it to the kill ring. You can paste the contents of
///                 the kill ring with Control-y.
///             </description>
///         </item>
///         <item>
///             <term>Control-q</term>
///             <description>
///                 Quotes the next input character, to prevent the normal processing of key handling to take
///                 place.
///             </description>
///         </item>
///     </list>
/// </remarks>
public class TextView : View
{
    private readonly HistoryText _historyText = new ();
    private bool _allowsReturn = true;
    private bool _allowsTab = true;
    private int _bottomOffset, _rightOffset;
    private bool _clickWithSelecting;

    // The column we are tracking, or -1 if we are not tracking any column
    private int _columnTrack = -1;
    private bool _continuousFind;
    private bool _copyWithoutSelection;
    private string? _currentCaller;
    private CultureInfo? _currentCulture;
    private CursorVisibility _desiredCursorVisibility = CursorVisibility.Default;
    private bool _isButtonShift;
    private bool _isDrawing;
    private bool _isReadOnly;
    private bool _lastWasKill;
    private int _leftColumn;
    private TextModel _model = new ();
    private bool _multiline = true;
    private CursorVisibility _savedCursorVisibility;
    private Dim? _savedHeight;
    private int _selectionStartColumn, _selectionStartRow;
    private bool _shiftSelecting;
    private int _tabWidth = 4;
    private int _topRow;
    private bool _wordWrap;
    private WordWrapManager? _wrapManager;
    private bool _wrapNeeded;

    /// <summary>
    ///     Initializes a <see cref="TextView"/> on the specified area, with dimensions controlled with the X, Y, Width
    ///     and Height properties.
    /// </summary>
    public TextView ()
    {
        CanFocus = true;
        Used = true;

        _model.LinesLoaded += Model_LinesLoaded!;
        _historyText.ChangeText += HistoryText_ChangeText!;

        Initialized += TextView_Initialized!;

        LayoutComplete += TextView_LayoutComplete;

        // Things this view knows how to do
        AddCommand (
                    Command.PageDown,
                    () =>
                    {
                        ProcessPageDown ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.PageDownExtend,
                    () =>
                    {
                        ProcessPageDownExtend ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.PageUp,
                    () =>
                    {
                        ProcessPageUp ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.PageUpExtend,
                    () =>
                    {
                        ProcessPageUpExtend ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.LineDown,
                    () =>
                    {
                        ProcessMoveDown ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.LineDownExtend,
                    () =>
                    {
                        ProcessMoveDownExtend ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.LineUp,
                    () =>
                    {
                        ProcessMoveUp ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.LineUpExtend,
                    () =>
                    {
                        ProcessMoveUpExtend ();

                        return true;
                    }
                   );
        AddCommand (Command.Right, () => ProcessMoveRight ());

        AddCommand (
                    Command.RightExtend,
                    () =>
                    {
                        ProcessMoveRightExtend ();

                        return true;
                    }
                   );
        AddCommand (Command.Left, () => ProcessMoveLeft ());

        AddCommand (
                    Command.LeftExtend,
                    () =>
                    {
                        ProcessMoveLeftExtend ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.DeleteCharLeft,
                    () =>
                    {
                        ProcessDeleteCharLeft ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.StartOfLine,
                    () =>
                    {
                        ProcessMoveStartOfLine ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.StartOfLineExtend,
                    () =>
                    {
                        ProcessMoveStartOfLineExtend ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.DeleteCharRight,
                    () =>
                    {
                        ProcessDeleteCharRight ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.EndOfLine,
                    () =>
                    {
                        ProcessMoveEndOfLine ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.EndOfLineExtend,
                    () =>
                    {
                        ProcessMoveEndOfLineExtend ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.CutToEndLine,
                    () =>
                    {
                        KillToEndOfLine ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.CutToStartLine,
                    () =>
                    {
                        KillToStartOfLine ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.Paste,
                    () =>
                    {
                        ProcessPaste ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.ToggleExtend,
                    () =>
                    {
                        ToggleSelecting ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.Copy,
                    () =>
                    {
                        ProcessCopy ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.Cut,
                    () =>
                    {
                        ProcessCut ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.WordLeft,
                    () =>
                    {
                        ProcessMoveWordBackward ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.WordLeftExtend,
                    () =>
                    {
                        ProcessMoveWordBackwardExtend ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.WordRight,
                    () =>
                    {
                        ProcessMoveWordForward ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.WordRightExtend,
                    () =>
                    {
                        ProcessMoveWordForwardExtend ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.KillWordForwards,
                    () =>
                    {
                        ProcessKillWordForward ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.KillWordBackwards,
                    () =>
                    {
                        ProcessKillWordBackward ();

                        return true;
                    }
                   );
        AddCommand (Command.NewLine, () => ProcessReturn ());

        AddCommand (
                    Command.BottomEnd,
                    () =>
                    {
                        MoveBottomEnd ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.BottomEndExtend,
                    () =>
                    {
                        MoveBottomEndExtend ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.TopHome,
                    () =>
                    {
                        MoveTopHome ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.TopHomeExtend,
                    () =>
                    {
                        MoveTopHomeExtend ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.SelectAll,
                    () =>
                    {
                        ProcessSelectAll ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.ToggleOverwrite,
                    () =>
                    {
                        ProcessSetOverwrite ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.EnableOverwrite,
                    () =>
                    {
                        SetOverwrite (true);

                        return true;
                    }
                   );

        AddCommand (
                    Command.DisableOverwrite,
                    () =>
                    {
                        SetOverwrite (false);

                        return true;
                    }
                   );
        AddCommand (Command.Tab, () => ProcessTab ());
        AddCommand (Command.BackTab, () => ProcessBackTab ());
        AddCommand (Command.NextView, () => ProcessMoveNextView ());
        AddCommand (Command.PreviousView, () => ProcessMovePreviousView ());

        AddCommand (
                    Command.Undo,
                    () =>
                    {
                        Undo ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.Redo,
                    () =>
                    {
                        Redo ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.DeleteAll,
                    () =>
                    {
                        DeleteAll ();

                        return true;
                    }
                   );

        AddCommand (
                    Command.ShowContextMenu,
                    () =>
                    {
                        ContextMenu!.Position = new Point (
                                                           CursorPosition.X - _leftColumn + 2,
                                                           CursorPosition.Y - _topRow + 2
                                                          );
                        ShowContextMenu ();

                        return true;
                    }
                   );

        // Default keybindings for this view
        KeyBindings.Add (Key.PageDown, Command.PageDown);
        KeyBindings.Add (Key.V.WithCtrl, Command.PageDown);

        KeyBindings.Add (Key.PageDown.WithShift, Command.PageDownExtend);

        KeyBindings.Add (Key.PageUp, Command.PageUp);
        KeyBindings.Add (Key.V.WithAlt, Command.PageUp);

        KeyBindings.Add (Key.PageUp.WithShift, Command.PageUpExtend);

        KeyBindings.Add (Key.N.WithCtrl, Command.LineDown);
        KeyBindings.Add (Key.CursorDown, Command.LineDown);

        KeyBindings.Add (Key.CursorDown.WithShift, Command.LineDownExtend);

        KeyBindings.Add (Key.P.WithCtrl, Command.LineUp);
        KeyBindings.Add (Key.CursorUp, Command.LineUp);

        KeyBindings.Add (Key.CursorUp.WithShift, Command.LineUpExtend);

        KeyBindings.Add (Key.F.WithCtrl, Command.Right);
        KeyBindings.Add (Key.CursorRight, Command.Right);

        KeyBindings.Add (Key.CursorRight.WithShift, Command.RightExtend);

        KeyBindings.Add (Key.B.WithCtrl, Command.Left);
        KeyBindings.Add (Key.CursorLeft, Command.Left);

        KeyBindings.Add (Key.CursorLeft.WithShift, Command.LeftExtend);

        KeyBindings.Add (Key.Backspace, Command.DeleteCharLeft);

        KeyBindings.Add (Key.Home, Command.StartOfLine);
        KeyBindings.Add (Key.A.WithCtrl, Command.StartOfLine);

        KeyBindings.Add (Key.Home.WithShift, Command.StartOfLineExtend);

        KeyBindings.Add (Key.Delete, Command.DeleteCharRight);
        KeyBindings.Add (Key.D.WithCtrl, Command.DeleteCharRight);

        KeyBindings.Add (Key.End, Command.EndOfLine);
        KeyBindings.Add (Key.E.WithCtrl, Command.EndOfLine);

        KeyBindings.Add (Key.End.WithShift, Command.EndOfLineExtend);

        KeyBindings.Add (Key.K.WithCtrl, Command.CutToEndLine); // kill-to-end

        KeyBindings.Add (Key.Delete.WithCtrl.WithShift, Command.CutToEndLine); // kill-to-end

        KeyBindings.Add (Key.K.WithAlt, Command.CutToStartLine); // kill-to-start

        KeyBindings.Add (Key.Backspace.WithCtrl.WithShift, Command.CutToStartLine); // kill-to-start

        KeyBindings.Add (Key.Y.WithCtrl, Command.Paste); // Control-y, yank
        KeyBindings.Add (Key.Space.WithCtrl, Command.ToggleExtend);

        KeyBindings.Add (Key.C.WithAlt, Command.Copy);
        KeyBindings.Add (Key.C.WithCtrl, Command.Copy);

        KeyBindings.Add (Key.W.WithAlt, Command.Cut);
        KeyBindings.Add (Key.W.WithCtrl, Command.Cut);
        KeyBindings.Add (Key.X.WithCtrl, Command.Cut);

        KeyBindings.Add (Key.CursorLeft.WithCtrl, Command.WordLeft);
        KeyBindings.Add (Key.B.WithAlt, Command.WordLeft);

        KeyBindings.Add (Key.CursorLeft.WithCtrl.WithShift, Command.WordLeftExtend);

        KeyBindings.Add (Key.CursorRight.WithCtrl, Command.WordRight);
        KeyBindings.Add (Key.F.WithAlt, Command.WordRight);

        KeyBindings.Add (Key.CursorRight.WithCtrl.WithShift, Command.WordRightExtend);
        KeyBindings.Add (Key.Delete.WithCtrl, Command.KillWordForwards); // kill-word-forwards
        KeyBindings.Add (Key.Backspace.WithCtrl, Command.KillWordBackwards); // kill-word-backwards

        // BUGBUG: If AllowsReturn is false, Key.Enter should not be bound (so that Toplevel can cause Command.Accept).
        KeyBindings.Add (Key.Enter, Command.NewLine);
        KeyBindings.Add (Key.End.WithCtrl, Command.BottomEnd);
        KeyBindings.Add (Key.End.WithCtrl.WithShift, Command.BottomEndExtend);
        KeyBindings.Add (Key.Home.WithCtrl, Command.TopHome);
        KeyBindings.Add (Key.Home.WithCtrl.WithShift, Command.TopHomeExtend);
        KeyBindings.Add (Key.T.WithCtrl, Command.SelectAll);
        KeyBindings.Add (Key.InsertChar, Command.ToggleOverwrite);
        KeyBindings.Add (Key.Tab, Command.Tab);
        KeyBindings.Add (Key.Tab.WithShift, Command.BackTab);

        KeyBindings.Add (Key.Tab.WithCtrl, Command.NextView);
        KeyBindings.Add (Application.AlternateForwardKey, Command.NextView);

        KeyBindings.Add (Key.Tab.WithCtrl.WithShift, Command.PreviousView);
        KeyBindings.Add (Application.AlternateBackwardKey, Command.PreviousView);

        KeyBindings.Add (Key.Z.WithCtrl, Command.Undo);
        KeyBindings.Add (Key.R.WithCtrl, Command.Redo);

        KeyBindings.Add (Key.G.WithCtrl, Command.DeleteAll);
        KeyBindings.Add (Key.D.WithCtrl.WithShift, Command.DeleteAll);

        _currentCulture = Thread.CurrentThread.CurrentUICulture;

        ContextMenu = new ContextMenu { MenuItems = BuildContextMenuBarItem () };
        ContextMenu.KeyChanged += ContextMenu_KeyChanged!;

        KeyBindings.Add ((KeyCode)ContextMenu.Key, KeyBindingScope.HotKey, Command.ShowContextMenu);
    }

    /// <summary>
    ///     Gets or sets a value indicating whether pressing ENTER in a <see cref="TextView"/> creates a new line of text
    ///     in the view or activates the default button for the Toplevel.
    /// </summary>
    public bool AllowsReturn
    {
        get => _allowsReturn;
        set
        {
            _allowsReturn = value;

            if (_allowsReturn && !_multiline)
            {
                Multiline = true;
            }

            if (!_allowsReturn && _multiline)
            {
                Multiline = false;
                AllowsTab = false;
            }

            SetNeedsDisplay ();
        }
    }

    /// <summary>
    ///     Gets or sets whether the <see cref="TextView"/> inserts a tab character into the text or ignores tab input. If
    ///     set to `false` and the user presses the tab key (or shift-tab) the focus will move to the next view (or previous
    ///     with shift-tab). The default is `true`; if the user presses the tab key, a tab character will be inserted into the
    ///     text.
    /// </summary>
    public bool AllowsTab
    {
        get => _allowsTab;
        set
        {
            _allowsTab = value;

            if (_allowsTab && _tabWidth == 0)
            {
                _tabWidth = 4;
            }

            if (_allowsTab && !_multiline)
            {
                Multiline = true;
            }

            if (!_allowsTab && _tabWidth > 0)
            {
                _tabWidth = 0;
            }

            SetNeedsDisplay ();
        }
    }

    /// <summary>
    ///     Provides autocomplete context menu based on suggestions at the current cursor position. Configure
    ///     <see cref="IAutocomplete.SuggestionGenerator"/> to enable this feature
    /// </summary>
    public IAutocomplete Autocomplete { get; protected set; } = new TextViewAutocomplete ();

    /// <summary>
    ///     The bottom offset needed to use a horizontal scrollbar or for another reason. This is only needed with the
    ///     keyboard navigation.
    /// </summary>
    public int BottomOffset
    {
        get => _bottomOffset;
        set
        {
            if (CurrentRow == Lines - 1 && _bottomOffset > 0 && value == 0)
            {
                _topRow = Math.Max (_topRow - _bottomOffset, 0);
            }

            _bottomOffset = value;
            Adjust ();
        }
    }

    /// <summary>Get the <see cref="ContextMenu"/> for this view.</summary>
    public ContextMenu? ContextMenu { get; }

    /// <summary>Gets the cursor column.</summary>
    /// <value>The cursor column.</value>
    public int CurrentColumn { get; private set; }

    /// <summary>Gets the current cursor row.</summary>
    public int CurrentRow { get; private set; }

    /// <summary>Sets or gets the current cursor position.</summary>
    public Point CursorPosition
    {
        get => new (CurrentColumn, CurrentRow);
        set
        {
            List<RuneCell> line = _model.GetLine (Math.Max (Math.Min (value.Y, _model.Count - 1), 0));

            CurrentColumn = value.X < 0 ? 0 :
                            value.X > line.Count ? line.Count : value.X;

            CurrentRow = value.Y < 0 ? 0 :
                         value.Y > _model.Count - 1 ? Math.Max (_model.Count - 1, 0) : value.Y;
            SetNeedsDisplay ();
            Adjust ();
        }
    }

    /// <summary>Get / Set the wished cursor when the field is focused</summary>
    public CursorVisibility DesiredCursorVisibility
    {
        get => _desiredCursorVisibility;
        set
        {
            if (HasFocus)
            {
                Application.Driver.SetCursorVisibility (value);
            }

            _desiredCursorVisibility = value;
            SetNeedsDisplay ();
        }
    }

    /// <summary>
    ///     Indicates whatever the text has history changes or not. <see langword="true"/> if the text has history changes
    ///     <see langword="false"/> otherwise.
    /// </summary>
    public bool HasHistoryChanges => _historyText.HasHistoryChanges;

    /// <summary>
    ///     If <see langword="true"/> and the current <see cref="RuneCell.ColorScheme"/> is null will inherit from the
    ///     previous, otherwise if <see langword="false"/> (default) do nothing. If the text is load with
    ///     <see cref="Load(List{RuneCell})"/> this property is automatically sets to <see langword="true"/>.
    /// </summary>
    public bool InheritsPreviousColorScheme { get; set; }

    /// <summary>
    ///     Indicates whatever the text was changed or not. <see langword="true"/> if the text was changed
    ///     <see langword="false"/> otherwise.
    /// </summary>
    public bool IsDirty
    {
        get => _historyText.IsDirty (Text);
        set => _historyText.Clear (Text);
    }

    /// <summary>Gets or sets the left column.</summary>
    public int LeftColumn
    {
        get => _leftColumn;
        set
        {
            if (value > 0 && _wordWrap)
            {
                return;
            }

            _leftColumn = Math.Max (Math.Min (value, Maxlength - 1), 0);
        }
    }

    /// <summary>Gets the number of lines.</summary>
    public int Lines => _model.Count;

    /// <summary>Gets the maximum visible length line.</summary>
    public int Maxlength => _model.GetMaxVisibleLine (_topRow, _topRow + Frame.Height, TabWidth);

    /// <summary>Gets or sets a value indicating whether this <see cref="TextView"/> is a multiline text view.</summary>
    public bool Multiline
    {
        get => _multiline;
        set
        {
            _multiline = value;

            if (_multiline && !_allowsTab)
            {
                AllowsTab = true;
            }

            if (_multiline && !_allowsReturn)
            {
                AllowsReturn = true;
            }

            if (!_multiline)
            {
                AllowsReturn = false;
                AllowsTab = false;
                WordWrap = false;
                CurrentColumn = 0;
                CurrentRow = 0;
                _savedHeight = Height;

                //var prevLayoutStyle = LayoutStyle;
                //if (LayoutStyle == LayoutStyle.Computed) {
                //	LayoutStyle = LayoutStyle.Absolute;
                //}
                Height = 1;

                //LayoutStyle = prevLayoutStyle;
                if (!IsInitialized)
                {
                    _model.LoadString (Text);
                }

                SetNeedsDisplay ();
            }
            else if (_multiline && _savedHeight is { })
            {
                //var lyout = LayoutStyle;
                //if (LayoutStyle == LayoutStyle.Computed) {
                //	LayoutStyle = LayoutStyle.Absolute;
                //}
                Height = _savedHeight;

                //LayoutStyle = lyout;
                SetNeedsDisplay ();
            }
        }
    }

    /// <summary>Gets or sets whether the <see cref="TextView"/> is in read-only mode or not</summary>
    /// <value>Boolean value(Default false)</value>
    public bool ReadOnly
    {
        get => _isReadOnly;
        set
        {
            if (value != _isReadOnly)
            {
                _isReadOnly = value;

                SetNeedsDisplay ();
                Adjust ();
            }
        }
    }

    /// <summary>
    ///     The right offset needed to use a vertical scrollbar or for another reason. This is only needed with the
    ///     keyboard navigation.
    /// </summary>
    public int RightOffset
    {
        get => _rightOffset;
        set
        {
            if (!_wordWrap && CurrentColumn == GetCurrentLine ().Count && _rightOffset > 0 && value == 0)
            {
                _leftColumn = Math.Max (_leftColumn - _rightOffset, 0);
            }

            _rightOffset = value;
            Adjust ();
        }
    }

    /// <summary>Length of the selected text.</summary>
    public int SelectedLength => GetSelectedLength ();

    /// <summary>The selected text.</summary>
    public string SelectedText
    {
        get
        {
            if (!Selecting || (_model.Count == 1 && _model.GetLine (0).Count == 0))
            {
                return string.Empty;
            }

            return GetSelectedRegion ();
        }
    }

    /// <summary>Get or sets the selecting.</summary>
    public bool Selecting { get; set; }

    /// <summary>Start column position of the selected text.</summary>
    public int SelectionStartColumn
    {
        get => _selectionStartColumn;
        set
        {
            List<RuneCell> line = _model.GetLine (_selectionStartRow);

            _selectionStartColumn = value < 0 ? 0 :
                                    value > line.Count ? line.Count : value;
            Selecting = true;
            SetNeedsDisplay ();
            Adjust ();
        }
    }

    /// <summary>Start row position of the selected text.</summary>
    public int SelectionStartRow
    {
        get => _selectionStartRow;
        set
        {
            _selectionStartRow = value < 0 ? 0 :
                                 value > _model.Count - 1 ? Math.Max (_model.Count - 1, 0) : value;
            Selecting = true;
            SetNeedsDisplay ();
            Adjust ();
        }
    }

    /// <summary>Gets or sets a value indicating the number of whitespace when pressing the TAB key.</summary>
    public int TabWidth
    {
        get => _tabWidth;
        set
        {
            _tabWidth = Math.Max (value, 0);

            if (_tabWidth > 0 && !AllowsTab)
            {
                AllowsTab = true;
            }

            SetNeedsDisplay ();
        }
    }

    /// <summary>Sets or gets the text in the <see cref="TextView"/>.</summary>
    /// <remarks>
    ///     The <see cref="View.TextChanged"/> event is fired whenever this property is set. Note, however, that Text is not
    ///     set by <see cref="TextView"/> as the user types.
    /// </remarks>
    public override string Text
    {
        get
        {
            if (_wordWrap)
            {
                return _wrapManager!.Model.ToString ();
            }

            return _model.ToString ();
        }
        set
        {
            var old = Text;
            ResetPosition ();
            _model.LoadString (value);

            if (_wordWrap)
            {
                _wrapManager = new WordWrapManager (_model);
                _model = _wrapManager.WrapModel (_frameWidth, out _, out _, out _, out _);
            }

            OnTextChanged (old,Text);
            SetNeedsDisplay ();

            _historyText.Clear (Text);
        }
    }

    /// <summary>Gets or sets the top row.</summary>
    public int TopRow
    {
        get => _topRow;
        set => _topRow = Math.Max (Math.Min (value, Lines - 1), 0);
    }

    /// <summary>
    ///     Tracks whether the text view should be considered "used", that is, that the user has moved in the entry, so
    ///     new input should be appended at the cursor position, rather than clearing the entry
    /// </summary>
    public bool Used { get; set; }

    /// <summary>Allows word wrap the to fit the available container width.</summary>
    public bool WordWrap
    {
        get => _wordWrap;
        set
        {
            if (value == _wordWrap)
            {
                return;
            }

            if (value && !_multiline)
            {
                return;
            }

            _wordWrap = value;
            ResetPosition ();

            if (_wordWrap)
            {
                _wrapManager = new WordWrapManager (_model);
                _model = _wrapManager.WrapModel (_frameWidth, out _, out _, out _, out _);
            }
            else if (!_wordWrap && _wrapManager is { })
            {
                _model = _wrapManager.Model;
            }

            SetNeedsDisplay ();
        }
    }

    private int _frameWidth => Math.Max (Frame.Width - (RightOffset != 0 ? 2 : 1), 0);

    /// <summary>Allows clearing the <see cref="HistoryText.HistoryTextItem"/> items updating the original text.</summary>
    public void ClearHistoryChanges () { _historyText?.Clear (Text); }

    /// <summary>Closes the contents of the stream into the <see cref="TextView"/>.</summary>
    /// <returns><c>true</c>, if stream was closed, <c>false</c> otherwise.</returns>
    public bool CloseFile ()
    {
        SetWrapModel ();
        bool res = _model.CloseFile ();
        ResetPosition ();
        SetNeedsDisplay ();
        UpdateWrapModel ();

        return res;
    }

    /// <summary>Raised when the contents of the <see cref="TextView"/> are changed.</summary>
    /// <remarks>
    ///     Unlike the <see cref="View.TextChanged"/> event, this event is raised whenever the user types or otherwise changes
    ///     the contents of the <see cref="TextView"/>.
    /// </remarks>
    public event EventHandler<ContentsChangedEventArgs>? ContentsChanged;

    /// <summary>Copy the selected text to the clipboard contents.</summary>
    public void Copy ()
    {
        SetWrapModel ();

        if (Selecting)
        {
            SetClipboard (GetRegion ());
            _copyWithoutSelection = false;
        }
        else
        {
            List<RuneCell> currentLine = GetCurrentLine ();
            SetClipboard (TextModel.ToString (currentLine));
            _copyWithoutSelection = true;
        }

        UpdateWrapModel ();
        DoNeededAction ();
    }

    /// <summary>Cut the selected text to the clipboard contents.</summary>
    public void Cut ()
    {
        SetWrapModel ();
        SetClipboard (GetRegion ());

        if (!_isReadOnly)
        {
            ClearRegion ();

            _historyText.Add (
                              new List<List<RuneCell>> { new (GetCurrentLine ()) },
                              CursorPosition,
                              HistoryText.LineStatus.Replaced
                             );
        }

        UpdateWrapModel ();
        Selecting = false;
        DoNeededAction ();
        OnContentsChanged ();
    }

    /// <summary>Deletes all text.</summary>
    public void DeleteAll ()
    {
        if (Lines == 0)
        {
            return;
        }

        _selectionStartColumn = 0;
        _selectionStartRow = 0;
        MoveBottomEndExtend ();
        DeleteCharLeft ();
        SetNeedsDisplay ();
    }

    /// <summary>Deletes all the selected or a single character at left from the position of the cursor.</summary>
    public void DeleteCharLeft ()
    {
        if (_isReadOnly)
        {
            return;
        }

        SetWrapModel ();

        if (Selecting)
        {
            _historyText.Add (new List<List<RuneCell>> { new (GetCurrentLine ()) }, CursorPosition);

            ClearSelectedRegion ();

            List<RuneCell> currentLine = GetCurrentLine ();

            _historyText.Add (
                              new List<List<RuneCell>> { new (currentLine) },
                              CursorPosition,
                              HistoryText.LineStatus.Replaced
                             );

            UpdateWrapModel ();
            OnContentsChanged ();

            return;
        }

        if (DeleteTextBackwards ())
        {
            UpdateWrapModel ();
            OnContentsChanged ();

            return;
        }

        UpdateWrapModel ();

        DoNeededAction ();
        OnContentsChanged ();
    }

    /// <summary>Deletes all the selected or a single character at right from the position of the cursor.</summary>
    public void DeleteCharRight ()
    {
        if (_isReadOnly)
        {
            return;
        }

        SetWrapModel ();

        if (Selecting)
        {
            _historyText.Add (new List<List<RuneCell>> { new (GetCurrentLine ()) }, CursorPosition);

            ClearSelectedRegion ();

            List<RuneCell> currentLine = GetCurrentLine ();

            _historyText.Add (
                              new List<List<RuneCell>> { new (currentLine) },
                              CursorPosition,
                              HistoryText.LineStatus.Replaced
                             );

            UpdateWrapModel ();
            OnContentsChanged ();

            return;
        }

        if (DeleteTextForwards ())
        {
            UpdateWrapModel ();
            OnContentsChanged ();

            return;
        }

        UpdateWrapModel ();

        DoNeededAction ();
        OnContentsChanged ();
    }

    /// <summary>Invoked when the normal color is drawn.</summary>
    public event EventHandler<RuneCellEventArgs>? DrawNormalColor;

    /// <summary>Invoked when the ready only color is drawn.</summary>
    public event EventHandler<RuneCellEventArgs>? DrawReadOnlyColor;

    /// <summary>Invoked when the selection color is drawn.</summary>
    public event EventHandler<RuneCellEventArgs>? DrawSelectionColor;

    /// <summary>
    ///     Invoked when the used color is drawn. The Used Color is used to indicate if the <see cref="Key.InsertChar"/>
    ///     was pressed and enabled.
    /// </summary>
    public event EventHandler<RuneCellEventArgs>? DrawUsedColor;

    /// <summary>Find the next text based on the match case with the option to replace it.</summary>
    /// <param name="textToFind">The text to find.</param>
    /// <param name="gaveFullTurn"><c>true</c>If all the text was forward searched.<c>false</c>otherwise.</param>
    /// <param name="matchCase">The match case setting.</param>
    /// <param name="matchWholeWord">The match whole word setting.</param>
    /// <param name="textToReplace">The text to replace.</param>
    /// <param name="replace"><c>true</c>If is replacing.<c>false</c>otherwise.</param>
    /// <returns><c>true</c>If the text was found.<c>false</c>otherwise.</returns>
    public bool FindNextText (
        string textToFind,
        out bool gaveFullTurn,
        bool matchCase = false,
        bool matchWholeWord = false,
        string? textToReplace = null,
        bool replace = false
    )
    {
        if (_model.Count == 0)
        {
            gaveFullTurn = false;

            return false;
        }

        SetWrapModel ();
        ResetContinuousFind ();

        (Point current, bool found) foundPos =
            _model.FindNextText (textToFind, out gaveFullTurn, matchCase, matchWholeWord);

        return SetFoundText (textToFind, foundPos, textToReplace, replace);
    }

    /// <summary>Find the previous text based on the match case with the option to replace it.</summary>
    /// <param name="textToFind">The text to find.</param>
    /// <param name="gaveFullTurn"><c>true</c>If all the text was backward searched.<c>false</c>otherwise.</param>
    /// <param name="matchCase">The match case setting.</param>
    /// <param name="matchWholeWord">The match whole word setting.</param>
    /// <param name="textToReplace">The text to replace.</param>
    /// <param name="replace"><c>true</c>If the text was found.<c>false</c>otherwise.</param>
    /// <returns><c>true</c>If the text was found.<c>false</c>otherwise.</returns>
    public bool FindPreviousText (
        string textToFind,
        out bool gaveFullTurn,
        bool matchCase = false,
        bool matchWholeWord = false,
        string? textToReplace = null,
        bool replace = false
    )
    {
        if (_model.Count == 0)
        {
            gaveFullTurn = false;

            return false;
        }

        SetWrapModel ();
        ResetContinuousFind ();

        (Point current, bool found) foundPos =
            _model.FindPreviousText (textToFind, out gaveFullTurn, matchCase, matchWholeWord);

        return SetFoundText (textToFind, foundPos, textToReplace, replace);
    }

    /// <summary>Reset the flag to stop continuous find.</summary>
    public void FindTextChanged () { _continuousFind = false; }

    /// <summary>Gets all lines of characters.</summary>
    /// <returns></returns>
    public List<List<RuneCell>> GetAllLines () { return _model.GetAllLines (); }

    /// <summary>
    ///     Returns the characters on the current line (where the cursor is positioned). Use <see cref="CurrentColumn"/>
    ///     to determine the position of the cursor within that line
    /// </summary>
    /// <returns></returns>
    public List<RuneCell> GetCurrentLine () { return _model.GetLine (CurrentRow); }

    /// <summary>Returns the characters on the <paramref name="line"/>.</summary>
    /// <param name="line">The intended line.</param>
    /// <returns></returns>
    public List<RuneCell> GetLine (int line) { return _model.GetLine (line); }

    /// <inheritdoc/>
    public override Attribute GetNormalColor ()
    {
        ColorScheme? cs = ColorScheme;

        if (ColorScheme is null)
        {
            cs = new ColorScheme ();
        }

        return Enabled ? cs.Focus : cs.Disabled;
    }

    /// <summary>
    ///     Inserts the given <paramref name="toAdd"/> text at the current cursor position exactly as if the user had just
    ///     typed it
    /// </summary>
    /// <param name="toAdd">Text to add</param>
    public void InsertText (string toAdd)
    {
        foreach (char ch in toAdd)
        {
            Key key;

            try
            {
                key = new Key (ch);
            }
            catch (Exception)
            {
                throw new ArgumentException (
                                             $"Cannot insert character '{ch}' because it does not map to a Key"
                                            );
            }

            InsertText (key);

            if (NeedsDisplay)
            {
                Adjust ();
            }
            else
            {
                PositionCursor ();
            }
        }
    }

    /// <summary>Loads the contents of the file into the <see cref="TextView"/>.</summary>
    /// <returns><c>true</c>, if file was loaded, <c>false</c> otherwise.</returns>
    /// <param name="path">Path to the file to load.</param>
    public bool Load (string path)
    {
        SetWrapModel ();
        bool res;

        try
        {
            SetWrapModel ();
            res = _model.LoadFile (path);
            _historyText.Clear (Text);
            ResetPosition ();
        }
        finally
        {
            UpdateWrapModel ();
            SetNeedsDisplay ();
            Adjust ();
        }

        UpdateWrapModel ();

        return res;
    }

    /// <summary>Loads the contents of the stream into the <see cref="TextView"/>.</summary>
    /// <returns><c>true</c>, if stream was loaded, <c>false</c> otherwise.</returns>
    /// <param name="stream">Stream to load the contents from.</param>
    public void Load (Stream stream)
    {
        SetWrapModel ();
        _model.LoadStream (stream);
        _historyText.Clear (Text);
        ResetPosition ();
        SetNeedsDisplay ();
        UpdateWrapModel ();
    }

    /// <summary>Loads the contents of the <see cref="RuneCell"/> list into the <see cref="TextView"/>.</summary>
    /// <param name="cells">Rune cells list to load the contents from.</param>
    public void Load (List<RuneCell> cells)
    {
        SetWrapModel ();
        _model.LoadRuneCells (cells, ColorScheme);
        _historyText.Clear (Text);
        ResetPosition ();
        SetNeedsDisplay ();
        UpdateWrapModel ();
        InheritsPreviousColorScheme = true;
    }

    /// <summary>Loads the contents of the list of <see cref="RuneCell"/> list into the <see cref="TextView"/>.</summary>
    /// <param name="cellsList">List of rune cells list to load the contents from.</param>
    public void Load (List<List<RuneCell>> cellsList)
    {
        SetWrapModel ();
        InheritsPreviousColorScheme = true;
        _model.LoadListRuneCells (cellsList, ColorScheme);
        _historyText.Clear (Text);
        ResetPosition ();
        SetNeedsDisplay ();
        UpdateWrapModel ();
    }

    /// <inheritdoc/>
    protected internal override bool OnMouseEvent  (MouseEvent ev)
    {
        if (!ev.Flags.HasFlag (MouseFlags.Button1Clicked)
            && !ev.Flags.HasFlag (MouseFlags.Button1Pressed)
            && !ev.Flags.HasFlag (MouseFlags.Button1Pressed | MouseFlags.ReportMousePosition)
            && !ev.Flags.HasFlag (MouseFlags.Button1Released)
            && !ev.Flags.HasFlag (MouseFlags.Button1Pressed | MouseFlags.ButtonShift)
            && !ev.Flags.HasFlag (MouseFlags.WheeledDown)
            && !ev.Flags.HasFlag (MouseFlags.WheeledUp)
            && !ev.Flags.HasFlag (MouseFlags.Button1DoubleClicked)
            && !ev.Flags.HasFlag (MouseFlags.Button1DoubleClicked | MouseFlags.ButtonShift)
            && !ev.Flags.HasFlag (MouseFlags.Button1TripleClicked)
            && !ev.Flags.HasFlag (ContextMenu!.MouseFlags))
        {
            return false;
        }

        if (!CanFocus)
        {
            return true;
        }

        if (!HasFocus)
        {
            SetFocus ();
        }

        _continuousFind = false;

        // Give autocomplete first opportunity to respond to mouse clicks
        if (SelectedLength == 0 && Autocomplete.OnMouseEvent (ev, true))
        {
            return true;
        }

        if (ev.Flags == MouseFlags.Button1Clicked)
        {
            if (_shiftSelecting && !_isButtonShift)
            {
                StopSelecting ();
            }

            ProcessMouseClick (ev, out _);

            if (Used)
            {
                PositionCursor ();
            }
            else
            {
                SetNeedsDisplay ();
            }

            _lastWasKill = false;
            _columnTrack = CurrentColumn;
        }
        else if (ev.Flags == MouseFlags.WheeledDown)
        {
            _lastWasKill = false;
            _columnTrack = CurrentColumn;
            ScrollTo (_topRow + 1);
        }
        else if (ev.Flags == MouseFlags.WheeledUp)
        {
            _lastWasKill = false;
            _columnTrack = CurrentColumn;
            ScrollTo (_topRow - 1);
        }
        else if (ev.Flags == MouseFlags.WheeledRight)
        {
            _lastWasKill = false;
            _columnTrack = CurrentColumn;
            ScrollTo (_leftColumn + 1, false);
        }
        else if (ev.Flags == MouseFlags.WheeledLeft)
        {
            _lastWasKill = false;
            _columnTrack = CurrentColumn;
            ScrollTo (_leftColumn - 1, false);
        }
        else if (ev.Flags.HasFlag (MouseFlags.Button1Pressed | MouseFlags.ReportMousePosition))
        {
            ProcessMouseClick (ev, out List<RuneCell> line);
            PositionCursor ();

            if (_model.Count > 0 && _shiftSelecting && Selecting)
            {
                if (CurrentRow - _topRow + BottomOffset >= Frame.Height - 1 && _model.Count + BottomOffset > _topRow + CurrentRow)
                {
                    ScrollTo (_topRow + Frame.Height);
                }
                else if (_topRow > 0 && CurrentRow <= _topRow)
                {
                    ScrollTo (_topRow - Frame.Height);
                }
                else if (ev.Y >= Frame.Height)
                {
                    ScrollTo (_model.Count + BottomOffset);
                }
                else if (ev.Y < 0 && _topRow > 0)
                {
                    ScrollTo (0);
                }

                if (CurrentColumn - _leftColumn + RightOffset >= Frame.Width - 1 && line.Count + RightOffset > _leftColumn + CurrentColumn)
                {
                    ScrollTo (_leftColumn + Frame.Width, false);
                }
                else if (_leftColumn > 0 && CurrentColumn <= _leftColumn)
                {
                    ScrollTo (_leftColumn - Frame.Width, false);
                }
                else if (ev.X >= Frame.Width)
                {
                    ScrollTo (line.Count + RightOffset, false);
                }
                else if (ev.X < 0 && _leftColumn > 0)
                {
                    ScrollTo (0, false);
                }
            }

            _lastWasKill = false;
            _columnTrack = CurrentColumn;
        }
        else if (ev.Flags.HasFlag (MouseFlags.Button1Pressed | MouseFlags.ButtonShift))
        {
            if (!_shiftSelecting)
            {
                _isButtonShift = true;
                StartSelecting ();
            }

            ProcessMouseClick (ev, out _);
            PositionCursor ();
            _lastWasKill = false;
            _columnTrack = CurrentColumn;
        }
        else if (ev.Flags.HasFlag (MouseFlags.Button1Pressed))
        {
            if (_shiftSelecting)
            {
                _clickWithSelecting = true;
                StopSelecting ();
            }

            ProcessMouseClick (ev, out _);
            PositionCursor ();

            if (!Selecting)
            {
                StartSelecting ();
            }

            _lastWasKill = false;
            _columnTrack = CurrentColumn;

            if (Application.MouseGrabView is null)
            {
                Application.GrabMouse (this);
            }
        }
        else if (ev.Flags.HasFlag (MouseFlags.Button1Released))
        {
            Application.UngrabMouse ();
        }
        else if (ev.Flags.HasFlag (MouseFlags.Button1DoubleClicked))
        {
            if (ev.Flags.HasFlag (MouseFlags.ButtonShift))
            {
                if (!Selecting)
                {
                    StartSelecting ();
                }
            }
            else if (Selecting)
            {
                StopSelecting ();
            }

            ProcessMouseClick (ev, out List<RuneCell> line);
            (int col, int row)? newPos;

            if (CurrentColumn == line.Count
                || (CurrentColumn > 0 && (line [CurrentColumn - 1].Rune.Value != ' ' || line [CurrentColumn].Rune.Value == ' ')))
            {
                newPos = _model.WordBackward (CurrentColumn, CurrentRow);

                if (newPos.HasValue)
                {
                    CurrentColumn = CurrentRow == newPos.Value.row ? newPos.Value.col : 0;
                }
            }

            if (!Selecting)
            {
                StartSelecting ();
            }

            newPos = _model.WordForward (CurrentColumn, CurrentRow);

            if (newPos is { } && newPos.HasValue)
            {
                CurrentColumn = CurrentRow == newPos.Value.row ? newPos.Value.col : line.Count;
            }

            PositionCursor ();
            _lastWasKill = false;
            _columnTrack = CurrentColumn;
        }
        else if (ev.Flags.HasFlag (MouseFlags.Button1TripleClicked))
        {
            if (Selecting)
            {
                StopSelecting ();
            }

            ProcessMouseClick (ev, out List<RuneCell> line);
            CurrentColumn = 0;

            if (!Selecting)
            {
                StartSelecting ();
            }

            CurrentColumn = line.Count;
            PositionCursor ();
            _lastWasKill = false;
            _columnTrack = CurrentColumn;
        }
        else if (ev.Flags == ContextMenu!.MouseFlags)
        {
            ContextMenu.Position = new Point (ev.X + 2, ev.Y + 2);
            ShowContextMenu ();
        }

        return true;
    }

    /// <summary>Will scroll the <see cref="TextView"/> to the last line and position the cursor there.</summary>
    public void MoveEnd ()
    {
        CurrentRow = _model.Count - 1;
        List<RuneCell> line = GetCurrentLine ();
        CurrentColumn = line.Count;
        TrackColumn ();
        PositionCursor ();
    }

    /// <summary>Will scroll the <see cref="TextView"/> to the first line and position the cursor there.</summary>
    public void MoveHome ()
    {
        CurrentRow = 0;
        _topRow = 0;
        CurrentColumn = 0;
        _leftColumn = 0;
        TrackColumn ();
        PositionCursor ();
        SetNeedsDisplay ();
    }

    /// <summary>
    ///     Called when the contents of the TextView change. E.g. when the user types text or deletes text. Raises the
    ///     <see cref="ContentsChanged"/> event.
    /// </summary>
    public virtual void OnContentsChanged ()
    {
        ContentsChanged?.Invoke (this, new ContentsChangedEventArgs (CurrentRow, CurrentColumn));

        ProcessInheritsPreviousColorScheme (CurrentRow, CurrentColumn);
        ProcessAutocomplete ();
    }

    /// <inheritdoc/>
    public override void OnDrawContent (Rectangle viewport)
    {
        _isDrawing = true;

        SetNormalColor ();

        (int width, int height) offB = OffSetBackground ();
        int right = Frame.Width + offB.width + RightOffset;
        int bottom = Frame.Height + offB.height + BottomOffset;
        var row = 0;

        for (int idxRow = _topRow; idxRow < _model.Count; idxRow++)
        {
            List<RuneCell> line = _model.GetLine (idxRow);
            int lineRuneCount = line.Count;
            var col = 0;

            Move (0, row);

            for (int idxCol = _leftColumn; idxCol < lineRuneCount; idxCol++)
            {
                Rune rune = idxCol >= lineRuneCount ? (Rune)' ' : line [idxCol].Rune;
                int cols = rune.GetColumns ();

                if (idxCol < line.Count && Selecting && PointInSelection (idxCol, idxRow))
                {
                    OnDrawSelectionColor (line, idxCol, idxRow);
                }
                else if (idxCol == CurrentColumn && idxRow == CurrentRow && !Selecting && !Used && HasFocus && idxCol < lineRuneCount)
                {
                    OnDrawUsedColor (line, idxCol, idxRow);
                }
                else if (ReadOnly)
                {
                    OnDrawReadOnlyColor (line, idxCol, idxRow);
                }
                else
                {
                    OnDrawNormalColor (line, idxCol, idxRow);
                }

                if (rune.Value == '\t')
                {
                    cols += TabWidth + 1;

                    if (col + cols > right)
                    {
                        cols = right - col;
                    }

                    for (var i = 0; i < cols; i++)
                    {
                        if (col + i < right)
                        {
                            AddRune (col + i, row, (Rune)' ');
                        }
                    }
                }
                else
                {
                    AddRune (col, row, rune);
                }

                if (!TextModel.SetCol (ref col, viewport.Right, cols))
                {
                    break;
                }

                if (idxCol + 1 < lineRuneCount && col + line [idxCol + 1].Rune.GetColumns () > right)
                {
                    break;
                }
            }

            if (col < right)
            {
                SetNormalColor ();
                ClearRegion (col, row, right, row + 1);
            }

            row++;
        }

        if (row < bottom)
        {
            SetNormalColor ();
            ClearRegion (viewport.Left, row, right, bottom);
        }

        PositionCursor ();

        _isDrawing = false;
    }

    /// <inheritdoc/>
    public override bool OnEnter (View view)
    {
        //TODO: Improve it by handling read only mode of the text field
        Application.Driver.SetCursorVisibility (DesiredCursorVisibility);

        return base.OnEnter (view);
    }

    /// <inheritdoc/>
    public override bool? OnInvokingKeyBindings (Key a)
    {
        if (!a.IsValid)
        {
            return false;
        }

        // Give autocomplete first opportunity to respond to key presses
        if (SelectedLength == 0 && Autocomplete.Suggestions.Count > 0 && Autocomplete.ProcessKey (a))
        {
            return true;
        }

        return base.OnInvokingKeyBindings (a);
    }

    /// <inheritdoc/>
    public override bool OnKeyUp (Key key)
    {
        if (key == Key.Space.WithCtrl)
        {
            return true;
        }

        return base.OnKeyUp (key);
    }

    /// <inheritdoc/>
    public override bool OnLeave (View view)
    {
        if (Application.MouseGrabView is { } && Application.MouseGrabView == this)
        {
            Application.UngrabMouse ();
        }

        return base.OnLeave (view);
    }

    /// <inheritdoc/>
    public override bool OnProcessKeyDown (Key a)
    {
        if (!CanFocus)
        {
            return true;
        }

        ResetColumnTrack ();

        // Ignore control characters and other special keys
        if (!a.IsKeyCodeAtoZ && (a.KeyCode < KeyCode.Space || a.KeyCode > KeyCode.CharMask))
        {
            return false;
        }

        InsertText (a);
        DoNeededAction ();

        return true;
    }

    /// <summary>Invoke the <see cref="UnwrappedCursorPosition"/> event with the unwrapped <see cref="CursorPosition"/>.</summary>
    public virtual void OnUnwrappedCursorPosition (int? cRow = null, int? cCol = null)
    {
        int? row = cRow is null ? CurrentRow : cRow;
        int? col = cCol is null ? CurrentColumn : cCol;

        if (cRow is null && cCol is null && _wordWrap)
        {
            row = _wrapManager!.GetModelLineFromWrappedLines (CurrentRow);
            col = _wrapManager.GetModelColFromWrappedLines (CurrentRow, CurrentColumn);
        }

        UnwrappedCursorPosition?.Invoke (this, new PointEventArgs (new Point ((int)col, (int)row)));
    }

    /// <summary>Paste the clipboard contents into the current selected position.</summary>
    public void Paste ()
    {
        if (_isReadOnly)
        {
            return;
        }

        SetWrapModel ();
        string? contents = Clipboard.Contents;

        if (_copyWithoutSelection && contents.FirstOrDefault (x => x == '\n' || x == '\r') == 0)
        {
            List<RuneCell> runeList = contents is null ? new List<RuneCell> () : TextModel.ToRuneCellList (contents);
            List<RuneCell> currentLine = GetCurrentLine ();

            _historyText.Add (new List<List<RuneCell>> { new (currentLine) }, CursorPosition);

            List<List<RuneCell>> addedLine = new () { new List<RuneCell> (currentLine), runeList };

            _historyText.Add (
                              new List<List<RuneCell>> (addedLine),
                              CursorPosition,
                              HistoryText.LineStatus.Added
                             );

            _model.AddLine (CurrentRow, runeList);
            CurrentRow++;

            _historyText.Add (
                              new List<List<RuneCell>> { new (GetCurrentLine ()) },
                              CursorPosition,
                              HistoryText.LineStatus.Replaced
                             );

            SetNeedsDisplay ();
            OnContentsChanged ();
        }
        else
        {
            if (Selecting)
            {
                ClearRegion ();
            }

            _copyWithoutSelection = false;
            InsertAllText (contents);

            if (Selecting)
            {
                _historyText.ReplaceLast (
                                          new List<List<RuneCell>> { new (GetCurrentLine ()) },
                                          CursorPosition,
                                          HistoryText.LineStatus.Original
                                         );
            }

            SetNeedsDisplay ();
        }

        UpdateWrapModel ();
        Selecting = false;
        DoNeededAction ();
    }

    /// <summary>Positions the cursor on the current row and column</summary>
    public override void PositionCursor ()
    {
        ProcessAutocomplete ();

        if (!CanFocus || !Enabled || Application.Driver is null)
        {
            return;
        }

        if (Selecting)
        {
            // BUGBUG: customized rect aren't supported now because the Redraw isn't using the Intersect method.
            //var minRow = Math.Min (Math.Max (Math.Min (selectionStartRow, currentRow) - topRow, 0), Frame.Height);
            //var maxRow = Math.Min (Math.Max (Math.Max (selectionStartRow, currentRow) - topRow, 0), Frame.Height);
            //SetNeedsDisplay (new (0, minRow, Frame.Width, maxRow));
            SetNeedsDisplay ();
        }

        List<RuneCell> line = _model.GetLine (CurrentRow);
        var col = 0;

        if (line.Count > 0)
        {
            for (int idx = _leftColumn; idx < line.Count; idx++)
            {
                if (idx >= CurrentColumn)
                {
                    break;
                }

                int cols = line [idx].Rune.GetColumns ();

                if (line [idx].Rune.Value == '\t')
                {
                    cols += TabWidth + 1;
                }

                if (!TextModel.SetCol (ref col, Frame.Width, cols))
                {
                    col = CurrentColumn;

                    break;
                }
            }
        }

        int posX = CurrentColumn - _leftColumn;
        int posY = CurrentRow - _topRow;

        if (posX > -1 && col >= posX && posX < Frame.Width - RightOffset && _topRow <= CurrentRow && posY < Frame.Height - BottomOffset)
        {
            ResetCursorVisibility ();
            Move (col, CurrentRow - _topRow);
        }
        else
        {
            SaveCursorVisibility ();
        }
    }

    /// <summary>Redoes the latest changes.</summary>
    public void Redo ()
    {
        if (ReadOnly)
        {
            return;
        }

        _historyText.Redo ();
    }

    /// <summary>Replaces all the text based on the match case.</summary>
    /// <param name="textToFind">The text to find.</param>
    /// <param name="matchCase">The match case setting.</param>
    /// <param name="matchWholeWord">The match whole word setting.</param>
    /// <param name="textToReplace">The text to replace.</param>
    /// <returns><c>true</c>If the text was found.<c>false</c>otherwise.</returns>
    public bool ReplaceAllText (
        string textToFind,
        bool matchCase = false,
        bool matchWholeWord = false,
        string? textToReplace = null
    )
    {
        if (_isReadOnly || _model.Count == 0)
        {
            return false;
        }

        SetWrapModel ();
        ResetContinuousFind ();

        (Point current, bool found) foundPos =
            _model.ReplaceAllText (textToFind, matchCase, matchWholeWord, textToReplace);

        return SetFoundText (textToFind, foundPos, textToReplace, false, true);
    }

    /// <summary>
    ///     Will scroll the <see cref="TextView"/> to display the specified row at the top if <paramref name="isRow"/> is
    ///     true or will scroll the <see cref="TextView"/> to display the specified column at the left if
    ///     <paramref name="isRow"/> is false.
    /// </summary>
    /// <param name="idx">
    ///     Row that should be displayed at the top or Column that should be displayed at the left, if the value
    ///     is negative it will be reset to zero
    /// </param>
    /// <param name="isRow">If true (default) the <paramref name="idx"/> is a row, column otherwise.</param>
    public void ScrollTo (int idx, bool isRow = true)
    {
        if (idx < 0)
        {
            idx = 0;
        }

        if (isRow)
        {
            _topRow = Math.Max (idx > _model.Count - 1 ? _model.Count - 1 : idx, 0);
        }
        else if (!_wordWrap)
        {
            int maxlength =
                _model.GetMaxVisibleLine (_topRow, _topRow + Frame.Height + RightOffset, TabWidth);
            _leftColumn = Math.Max (!_wordWrap && idx > maxlength - 1 ? maxlength - 1 : idx, 0);
        }

        SetNeedsDisplay ();
    }

    /// <summary>Select all text.</summary>
    public void SelectAll ()
    {
        if (_model.Count == 0)
        {
            return;
        }

        StartSelecting ();
        _selectionStartColumn = 0;
        _selectionStartRow = 0;
        CurrentColumn = _model.GetLine (_model.Count - 1).Count;
        CurrentRow = _model.Count - 1;
        SetNeedsDisplay ();
    }

    ///// <summary>Raised when the <see cref="Text"/> property of the <see cref="TextView"/> changes.</summary>
    ///// <remarks>
    /////     The <see cref="Text"/> property of <see cref="TextView"/> only changes when it is explicitly set, not as the
    /////     user types. To be notified as the user changes the contents of the TextView see <see cref="IsDirty"/>.
    ///// </remarks>
    //public event EventHandler? TextChanged;

    /// <summary>Undoes the latest changes.</summary>
    public void Undo ()
    {
        if (ReadOnly)
        {
            return;
        }

        _historyText.Undo ();
    }

    /// <summary>Invoked with the unwrapped <see cref="CursorPosition"/>.</summary>
    public event EventHandler<PointEventArgs>? UnwrappedCursorPosition;

    /// <summary>
    ///     Sets the <see cref="View.Driver"/> to an appropriate color for rendering the given <paramref name="idxCol"/>
    ///     of the current <paramref name="line"/>. Override to provide custom coloring by calling
    ///     <see cref="ConsoleDriver.SetAttribute(Attribute)"/> Defaults to <see cref="ColorScheme.Normal"/>.
    /// </summary>
    /// <param name="line">The line.</param>
    /// <param name="idxCol">The col index.</param>
    /// <param name="idxRow">The row index.</param>
    protected virtual void OnDrawNormalColor (List<RuneCell> line, int idxCol, int idxRow)
    {
        (int Row, int Col) unwrappedPos = GetUnwrappedPosition (idxRow, idxCol);
        var ev = new RuneCellEventArgs (line, idxCol, unwrappedPos);
        DrawNormalColor?.Invoke (this, ev);

        if (line [idxCol].ColorScheme is { })
        {
            ColorScheme? colorScheme = line [idxCol].ColorScheme;
            Driver.SetAttribute (Enabled ? colorScheme!.Focus : colorScheme!.Disabled);
        }
        else
        {
            Driver.SetAttribute (GetNormalColor ());
        }
    }

    /// <summary>
    ///     Sets the <see cref="View.Driver"/> to an appropriate color for rendering the given <paramref name="idxCol"/>
    ///     of the current <paramref name="line"/>. Override to provide custom coloring by calling
    ///     <see cref="ConsoleDriver.SetAttribute(Attribute)"/> Defaults to <see cref="ColorScheme.Focus"/>.
    /// </summary>
    /// <param name="line">The line.</param>
    /// <param name="idxCol">The col index.</param>
    /// ///
    /// <param name="idxRow">The row index.</param>
    protected virtual void OnDrawReadOnlyColor (List<RuneCell> line, int idxCol, int idxRow)
    {
        (int Row, int Col) unwrappedPos = GetUnwrappedPosition (idxRow, idxCol);
        var ev = new RuneCellEventArgs (line, idxCol, unwrappedPos);
        DrawReadOnlyColor?.Invoke (this, ev);

        ColorScheme? colorScheme = line [idxCol].ColorScheme is { } ? line [idxCol].ColorScheme : ColorScheme;
        Attribute attribute;

        if (colorScheme!.Disabled.Foreground == colorScheme.Focus.Background)
        {
            attribute = new Attribute (colorScheme.Focus.Foreground, colorScheme.Focus.Background);
        }
        else
        {
            attribute = new Attribute (colorScheme.Disabled.Foreground, colorScheme.Focus.Background);
        }

        Driver.SetAttribute (attribute);
    }

    /// <summary>
    ///     Sets the <see cref="View.Driver"/> to an appropriate color for rendering the given <paramref name="idxCol"/>
    ///     of the current <paramref name="line"/>. Override to provide custom coloring by calling
    ///     <see cref="ConsoleDriver.SetAttribute(Attribute)"/> Defaults to <see cref="ColorScheme.Focus"/>.
    /// </summary>
    /// <param name="line">The line.</param>
    /// <param name="idxCol">The col index.</param>
    /// ///
    /// <param name="idxRow">The row index.</param>
    protected virtual void OnDrawSelectionColor (List<RuneCell> line, int idxCol, int idxRow)
    {
        (int Row, int Col) unwrappedPos = GetUnwrappedPosition (idxRow, idxCol);
        var ev = new RuneCellEventArgs (line, idxCol, unwrappedPos);
        DrawSelectionColor?.Invoke (this, ev);

        if (line [idxCol].ColorScheme is { })
        {
            ColorScheme? colorScheme = line [idxCol].ColorScheme;

            Driver.SetAttribute (
                                 new Attribute (colorScheme!.Focus.Background, colorScheme.Focus.Foreground)
                                );
        }
        else
        {
            Driver.SetAttribute (
                                 new Attribute (
                                                ColorScheme.Focus.Background,
                                                ColorScheme.Focus.Foreground
                                               )
                                );
        }
    }

    /// <summary>
    ///     Sets the <see cref="View.Driver"/> to an appropriate color for rendering the given <paramref name="idxCol"/>
    ///     of the current <paramref name="line"/>. Override to provide custom coloring by calling
    ///     <see cref="ConsoleDriver.SetAttribute(Attribute)"/> Defaults to <see cref="ColorScheme.HotFocus"/>.
    /// </summary>
    /// <param name="line">The line.</param>
    /// <param name="idxCol">The col index.</param>
    /// ///
    /// <param name="idxRow">The row index.</param>
    protected virtual void OnDrawUsedColor (List<RuneCell> line, int idxCol, int idxRow)
    {
        (int Row, int Col) unwrappedPos = GetUnwrappedPosition (idxRow, idxCol);
        var ev = new RuneCellEventArgs (line, idxCol, unwrappedPos);
        DrawUsedColor?.Invoke (this, ev);

        if (line [idxCol].ColorScheme is { })
        {
            ColorScheme? colorScheme = line [idxCol].ColorScheme;
            SetValidUsedColor (colorScheme!);
        }
        else
        {
            SetValidUsedColor (ColorScheme);
        }
    }

    /// <summary>
    ///     Sets the driver to the default color for the control where no text is being rendered. Defaults to
    ///     <see cref="ColorScheme.Normal"/>.
    /// </summary>
    protected virtual void SetNormalColor () { Driver.SetAttribute (GetNormalColor ()); }

    private void Adjust ()
    {
        (int width, int height) offB = OffSetBackground ();
        List<RuneCell> line = GetCurrentLine ();
        bool need = NeedsDisplay || _wrapNeeded || !Used;
        (int size, int length) tSize = TextModel.DisplaySize (line, -1, -1, false, TabWidth);
        (int size, int length) dSize = TextModel.DisplaySize (line, _leftColumn, CurrentColumn, true, TabWidth);

        if (!_wordWrap && CurrentColumn < _leftColumn)
        {
            _leftColumn = CurrentColumn;
            need = true;
        }
        else if (!_wordWrap
                 && (CurrentColumn - _leftColumn + RightOffset > Frame.Width + offB.width || dSize.size + RightOffset >= Frame.Width + offB.width))
        {
            _leftColumn = TextModel.CalculateLeftColumn (
                                                         line,
                                                         _leftColumn,
                                                         CurrentColumn,
                                                         Frame.Width + offB.width - RightOffset,
                                                         TabWidth
                                                        );
            need = true;
        }
        else if ((_wordWrap && _leftColumn > 0) || (dSize.size + RightOffset < Frame.Width + offB.width && tSize.size + RightOffset < Frame.Width + offB.width))
        {
            if (_leftColumn > 0)
            {
                _leftColumn = 0;
                need = true;
            }
        }

        if (CurrentRow < _topRow)
        {
            _topRow = CurrentRow;
            need = true;
        }
        else if (CurrentRow - _topRow + BottomOffset >= Frame.Height + offB.height)
        {
            _topRow = Math.Min (Math.Max (CurrentRow - Frame.Height + 1 + BottomOffset, 0), CurrentRow);
            need = true;
        }
        else if (_topRow > 0 && CurrentRow < _topRow)
        {
            _topRow = Math.Max (_topRow - 1, 0);
            need = true;
        }

        if (need)
        {
            if (_wrapNeeded)
            {
                WrapTextModel ();
                _wrapNeeded = false;
            }

            SetNeedsDisplay ();
        }
        else
        {
            PositionCursor ();
        }

        OnUnwrappedCursorPosition ();
    }

    private void AppendClipboard (string text) { Clipboard.Contents += text; }

    private MenuBarItem BuildContextMenuBarItem ()
    {
        return new MenuBarItem (
                                new MenuItem []
                                {
                                    new (
                                         Strings.ctxSelectAll,
                                         "",
                                         SelectAll,
                                         null,
                                         null,
                                         (KeyCode)KeyBindings.GetKeyFromCommands (Command.SelectAll)
                                        ),
                                    new (
                                         Strings.ctxDeleteAll,
                                         "",
                                         DeleteAll,
                                         null,
                                         null,
                                         (KeyCode)KeyBindings.GetKeyFromCommands (Command.DeleteAll)
                                        ),
                                    new (
                                         Strings.ctxCopy,
                                         "",
                                         Copy,
                                         null,
                                         null,
                                         (KeyCode)KeyBindings.GetKeyFromCommands (Command.Copy)
                                        ),
                                    new (
                                         Strings.ctxCut,
                                         "",
                                         Cut,
                                         null,
                                         null,
                                         (KeyCode)KeyBindings.GetKeyFromCommands (Command.Cut)
                                        ),
                                    new (
                                         Strings.ctxPaste,
                                         "",
                                         Paste,
                                         null,
                                         null,
                                         (KeyCode)KeyBindings.GetKeyFromCommands (Command.Paste)
                                        ),
                                    new (
                                         Strings.ctxUndo,
                                         "",
                                         Undo,
                                         null,
                                         null,
                                         (KeyCode)KeyBindings.GetKeyFromCommands (Command.Undo)
                                        ),
                                    new (
                                         Strings.ctxRedo,
                                         "",
                                         Redo,
                                         null,
                                         null,
                                         (KeyCode)KeyBindings.GetKeyFromCommands (Command.Redo)
                                        )
                                }
                               );
    }

    private void ClearRegion (int left, int top, int right, int bottom)
    {
        for (int row = top; row < bottom; row++)
        {
            Move (left, row);

            for (int col = left; col < right; col++)
            {
                AddRune (col, row, (Rune)' ');
            }
        }
    }

    //
    // Clears the contents of the selected region
    //
    private void ClearRegion ()
    {
        SetWrapModel ();

        long start, end;
        long currentEncoded = ((long)(uint)CurrentRow << 32) | (uint)CurrentColumn;
        GetEncodedRegionBounds (out start, out end);
        var startRow = (int)(start >> 32);
        var maxrow = (int)(end >> 32);
        var startCol = (int)(start & 0xffffffff);
        var endCol = (int)(end & 0xffffffff);
        List<RuneCell> line = _model.GetLine (startRow);

        _historyText.Add (new List<List<RuneCell>> { new (line) }, new Point (startCol, startRow));

        List<List<RuneCell>> removedLines = new ();

        if (startRow == maxrow)
        {
            removedLines.Add (new List<RuneCell> (line));

            line.RemoveRange (startCol, endCol - startCol);
            CurrentColumn = startCol;

            if (_wordWrap)
            {
                SetNeedsDisplay ();
            }
            else
            {
                //QUESTION: Is the below comment still relevant?
                // BUGBUG: customized rect aren't supported now because the Redraw isn't using the Intersect method.
                //SetNeedsDisplay (new (0, startRow - topRow, Frame.Width, startRow - topRow + 1));
                SetNeedsDisplay ();
            }

            _historyText.Add (
                              new List<List<RuneCell>> (removedLines),
                              CursorPosition,
                              HistoryText.LineStatus.Removed
                             );

            UpdateWrapModel ();

            return;
        }

        removedLines.Add (new List<RuneCell> (line));

        line.RemoveRange (startCol, line.Count - startCol);
        List<RuneCell> line2 = _model.GetLine (maxrow);
        line.AddRange (line2.Skip (endCol));

        for (int row = startRow + 1; row <= maxrow; row++)
        {
            removedLines.Add (new List<RuneCell> (_model.GetLine (startRow + 1)));

            _model.RemoveLine (startRow + 1);
        }

        if (currentEncoded == end)
        {
            CurrentRow -= maxrow - startRow;
        }

        CurrentColumn = startCol;

        _historyText.Add (
                          new List<List<RuneCell>> (removedLines),
                          CursorPosition,
                          HistoryText.LineStatus.Removed
                         );

        UpdateWrapModel ();

        SetNeedsDisplay ();
    }

    private void ClearSelectedRegion ()
    {
        SetWrapModel ();

        if (!_isReadOnly)
        {
            ClearRegion ();
        }

        UpdateWrapModel ();
        Selecting = false;
        DoNeededAction ();
    }

    private void ContextMenu_KeyChanged (object sender, KeyChangedEventArgs e) { KeyBindings.Replace (e.OldKey, e.NewKey); }

    private bool DeleteTextBackwards ()
    {
        SetWrapModel ();

        if (CurrentColumn > 0)
        {
            // Delete backwards 
            List<RuneCell> currentLine = GetCurrentLine ();

            _historyText.Add (new List<List<RuneCell>> { new (currentLine) }, CursorPosition);

            currentLine.RemoveAt (CurrentColumn - 1);

            if (_wordWrap)
            {
                _wrapNeeded = true;
            }

            CurrentColumn--;

            _historyText.Add (
                              new List<List<RuneCell>> { new (currentLine) },
                              CursorPosition,
                              HistoryText.LineStatus.Replaced
                             );

            if (CurrentColumn < _leftColumn)
            {
                _leftColumn--;
                SetNeedsDisplay ();
            }
            else
            {
                // BUGBUG: customized rect aren't supported now because the Redraw isn't using the Intersect method.
                //SetNeedsDisplay (new (0, currentRow - topRow, 1, Frame.Width));
                SetNeedsDisplay ();
            }
        }
        else
        {
            // Merges the current line with the previous one.
            if (CurrentRow == 0)
            {
                return true;
            }

            int prowIdx = CurrentRow - 1;
            List<RuneCell> prevRow = _model.GetLine (prowIdx);

            _historyText.Add (new List<List<RuneCell>> { new (prevRow) }, CursorPosition);

            List<List<RuneCell>> removedLines = new () { new List<RuneCell> (prevRow) };

            removedLines.Add (new List<RuneCell> (GetCurrentLine ()));

            _historyText.Add (
                              removedLines,
                              new Point (CurrentColumn, prowIdx),
                              HistoryText.LineStatus.Removed
                             );

            int prevCount = prevRow.Count;
            _model.GetLine (prowIdx).AddRange (GetCurrentLine ());
            _model.RemoveLine (CurrentRow);

            if (_wordWrap)
            {
                _wrapNeeded = true;
            }

            CurrentRow--;

            _historyText.Add (
                              new List<List<RuneCell>> { GetCurrentLine () },
                              new Point (CurrentColumn, prowIdx),
                              HistoryText.LineStatus.Replaced
                             );

            CurrentColumn = prevCount;
            SetNeedsDisplay ();
        }

        UpdateWrapModel ();

        return false;
    }

    private bool DeleteTextForwards ()
    {
        SetWrapModel ();

        List<RuneCell> currentLine = GetCurrentLine ();

        if (CurrentColumn == currentLine.Count)
        {
            if (CurrentRow + 1 == _model.Count)
            {
                UpdateWrapModel ();

                return true;
            }

            _historyText.Add (new List<List<RuneCell>> { new (currentLine) }, CursorPosition);

            List<List<RuneCell>> removedLines = new () { new List<RuneCell> (currentLine) };

            List<RuneCell> nextLine = _model.GetLine (CurrentRow + 1);

            removedLines.Add (new List<RuneCell> (nextLine));

            _historyText.Add (removedLines, CursorPosition, HistoryText.LineStatus.Removed);

            currentLine.AddRange (nextLine);
            _model.RemoveLine (CurrentRow + 1);

            _historyText.Add (
                              new List<List<RuneCell>> { new (currentLine) },
                              CursorPosition,
                              HistoryText.LineStatus.Replaced
                             );

            if (_wordWrap)
            {
                _wrapNeeded = true;
            }

            DoSetNeedsDisplay (new (0, CurrentRow - _topRow, Frame.Width, CurrentRow - _topRow + 1));
        }
        else
        {
            _historyText.Add ([[..currentLine]], CursorPosition);

            currentLine.RemoveAt (CurrentColumn);

            _historyText.Add (
                              [[..currentLine]],
                              CursorPosition,
                              HistoryText.LineStatus.Replaced
                             );

            if (_wordWrap)
            {
                _wrapNeeded = true;
            }

            DoSetNeedsDisplay (
                               new (
                                    CurrentColumn - _leftColumn,
                                    CurrentRow - _topRow,
                                    Frame.Width,
                                    CurrentRow - _topRow + 1
                                   )
                              );
        }

        UpdateWrapModel ();

        return false;
    }

    private void DoNeededAction ()
    {
        if (NeedsDisplay)
        {
            Adjust ();
        }
        else
        {
            PositionCursor ();
        }
    }

    private void DoSetNeedsDisplay (Rectangle rect)
    {
        if (_wrapNeeded)
        {
            SetNeedsDisplay ();
        }
        else
        {
            // BUGBUG: customized rect aren't supported now because the Redraw isn't using the Intersect method.
            //SetNeedsDisplay (rect);
            SetNeedsDisplay ();
        }
    }

    private IEnumerable<(int col, int row, RuneCell rune)> ForwardIterator (int col, int row)
    {
        if (col < 0 || row < 0)
        {
            yield break;
        }

        if (row >= _model.Count)
        {
            yield break;
        }

        List<RuneCell> line = GetCurrentLine ();

        if (col >= line.Count)
        {
            yield break;
        }

        while (row < _model.Count)
        {
            for (int c = col; c < line.Count; c++)
            {
                yield return (c, row, line [c]);
            }

            col = 0;
            row++;
            line = GetCurrentLine ();
        }
    }

    private void GenerateSuggestions ()
    {
        List<RuneCell> currentLine = GetCurrentLine ();
        int cursorPosition = Math.Min (CurrentColumn, currentLine.Count);

        Autocomplete.Context = new AutocompleteContext (
                                                        currentLine,
                                                        cursorPosition,
                                                        Autocomplete.Context != null
                                                            ? Autocomplete.Context.Canceled
                                                            : false
                                                       );

        Autocomplete.GenerateSuggestions (
                                          Autocomplete.Context
                                         );
    }

    // Returns an encoded region start..end (top 32 bits are the row, low32 the column)
    private void GetEncodedRegionBounds (
        out long start,
        out long end,
        int? startRow = null,
        int? startCol = null,
        int? cRow = null,
        int? cCol = null
    )
    {
        long selection;
        long point;

        if (startRow is null || startCol is null || cRow is null || cCol is null)
        {
            selection = ((long)(uint)_selectionStartRow << 32) | (uint)_selectionStartColumn;
            point = ((long)(uint)CurrentRow << 32) | (uint)CurrentColumn;
        }
        else
        {
            selection = ((long)(uint)startRow << 32) | (uint)startCol;
            point = ((long)(uint)cRow << 32) | (uint)cCol;
        }

        if (selection > point)
        {
            start = point;
            end = selection;
        }
        else
        {
            start = selection;
            end = point;
        }
    }

    //
    // Returns a string with the text in the selected 
    // region.
    //
    private string GetRegion (
        int? sRow = null,
        int? sCol = null,
        int? cRow = null,
        int? cCol = null,
        TextModel? model = null
    )
    {
        long start, end;
        GetEncodedRegionBounds (out start, out end, sRow, sCol, cRow, cCol);

        if (start == end)
        {
            return string.Empty;
        }

        var startRow = (int)(start >> 32);
        var maxrow = (int)(end >> 32);
        var startCol = (int)(start & 0xffffffff);
        var endCol = (int)(end & 0xffffffff);
        List<RuneCell> line = model is null ? _model.GetLine (startRow) : model.GetLine (startRow);

        if (startRow == maxrow)
        {
            return StringFromRunes (line.GetRange (startCol, endCol - startCol));
        }

        string res = StringFromRunes (line.GetRange (startCol, line.Count - startCol));

        for (int row = startRow + 1; row < maxrow; row++)
        {
            res = res
                  + Environment.NewLine
                  + StringFromRunes (
                                     model == null
                                         ? _model.GetLine (row)
                                         : model.GetLine (row)
                                    );
        }

        line = model is null ? _model.GetLine (maxrow) : model.GetLine (maxrow);
        res = res + Environment.NewLine + StringFromRunes (line.GetRange (0, endCol));

        return res;
    }

    private int GetSelectedLength () { return SelectedText.Length; }

    private string GetSelectedRegion ()
    {
        int cRow = CurrentRow;
        int cCol = CurrentColumn;
        int startRow = _selectionStartRow;
        int startCol = _selectionStartColumn;
        TextModel model = _model;

        if (_wordWrap)
        {
            cRow = _wrapManager!.GetModelLineFromWrappedLines (CurrentRow);
            cCol = _wrapManager.GetModelColFromWrappedLines (CurrentRow, CurrentColumn);
            startRow = _wrapManager.GetModelLineFromWrappedLines (_selectionStartRow);
            startCol = _wrapManager.GetModelColFromWrappedLines (_selectionStartRow, _selectionStartColumn);
            model = _wrapManager.Model;
        }

        OnUnwrappedCursorPosition (cRow, cCol);

        return GetRegion (startRow, startCol, cRow, cCol, model);
    }

    private (int Row, int Col) GetUnwrappedPosition (int line, int col)
    {
        if (WordWrap)
        {
            return new ValueTuple<int, int> (
                                             _wrapManager!.GetModelLineFromWrappedLines (line),
                                             _wrapManager.GetModelColFromWrappedLines (line, col)
                                            );
        }

        return new ValueTuple<int, int> (line, col);
    }

    private void HistoryText_ChangeText (object sender, HistoryText.HistoryTextItem obj)
    {
        SetWrapModel ();

        if (obj is { })
        {
            int startLine = obj.CursorPosition.Y;

            if (obj.RemovedOnAdded is { })
            {
                int offset;

                if (obj.IsUndoing)
                {
                    offset = Math.Max (obj.RemovedOnAdded.Lines.Count - obj.Lines.Count, 1);
                }
                else
                {
                    offset = obj.RemovedOnAdded.Lines.Count - 1;
                }

                for (var i = 0; i < offset; i++)
                {
                    if (Lines > obj.RemovedOnAdded.CursorPosition.Y)
                    {
                        _model.RemoveLine (obj.RemovedOnAdded.CursorPosition.Y);
                    }
                    else
                    {
                        break;
                    }
                }
            }

            for (var i = 0; i < obj.Lines.Count; i++)
            {
                if (i == 0)
                {
                    _model.ReplaceLine (startLine, obj.Lines [i]);
                }
                else if ((obj.IsUndoing && obj.LineStatus == HistoryText.LineStatus.Removed)
                         || (!obj.IsUndoing && obj.LineStatus == HistoryText.LineStatus.Added))
                {
                    _model.AddLine (startLine, obj.Lines [i]);
                }
                else if (Lines > obj.CursorPosition.Y + 1)
                {
                    _model.RemoveLine (obj.CursorPosition.Y + 1);
                }

                startLine++;
            }

            CursorPosition = obj.FinalCursorPosition;
        }

        UpdateWrapModel ();

        Adjust ();
        OnContentsChanged ();
    }

    private void Insert (RuneCell cell)
    {
        List<RuneCell> line = GetCurrentLine ();

        if (Used)
        {
            line.Insert (Math.Min (CurrentColumn, line.Count), cell);
        }
        else
        {
            if (CurrentColumn < line.Count)
            {
                line.RemoveAt (CurrentColumn);
            }

            line.Insert (Math.Min (CurrentColumn, line.Count), cell);
        }

        int prow = CurrentRow - _topRow;

        if (!_wrapNeeded)
        {
            // BUGBUG: customized rect aren't supported now because the Redraw isn't using the Intersect method.
            //SetNeedsDisplay (new (0, prow, Math.Max (Frame.Width, 0), Math.Max (prow + 1, 0)));
            SetNeedsDisplay ();
        }
    }

    private void InsertAllText (string text)
    {
        if (string.IsNullOrEmpty (text))
        {
            return;
        }

        List<List<RuneCell>> lines = TextModel.StringToLinesOfRuneCells (text);

        if (lines.Count == 0)
        {
            return;
        }

        SetWrapModel ();

        List<RuneCell> line = GetCurrentLine ();

        _historyText.Add (new List<List<RuneCell>> { new (line) }, CursorPosition);

        // Optimize single line
        if (lines.Count == 1)
        {
            line.InsertRange (CurrentColumn, lines [0]);
            CurrentColumn += lines [0].Count;

            _historyText.Add (
                              new List<List<RuneCell>> { new (line) },
                              CursorPosition,
                              HistoryText.LineStatus.Replaced
                             );

            if (!_wordWrap && CurrentColumn - _leftColumn > Frame.Width)
            {
                _leftColumn = Math.Max (CurrentColumn - Frame.Width + 1, 0);
            }

            if (_wordWrap)
            {
                SetNeedsDisplay ();
            }
            else
            {
                // BUGBUG: customized rect aren't supported now because the Redraw isn't using the Intersect method.
                //SetNeedsDisplay (new (0, currentRow - topRow, Frame.Width, Math.Max (currentRow - topRow + 1, 0)));
                SetNeedsDisplay ();
            }

            UpdateWrapModel ();

            OnContentsChanged ();

            return;
        }

        List<RuneCell>? rest = null;
        var lastp = 0;

        if (_model.Count > 0 && line.Count > 0 && !_copyWithoutSelection)
        {
            // Keep a copy of the rest of the line
            int restCount = line.Count - CurrentColumn;
            rest = line.GetRange (CurrentColumn, restCount);
            line.RemoveRange (CurrentColumn, restCount);
        }

        // First line is inserted at the current location, the rest is appended
        line.InsertRange (CurrentColumn, lines [0]);

        //model.AddLine (currentRow, lines [0]);

        List<List<RuneCell>> addedLines = new () { new List<RuneCell> (line) };

        for (var i = 1; i < lines.Count; i++)
        {
            _model.AddLine (CurrentRow + i, lines [i]);

            addedLines.Add (new List<RuneCell> (lines [i]));
        }

        if (rest is { })
        {
            List<RuneCell> last = _model.GetLine (CurrentRow + lines.Count - 1);
            lastp = last.Count;
            last.InsertRange (last.Count, rest);

            addedLines.Last ().InsertRange (addedLines.Last ().Count, rest);
        }

        _historyText.Add (addedLines, CursorPosition, HistoryText.LineStatus.Added);

        // Now adjust column and row positions
        CurrentRow += lines.Count - 1;
        CurrentColumn = rest is { } ? lastp : lines [lines.Count - 1].Count;
        Adjust ();

        _historyText.Add (
                          new List<List<RuneCell>> { new (line) },
                          CursorPosition,
                          HistoryText.LineStatus.Replaced
                         );

        UpdateWrapModel ();
        OnContentsChanged ();
    }

    private bool InsertText (Key a, ColorScheme? colorScheme = null)
    {
        //So that special keys like tab can be processed
        if (_isReadOnly)
        {
            return true;
        }

        SetWrapModel ();

        _historyText.Add (new List<List<RuneCell>> { new (GetCurrentLine ()) }, CursorPosition);

        if (Selecting)
        {
            ClearSelectedRegion ();
        }

        if ((uint)a.KeyCode == '\n')
        {
            _model.AddLine (CurrentRow + 1, new List<RuneCell> ());
            CurrentRow++;
            CurrentColumn = 0;
        }
        else if ((uint)a.KeyCode == '\r')
        {
            CurrentColumn = 0;
        }
        else
        {
            if (Used)
            {
                Insert (new RuneCell { Rune = a.AsRune, ColorScheme = colorScheme });
                CurrentColumn++;

                if (CurrentColumn >= _leftColumn + Frame.Width)
                {
                    _leftColumn++;
                    SetNeedsDisplay ();
                }
            }
            else
            {
                Insert (new RuneCell { Rune = a.AsRune, ColorScheme = colorScheme });
                CurrentColumn++;
            }
        }

        _historyText.Add (
                          new List<List<RuneCell>> { new (GetCurrentLine ()) },
                          CursorPosition,
                          HistoryText.LineStatus.Replaced
                         );

        UpdateWrapModel ();
        OnContentsChanged ();

        return true;
    }

    private void KillToEndOfLine ()
    {
        if (_isReadOnly)
        {
            return;
        }

        if (_model.Count == 1 && GetCurrentLine ().Count == 0)
        {
            // Prevents from adding line feeds if there is no more lines.
            return;
        }

        SetWrapModel ();

        List<RuneCell> currentLine = GetCurrentLine ();
        var setLastWasKill = true;

        if (currentLine.Count > 0 && CurrentColumn == currentLine.Count)
        {
            UpdateWrapModel ();

            DeleteTextForwards ();

            return;
        }

        _historyText.Add (new List<List<RuneCell>> { new (currentLine) }, CursorPosition);

        if (currentLine.Count == 0)
        {
            if (CurrentRow < _model.Count - 1)
            {
                List<List<RuneCell>> removedLines = new () { new List<RuneCell> (currentLine) };

                _model.RemoveLine (CurrentRow);

                removedLines.Add (new List<RuneCell> (GetCurrentLine ()));

                _historyText.Add (
                                  new List<List<RuneCell>> (removedLines),
                                  CursorPosition,
                                  HistoryText.LineStatus.Removed
                                 );
            }

            if (_model.Count > 0 || _lastWasKill)
            {
                string val = Environment.NewLine;

                if (_lastWasKill)
                {
                    AppendClipboard (val);
                }
                else
                {
                    SetClipboard (val);
                }
            }

            if (_model.Count == 0)
            {
                // Prevents from adding line feeds if there is no more lines.
                setLastWasKill = false;
            }
        }
        else
        {
            int restCount = currentLine.Count - CurrentColumn;
            List<RuneCell> rest = currentLine.GetRange (CurrentColumn, restCount);
            var val = string.Empty;
            val += StringFromRunes (rest);

            if (_lastWasKill)
            {
                AppendClipboard (val);
            }
            else
            {
                SetClipboard (val);
            }

            currentLine.RemoveRange (CurrentColumn, restCount);
        }

        _historyText.Add (
                          [[..GetCurrentLine ()]],
                          CursorPosition,
                          HistoryText.LineStatus.Replaced
                         );

        UpdateWrapModel ();

        DoSetNeedsDisplay (new (0, CurrentRow - _topRow, Frame.Width, Frame.Height));

        _lastWasKill = setLastWasKill;
        DoNeededAction ();
    }

    private void KillToStartOfLine ()
    {
        if (_isReadOnly)
        {
            return;
        }

        if (_model.Count == 1 && GetCurrentLine ().Count == 0)
        {
            // Prevents from adding line feeds if there is no more lines.
            return;
        }

        SetWrapModel ();

        List<RuneCell> currentLine = GetCurrentLine ();
        var setLastWasKill = true;

        if (currentLine.Count > 0 && CurrentColumn == 0)
        {
            UpdateWrapModel ();

            DeleteTextBackwards ();

            return;
        }

        _historyText.Add ([[..currentLine]], CursorPosition);

        if (currentLine.Count == 0)
        {
            if (CurrentRow > 0)
            {
                _model.RemoveLine (CurrentRow);

                if (_model.Count > 0 || _lastWasKill)
                {
                    string val = Environment.NewLine;

                    if (_lastWasKill)
                    {
                        AppendClipboard (val);
                    }
                    else
                    {
                        SetClipboard (val);
                    }
                }

                if (_model.Count == 0)
                {
                    // Prevents from adding line feeds if there is no more lines.
                    setLastWasKill = false;
                }

                CurrentRow--;
                currentLine = _model.GetLine (CurrentRow);

                List<List<RuneCell>> removedLine =
                [
                    [..currentLine],
                    []
                ];

                _historyText.Add (
                                  [..removedLine],
                                  CursorPosition,
                                  HistoryText.LineStatus.Removed
                                 );

                CurrentColumn = currentLine.Count;
            }
        }
        else
        {
            int restCount = CurrentColumn;
            List<RuneCell> rest = currentLine.GetRange (0, restCount);
            var val = string.Empty;
            val += StringFromRunes (rest);

            if (_lastWasKill)
            {
                AppendClipboard (val);
            }
            else
            {
                SetClipboard (val);
            }

            currentLine.RemoveRange (0, restCount);
            CurrentColumn = 0;
        }

        _historyText.Add (
                          [[..GetCurrentLine ()]],
                          CursorPosition,
                          HistoryText.LineStatus.Replaced
                         );

        UpdateWrapModel ();

        DoSetNeedsDisplay (new (0, CurrentRow - _topRow, Frame.Width, Frame.Height));

        _lastWasKill = setLastWasKill;
        DoNeededAction ();
    }

    private void KillWordBackward ()
    {
        if (_isReadOnly)
        {
            return;
        }

        SetWrapModel ();

        List<RuneCell> currentLine = GetCurrentLine ();

        _historyText.Add ([[..GetCurrentLine ()]], CursorPosition);

        if (CurrentColumn == 0)
        {
            DeleteTextBackwards ();

            _historyText.ReplaceLast (
                                      [[..GetCurrentLine ()]],
                                      CursorPosition,
                                      HistoryText.LineStatus.Replaced
                                     );

            UpdateWrapModel ();

            return;
        }

        (int col, int row)? newPos = _model.WordBackward (CurrentColumn, CurrentRow);

        if (newPos.HasValue && CurrentRow == newPos.Value.row)
        {
            int restCount = CurrentColumn - newPos.Value.col;
            currentLine.RemoveRange (newPos.Value.col, restCount);

            if (_wordWrap)
            {
                _wrapNeeded = true;
            }

            CurrentColumn = newPos.Value.col;
        }
        else if (newPos.HasValue)
        {
            int restCount = currentLine.Count - CurrentColumn;
            currentLine.RemoveRange (CurrentColumn, restCount);

            if (_wordWrap)
            {
                _wrapNeeded = true;
            }

            CurrentColumn = newPos.Value.col;
            CurrentRow = newPos.Value.row;
        }

        _historyText.Add (
                          [[..GetCurrentLine ()]],
                          CursorPosition,
                          HistoryText.LineStatus.Replaced
                         );

        UpdateWrapModel ();

        DoSetNeedsDisplay (new (0, CurrentRow - _topRow, Frame.Width, Frame.Height));
        DoNeededAction ();
    }

    private void KillWordForward ()
    {
        if (_isReadOnly)
        {
            return;
        }

        SetWrapModel ();

        List<RuneCell> currentLine = GetCurrentLine ();

        _historyText.Add ([[..GetCurrentLine ()]], CursorPosition);

        if (currentLine.Count == 0 || CurrentColumn == currentLine.Count)
        {
            DeleteTextForwards ();

            _historyText.ReplaceLast (
                                      [[..GetCurrentLine ()]],
                                      CursorPosition,
                                      HistoryText.LineStatus.Replaced
                                     );

            UpdateWrapModel ();

            return;
        }

        (int col, int row)? newPos = _model.WordForward (CurrentColumn, CurrentRow);
        var restCount = 0;

        if (newPos.HasValue && CurrentRow == newPos.Value.row)
        {
            restCount = newPos.Value.col - CurrentColumn;
            currentLine.RemoveRange (CurrentColumn, restCount);
        }
        else if (newPos.HasValue)
        {
            restCount = currentLine.Count - CurrentColumn;
            currentLine.RemoveRange (CurrentColumn, restCount);
        }

        if (_wordWrap)
        {
            _wrapNeeded = true;
        }

        _historyText.Add (
                          [[..GetCurrentLine ()]],
                          CursorPosition,
                          HistoryText.LineStatus.Replaced
                         );

        UpdateWrapModel ();

        DoSetNeedsDisplay (new (0, CurrentRow - _topRow, Frame.Width, Frame.Height));
        DoNeededAction ();
    }

    private void Model_LinesLoaded (object sender, EventArgs e)
    {
        // This call is not needed. Model_LinesLoaded gets invoked when
        // model.LoadString (value) is called. LoadString is called from one place
        // (Text.set) and historyText.Clear() is called immediately after.
        // If this call happens, HistoryText_ChangeText will get called multiple times
        // when Text is set, which is wrong.
        //historyText.Clear (Text);

        if (!_multiline && !IsInitialized)
        {
            CurrentColumn = Text.GetRuneCount ();
            _leftColumn = CurrentColumn > Frame.Width + 1 ? CurrentColumn - Frame.Width + 1 : 0;
        }
    }

    private void MoveBottomEnd ()
    {
        ResetAllTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MoveEnd ();
    }

    private void MoveBottomEndExtend ()
    {
        ResetAllTrack ();
        StartSelecting ();
        MoveEnd ();
    }

    private void MoveDown ()
    {
        if (CurrentRow + 1 < _model.Count)
        {
            if (_columnTrack == -1)
            {
                _columnTrack = CurrentColumn;
            }

            CurrentRow++;

            if (CurrentRow + BottomOffset >= _topRow + Frame.Height)
            {
                _topRow++;
                SetNeedsDisplay ();
            }

            TrackColumn ();
            PositionCursor ();
        }
        else if (CurrentRow > Frame.Height)
        {
            Adjust ();
        }

        DoNeededAction ();
    }

    private void MoveEndOfLine ()
    {
        List<RuneCell> currentLine = GetCurrentLine ();
        CurrentColumn = currentLine.Count;
        Adjust ();
        DoNeededAction ();
    }

    private void MoveLeft ()
    {
        if (CurrentColumn > 0)
        {
            CurrentColumn--;
        }
        else
        {
            if (CurrentRow > 0)
            {
                CurrentRow--;

                if (CurrentRow < _topRow)
                {
                    _topRow--;
                    SetNeedsDisplay ();
                }

                List<RuneCell> currentLine = GetCurrentLine ();
                CurrentColumn = currentLine.Count;
            }
        }

        Adjust ();
        DoNeededAction ();
    }

    private bool MoveNextView ()
    {
        if (Application.OverlappedTop is { })
        {
            return SuperView?.FocusNext () == true;
        }

        return false;
    }

    private void MovePageDown ()
    {
        int nPageDnShift = Frame.Height - 1;

        if (CurrentRow >= 0 && CurrentRow < _model.Count)
        {
            if (_columnTrack == -1)
            {
                _columnTrack = CurrentColumn;
            }

            CurrentRow = CurrentRow + nPageDnShift > _model.Count
                             ? _model.Count > 0 ? _model.Count - 1 : 0
                             : CurrentRow + nPageDnShift;

            if (_topRow < CurrentRow - nPageDnShift)
            {
                _topRow = CurrentRow >= _model.Count
                              ? CurrentRow - nPageDnShift
                              : _topRow + nPageDnShift;
                SetNeedsDisplay ();
            }

            TrackColumn ();
            PositionCursor ();
        }

        DoNeededAction ();
    }

    private void MovePageUp ()
    {
        int nPageUpShift = Frame.Height - 1;

        if (CurrentRow > 0)
        {
            if (_columnTrack == -1)
            {
                _columnTrack = CurrentColumn;
            }

            CurrentRow = CurrentRow - nPageUpShift < 0 ? 0 : CurrentRow - nPageUpShift;

            if (CurrentRow < _topRow)
            {
                _topRow = _topRow - nPageUpShift < 0 ? 0 : _topRow - nPageUpShift;
                SetNeedsDisplay ();
            }

            TrackColumn ();
            PositionCursor ();
        }

        DoNeededAction ();
    }

    private bool MovePreviousView ()
    {
        if (Application.OverlappedTop is { })
        {
            return SuperView?.FocusPrev () == true;
        }

        return false;
    }

    private void MoveRight ()
    {
        List<RuneCell> currentLine = GetCurrentLine ();

        if (CurrentColumn < currentLine.Count)
        {
            CurrentColumn++;
        }
        else
        {
            if (CurrentRow + 1 < _model.Count)
            {
                CurrentRow++;
                CurrentColumn = 0;

                if (CurrentRow >= _topRow + Frame.Height)
                {
                    _topRow++;
                    SetNeedsDisplay ();
                }
            }
        }

        Adjust ();
        DoNeededAction ();
    }

    private void MoveStartOfLine ()
    {
        if (_leftColumn > 0)
        {
            SetNeedsDisplay ();
        }

        CurrentColumn = 0;
        _leftColumn = 0;
        Adjust ();
        DoNeededAction ();
    }

    private void MoveTopHome ()
    {
        ResetAllTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MoveHome ();
    }

    private void MoveTopHomeExtend ()
    {
        ResetColumnTrack ();
        StartSelecting ();
        MoveHome ();
    }

    private void MoveUp ()
    {
        if (CurrentRow > 0)
        {
            if (_columnTrack == -1)
            {
                _columnTrack = CurrentColumn;
            }

            CurrentRow--;

            if (CurrentRow < _topRow)
            {
                _topRow--;
                SetNeedsDisplay ();
            }

            TrackColumn ();
            PositionCursor ();
        }

        DoNeededAction ();
    }

    private void MoveWordBackward ()
    {
        (int col, int row)? newPos = _model.WordBackward (CurrentColumn, CurrentRow);

        if (newPos.HasValue)
        {
            CurrentColumn = newPos.Value.col;
            CurrentRow = newPos.Value.row;
        }

        Adjust ();
        DoNeededAction ();
    }

    private void MoveWordForward ()
    {
        (int col, int row)? newPos = _model.WordForward (CurrentColumn, CurrentRow);

        if (newPos.HasValue)
        {
            CurrentColumn = newPos.Value.col;
            CurrentRow = newPos.Value.row;
        }

        Adjust ();
        DoNeededAction ();
    }

    private (int width, int height) OffSetBackground ()
    {
        var w = 0;
        var h = 0;

        if (SuperView?.Frame.Right - Frame.Right < 0)
        {
            w = SuperView!.Frame.Right - Frame.Right - 1;
        }

        if (SuperView?.Frame.Bottom - Frame.Bottom < 0)
        {
            h = SuperView!.Frame.Bottom - Frame.Bottom - 1;
        }

        return (w, h);
    }

    private bool PointInSelection (int col, int row)
    {
        long start, end;
        GetEncodedRegionBounds (out start, out end);
        long q = ((long)(uint)row << 32) | (uint)col;

        return q >= start && q <= end - 1;
    }

    private void ProcessAutocomplete ()
    {
        if (_isDrawing)
        {
            return;
        }

        if (_clickWithSelecting)
        {
            _clickWithSelecting = false;

            return;
        }

        if (SelectedLength > 0)
        {
            return;
        }

        // draw autocomplete
        GenerateSuggestions ();

        var renderAt = new Point (
                                  Autocomplete.Context.CursorPosition,
                                  Autocomplete.PopupInsideContainer
                                      ? CursorPosition.Y + 1 - TopRow
                                      : 0
                                 );

        Autocomplete.RenderOverlay (renderAt);
    }

    private bool ProcessBackTab ()
    {
        ResetColumnTrack ();

        if (!AllowsTab || _isReadOnly)
        {
            return ProcessMovePreviousView ();
        }

        if (CurrentColumn > 0)
        {
            SetWrapModel ();

            List<RuneCell> currentLine = GetCurrentLine ();

            if (currentLine.Count > 0 && currentLine [CurrentColumn - 1].Rune.Value == '\t')
            {
                _historyText.Add (new List<List<RuneCell>> { new (currentLine) }, CursorPosition);

                currentLine.RemoveAt (CurrentColumn - 1);
                CurrentColumn--;

                _historyText.Add (
                                  new List<List<RuneCell>> { new (GetCurrentLine ()) },
                                  CursorPosition,
                                  HistoryText.LineStatus.Replaced
                                 );
            }

            SetNeedsDisplay ();

            UpdateWrapModel ();
        }

        DoNeededAction ();

        return true;
    }

    private void ProcessCopy ()
    {
        ResetColumnTrack ();
        Copy ();
    }

    private void ProcessCut ()
    {
        ResetColumnTrack ();
        Cut ();
    }

    private void ProcessDeleteCharLeft ()
    {
        ResetColumnTrack ();
        DeleteCharLeft ();
    }

    private void ProcessDeleteCharRight ()
    {
        ResetColumnTrack ();
        DeleteCharRight ();
    }

    // If InheritsPreviousColorScheme is enabled this method will check if the rune cell on
    // the row and col location and around has a not null color scheme. If it's null will set it with
    // the very most previous valid color scheme.
    private void ProcessInheritsPreviousColorScheme (int row, int col)
    {
        if (!InheritsPreviousColorScheme || (Lines == 1 && GetLine (Lines).Count == 0))
        {
            return;
        }

        List<RuneCell> line = GetLine (row);
        List<RuneCell> lineToSet = line;

        while (line.Count == 0)
        {
            if (row == 0 && line.Count == 0)
            {
                return;
            }

            row--;
            line = GetLine (row);
            lineToSet = line;
        }

        int colWithColor = Math.Max (Math.Min (col - 2, line.Count - 1), 0);
        RuneCell cell = line [colWithColor];
        int colWithoutColor = Math.Max (col - 1, 0);

        if (cell.ColorScheme is { } && colWithColor == 0 && lineToSet [colWithoutColor].ColorScheme is { })
        {
            for (int r = row - 1; r > -1; r--)
            {
                List<RuneCell> l = GetLine (r);

                for (int c = l.Count - 1; c > -1; c--)
                {
                    if (l [c].ColorScheme is null)
                    {
                        l [c].ColorScheme = cell.ColorScheme;
                    }
                    else
                    {
                        return;
                    }
                }
            }

            return;
        }

        if (cell.ColorScheme is null)
        {
            for (int r = row; r > -1; r--)
            {
                List<RuneCell> l = GetLine (r);

                colWithColor = l.FindLastIndex (
                                                colWithColor > -1 ? colWithColor : l.Count - 1,
                                                rc => rc.ColorScheme != null
                                               );

                if (colWithColor > -1 && l [colWithColor].ColorScheme is { })
                {
                    cell = l [colWithColor];

                    break;
                }
            }
        }
        else
        {
            int cRow = row;

            while (cell.ColorScheme is null)
            {
                if ((colWithColor == 0 || cell.ColorScheme is null) && cRow > 0)
                {
                    line = GetLine (--cRow);
                    colWithColor = line.Count - 1;
                    cell = line [colWithColor];
                }
                else if (cRow == 0 && colWithColor < line.Count)
                {
                    cell = line [colWithColor + 1];
                }
            }
        }

        if (cell.ColorScheme is { } && colWithColor > -1 && colWithoutColor < lineToSet.Count && lineToSet [colWithoutColor].ColorScheme is null)
        {
            while (lineToSet [colWithoutColor].ColorScheme is null)
            {
                lineToSet [colWithoutColor].ColorScheme = cell.ColorScheme;
                colWithoutColor--;

                if (colWithoutColor == -1 && row > 0)
                {
                    lineToSet = GetLine (--row);
                    colWithoutColor = lineToSet.Count - 1;
                }
            }
        }
    }

    private void ProcessKillWordBackward ()
    {
        ResetColumnTrack ();
        KillWordBackward ();
    }

    private void ProcessKillWordForward ()
    {
        ResetColumnTrack ();
        KillWordForward ();
    }

    private void ProcessMouseClick (MouseEvent ev, out List<RuneCell> line)
    {
        List<RuneCell>? r = null;

        if (_model.Count > 0)
        {
            int maxCursorPositionableLine = Math.Max (_model.Count - 1 - _topRow, 0);

            if (Math.Max (ev.Y, 0) > maxCursorPositionableLine)
            {
                CurrentRow = maxCursorPositionableLine + _topRow;
            }
            else
            {
                CurrentRow = Math.Max (ev.Y + _topRow, 0);
            }

            r = GetCurrentLine ();
            int idx = TextModel.GetColFromX (r, _leftColumn, Math.Max (ev.X, 0), TabWidth);

            if (idx - _leftColumn >= r.Count + RightOffset)
            {
                CurrentColumn = Math.Max (r.Count - _leftColumn + RightOffset, 0);
            }
            else
            {
                CurrentColumn = idx + _leftColumn;
            }
        }

        line = r!;
    }

    private void ProcessMoveDown ()
    {
        ResetContinuousFindTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MoveDown ();
    }

    private void ProcessMoveDownExtend ()
    {
        ResetColumnTrack ();
        StartSelecting ();
        MoveDown ();
    }

    private void ProcessMoveEndOfLine ()
    {
        ResetAllTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MoveEndOfLine ();
    }

    private void ProcessMoveEndOfLineExtend ()
    {
        ResetAllTrack ();
        StartSelecting ();
        MoveEndOfLine ();
    }

    private bool ProcessMoveLeft ()
    {
        // if the user presses Left (without any control keys) and they are at the start of the text
        if (CurrentColumn == 0 && CurrentRow == 0)
        {
            // do not respond (this lets the key press fall through to navigation system - which usually changes focus backward)
            return false;
        }

        ResetAllTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MoveLeft ();

        return true;
    }

    private void ProcessMoveLeftExtend ()
    {
        ResetAllTrack ();
        StartSelecting ();
        MoveLeft ();
    }

    private bool ProcessMoveNextView ()
    {
        ResetColumnTrack ();

        return MoveNextView ();
    }

    private bool ProcessMovePreviousView ()
    {
        ResetColumnTrack ();

        return MovePreviousView ();
    }

    private bool ProcessMoveRight ()
    {
        // if the user presses Right (without any control keys)
        // determine where the last cursor position in the text is
        int lastRow = _model.Count - 1;
        int lastCol = _model.GetLine (lastRow).Count;

        // if they are at the very end of all the text do not respond (this lets the key press fall through to navigation system - which usually changes focus forward)
        if (CurrentColumn == lastCol && CurrentRow == lastRow)
        {
            return false;
        }

        ResetAllTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MoveRight ();

        return true;
    }

    private void ProcessMoveRightExtend ()
    {
        ResetAllTrack ();
        StartSelecting ();
        MoveRight ();
    }

    private void ProcessMoveStartOfLine ()
    {
        ResetAllTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MoveStartOfLine ();
    }

    private void ProcessMoveStartOfLineExtend ()
    {
        ResetAllTrack ();
        StartSelecting ();
        MoveStartOfLine ();
    }

    private void ProcessMoveUp ()
    {
        ResetContinuousFindTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MoveUp ();
    }

    private void ProcessMoveUpExtend ()
    {
        ResetColumnTrack ();
        StartSelecting ();
        MoveUp ();
    }

    private void ProcessMoveWordBackward ()
    {
        ResetAllTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MoveWordBackward ();
    }

    private void ProcessMoveWordBackwardExtend ()
    {
        ResetAllTrack ();
        StartSelecting ();
        MoveWordBackward ();
    }

    private void ProcessMoveWordForward ()
    {
        ResetAllTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MoveWordForward ();
    }

    private void ProcessMoveWordForwardExtend ()
    {
        ResetAllTrack ();
        StartSelecting ();
        MoveWordForward ();
    }

    private void ProcessPageDown ()
    {
        ResetColumnTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MovePageDown ();
    }

    private void ProcessPageDownExtend ()
    {
        ResetColumnTrack ();
        StartSelecting ();
        MovePageDown ();
    }

    private void ProcessPageUp ()
    {
        ResetColumnTrack ();

        if (_shiftSelecting && Selecting)
        {
            StopSelecting ();
        }

        MovePageUp ();
    }

    private void ProcessPageUpExtend ()
    {
        ResetColumnTrack ();
        StartSelecting ();
        MovePageUp ();
    }

    private void ProcessPaste ()
    {
        ResetColumnTrack ();

        if (_isReadOnly)
        {
            return;
        }

        Paste ();
    }

    private bool ProcessReturn ()
    {
        ResetColumnTrack ();

        if (!AllowsReturn || _isReadOnly)
        {
            return false;
        }

        SetWrapModel ();

        List<RuneCell> currentLine = GetCurrentLine ();

        _historyText.Add (new List<List<RuneCell>> { new (currentLine) }, CursorPosition);

        if (Selecting)
        {
            ClearSelectedRegion ();
            currentLine = GetCurrentLine ();
        }

        int restCount = currentLine.Count - CurrentColumn;
        List<RuneCell> rest = currentLine.GetRange (CurrentColumn, restCount);
        currentLine.RemoveRange (CurrentColumn, restCount);

        List<List<RuneCell>> addedLines = new () { new List<RuneCell> (currentLine) };

        _model.AddLine (CurrentRow + 1, rest);

        addedLines.Add (new List<RuneCell> (_model.GetLine (CurrentRow + 1)));

        _historyText.Add (addedLines, CursorPosition, HistoryText.LineStatus.Added);

        CurrentRow++;

        var fullNeedsDisplay = false;

        if (CurrentRow >= _topRow + Frame.Height)
        {
            _topRow++;
            fullNeedsDisplay = true;
        }

        CurrentColumn = 0;

        _historyText.Add (
                          new List<List<RuneCell>> { new (GetCurrentLine ()) },
                          CursorPosition,
                          HistoryText.LineStatus.Replaced
                         );

        if (!_wordWrap && CurrentColumn < _leftColumn)
        {
            fullNeedsDisplay = true;
            _leftColumn = 0;
        }

        if (fullNeedsDisplay)
        {
            SetNeedsDisplay ();
        }
        else
        {
            // BUGBUG: customized rect aren't supported now because the Redraw isn't using the Intersect method.
            //SetNeedsDisplay (new (0, currentRow - topRow, 2, Frame.Height));
            SetNeedsDisplay ();
        }

        UpdateWrapModel ();

        DoNeededAction ();
        OnContentsChanged ();

        return true;
    }

    private void ProcessSelectAll ()
    {
        ResetColumnTrack ();
        SelectAll ();
    }

    private void ProcessSetOverwrite ()
    {
        ResetColumnTrack ();
        SetOverwrite (!Used);
    }

    private bool ProcessTab ()
    {
        ResetColumnTrack ();

        if (!AllowsTab || _isReadOnly)
        {
            return ProcessMoveNextView ();
        }

        InsertText (new Key ((KeyCode)'\t'));
        DoNeededAction ();

        return true;
    }

    private void ResetAllTrack ()
    {
        // Handle some state here - whether the last command was a kill
        // operation and the column tracking (up/down)
        _lastWasKill = false;
        _columnTrack = -1;
        _continuousFind = false;
    }

    private void ResetColumnTrack ()
    {
        // Handle some state here - whether the last command was a kill
        // operation and the column tracking (up/down)
        _lastWasKill = false;
        _columnTrack = -1;
    }

    private void ResetContinuousFind ()
    {
        if (!_continuousFind)
        {
            int col = Selecting ? _selectionStartColumn : CurrentColumn;
            int row = Selecting ? _selectionStartRow : CurrentRow;
            _model.ResetContinuousFind (new Point (col, row));
        }
    }

    private void ResetContinuousFindTrack ()
    {
        // Handle some state here - whether the last command was a kill
        // operation and the column tracking (up/down)
        _lastWasKill = false;
        _continuousFind = false;
    }

    private void ResetCursorVisibility ()
    {
        if (_savedCursorVisibility != 0)
        {
            DesiredCursorVisibility = _savedCursorVisibility;
            _savedCursorVisibility = 0;
        }
    }

    private void ResetPosition ()
    {
        _topRow = _leftColumn = CurrentRow = CurrentColumn = 0;
        StopSelecting ();
        ResetCursorVisibility ();
    }

    private void SaveCursorVisibility ()
    {
        if (_desiredCursorVisibility != CursorVisibility.Invisible)
        {
            if (_savedCursorVisibility == 0)
            {
                _savedCursorVisibility = _desiredCursorVisibility;
            }

            DesiredCursorVisibility = CursorVisibility.Invisible;
        }
    }

    private void SetClipboard (string text)
    {
        if (text is { })
        {
            Clipboard.Contents = text;
        }
    }

    private bool SetFoundText (
        string text,
        (Point current, bool found) foundPos,
        string? textToReplace = null,
        bool replace = false,
        bool replaceAll = false
    )
    {
        if (foundPos.found)
        {
            StartSelecting ();
            _selectionStartColumn = foundPos.current.X;
            _selectionStartRow = foundPos.current.Y;

            if (!replaceAll)
            {
                CurrentColumn = _selectionStartColumn + text.GetRuneCount ();
            }
            else
            {
                CurrentColumn = _selectionStartColumn + textToReplace!.GetRuneCount ();
            }

            CurrentRow = foundPos.current.Y;

            if (!_isReadOnly && replace)
            {
                Adjust ();
                ClearSelectedRegion ();
                InsertAllText (textToReplace!);
                StartSelecting ();
                _selectionStartColumn = CurrentColumn - textToReplace!.GetRuneCount ();
            }
            else
            {
                UpdateWrapModel ();
                SetNeedsDisplay ();
                Adjust ();
            }

            _continuousFind = true;

            return foundPos.found;
        }

        UpdateWrapModel ();
        _continuousFind = false;

        return foundPos.found;
    }

    private void SetOverwrite (bool overwrite)
    {
        Used = overwrite;
        SetNeedsDisplay ();
        DoNeededAction ();
    }

    private static void SetValidUsedColor (ColorScheme colorScheme)
    {
        // BUGBUG: (v2 truecolor) This code depends on 8-bit color names; disabling for now
        //if ((colorScheme!.HotNormal.Foreground & colorScheme.Focus.Background) == colorScheme.Focus.Foreground) {
        Driver.SetAttribute (new Attribute (colorScheme.Focus.Background, colorScheme.Focus.Foreground));
    }

    /// <summary>Restore from original model.</summary>
    private void SetWrapModel ([CallerMemberName] string? caller = null)
    {
        if (_currentCaller is { })
        {
            return;
        }

        if (_wordWrap)
        {
            _currentCaller = caller;

            CurrentColumn = _wrapManager!.GetModelColFromWrappedLines (CurrentRow, CurrentColumn);
            CurrentRow = _wrapManager.GetModelLineFromWrappedLines (CurrentRow);

            _selectionStartColumn =
                _wrapManager.GetModelColFromWrappedLines (_selectionStartRow, _selectionStartColumn);
            _selectionStartRow = _wrapManager.GetModelLineFromWrappedLines (_selectionStartRow);
            _model = _wrapManager.Model;
        }
    }

    private void ShowContextMenu ()
    {
        if (_currentCulture != Thread.CurrentThread.CurrentUICulture)
        {
            _currentCulture = Thread.CurrentThread.CurrentUICulture;

            ContextMenu!.MenuItems = BuildContextMenuBarItem ();
        }

        ContextMenu!.Show ();
    }

    private void StartSelecting ()
    {
        if (_shiftSelecting && Selecting)
        {
            return;
        }

        _shiftSelecting = true;
        Selecting = true;
        _selectionStartColumn = CurrentColumn;
        _selectionStartRow = CurrentRow;
    }

    private void StopSelecting ()
    {
        _shiftSelecting = false;
        Selecting = false;
        _isButtonShift = false;
    }

    private string StringFromRunes (List<RuneCell> cells)
    {
        if (cells is null)
        {
            throw new ArgumentNullException (nameof (cells));
        }

        var size = 0;

        foreach (RuneCell cell in cells)
        {
            size += cell.Rune.GetEncodingLength ();
        }

        var encoded = new byte [size];
        var offset = 0;

        foreach (RuneCell cell in cells)
        {
            offset += cell.Rune.Encode (encoded, offset);
        }

        return StringExtensions.ToString (encoded);
    }

    private void TextView_Initialized (object sender, EventArgs e)
    {
        Autocomplete.HostControl = this;

        if (Application.Top is { })
        {
            Application.Top.AlternateForwardKeyChanged += Top_AlternateForwardKeyChanged!;
            Application.Top.AlternateBackwardKeyChanged += Top_AlternateBackwardKeyChanged!;
        }

        OnContentsChanged ();
    }

    private void TextView_LayoutComplete (object? sender, LayoutEventArgs e)
    {
        WrapTextModel ();
        Adjust ();
    }

    private void ToggleSelecting ()
    {
        ResetColumnTrack ();
        Selecting = !Selecting;
        _selectionStartColumn = CurrentColumn;
        _selectionStartRow = CurrentRow;
    }

    private void Top_AlternateBackwardKeyChanged (object sender, KeyChangedEventArgs e) { KeyBindings.Replace (e.OldKey, e.NewKey); }
    private void Top_AlternateForwardKeyChanged (object sender, KeyChangedEventArgs e) { KeyBindings.Replace (e.OldKey, e.NewKey); }

    // Tries to snap the cursor to the tracking column
    private void TrackColumn ()
    {
        // Now track the column
        List<RuneCell> line = GetCurrentLine ();

        if (line.Count < _columnTrack)
        {
            CurrentColumn = line.Count;
        }
        else if (_columnTrack != -1)
        {
            CurrentColumn = _columnTrack;
        }
        else if (CurrentColumn > line.Count)
        {
            CurrentColumn = line.Count;
        }

        Adjust ();
    }

    /// <summary>Update the original model.</summary>
    private void UpdateWrapModel ([CallerMemberName] string? caller = null)
    {
        if (_currentCaller is { } && _currentCaller != caller)
        {
            return;
        }

        if (_wordWrap)
        {
            _currentCaller = null;

            _wrapManager!.UpdateModel (
                                       _model,
                                       out int nRow,
                                       out int nCol,
                                       out int nStartRow,
                                       out int nStartCol,
                                       CurrentRow,
                                       CurrentColumn,
                                       _selectionStartRow,
                                       _selectionStartColumn,
                                       true
                                      );
            CurrentRow = nRow;
            CurrentColumn = nCol;
            _selectionStartRow = nStartRow;
            _selectionStartColumn = nStartCol;
            _wrapNeeded = true;

            SetNeedsDisplay ();
        }

        if (_currentCaller is { })
        {
            throw new InvalidOperationException (
                                                 $"WordWrap settings was changed after the {_currentCaller} call."
                                                );
        }
    }

    private void WrapTextModel ()
    {
        if (_wordWrap && _wrapManager is { })
        {
            _model = _wrapManager.WrapModel (
                                             _frameWidth,
                                             out int nRow,
                                             out int nCol,
                                             out int nStartRow,
                                             out int nStartCol,
                                             CurrentRow,
                                             CurrentColumn,
                                             _selectionStartRow,
                                             _selectionStartColumn,
                                             _tabWidth
                                            );
            CurrentRow = nRow;
            CurrentColumn = nCol;
            _selectionStartRow = nStartRow;
            _selectionStartColumn = nStartCol;
            SetNeedsDisplay ();
        }
    }
}

/// <summary>
///     Renders an overlay on another view at a given point that allows selecting from a range of 'autocomplete'
///     options. An implementation on a TextView.
/// </summary>
public class TextViewAutocomplete : PopupAutocomplete
{
    /// <inheritdoc/>
    protected override void DeleteTextBackwards () { ((TextView)HostControl).DeleteCharLeft (); }

    /// <inheritdoc/>
    protected override void InsertText (string accepted) { ((TextView)HostControl).InsertText (accepted); }

    /// <inheritdoc/>
    protected override void SetCursorPosition (int column)
    {
        ((TextView)HostControl).CursorPosition =
            new Point (column, ((TextView)HostControl).CurrentRow);
    }
}