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

#nullable enable

// TextView.cs: multi-line text editing
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Runtime.CompilerServices;
using System.Text;
using System.Text.Json.Serialization;
using System.Threading;
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 ("{DebuggerDisplay}")]
public class RuneCell : IEquatable<RuneCell> {
	/// <summary>
	/// The glyph to draw.
	/// </summary>
	[JsonConverter (typeof (RuneJsonConverter))]
	public Rune Rune { get; set; }

	/// <summary>
	/// The <see cref="Terminal.Gui.ColorScheme"/> color sets to draw the glyph with.
	/// </summary>
	[JsonConverter (typeof (ColorSchemeJsonConverter))]
	public ColorScheme? ColorScheme { get; set; }

	/// <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) => other != null &&
						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 = ColorSchemeDebuggerDisplay ();
		return DebuggerDisplay;
	}

	string ColorSchemeDebuggerDisplay ()
	{
		string colorSchemeStr = "null";
		if (ColorScheme != null) {
			colorSchemeStr = $"Normal: {ColorScheme.Normal.Foreground},{ColorScheme.Normal.Background}; " +
					$"Focus: {ColorScheme.Focus.Foreground},{ColorScheme.Focus.Background}; " +
					$"HotNormal: {ColorScheme.HotNormal.Foreground},{ColorScheme.HotNormal.Background}; " +
					$"HotFocus: {ColorScheme.HotFocus.Foreground},{ColorScheme.HotFocus.Background}; " +
					$"Disabled: {ColorScheme.Disabled.Foreground},{ColorScheme.Disabled.Background}";
		}

		return colorSchemeStr;
	}

	string DebuggerDisplay {
		get {
			string colorSchemeStr = ColorSchemeDebuggerDisplay ();
			return $"U+{Rune.Value:X4} '{Rune.ToString ()}'; {colorSchemeStr}";
		}
	}
}

class TextModel {
	List<List<RuneCell>> _lines = new ();

	public event EventHandler? LinesLoaded;

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

		using (var stream = File.OpenRead (file)) {
			LoadStream (stream);
			return true;
		}
	}

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

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

	// 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)
	{
		var cells = new List<RuneCell> ();
		foreach (var 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)
	{
		var cells = new List<RuneCell> ();
		foreach (var rune in runes) {
			cells.Add (new RuneCell { Rune = rune, ColorScheme = colorScheme });
		}
		return cells;
	}

	static List<List<RuneCell>> ToRuneCells (List<RuneCell> cells) => SplitNewLines (cells);

	// 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)
	{
		var cells = content.EnumerateRunes ().Select (x => new RuneCell () { Rune = x, ColorScheme = colorScheme }).ToList ();

		return SplitNewLines (cells);
	}

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

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

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

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

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

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

	void SetColorSchemes (ColorScheme? colorScheme)
	{
		foreach (var line in _lines) {
			foreach (var cell in line) {
				if (cell.ColorScheme == null) {
					cell.ColorScheme = colorScheme;
				}
			}
		}
	}

	void OnLinesLoaded () => LinesLoaded?.Invoke (this, EventArgs.Empty);

	public override string ToString ()
	{
		var sb = new StringBuilder ();
		for (int i = 0; i < _lines.Count; i++) {
			sb.Append (ToString (_lines [i]));
			if (i + 1 < _lines.Count) {
				sb.AppendLine ();
			}
		}
		return sb.ToString ();
	}

	public string? FilePath { get; set; }

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

	/// <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];
			} else {
				return _lines [Count - 1];
			}
		} else {
			_lines.Add (new List<RuneCell> ());
			return _lines [0];
		}
	}

	public List<List<RuneCell>> GetAllLines () => _lines;

	/// <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);

	/// <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);
		}
	}

	/// <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)
	{
		int maxLength = 0;
		last = last < _lines.Count ? last : _lines.Count;
		for (int i = first; i < last; i++) {
			var 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;
	}

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

		return false;
	}

	internal static int GetColFromX (List<RuneCell> t, int start, int x, int tabWidth = 0)
	{
		var runes = new List<Rune> ();
		foreach (var 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++) {
			var 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 static (int size, int length) DisplaySize (List<RuneCell> t, int start = -1, int end = -1,
							bool checkNextRune = true, int tabWidth = 0)
	{
		var runes = new List<Rune> ();
		foreach (var 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 == null || t.Count == 0) {
			return (0, 0);
		}
		int size = 0;
		int len = 0;
		int tcount = end == -1 ? t.Count : end > t.Count ? t.Count : end;
		int i = start == -1 ? 0 : start;
		for (; i < tcount; i++) {
			var 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 static int CalculateLeftColumn (List<RuneCell> t, int start, int end, int width, int tabWidth = 0)
	{
		var runes = new List<Rune> ();
		foreach (var 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 == null || t.Count == 0) {
			return 0;
		}
		int size = 0;
		int tcount = end > t.Count - 1 ? t.Count - 1 : end;
		int col = 0;

		for (int i = tcount; i >= 0; i--) {
			var rune = t [i];
			size += rune.GetColumns ();
			if (rune.Value == '\t') {
				size += tabWidth + 1;
			}
			if (size > width) {
				if (col + width == end) {
					col++;
				}
				break;
			} else if (end < t.Count && col > 0 && start < end && col == start || end - col == width - 1) {
				break;
			}
			col = i;
		}

		return col;
	}

	(Point startPointToFind, Point currentPointToFind, bool found) _toFind;

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

		if (_toFind.found) {
			_toFind.currentPointToFind.X++;
		}
		var 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 == 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;
		var 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 (Point current, bool found) ReplaceAllText (string text, bool matchCase = false, bool matchWholeWord = false, string? textToReplace = null)
	{
		bool found = false;
		var pos = Point.Empty;

		for (int i = 0; i < _lines.Count; i++) {
			var 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);
	}

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

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

	bool ApplyToFind ((Point current, bool found) foundPos)
	{
		bool 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;
	}

	(Point current, bool found) GetFoundNextTextPoint (string text, int linesCount, bool matchCase, bool matchWholeWord, Point start)
	{
		for (int i = start.Y; i < linesCount; i++) {
			var 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);
			} else if (col == -1 && start.X > 0) {
				start.X = 0;
			}
		}

		return (Point.Empty, false);
	}

	(Point current, bool found) GetFoundPreviousTextPoint (string text, int linesCount, bool matchCase, bool matchWholeWord, Point start)
	{
		for (int i = linesCount; i >= 0; i--) {
			var 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);
	}

	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;
	}

	/// <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;
	}

	RuneCell RuneAt (int col, int row)
	{
		var line = GetLine (row);
		if (line.Count > 0) {
			return line [col > line.Count - 1 ? line.Count - 1 : col];
		} else {
			return default!;
		}
	}

	bool MoveNext (ref int col, ref int row, out Rune rune)
	{
		var 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;
		} else 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;
		return false;
	}

	bool MovePrev (ref int col, ref int row, out Rune rune)
	{
		var line = GetLine (row);

		if (col > 0) {
			col--;
			rune = line [col].Rune;
			return true;
		}
		if (row == 0) {
			rune = default;
			return false;
		}
		while (row > 0) {
			row--;
			line = GetLine (row);
			col = line.Count - 1;
			if (col >= 0) {
				rune = line [col].Rune;
				return true;
			}
		}
		rune = default;
		return false;
	}

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

	RuneType GetRuneType (Rune rune)
	{
		if (Rune.IsSymbol (rune)) {
			return RuneType.IsSymbol;
		} else if (Rune.IsWhiteSpace (rune)) {
			return RuneType.IsWhiteSpace;
		} else if (Rune.IsLetterOrDigit (rune)) {
			return RuneType.IsLetterOrDigit;
		} else if (Rune.IsPunctuation (rune)) {
			return RuneType.IsPunctuation;
		}
		return RuneType.IsUnknow;
	}

	bool IsSameRuneType (Rune newRune, RuneType runeType)
	{
		var rt = GetRuneType (newRune);
		return rt == runeType;
	}

	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 {
			var rune = RuneAt (col, row).Rune;
			var 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;
					}
					var 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;
		}
	}

	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 {
			var cell = RuneAt (col, row);
			Rune rune;
			if (cell != null) {
				rune = cell.Rune;
			} else {
				if (col > 0) {
					return (col, row);
				} else if (col == 0 && row > 0) {
					row--;
					var line = GetLine (row);
					return (line.Count, row);
				} else {
					return null;
				}
			}
			var 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;
					}

					var 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;
		}
	}

	/// <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)
	{
		var cells = new List<RuneCell> ();
		foreach (var rune in str.EnumerateRunes ()) {
			cells.Add (new RuneCell { Rune = rune, ColorScheme = colorScheme });
		}
		return cells;
	}

	/// <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)
	{
		string str = string.Empty;

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

		return str;
	}
}

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

	List<HistoryTextItem> _historyTextItems = new ();
	int _idxHistoryText = -1;
	string? _originalText;

	public bool IsFromHistory { get; private set; }

	public bool HasHistoryChanges => _idxHistoryText > -1;

	public event EventHandler<HistoryTextItem>? ChangeText;

	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 void ReplaceLast (List<List<RuneCell>> lines, Point curPos, LineStatus lineStatus)
	{
		var found = _historyTextItems.FindLast (x => x.LineStatus == lineStatus);
		if (found != null) {
			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;
		}
	}

	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;
		}
	}

	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++;
			}
		}
	}

	void OnChangeText (HistoryTextItem? lines) => ChangeText?.Invoke (this, lines!);

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

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

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

	List<WrappedLine> _wrappedModelLines = new ();
	int _frameWidth;
	bool _isWrapModelRefreshing;

	public TextModel Model { get; private set; }

	public WordWrapManager (TextModel model) => Model = model;

	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 ();
		int lines = 0;
		nRow = 0;
		nCol = 0;
		nStartRow = 0;
		nStartCol = 0;
		bool isRowAndColSetted = row == 0 && col == 0;
		bool isStartRowAndColSetted = startRow == 0 && startCol == 0;
		var wModelLines = new List<WrappedLine> ();

		for (int i = 0; i < Model.Count; i++) {
			var line = Model.GetLine (i);
			var wrappedLines = ToListRune (
				TextFormatter.Format (TextModel.ToString (line), width, TextAlignment.Left, true, preserveTrailingSpaces, tabWidth));
			int sumColWidth = 0;
			for (int j = 0; j < wrappedLines.Count; j++) {
				var 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;
	}

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

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

		return runesList;
	}

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

	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);
		int modelCol = 0;

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

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

		return modelCol;
	}

	List<RuneCell> GetCurrentLine (int row) => Model.GetLine (row);

	public void AddLine (int row, int col)
	{
		int modelRow = GetModelLineFromWrappedLines (row);
		int modelCol = GetModelColFromWrappedLines (row, col);
		var line = GetCurrentLine (modelRow);
		int restCount = line.Count - modelCol;
		var rest = line.GetRange (modelCol, restCount);
		line.RemoveRange (modelCol, restCount);
		Model.AddLine (modelRow + 1, rest);
		_isWrapModelRefreshing = true;
		WrapModel (_frameWidth, out _, out _, out _, out _, modelRow + 1, 0);
		_isWrapModelRefreshing = false;
	}

	public bool Insert (int row, int col, RuneCell cell)
	{
		var line = GetCurrentLine (GetModelLineFromWrappedLines (row));
		line.Insert (GetModelColFromWrappedLines (row, col), cell);
		if (line.Count > _frameWidth) {
			return true;
		} else {
			return false;
		}
	}

	public bool RemoveAt (int row, int col)
	{
		int modelRow = GetModelLineFromWrappedLines (row);
		var 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);
		var line = GetCurrentLine (modelRow);
		int modelCol = GetModelColFromWrappedLines (row, col);

		if (modelCol == 0 && line.Count == 0) {
			Model.RemoveLine (modelRow);
			return false;
		} else if (modelCol < line.Count) {
			if (forward) {
				line.RemoveAt (modelCol);
				return true;
			} else if (modelCol - 1 > -1) {
				line.RemoveAt (modelCol - 1);
				return true;
			}
		}
		lineRemoved = true;
		if (forward) {
			if (modelRow + 1 == Model.Count) {
				return false;
			}

			var nextLine = Model.GetLine (modelRow + 1);
			line.AddRange (nextLine);
			Model.RemoveLine (modelRow + 1);
			if (line.Count > _frameWidth) {
				return true;
			}
		} else {
			if (modelRow == 0) {
				return false;
			}

			var 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);
		var line = GetCurrentLine (modelRow);
		int modelCol = GetModelColFromWrappedLines (row, index);

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

		return true;
	}

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

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

		while (modelCol < col) {
			var wLine = _wrappedModelLines! [i];
			var 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;
	}
}

/// <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 {
	TextModel _model = new ();
	int _topRow;
	int _leftColumn;
	int _currentRow;
	int _currentColumn;
	int _selectionStartColumn, _selectionStartRow;
	bool _selecting;
	bool _wordWrap;
	WordWrapManager? _wrapManager;
	bool _continuousFind;
	int _bottomOffset, _rightOffset;
	int _tabWidth = 4;
	bool _allowsTab = true;
	bool _allowsReturn = true;
	bool _multiline = true;
	HistoryText _historyText = new ();
	CultureInfo? _currentCulture;

	/// <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>
	///  Raised when the contents of the <see cref="TextView"/> are changed. 
	/// </summary>
	/// <remarks>
	/// Unlike the <see cref="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>
	/// Invoked with the unwrapped <see cref="CursorPosition"/>.
	/// </summary>
	public event EventHandler<PointEventArgs>? UnwrappedCursorPosition;

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

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

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

	/// <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>
	/// 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>
	///  Initializes a <see cref="TextView"/> on the specified area, with absolute position and size.
	/// </summary>
	/// <remarks>
	/// </remarks>
	public TextView (Rect frame) : base (frame) => SetInitialProperties ();

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

	void SetInitialProperties ()
	{
		CanFocus = true;
		Used = true;

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

		Initialized += TextView_Initialized!;

			// 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 (KeyCode.PageDown, Command.PageDown);
		KeyBindings.Add (KeyCode.V | KeyCode.CtrlMask, Command.PageDown);

		KeyBindings.Add (KeyCode.PageDown | KeyCode.ShiftMask, Command.PageDownExtend);

		KeyBindings.Add (KeyCode.PageUp, Command.PageUp);
		KeyBindings.Add ((int)'V' + KeyCode.AltMask, Command.PageUp);

		KeyBindings.Add (KeyCode.PageUp | KeyCode.ShiftMask, Command.PageUpExtend);

		KeyBindings.Add (KeyCode.N | KeyCode.CtrlMask, Command.LineDown);
		KeyBindings.Add (KeyCode.CursorDown, Command.LineDown);

		KeyBindings.Add (KeyCode.CursorDown | KeyCode.ShiftMask, Command.LineDownExtend);

		KeyBindings.Add (KeyCode.P | KeyCode.CtrlMask, Command.LineUp);
		KeyBindings.Add (KeyCode.CursorUp, Command.LineUp);

		KeyBindings.Add (KeyCode.CursorUp | KeyCode.ShiftMask, Command.LineUpExtend);

		KeyBindings.Add (KeyCode.F | KeyCode.CtrlMask, Command.Right);
		KeyBindings.Add (KeyCode.CursorRight, Command.Right);

		KeyBindings.Add (KeyCode.CursorRight | KeyCode.ShiftMask, Command.RightExtend);

		KeyBindings.Add (KeyCode.B | KeyCode.CtrlMask, Command.Left);
		KeyBindings.Add (KeyCode.CursorLeft, Command.Left);

		KeyBindings.Add (KeyCode.CursorLeft | KeyCode.ShiftMask, Command.LeftExtend);

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

		KeyBindings.Add (KeyCode.Home, Command.StartOfLine);
		KeyBindings.Add (KeyCode.A | KeyCode.CtrlMask, Command.StartOfLine);

		KeyBindings.Add (KeyCode.Home | KeyCode.ShiftMask, Command.StartOfLineExtend);

		KeyBindings.Add (KeyCode.Delete, Command.DeleteCharRight);
		KeyBindings.Add (KeyCode.D | KeyCode.CtrlMask, Command.DeleteCharRight);

		KeyBindings.Add (KeyCode.End, Command.EndOfLine);
		KeyBindings.Add (KeyCode.E | KeyCode.CtrlMask, Command.EndOfLine);

		KeyBindings.Add (KeyCode.End | KeyCode.ShiftMask, Command.EndOfLineExtend);

		KeyBindings.Add (KeyCode.K | KeyCode.CtrlMask, Command.CutToEndLine); // kill-to-end
		KeyBindings.Add (KeyCode.Delete | KeyCode.CtrlMask | KeyCode.ShiftMask, Command.CutToEndLine); // kill-to-end

		KeyBindings.Add (KeyCode.K | KeyCode.AltMask, Command.CutToStartLine); // kill-to-start
		KeyBindings.Add (KeyCode.Backspace | KeyCode.CtrlMask | KeyCode.ShiftMask, Command.CutToStartLine); // kill-to-start

		KeyBindings.Add (KeyCode.Y | KeyCode.CtrlMask, Command.Paste); // Control-y, yank
		KeyBindings.Add (KeyCode.Space | KeyCode.CtrlMask, Command.ToggleExtend);

		KeyBindings.Add ((int)'C' + KeyCode.AltMask, Command.Copy);
		KeyBindings.Add (KeyCode.C | KeyCode.CtrlMask, Command.Copy);

		KeyBindings.Add ((int)'W' + KeyCode.AltMask, Command.Cut);
		KeyBindings.Add (KeyCode.W | KeyCode.CtrlMask, Command.Cut);
		KeyBindings.Add (KeyCode.X | KeyCode.CtrlMask, Command.Cut);

		KeyBindings.Add (KeyCode.CursorLeft | KeyCode.CtrlMask, Command.WordLeft);
		KeyBindings.Add ((KeyCode)((int)'B' + KeyCode.AltMask), Command.WordLeft);

		KeyBindings.Add (KeyCode.CursorLeft | KeyCode.CtrlMask | KeyCode.ShiftMask, Command.WordLeftExtend);

		KeyBindings.Add (KeyCode.CursorRight | KeyCode.CtrlMask, Command.WordRight);
		KeyBindings.Add ((KeyCode)((int)'F' + KeyCode.AltMask), Command.WordRight);

		KeyBindings.Add (KeyCode.CursorRight | KeyCode.CtrlMask | KeyCode.ShiftMask, Command.WordRightExtend);
		KeyBindings.Add (KeyCode.Delete | KeyCode.CtrlMask, Command.KillWordForwards); // kill-word-forwards
		KeyBindings.Add (KeyCode.Backspace | KeyCode.CtrlMask, 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 (KeyCode.Enter, Command.NewLine);
		KeyBindings.Add (KeyCode.End | KeyCode.CtrlMask, Command.BottomEnd);
		KeyBindings.Add (KeyCode.End | KeyCode.CtrlMask | KeyCode.ShiftMask, Command.BottomEndExtend);
		KeyBindings.Add (KeyCode.Home | KeyCode.CtrlMask, Command.TopHome);
		KeyBindings.Add (KeyCode.Home | KeyCode.CtrlMask | KeyCode.ShiftMask, Command.TopHomeExtend);
		KeyBindings.Add (KeyCode.T | KeyCode.CtrlMask, Command.SelectAll);
		KeyBindings.Add (KeyCode.Insert, Command.ToggleOverwrite);
		KeyBindings.Add (KeyCode.Tab, Command.Tab);
		KeyBindings.Add (KeyCode.Tab | KeyCode.ShiftMask, Command.BackTab);

		KeyBindings.Add (KeyCode.Tab | KeyCode.CtrlMask, Command.NextView);
		KeyBindings.Add ((KeyCode)Application.AlternateForwardKey, Command.NextView);

		KeyBindings.Add (KeyCode.Tab | KeyCode.CtrlMask | KeyCode.ShiftMask, Command.PreviousView);
		KeyBindings.Add ((KeyCode)Application.AlternateBackwardKey, Command.PreviousView);

		KeyBindings.Add (KeyCode.Z | KeyCode.CtrlMask, Command.Undo);
		KeyBindings.Add (KeyCode.R | KeyCode.CtrlMask, Command.Redo);

		KeyBindings.Add (KeyCode.G | KeyCode.CtrlMask, Command.DeleteAll);
		KeyBindings.Add (KeyCode.D | KeyCode.CtrlMask | KeyCode.ShiftMask, Command.DeleteAll);

		_currentCulture = Thread.CurrentThread.CurrentUICulture;

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

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

	MenuBarItem BuildContextMenuBarItem () => new (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))
	});

	void ContextMenu_KeyChanged (object sender, KeyChangedEventArgs e) => KeyBindings.Replace ((KeyCode)e.OldKey, (KeyCode)e.NewKey);

	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;
		}
	}

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

		if (obj != null) {
			int startLine = obj.CursorPosition.Y;

			if (obj.RemovedOnAdded != null) {
				int offset;
				if (obj.IsUndoing) {
					offset = Math.Max (obj.RemovedOnAdded.Lines.Count - obj.Lines.Count, 1);
				} else {
					offset = obj.RemovedOnAdded.Lines.Count - 1;
				}
				for (int i = 0; i < offset; i++) {
					if (Lines > obj.RemovedOnAdded.CursorPosition.Y) {
						_model.RemoveLine (obj.RemovedOnAdded.CursorPosition.Y);
					} else {
						break;
					}
				}
			}

			for (int 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 ();
	}

	void TextView_Initialized (object sender, EventArgs e)
	{
		Autocomplete.HostControl = this;
		if (Application.Top != null) {
			Application.Top.AlternateForwardKeyChanged += Top_AlternateForwardKeyChanged!;
			Application.Top.AlternateBackwardKeyChanged += Top_AlternateBackwardKeyChanged!;
		}
		OnContentsChanged ();
	}

	void Top_AlternateBackwardKeyChanged (object sender, KeyChangedEventArgs e) => KeyBindings.Replace ((KeyCode)e.OldKey, (KeyCode)e.NewKey);

	void Top_AlternateForwardKeyChanged (object sender, KeyChangedEventArgs e) => KeyBindings.Replace ((KeyCode)e.OldKey, (KeyCode)e.NewKey);

	/// <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; }

	void ResetPosition ()
	{
		_topRow = _leftColumn = _currentRow = _currentColumn = 0;
		StopSelecting ();
		ResetCursorVisibility ();
	}

	/// <summary>
	///  Sets or gets the text in the <see cref="TextView"/>.
	/// </summary>
	/// <remarks>
	/// The <see cref="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 ();
			} else {
				return _model.ToString ();
			}
		}

		set {
			ResetPosition ();
			_model.LoadString (value);
			if (_wordWrap) {
				_wrapManager = new WordWrapManager (_model);
				_model = _wrapManager.WrapModel (_frameWidth, out _, out _, out _, out _);
			}
			TextChanged?.Invoke (this, EventArgs.Empty);
			SetNeedsDisplay ();

			_historyText.Clear (Text);
		}
	}

	///<inheritdoc/>
	public override Rect Frame {
		get => base.Frame;
		set {
			base.Frame = value;
			if (IsInitialized) {
				WrapTextModel ();
				Adjust ();
			}
		}
	}

	void WrapTextModel ()
	{
		if (_wordWrap && _wrapManager != null) {
			_model = _wrapManager.WrapModel (_frameWidth,
				out int nRow, out int nCol,
				out int nStartRow, out int nStartCol,
				_currentRow, _currentColumn,
				_selectionStartRow, _selectionStartColumn,
				_tabWidth, true);
			_currentRow = nRow;
			_currentColumn = nCol;
			_selectionStartRow = nStartRow;
			_selectionStartColumn = nStartCol;
			SetNeedsDisplay ();
		}
	}

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

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

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

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

	/// <summary>
	///  Sets or gets the current cursor position.
	/// </summary>
	public Point CursorPosition {
		get => new (_currentColumn, _currentRow);
		set {
			var 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>
	/// Start column position of the selected text.
	/// </summary>
	public int SelectionStartColumn {
		get => _selectionStartColumn;
		set {
			var 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>
	/// The selected text.
	/// </summary>
	public string SelectedText {
		get {
			if (!_selecting || _model.Count == 1 && _model.GetLine (0).Count == 0) {
				return string.Empty;
			}

			return GetSelectedRegion ();
		}
	}

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

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

	/// <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 != null) {
				_model = _wrapManager.Model;
			}
			SetNeedsDisplay ();
		}
	}

	/// <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>
	/// 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>
	/// 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>
	/// 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 ();
		}
	}

	Dim? savedHeight = null;

	/// <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 != null) {
				var lyout = LayoutStyle;
				if (LayoutStyle == LayoutStyle.Computed) {
					LayoutStyle = LayoutStyle.Absolute;
				}
				Height = savedHeight;
				LayoutStyle = lyout;
				SetNeedsDisplay ();
			}
		}
	}

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

	/// <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; }

	int GetSelectedLength () => SelectedText.Length;

	CursorVisibility _savedCursorVisibility;

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

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

	/// <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 ();
		} catch (Exception) {
			throw;
		} 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 ();
	}

	/// <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>
	///  Gets the current cursor row.
	/// </summary>
	public int CurrentRow => _currentRow;

	/// <summary>
	/// Gets the cursor column.
	/// </summary>
	/// <value>The cursor column.</value>
	public int CurrentColumn => _currentColumn;

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

		if (!CanFocus || !Enabled || Application.Driver == 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 Rect (0, minRow, Frame.Width, maxRow));
			SetNeedsDisplay ();
		}
		var line = _model.GetLine (_currentRow);
		int 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 ();
		}
	}

	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)' ');
			}
		}
	}

	/// <inheritdoc/>
	public override Attribute GetNormalColor ()
	{
		var cs = ColorScheme;
		if (ColorScheme == null) {
			cs = new ColorScheme ();
		}
		return Enabled ? cs.Focus : cs.Disabled;
	}

	/// <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 ());

	/// <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)
	{
		var unwrappedPos = GetUnwrappedPosition (idxRow, idxCol);
		var ev = new RuneCellEventArgs (line, idxCol, unwrappedPos);
		DrawNormalColor?.Invoke (this, ev);

		if (line [idxCol].ColorScheme != null) {
			var 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 OnDrawSelectionColor (List<RuneCell> line, int idxCol, int idxRow)
	{
		var unwrappedPos = GetUnwrappedPosition (idxRow, idxCol);
		var ev = new RuneCellEventArgs (line, idxCol, unwrappedPos);
		DrawSelectionColor?.Invoke (this, ev);

		if (line [idxCol].ColorScheme != null) {
			var 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.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)
	{
		var unwrappedPos = GetUnwrappedPosition (idxRow, idxCol);
		var ev = new RuneCellEventArgs (line, idxCol, unwrappedPos);
		DrawReadOnlyColor?.Invoke (this, ev);

		var colorScheme = line [idxCol].ColorScheme != null ? 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.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)
	{
		var unwrappedPos = GetUnwrappedPosition (idxRow, idxCol);
		var ev = new RuneCellEventArgs (line, idxCol, unwrappedPos);
		DrawUsedColor?.Invoke (this, ev);

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

	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));

	//} else {
	//Driver.SetAttribute (new Attribute (colorScheme!.HotNormal.Foreground & colorScheme.Focus.Background, colorScheme.Focus.Foreground));
	//}
	bool _isReadOnly = false;

	/// <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 ();
			}
		}
	}

	CursorVisibility _desiredCursorVisibility = CursorVisibility.Default;

	/// <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 ();
		}
	}

	///<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 OnLeave (View view)
	{
		if (Application.MouseGrabView != null && Application.MouseGrabView == this) {
			Application.UngrabMouse ();
		}

		return base.OnLeave (view);
	}

	// Returns an encoded region start..end (top 32 bits are the row, low32 the column)
	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 == null || startCol == null || cRow == null || cCol == 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;
		}
	}

	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;
	}

	//
	// Returns a string with the text in the selected 
	// region.
	//
	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;
		}
		int startRow = (int)(start >> 32);
		int maxrow = (int)(end >> 32);
		int startCol = (int)(start & 0xffffffff);
		int endCol = (int)(end & 0xffffffff);
		var line = model == 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 == null ? _model.GetLine (maxrow) : model.GetLine (maxrow);
		res = res + Environment.NewLine + StringFromRunes (line.GetRange (0, endCol));
		return res;
	}

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

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

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

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

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

			line.RemoveRange (startCol, endCol - startCol);
			_currentColumn = startCol;
			if (_wordWrap) {
				SetNeedsDisplay ();
			} else {
				// BUGBUG: customized rect aren't supported now because the Redraw isn't using the Intersect method.
				//SetNeedsDisplay (new Rect (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);
		var 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 ();
	}

	/// <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>
	/// 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 ();
		var 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 ();
		var 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>
	/// 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 ();
		var foundPos = _model.ReplaceAllText (textToFind, matchCase, matchWholeWord, textToReplace);

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

	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;
	}

	void ResetContinuousFind ()
	{
		if (!_continuousFind) {
			int col = _selecting ? _selectionStartColumn : _currentColumn;
			int row = _selecting ? _selectionStartRow : _currentRow;
			_model.ResetContinuousFind (new Point (col, row));
		}
	}

	string? _currentCaller;

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

	/// <summary>
	/// Update the original model.
	/// </summary>
	void UpdateWrapModel ([CallerMemberName] string? caller = null)
	{
		if (_currentCaller != null && _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 != null) {
			throw new InvalidOperationException ($"WordWrap settings was changed after the {_currentCaller} call.");
		}
	}

	/// <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 == null ? _currentRow : cRow;
		int? col = cCol == null ? _currentColumn : cCol;
		if (cRow == null && cCol == null && _wordWrap) {
			row = _wrapManager!.GetModelLineFromWrappedLines (_currentRow);
			col = _wrapManager.GetModelColFromWrappedLines (_currentRow, _currentColumn);
		}
		UnwrappedCursorPosition?.Invoke (this, new PointEventArgs (new Point ((int)col, (int)row)));
	}

	string GetSelectedRegion ()
	{
		int cRow = _currentRow;
		int cCol = _currentColumn;
		int startRow = _selectionStartRow;
		int startCol = _selectionStartColumn;
		var 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);
	}

	bool _isDrawing = false;

	///<inheritdoc/>
	public override void OnDrawContent (Rect contentArea)
	{
		_isDrawing = true;

		SetNormalColor ();

		var offB = OffSetBackground ();
		int right = Frame.Width + offB.width + RightOffset;
		int bottom = Frame.Height + offB.height + BottomOffset;
		int row = 0;
		for (int idxRow = _topRow; idxRow < _model.Count; idxRow++) {
			var line = _model.GetLine (idxRow);
			int lineRuneCount = line.Count;
			int col = 0;

			Move (0, row);
			for (int idxCol = _leftColumn; idxCol < lineRuneCount; idxCol++) {
				var 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 (int i = 0; i < cols; i++) {
						if (col + i < right) {
							AddRune (col + i, row, (Rune)' ');
						}
					}
				} else {
					AddRune (col, row, rune);
				}
				if (!TextModel.SetCol (ref col, contentArea.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 (contentArea.Left, row, right, bottom);
		}

		PositionCursor ();

		_isDrawing = false;
	}

	(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);
	}

	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);
	}

	void GenerateSuggestions ()
	{
		var currentLine = this.GetCurrentLine ();
		var cursorPosition = Math.Min (CurrentColumn, currentLine.Count);
		Autocomplete.Context = new AutocompleteContext (currentLine, cursorPosition,
			Autocomplete.Context != null ? Autocomplete.Context.Canceled : false);
		Autocomplete.GenerateSuggestions (
			Autocomplete.Context);
	}

	///<inheritdoc/>
	public override bool CanFocus {
		get => base.CanFocus;
		set => base.CanFocus = value;
	}

	void SetClipboard (string text)
	{
		if (text != null) {
			Clipboard.Contents = text;
		}
	}

	void AppendClipboard (string text) => Clipboard.Contents += text;

	/// <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 ();
			}
		}
	}

	void Insert (RuneCell cell)
		{
			var 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 Rect (0, prow, Math.Max (Frame.Width, 0), Math.Max (prow + 1, 0)));
				SetNeedsDisplay ();
			}
		}

		string StringFromRunes (List<RuneCell> cells)
		{
			if (cells == null) {
				throw new ArgumentNullException (nameof (cells));
			}
			int size = 0;
			foreach (var cell in cells) {
				size += cell.Rune.GetEncodingLength ();
			}
			byte [] encoded = new byte [size];
			int offset = 0;
			foreach (var cell in cells) {
				offset += cell.Rune.Encode (encoded, offset);
			}
			return StringExtensions.ToString (encoded);
		}

		/// <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 () => _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) => _model.GetLine (line);

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

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

			var lines = TextModel.StringToLinesOfRuneCells (text);

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

			SetWrapModel ();

			var 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 Rect (0, currentRow - topRow, Frame.Width, Math.Max (currentRow - topRow + 1, 0)));
					SetNeedsDisplay ();
				}

				UpdateWrapModel ();

				OnContentsChanged ();

				return;
			}

			List<RuneCell>? rest = null;
			int 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]);

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

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

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

			if (rest != null) {
				var 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 != null ? lastp : lines [lines.Count - 1].Count;
			Adjust ();

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

			UpdateWrapModel ();
			OnContentsChanged ();
		}

		// The column we are tracking, or -1 if we are not tracking any column
		int _columnTrack = -1;

		// Tries to snap the cursor to the tracking column
		void TrackColumn ()
		{
			// Now track the column
			var line = GetCurrentLine ();
			if (line.Count < _columnTrack) {
				_currentColumn = line.Count;
			} else if (_columnTrack != -1) {
				_currentColumn = _columnTrack;
			} else if (_currentColumn > line.Count) {
				_currentColumn = line.Count;
			}
			Adjust ();
		}

		void Adjust ()
		{
			var offB = OffSetBackground ();
			var line = GetCurrentLine ();
			bool need = NeedsDisplay || _wrapNeeded || !Used;
			var tSize = TextModel.DisplaySize (line, -1, -1, false, TabWidth);
			var 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 ();
		}

	/// <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 ();
	}

	// 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.
	void ProcessInheritsPreviousColorScheme (int row, int col)
	{
		if (!InheritsPreviousColorScheme || Lines == 1 && GetLine (Lines).Count == 0) {
			return;
		}

		var line = GetLine (row);
		var 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);
		var cell = line [colWithColor];
		int colWithoutColor = Math.Max (col - 1, 0);

		if (cell.ColorScheme != null && colWithColor == 0 && lineToSet [colWithoutColor].ColorScheme != null) {
			for (int r = row - 1; r > -1; r--) {
				var l = GetLine (r);
				for (int c = l.Count - 1; c > -1; c--) {
					if (l [c].ColorScheme == null) {
						l [c].ColorScheme = cell.ColorScheme;
					} else {
						return;
					}
				}
			}
			return;
		} else if (cell.ColorScheme == null) {
			for (int r = row; r > -1; r--) {
				var l = GetLine (r);
				colWithColor = l.FindLastIndex (colWithColor > -1 ? colWithColor : l.Count - 1, rc => rc.ColorScheme != null);
				if (colWithColor > -1 && l [colWithColor].ColorScheme != null) {
					cell = l [colWithColor];
					break;
				}
			}
		} else {
			int cRow = row;
			while (cell.ColorScheme == null) {
				if ((colWithColor == 0 || cell.ColorScheme == 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 != null && colWithColor > -1 && colWithoutColor < lineToSet.Count && lineToSet [colWithoutColor].ColorScheme == null) {
			while (lineToSet [colWithoutColor].ColorScheme == null) {
				lineToSet [colWithoutColor].ColorScheme = cell.ColorScheme;
				colWithoutColor--;
				if (colWithoutColor == -1 && row > 0) {
					lineToSet = GetLine (--row);
					colWithoutColor = lineToSet.Count - 1;
				}
			}
		}
	}

	(int width, int height) OffSetBackground ()
	{
		int w = 0;
		int 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);
	}

	/// <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 ();
	}

	bool _lastWasKill;
	bool _wrapNeeded;
	bool _shiftSelecting;

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

		_historyText.Redo ();
	}

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

		_historyText.Undo ();
	}

	bool ProcessMovePreviousView ()
	{
		ResetColumnTrack ();
		return MovePreviousView ();
	}

	bool ProcessMoveNextView ()
	{
		ResetColumnTrack ();
		return MoveNextView ();
	}

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

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

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

	void MoveTopHome ()
	{
		ResetAllTrack ();
		if (_shiftSelecting && _selecting) {
			StopSelecting ();
		}
		MoveHome ();
	}

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

	void MoveBottomEnd ()
	{
		ResetAllTrack ();
		if (_shiftSelecting && _selecting) {
			StopSelecting ();
		}
		MoveEnd ();
	}

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

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

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

	void ProcessMoveWordForward ()
	{
		ResetAllTrack ();
		if (_shiftSelecting && _selecting) {
			StopSelecting ();
		}
		MoveWordForward ();
	}

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

	void ProcessMoveWordBackward ()
	{
		ResetAllTrack ();
		if (_shiftSelecting && _selecting) {
			StopSelecting ();
		}
		MoveWordBackward ();
	}

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

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

	void ToggleSelecting ()
	{
		ResetColumnTrack ();
		_selecting = !_selecting;
		_selectionStartColumn = _currentColumn;
		_selectionStartRow = _currentRow;
	}

	void ProcessPaste ()
	{
		ResetColumnTrack ();
		if (_isReadOnly) {
			return;
		}
		Paste ();
	}

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

	void ProcessMoveEndOfLine ()
	{
		ResetAllTrack ();
		if (_shiftSelecting && _selecting) {
			StopSelecting ();
		}
		MoveEndOfLine ();
	}

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

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

	void ProcessMoveStartOfLine ()
	{
		ResetAllTrack ();
		if (_shiftSelecting && _selecting) {
			StopSelecting ();
		}
		MoveStartOfLine ();
	}

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

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

	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;
	}

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

	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;
	}

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

	void ProcessMoveUp ()
	{
		ResetContinuousFindTrack ();
		if (_shiftSelecting && _selecting) {
			StopSelecting ();
		}
		MoveUp ();
	}

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

	void ProcessMoveDown ()
	{
		ResetContinuousFindTrack ();
		if (_shiftSelecting && _selecting) {
			StopSelecting ();
		}
		MoveDown ();
	}

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

	void ProcessPageUp ()
	{
		ResetColumnTrack ();
		if (_shiftSelecting && _selecting) {
			StopSelecting ();
		}
		MovePageUp ();
	}

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

	void ProcessPageDown ()
	{
		ResetColumnTrack ();
		if (_shiftSelecting && _selecting) {
			StopSelecting ();
		}
		MovePageDown ();
	}

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

		return false;
	}

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

		return false;
	}

	bool ProcessBackTab ()
	{
		ResetColumnTrack ();

		if (!AllowsTab || _isReadOnly) {
			return ProcessMovePreviousView ();
		}
		if (_currentColumn > 0) {
			SetWrapModel ();

			var currentLine = GetCurrentLine ();
			if (currentLine.Count > 0 && currentLine [_currentColumn - 1].Rune.Value == '\t') {

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

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

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

			SetNeedsDisplay ();

			UpdateWrapModel ();
		}
		DoNeededAction ();
		return true;
	}

	bool ProcessTab ()
	{
		ResetColumnTrack ();

		if (!AllowsTab || _isReadOnly) {
			return ProcessMoveNextView ();
		}
		InsertText (new Key ((KeyCode)'\t'));
		DoNeededAction ();
		return true;
	}

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

	bool ProcessReturn ()
	{
		ResetColumnTrack ();

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

		SetWrapModel ();

		var currentLine = GetCurrentLine ();

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

		if (_selecting) {
			ClearSelectedRegion ();
			currentLine = GetCurrentLine ();
		}
		int restCount = currentLine.Count - _currentColumn;
		var rest = currentLine.GetRange (_currentColumn, restCount);
		currentLine.RemoveRange (_currentColumn, restCount);

		var addedLines = new List<List<RuneCell>> () { 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++;

		bool fullNeedsDisplay = false;
		if (_currentRow >= _topRow + Frame.Height) {
			_topRow++;
			fullNeedsDisplay = true;
		}
		_currentColumn = 0;

		_historyText.Add (new List<List<RuneCell>> () { new List<RuneCell> (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 Rect (0, currentRow - topRow, 2, Frame.Height));
			SetNeedsDisplay ();
		}

		UpdateWrapModel ();

		DoNeededAction ();
		OnContentsChanged ();
		return true;
	}

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

		SetWrapModel ();

		var currentLine = GetCurrentLine ();

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

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

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

			UpdateWrapModel ();

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

		UpdateWrapModel ();

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

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

		SetWrapModel ();

		var currentLine = GetCurrentLine ();

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

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

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

			UpdateWrapModel ();

			return;
		}
		var newPos = _model.WordForward (_currentColumn, _currentRow);
		int 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 (new List<List<RuneCell>> () { new List<RuneCell> (GetCurrentLine ()) }, CursorPosition,
			HistoryText.LineStatus.Replaced);

		UpdateWrapModel ();

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

	void MoveWordForward ()
	{
		var newPos = _model.WordForward (_currentColumn, _currentRow);
		if (newPos.HasValue) {
			_currentColumn = newPos.Value.col;
			_currentRow = newPos.Value.row;
		}
		Adjust ();
		DoNeededAction ();
	}

	void MoveWordBackward ()
	{
		var newPos = _model.WordBackward (_currentColumn, _currentRow);
		if (newPos.HasValue) {
			_currentColumn = newPos.Value.col;
			_currentRow = newPos.Value.row;
		}
		Adjust ();
		DoNeededAction ();
	}

	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 ();

		var currentLine = GetCurrentLine ();
		bool setLastWasKill = true;
		if (currentLine.Count > 0 && _currentColumn == 0) {
			UpdateWrapModel ();

			DeleteTextBackwards ();
			return;
		}

		_historyText.Add (new List<List<RuneCell>> () { new List<RuneCell> (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);

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

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

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

				_currentColumn = currentLine.Count;
			}
		} else {
			int restCount = _currentColumn;
			var rest = currentLine.GetRange (0, restCount);
			string val = string.Empty;
			val += StringFromRunes (rest);
			if (_lastWasKill) {
				AppendClipboard (val);
			} else {
				SetClipboard (val);
			}
			currentLine.RemoveRange (0, restCount);
			_currentColumn = 0;
		}

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

		UpdateWrapModel ();

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

		_lastWasKill = setLastWasKill;
		DoNeededAction ();
	}

	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 ();

		var currentLine = GetCurrentLine ();
		bool setLastWasKill = true;
		if (currentLine.Count > 0 && _currentColumn == currentLine.Count) {
			UpdateWrapModel ();

			DeleteTextForwards ();
			return;
		}

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

		if (currentLine.Count == 0) {
			if (_currentRow < _model.Count - 1) {
				var removedLines = new List<List<RuneCell>> () { 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;
			var rest = currentLine.GetRange (_currentColumn, restCount);
			string val = string.Empty;
			val += StringFromRunes (rest);
			if (_lastWasKill) {
				AppendClipboard (val);
			} else {
				SetClipboard (val);
			}
			currentLine.RemoveRange (_currentColumn, restCount);
		}

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

		UpdateWrapModel ();

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

		_lastWasKill = setLastWasKill;
		DoNeededAction ();
	}

	void MoveEndOfLine ()
	{
		var currentLine = GetCurrentLine ();
		_currentColumn = currentLine.Count;
		Adjust ();
		DoNeededAction ();
	}

	void MoveStartOfLine ()
	{
		if (_leftColumn > 0) {
			SetNeedsDisplay ();
		}
		_currentColumn = 0;
		_leftColumn = 0;
		Adjust ();
		DoNeededAction ();
	}

	/// <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 List<RuneCell> (GetCurrentLine ()) }, CursorPosition,
				HistoryText.LineStatus.Original);

			ClearSelectedRegion ();

			var currentLine = GetCurrentLine ();

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

			UpdateWrapModel ();
			OnContentsChanged ();

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

			return;
		}

		UpdateWrapModel ();

		DoNeededAction ();
		OnContentsChanged ();
	}

	/// <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 List<RuneCell> (GetCurrentLine ()) }, CursorPosition,
				HistoryText.LineStatus.Original);

			ClearSelectedRegion ();

			var currentLine = GetCurrentLine ();

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

			UpdateWrapModel ();
			OnContentsChanged ();

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

			return;
		}

		UpdateWrapModel ();

		DoNeededAction ();
		OnContentsChanged ();
	}

	void MoveLeft ()
	{
		if (_currentColumn > 0) {
			_currentColumn--;
		} else {
			if (_currentRow > 0) {
				_currentRow--;
				if (_currentRow < _topRow) {
					_topRow--;
					SetNeedsDisplay ();
				}
				var currentLine = GetCurrentLine ();
				_currentColumn = currentLine.Count;
			}
		}
		Adjust ();
		DoNeededAction ();
	}

	void MoveRight ()
	{
		var 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 ();
	}

	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 ();
	}

	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 ();
	}

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

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

	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;
	}

	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 List<RuneCell> (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 List<RuneCell> (GetCurrentLine ()) }, CursorPosition,
			HistoryText.LineStatus.Replaced);

		UpdateWrapModel ();
		OnContentsChanged ();

		return true;
	}

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

			_currentCulture = Thread.CurrentThread.CurrentUICulture;

			ContextMenu!.MenuItems = BuildContextMenuBarItem ();
		}
		ContextMenu!.Show ();
	}

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

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

	///<inheritdoc/>
	public override bool OnKeyUp (Key a)
	{
		switch (a.KeyCode) {
		case KeyCode.Space | KeyCode.CtrlMask:
			return true;
		}

		return base.OnKeyUp (a);
	}

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

	bool DeleteTextForwards ()
	{
		SetWrapModel ();

		var currentLine = GetCurrentLine ();
		if (_currentColumn == currentLine.Count) {
			if (_currentRow + 1 == _model.Count) {
				UpdateWrapModel ();

				return true;
			}

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

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

			var 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 List<RuneCell> (currentLine) }, CursorPosition,
				HistoryText.LineStatus.Replaced);

			if (_wordWrap) {
				_wrapNeeded = true;
			}
			DoSetNeedsDisplay (new Rect (0, _currentRow - _topRow, Frame.Width, _currentRow - _topRow + 1));
		} else {
			_historyText.Add (new List<List<RuneCell>> () { new List<RuneCell> (currentLine) }, CursorPosition);

			currentLine.RemoveAt (_currentColumn);

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

			if (_wordWrap) {
				_wrapNeeded = true;
			}

			DoSetNeedsDisplay (new Rect (_currentColumn - _leftColumn, _currentRow - _topRow, Frame.Width, _currentRow - _topRow + 1));
		}

		UpdateWrapModel ();

		return false;
	}

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

	bool DeleteTextBackwards ()
	{
		SetWrapModel ();

		if (_currentColumn > 0) {
			// Delete backwards 
			var currentLine = GetCurrentLine ();

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

			currentLine.RemoveAt (_currentColumn - 1);
			if (_wordWrap) {
				_wrapNeeded = true;
			}
			_currentColumn--;

			_historyText.Add (new List<List<RuneCell>> () { new List<RuneCell> (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 Rect (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;
			var 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;
	}

	bool _copyWithoutSelection;

	/// <summary>
	/// Copy the selected text to the clipboard contents.
	/// </summary>
	public void Copy ()
	{
		SetWrapModel ();
		if (_selecting) {
			SetClipboard (GetRegion ());
			_copyWithoutSelection = false;
		} else {
			var 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 List<RuneCell> (GetCurrentLine ()) }, CursorPosition,
				HistoryText.LineStatus.Replaced);
		}
		UpdateWrapModel ();
		_selecting = false;
		DoNeededAction ();
		OnContentsChanged ();
	}

	/// <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) {
			var runeList = contents == null ? new List<RuneCell> () : TextModel.ToRuneCellList (contents);
			var currentLine = GetCurrentLine ();

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

			var addedLine = new List<List<RuneCell>> {
				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 List<RuneCell> (GetCurrentLine ()) }, CursorPosition,
				HistoryText.LineStatus.Replaced);

			SetNeedsDisplay ();
			OnContentsChanged ();
		} else {
			if (_selecting) {
				ClearRegion ();
			}
			_copyWithoutSelection = false;
			InsertAllText (contents);

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

			SetNeedsDisplay ();
		}
		UpdateWrapModel ();
		_selecting = false;
		DoNeededAction ();
	}

	void StartSelecting ()
	{
		if (_shiftSelecting && _selecting) {
			return;
		}
		_shiftSelecting = true;
		_selecting = true;
		_selectionStartColumn = _currentColumn;
		_selectionStartRow = _currentRow;
	}

	void StopSelecting ()
	{
		_shiftSelecting = false;
		_selecting = false;
		_isButtonShift = false;
	}

	void ClearSelectedRegion ()
	{
		SetWrapModel ();
		if (!_isReadOnly) {
			ClearRegion ();
		}
		UpdateWrapModel ();
		_selecting = false;
		DoNeededAction ();
	}

	void MoveUp ()
	{
		if (_currentRow > 0) {
			if (_columnTrack == -1) {
				_columnTrack = _currentColumn;
			}
			_currentRow--;
			if (_currentRow < _topRow) {
				_topRow--;
				SetNeedsDisplay ();
			}
			TrackColumn ();
			PositionCursor ();
		}
		DoNeededAction ();
	}

	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 ();
	}

	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;
		}
		var 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 ();
		}
	}

	/// <summary>
	/// Will scroll the <see cref="TextView"/> to the last line and position the cursor there.
	/// </summary>
	public void MoveEnd ()
	{
		_currentRow = _model.Count - 1;
		var 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 ();
	}

	bool _isButtonShift;
	bool _clickWithSelecting;

	///<inheritdoc/>
	public override bool MouseEvent (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.MouseEvent (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 var 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 == 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 var 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 != null && 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 var 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;
	}

	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!;
	}

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

/// <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);
}