#nullable enable

using System.Text;

namespace UICatalog.Scenarios;

[ScenarioMetadata ("HexEditor", "A binary (hex) editor using the HexView control.")]
[ScenarioCategory ("Controls")]
[ScenarioCategory ("Dialogs")]
[ScenarioCategory ("Text and Formatting")]
[ScenarioCategory ("Navigation")]
[ScenarioCategory ("Files and IO")]
public class HexEditor : Scenario
{
    private string? _fileName;
    private HexView? _hexView;
    private MenuItem? _miReadOnly;
    private bool _saved = true;
    private Shortcut? _scAddress;
    private Shortcut? _scInfo;
    private Shortcut? _scPosition;
    private StatusBar? _statusBar;

    public override void Main ()
    {
        Application.Init ();

        var app = new Window ()
        {
            BorderStyle = LineStyle.None
        };

        _fileName = "demo.bin";
        CreateDemoFile (_fileName);

        _hexView = new (new MemoryStream (Encoding.UTF8.GetBytes ("Demo text.")))
        {
            X = 0,
            Y = 1,
            Width = Dim.Fill (),
            Height = Dim.Fill (1),
            Title = _fileName ?? "Untitled",
            BorderStyle = LineStyle.Rounded,
        };
        _hexView.Arrangement = ViewArrangement.Resizable;
        _hexView.Edited += _hexView_Edited;
        _hexView.PositionChanged += _hexView_PositionChanged;
        _hexView.VerticalScrollBar.AutoShow = false;

        app.Add (_hexView);

        var menu = new MenuBar
        {
            Menus =
            [
                new (
                     "_File",
                     new MenuItem []
                     {
                         new ("_New", "", New),
                         new ("_Open", "", Open),
                         new ("_Save", "", Save),
                         null!,                     // Passing null automatically creates a separator (a Line object).
                         new ("_Quit", "", Quit)
                     }
                    ),
                new (
                     "_Edit",
                     new MenuItem []
                     {
                         new ("_Copy", "", Copy),
                         new ("C_ut", "", Cut),
                         new ("_Paste", "", Paste)
                     }
                    ),
                new (
                     "_Options",
                     new MenuItem []
                     {
                         _miReadOnly = new (
                                              "_Read Only",
                                              "",
                                              ToggleReadOnly
                                             )
                         {

                         }
                     }
                    )
            ]
        };

        CheckBox cb = new CheckBox ()
        {
            Title = _miReadOnly.Title,
            CheckedState = _hexView.ReadOnly ? CheckState.Checked : CheckState.None,
        };
        _miReadOnly.CommandView = cb;
        app.Add (menu);

        var addressWidthUpDown = new NumericUpDown
        {
            Value = _hexView.AddressWidth
        };

        NumericUpDown<long> addressUpDown = new NumericUpDown<long>
        {
            Value = _hexView.Address,
            Format = $"0x{{0:X{_hexView.AddressWidth}}}"
        };

        addressWidthUpDown.ValueChanging += (sender, args) =>
                                            {
                                                args.Cancel = args.NewValue is < 0 or > 8;

                                                if (!args.Cancel)
                                                {
                                                    _hexView.AddressWidth = args.NewValue;

                                                    // ReSharper disable once AccessToDisposedClosure
                                                    addressUpDown.Format = $"0x{{0:X{_hexView.AddressWidth}}}";
                                                }
                                            };

        addressUpDown.ValueChanging += (sender, args) =>
                                       {
                                           args.Cancel = args.NewValue is < 0;

                                           if (!args.Cancel)
                                           {
                                               _hexView.Address = args.NewValue;
                                           }
                                       };

        _statusBar = new (
                          [
                              new (Key.F2, "Open", Open),
                              new (Key.F3, "Save", Save),
                              new ()
                              {
                                  CommandView = addressWidthUpDown,
                                  HelpText = "Address Width"
                              },
                              _scAddress = new ()
                              {
                                  CommandView = addressUpDown,
                                  HelpText = "Address:"
                              },
                              _scInfo = new (Key.Empty, string.Empty, () => { }),
                              _scPosition = new (Key.Empty, string.Empty, () => { })
                          ])
        {
            AlignmentModes = AlignmentModes.IgnoreFirstOrLast
        };
        app.Add (_statusBar);

        _hexView.VerticalScrollBar.AutoShow = true;
        _hexView.HorizontalScrollBar.AutoShow = true;

        _hexView.Source = LoadFile ();

        Application.Run (app);
        addressUpDown.Dispose ();
        addressWidthUpDown.Dispose ();
        app.Dispose ();
        Application.Shutdown ();
    }

    private void _hexView_Edited (object? sender, HexViewEditEventArgs e) { _saved = false; }

    private void _hexView_PositionChanged (object? sender, HexViewEventArgs obj)
    {
        _scInfo!.Title =
            $"Bytes: {_hexView!.Source!.Length}";
        _scPosition!.Title =
            $"L: {obj.Position.Y} C: {obj.Position.X} Per Line: {obj.BytesPerLine}";

        if (_scAddress!.CommandView is NumericUpDown<long> addrNumericUpDown)
        {
            addrNumericUpDown.Value = obj.Address;
        }
    }

    private void Copy () { MessageBox.ErrorQuery (ApplicationImpl.Instance, "Not Implemented", "Functionality not yet implemented.", "Ok"); }

    private void CreateDemoFile (string fileName)
    {
        var sb = new StringBuilder ();
        sb.Append ("Hello world.\n");
        sb.Append ("This is a test of the Emergency Broadcast System.\n");

        StreamWriter sw = File.CreateText (fileName);
        sw.Write (sb.ToString ());
        sw.Close ();
    }

    private void CreateUnicodeDemoFile (string fileName)
    {
        var sb = new StringBuilder ();
        sb.Append ("Hello world with wide codepoints: 𝔹Aℝ𝔽.\n");
        sb.Append ("This is a test of the Emergency Broadcast System.\n");

        byte [] buffer = Encoding.Unicode.GetBytes (sb.ToString ());
        var ms = new MemoryStream (buffer);
        var file = new FileStream (fileName, FileMode.Create, FileAccess.Write);
        ms.WriteTo (file);
        file.Close ();
        ms.Close ();
    }

    private void Cut () { MessageBox.ErrorQuery (ApplicationImpl.Instance, "Not Implemented", "Functionality not yet implemented.", "Ok"); }

    private Stream LoadFile ()
    {
        var stream = new MemoryStream ();

        if (!_saved && _hexView!.Edits.Count > 0 && _hexView.Source is {})
        {
            if (MessageBox.ErrorQuery (ApplicationImpl.Instance,
                                       "Save",
                                       "The changes were not saved. Want to open without saving?",
                                       "_Yes",
                                       "_No"
                                      )
                == 1)
            {
                return _hexView.Source;
            }

            _hexView.DiscardEdits ();
            _saved = true;
        }

        if (_fileName is { })
        {
            byte [] bin = File.ReadAllBytes (_fileName);
            stream.Write (bin);
            _hexView!.Title = _fileName;
            _saved = true;
        }
        else
        {
            _hexView!.Title = _fileName ?? "Untitled";
        }

        return stream;
    }

    private void New ()
    {
        _fileName = null;
        _hexView!.Source = LoadFile ();
    }

    private void Open ()
    {
        var d = new OpenDialog { Title = "Open", AllowsMultipleSelection = false };
        Application.Run (d);

        if (!d.Canceled)
        {
            _fileName = d.FilePaths [0];
            _hexView!.Source = LoadFile ();
            //_hexView.DisplayStart = 0;
        }

        d.Dispose ();
    }

    private void Paste () { MessageBox.ErrorQuery (ApplicationImpl.Instance, "Not Implemented", "Functionality not yet implemented.", "_Ok"); }
    private void Quit () { Application.RequestStop (); }

    private void Save ()
    {
        if (_fileName != null)
        {
            using (var fs = new FileStream (_fileName, FileMode.OpenOrCreate))
            {
                _hexView?.ApplyEdits (fs);

                //_hexView.Source.Position = 0;
                //_hexView.Source.CopyTo (fs);
                //fs.Flush ();
            }

            _saved = true;
        }
        else
        {
            _hexView!.ApplyEdits ();
        }
    }

    private void ToggleReadOnly ()
    {
        if (_miReadOnly?.CommandView is not CheckBox cb)
        {
            return;
        }

        _hexView!.ReadOnly = cb.CheckedState == CheckState.Checked;
    }
}