using Qrakhen.Qamp.Editor.Primitives;
using Qrakhen.Qamp.Editor.ViewModel;
using Qrakhen.Qamp.Memory;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;

namespace Qrakhen.Qamp.Editor.Controls;

public partial class EditorFrame : UserControl
{
    public Caret Caret { get; private set; }

    public EditorFrame()
    {
        InitializeComponent();
        Loaded += OnLoaded;
        PreviewKeyDown += OnKeyDown;
    }

  private void OnKeyDown(object sender, KeyEventArgs e)
  {
    if (DataContext is EditorFrameViewModel vm) {
      BufferPosition position = e.Key switch {
        Key.Right => new(0, 1),
        Key.Left => new(0, -1),
        Key.Up => new(-1, 0),
        Key.Down => new(1, 0),
        _ => new(0, 0)
      };
      if (position != BufferPosition.Void) 
        vm.MoveCaretCommand.Execute(position);
      else if (e.Key == Key.Back)
        vm.DeleteCommand.Execute(-1);
      else if (e.Key == Key.Delete)
        vm.DeleteCommand.Execute(1);
      else if (e.Key == Key.Enter)
        vm.InsertCommand.Execute(Environment.NewLine);
      else if (e.Key == Key.Delete)
        vm.DeleteCommand.Execute(1);
      else {
        string c = e.Key.ToString();
        if (c.Length == 1)
          vm.InsertCommand.Execute(c);               
        }

      e.Handled = true;
    }
  }

    private void OnLoaded(object sender, RoutedEventArgs e)
    {
        Focus();
        AdornerLayer adornerLayer = AdornerLayer.GetAdornerLayer(this);
        if (adornerLayer != null) {
            Caret = new Caret(this, Brushes.LimeGreen);
            adornerLayer.Add(Caret);
        } else {
            System.Diagnostics.Debug.WriteLine("AdornerLayer still null. Check parent hierarchy.");
        }
        Loaded -= OnLoaded;
    }

    private Point CalculateCaretPosition(int line, int index, double scrollY, double scrollX)
    {
        var ft = TextHelper.GetText(new string('_', index), 14, null, VisualTreeHelper.GetDpi(this).PixelsPerDip);
        return new Point(ft.Width + scrollX + 2, line * TextHelper.LineHeight + scrollY);
    }

    private void MoveCaret(Point point)
    {
        Caret?.UpdatePosition(point);
    }

    private void UpdateCaret()
    {
        int line = CursorPosition.Line;
        int charIndex = CursorPosition.Column;

        double scrollY = ScrollView.VerticalOffset;
        double scrollX = ScrollView.HorizontalOffset;

        MoveCaret(
            CalculateCaretPosition(
                line,
                charIndex,
                scrollY,
                scrollX));
    }

    public LineBuffer CurrentLineBuffer {
        get => (LineBuffer)GetValue(CurrentLineBufferProperty);
        set => SetValue(CurrentLineBufferProperty, value);
    }

    public static readonly DependencyProperty CurrentLineBufferProperty =
        DependencyProperty.Register(
            nameof(CurrentLineBuffer),
            typeof(LineBuffer),
            typeof(EditorFrame),
            new PropertyMetadata(null));

    public BufferPosition CursorPosition {
        get => (BufferPosition)GetValue(CursorPositionProperty);
        set => SetValue(CursorPositionProperty, value);
    }

    public static readonly DependencyProperty CursorPositionProperty =
        DependencyProperty.Register(
            nameof(CursorPosition), 
            typeof(BufferPosition), 
            typeof(EditorFrame), 
            new PropertyMetadata(BufferPosition.Void, OnCursorPositionChanged));

    private static void OnCursorPositionChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var frame = (EditorFrame)d;
        frame.UpdateCaret();
    }
}