using Microsoft.Win32;
using Qrakhen.Qamp.Editor.Commands;
using Qrakhen.Qamp.Editor.Primitives;
using Qrakhen.Qamp.Memory;
using System;
using System.Collections.ObjectModel;
using System.IO;
using System.Text;
using System.Windows.Documents;
using System.Windows.Input;

namespace Qrakhen.Qamp.Editor.ViewModel;

public class SelectableLineBuffer(LineBuffer buffer)
{
   public LineBuffer Buffer { get; private set; } = buffer;
   public BufferRegion Selection { get; private set; } = new();
}

public class EditorFrameViewModel : ObservableObject
{
   private Encoding _encoding;
   public Encoding Encoding {
      get => _encoding;
      set => SetProperty(ref _encoding, value);
   }

   private FileInfo _fileInfo;
   public FileInfo FileInfo {
      get => _fileInfo;
      set => SetProperty(ref _fileInfo, value);
   }

   private BufferPosition _cursorPosition;
   public BufferPosition CursorPosition {
      get => _cursorPosition;
      set => SetProperty(ref _cursorPosition, value);
   }

   private BufferRegion _currentSelection;
   public BufferRegion CurrentSelection {
      get => _currentSelection;
      set => SetProperty(ref _currentSelection, value);
   }

   public int CursorLine => _cursorPosition.Line;

   public int CursorColumn => _cursorPosition.Column;

   public SelectableLineBuffer CurrentLine => Lines[CursorLine];

   public ICommand MoveCaretCommand { get; }
   public ICommand MoveBlockCommand { get; }
   public ICommand InsertCommand { get; }
   public ICommand DeleteCommand { get; }
   public ICommand ClipBoardCommand { get; }

   public ObservableCollection<SelectableLineBuffer> Lines { get; private set; } = new() {
      new SelectableLineBuffer(new LineBuffer("test {")),
      new SelectableLineBuffer(new LineBuffer("   is very good;")),
      new SelectableLineBuffer(new LineBuffer("   jaja();")),
      new SelectableLineBuffer(new LineBuffer("}"))
   };

   public EditorFrameViewModel()
   {
      Encoding = Encoding.ASCII;

      MoveCaretCommand = new RelayCommand(ExecuteMoveCaret);
      MoveBlockCommand = new RelayCommand(ExecuteMoveBlock);
      InsertCommand = new RelayCommand(ExecuteInsert);
      DeleteCommand = new RelayCommand(ExecuteDelete);
      ClipBoardCommand = new RelayCommand(() => { });
   }

   public void SetCursor(int line, int column) => SetCursor(new BufferPosition(line, column));
   public void SetCursor(BufferPosition position)
   {
      CursorPosition = AlignBufferPosition(position);
      OnPropertyChanged(nameof(CurrentLine));
   }

   public void MoveCursor(int lines, int columns) => MoveCursor(new BufferPosition(lines, columns));
   public void MoveCursor(BufferPosition relative, bool jump = false)
   {
      SetCursor(CursorPosition + relative);
      OnPropertyChanged(nameof(CurrentLine));
   }

   public void Delete(BufferRegion region, bool follow = true)
   {
      if (follow)
         SetCursor(new BufferPosition(region.From.Line, region.From.Column));
      for (int line = region.From.Line; line < region.To.Line; line++) {

      }
   }

   public void Delete(int count = 1, bool follow = true)
   {
      if (count < 1)
         return;

      if (follow) {
         // remove newline
         if (CursorColumn - count < 0 && CursorLine > 0) {
            int position = Lines[CursorLine - 1].Buffer.Tail;
            Lines[CursorLine - 1].Buffer.Insert(
                position,
                CurrentLine.Buffer.Slice(0));
            Lines.RemoveAt(CursorLine);
            SetCursor(CursorLine - 1, position);
         } else {
            MoveCursor(0, -count);
            CurrentLine.Buffer.Delete(CursorColumn, count);
         }
      } else {
         if (CursorColumn + count > CurrentLine.Buffer.Tail &&
             CursorLine < Lines.Count - 1) {
            CurrentLine.Buffer.Insert(
               CurrentLine.Buffer.Tail,
               Lines[CursorLine + 1].Buffer.Slice(0));
            Lines.RemoveAt(CursorLine + 1);
         }
         CurrentLine.Buffer.Delete(CursorColumn, count);
      }
   }

   public void Select(BufferPosition relativePosition, bool jump = false)
   {
      if (CurrentSelection.IsVoid) {
         CurrentSelection = new BufferRegion(CursorPosition, CursorPosition);
      }

      CurrentSelection += relativePosition;
   }

   public void Deselect()
   {
      CurrentSelection = BufferRegion.Void;
   }

   public void Insert(string data, bool follow = true)
   {
      data = data.Replace("\t", "   ");
      var lines = data.Split(Environment.NewLine, StringSplitOptions.None);
      for (int i = 0; i < lines.Length; i++) {
         if (i > 0) {
            LineBuffer split = new LineBuffer(
                    CurrentLine.Buffer.Slice(CursorColumn),
                    CurrentLine.Buffer.Encoding);
            Lines.Insert(CursorLine + 1, new SelectableLineBuffer(split));
            SetCursor(new BufferPosition(CursorLine + 1, 0));
         }
         CurrentLine.Buffer.Insert(CursorColumn, lines[i]);
         if (follow)
            MoveCursor(new BufferPosition(0, lines[i].Length));
      }
   }

   private BufferPosition AlignBufferPosition(BufferPosition position)
   {
      int line = Math.Max(0, Math.Min(position.Line, Lines.Count - 1));
      LineBuffer buffer = Lines[line].Buffer;
      int column = Math.Max(0, Math.Min(position.Column, buffer.Tail));
      return new BufferPosition(line, column);
   }

   #region Commands

   private void ExecuteMoveCaret(object? parameter)
   {
      if (parameter is MoveCaretOptions options) {
         if (options.Relative)
            MoveCursor(options.Position, options.Jump);
         else
            SetCursor(options.Position);
      }
   }

   private void ExecuteMoveBlock(object? parameter)
   {
      if (parameter is BufferPosition relative)
         MoveCursor(relative);
   }

   private void ExecuteInsert(object? parameter)
   {
      if (parameter is string str)
         Insert(str, true);
      if (parameter is char c)
         Insert(c + "", true);
   }

   private void ExecuteDelete(object? parameter)
   {
      if (parameter is int count)
         Delete(Math.Abs(count), count < 0);
      if (parameter is BufferRegion region)
         Delete(region);
   }

   #endregion

   public string Serialize(string? lineTerminator = null)
   {
      lineTerminator ??= Environment.NewLine;
      string result = "";
      foreach (var line in Lines) {
         result += $"{line.Buffer.ToString()}{lineTerminator}";
      }
      return result;
   }

   public void Deserialize(string source, Encoding? encoding = null, string? lineTerminator = null)
   {
      encoding ??= Encoding.ASCII;
      lineTerminator ??= Environment.NewLine;
      Lines.Clear();
      string[] lines = source.Split(lineTerminator);
      foreach (var line in lines) {
         Lines.Add(new SelectableLineBuffer(new LineBuffer(line, encoding)));
      }
   }
}