using System.Text;

public class ConsoleWriter
{
    private const string SYMBOL_INPUT = " <: ";
    private const string SYMBOL_INPUT_CONTINUE = "  : ";

    private readonly List<char> _buffer = [];
    private readonly Stack<char[]> _history = [];
    private readonly Encoding _encoding;

    private int _position;
    private (int x, int y) _origin;
    private (int x, int y) _cursorPosition => Console.GetCursorPosition();

    private int _cursorOffset => SYMBOL_INPUT.Length;
    private int _cursorLeft { get => Console.CursorLeft; set => Console.CursorLeft = value; }
    private int _cursorTop { get => Console.CursorTop; set => Console.CursorTop = value; }

    public bool UseSyntaxHighlighting { get; set; } = false;

    public ConsoleWriter(Encoding encoding)
    {
        _encoding = encoding; 
    }

    private void Write(char c) => Console.Write(c); 
    private void Write(string str) => Console.Write(str);
    private void SetCursor((int x, int y) position) => Console.SetCursorPosition(position.x, position.y);

    private void SetColor(ConsoleColor color, ConsoleColor background = ConsoleColor.Black)
    {
        Console.ForegroundColor = color;
        Console.BackgroundColor = background;
    }

    private void Move(int x, int y = 0)
    {
        _position = Math.Min(_buffer.Count, Math.Max(0, _position + x));
        _cursorLeft -= 1; //????
    }

    private void ClearLine()
    {
        int left = _cursorLeft;
        while (_cursorLeft < Console.BufferWidth - 1)
            Write(' ');
        _cursorLeft = left;
    }

    private void Print((int x, int y) origin, (int x, int y)? remain = null)
    {
        SetColor(ConsoleColor.White);
        SetCursor(origin);
        Write(" <: ");
        foreach (var c in _buffer) {
            if (c == '\n') {
                ClearLine();
                Write("\n  : ");
            } else {
                Write(c);
            }
        }
        ClearLine();
        if (remain.HasValue)
            SetCursor(remain.Value);
    }

    private Stream Dispatch()
    {
        var stream = new MemoryStream();
        var data = _buffer.ToArray();
        stream.Write(_encoding.GetBytes(data));
        _history.Push(data);
        _buffer.Clear();
        return stream;
    }

    public ConsoleCode Read(out Stream? stream)
    {
        stream = null;
        ConsoleKeyInfo input;
        _origin = _cursorPosition;
        _position = 0;
        Print(_origin);
        do {
            if (UseSyntaxHighlighting)
                new ConsoleRenderer(new MemoryStream(_encoding.GetBytes(_buffer.ToArray()))).Render(_origin); // ~ so efficient ~ XD
            Print(_origin, _cursorPosition);
            input = Console.ReadKey(true);

            if (input.Modifiers == ConsoleModifiers.Control) {
                if (input.Key == ConsoleKey.C)
                    return ConsoleCode.Exit;

                if (input.Key == ConsoleKey.H) {
                    UseSyntaxHighlighting = !UseSyntaxHighlighting;
                    Write($"\n #: {nameof(UseSyntaxHighlighting)} = {UseSyntaxHighlighting}\n <: ");
                    _origin = _cursorPosition;
                }
                if (input.Key == ConsoleKey.LeftArrow) {
                    
                }
                continue;
            }

            if (input.Key == ConsoleKey.LeftArrow) {
                if (_position > 0) {
                    _position--;
                    _cursorLeft--;
                }
                continue;
            }

            if (input.Key == ConsoleKey.RightArrow) {
                if (_position < _buffer.Count) {
                    _position++;
                    _cursorLeft++;
                }
                continue;
            }

            if (input.Key == ConsoleKey.Backspace) {
                if (_position > 0) {
                    _cursorLeft--;
                    _buffer.RemoveRange(--_position, 1);
                }
                continue;
            } else if (input.Check(ConsoleKey.Enter, ConsoleModifiers.Shift)) {
                _buffer.Insert(_position++, '\n');
                _cursorLeft = _cursorOffset;
                _cursorTop++;
                continue;
            } else {
                _buffer.Insert(_position++, input.KeyChar);
                _cursorLeft++;
            }
        } while (!input.Check(ConsoleKey.Enter, ConsoleModifiers.None, true));
        stream = Dispatch();
        return ConsoleCode.OK;
    }
}