using System;
using Vector2 = Godot.Vector2;

public class VirtualBoard {
    private readonly int Rows;
    private readonly int Cols;
    private readonly VirtualPiece[,] pieces;

    public class SetPiecePosEventArgs : EventArgs
    {
        public VirtualPiece OldPiece { get; set; }
        public VirtualPiece NewPiece { get; set; }
    }

    public class MoveEventArgs : EventArgs
    {
        public Vector2 From { get; set; }
        public Vector2 To { get; set; }
    }

    public event EventHandler<SetPiecePosEventArgs> OnSetPiecePos;
    public event EventHandler<VirtualPiece> OnInsert;
    public event EventHandler<VirtualPiece> OnRemove;
    public event EventHandler<MoveEventArgs> OnMove;

    public VirtualBoard(int rows, int cols) {
        this.Rows = rows;
        this.Cols = cols;
        pieces = new VirtualPiece[rows, cols];
    }

    public bool ArrPosOutOfRange(Vector2 arrayPos) {
        return arrayPos.X < 0 || arrayPos.X >= Rows || arrayPos.Y < 0 || arrayPos.Y >= Cols;
    }

    public VirtualPiece GetPiece(Vector2 arrayPos) {
        if (ArrPosOutOfRange(arrayPos)) return null;
        return pieces[(int)arrayPos.X, (int)arrayPos.Y];
    }

    public VirtualPiece SetPiecePos(VirtualPiece piece, Vector2 arrayPos) {
        if (ArrPosOutOfRange(arrayPos)) return null;

        VirtualPiece oldPiece = pieces[(int)arrayPos.X, (int)arrayPos.Y];
        pieces[(int)arrayPos.X, (int)arrayPos.Y] = piece;

        OnSetPiecePos?.Invoke(this, new SetPiecePosEventArgs { OldPiece = oldPiece, NewPiece = piece });

        piece?.Move(arrayPos);

        return oldPiece;
    }

    public bool InsertPiece(VirtualPiece piece, Vector2 arrayPos) {
        if (GetPiece(arrayPos) != null) {
            return false;
        }

        OnInsert?.Invoke(this, piece);
        SetPiecePos(piece, arrayPos);

        return true;
    }

    public bool MovePiece(Vector2 from, Vector2 to) {
        if (ArrPosOutOfRange(to) || ArrPosOutOfRange(from)) {
            return false;
        }

        if (GetPiece(to) != null) {
            return false;
        }

        OnMove?.Invoke(this, new MoveEventArgs { From = from, To = to });

        SetPiecePos(SetPiecePos(null, from), to);

        return true;
    }

    public bool RemovePiece(Vector2 pos) {
        VirtualPiece piece = GetPiece(pos);
        if (piece == null) {
            return false;
        }

        OnRemove?.Invoke(this, piece);

        return SetPiecePos(null, pos) != null;
    }

    public void Clear() {
        for (int i = 0; i < Rows; i++) {
            for (int j = 0; j < Cols; j++) {
                RemovePiece(new Vector2(i, j));
            }
        }
    }
}