chinese_chess/Scripts/Utilities/VirtualBoard.cs

// using System.Numerics;
using Godot;
using System;

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

    // <oldPiece, newPiece>
    public event Action<VirtualPiece, VirtualPiece> OnSetPiecePos;
    public event Action<VirtualPiece> OnInsert;
    public event Action<VirtualPiece> OnRemove;
    public event Action<Vector2, Vector2> 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) {
		VirtualPiece ret = null;
		if (ArrPosOutOfRange(arrayPos)) return ret;
        ret = pieces[(int)arrayPos.X, (int)arrayPos.Y];
		pieces[(int)arrayPos.X, (int)arrayPos.Y] = piece;
        OnSetPiecePos?.Invoke(ret, piece);
		piece?.Move(arrayPos);
		return ret;
    }

    public bool InsertPiece(VirtualPiece piece, Vector2 arrayPos) {
        if (GetPiece(arrayPos) != null) {
            return false;
        }
        OnInsert?.Invoke(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(from, to);
        SetPiecePos(SetPiecePos(null, from), to);
		return true;
	}

	public bool RemovePiece(Vector2 pos) {
        OnRemove?.Invoke(GetPiece(pos));
		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));
			}
		}
	}
}