namespace ChineseChess;

using System;
using System.Collections.Generic;
using System.Linq;
using Vector;
using static ChineseChess.ChessCore;

public class CCPiece : AbstractPiece {
    public string CNName { get; protected set; }
    public TurnsSideType TurnsSide { get; }
    protected CCBoard board;
    protected Vector2I localPos = new();

    static readonly Trans2DI transRedGlobal2Local =
        new(new Vector2I(1, 0), new Vector2I(0, -1), new Vector2I(-4, 9));
    static readonly Trans2DI transBlackGlobal2Local =
        new(new Vector2I(-1, 0), new Vector2I(0, 1), new Vector2I(4, 0));
    public CCPiece(CCBoard board = null, TurnsSideType turnsSide = TurnsSideType.Red,
            string name = "", Vector2I pos = null) : base(name) {
        this.board = board;
        TurnsSide = turnsSide;
        OnPos += (sender, args) => {
            localPos = Global2Local(Pos);
        };
        Pos = pos != null ? Local2Global(pos) : Vector2I.Zero;
    }

    public override bool CanMove(Vector2I to) {
        return CanMoveAllPos().Any(item => item == to);
    }

    protected Vector2I Local2Global(in Vector2I pos) {
        return TurnsSide == TurnsSideType.Red ? (pos * transRedGlobal2Local) : (pos * transBlackGlobal2Local);
    }

    protected Vector2I Global2Local(in Vector2I pos) {
        return TurnsSide == TurnsSideType.Red ? (transRedGlobal2Local * pos) : (transBlackGlobal2Local * pos);
    }

    protected CCPiece GetCCPieceLocal(in Vector2I pos) {
        return (CCPiece)board.GetPiece(Local2Global(pos));
    }

    public virtual List<Vector2I> CanMoveAllPosSelf() {
        return new List<Vector2I>();
    }

    public IEnumerable<Vector2I> CanMoveAllPosLocal() {
        var self = CanMoveAllPosSelf().Select(item => item + localPos);// 转换局部坐标
        var ret = self.Where(item => {
            bool ret = GetCCPieceLocal(item) == null || GetCCPieceLocal(item).TurnsSide != TurnsSide;
            // Console.WriteLine($"{item} can move: {ret}");
            return ret;
        });  // 过滤无效位置
        
        // Console.WriteLine("localPos: {0}", localPos);
        // Console.WriteLine("CanMoveAllPosSelf: {0}", string.Join(",", self));
        // Console.WriteLine("CanMoveAllPosLocal: {0}", string.Join(",", ret));
        return ret;
    }

    public IEnumerable<Vector2I> CanMoveAllPos() {
        var ret = CanMoveAllPosLocal()
            .Select(item => Local2Global(item));  // 转换为全局坐标
        // Console.WriteLine("CanMoveAllPos: {0}", string.Join(",", ret));
        return ret;
    }

    protected bool IsPosOutOfRangeLocal(Vector2I pos) {
        return board.IsPosOutOfRange(Local2Global(pos));
    }

    protected CCPiece GetRecursivePieceLocal(Vector2I origin, Vector2I pos) {
        Vector2I with = origin + pos;
        while (!IsPosOutOfRangeLocal(with) && GetCCPieceLocal(with) == null) {
            with += pos;
        }
        return GetCCPieceLocal(with);
    }
}