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[vchess.git] / client / src / variants / Wildebeest.js

import { ChessRules } from "@/base_rules";
import { ArrayFun } from "@/utils/array";
import { sample, randInt } from "@/utils/alea";

export const VariantRules = class  WildebeestRules extends ChessRules
{
	static getPpath(b)
	{
		return ([V.CAMEL,V.WILDEBEEST].includes(b[1]) ? "Wildebeest/" : "") + b;
	}

	static get size() { return {x:10,y:11}; }

	static get CAMEL() { return 'c'; }
	static get WILDEBEEST() { return 'w'; }

	static get PIECES()
	{
		return ChessRules.PIECES.concat([V.CAMEL,V.WILDEBEEST]);
	}

	static get steps()
	{
		return Object.assign(
			ChessRules.steps, //add camel moves:
			{'c': [ [-3,-1],[-3,1],[-1,-3],[-1,3],[1,-3],[1,3],[3,-1],[3,1] ]}
		);
	}

	static IsGoodEnpassant(enpassant)
	{
		if (enpassant != "-")
		{
			const squares = enpassant.split(",");
			if (squares.length > 2)
				return false;
			for (let sq of squares)
			{
				const ep = V.SquareToCoords(sq);
				if (isNaN(ep.x) || !V.OnBoard(ep))
					return false;
			}
		}
		return true;
	}

	// There may be 2 enPassant squares (if pawn jump 3 squares)
	getEnpassantFen()
	{
		const L = this.epSquares.length;
		if (!this.epSquares[L-1])
			return "-"; //no en-passant
		let res = "";
		this.epSquares[L-1].forEach(sq => {
			res += V.CoordsToSquare(sq) + ",";
		});
		return res.slice(0,-1); //remove last comma
	}

	// En-passant after 2-sq or 3-sq jumps
	getEpSquare(moveOrSquare)
	{
		if (!moveOrSquare)
			return undefined;
		if (typeof moveOrSquare === "string")
		{
			const square = moveOrSquare;
			if (square == "-")
				return undefined;
			let res = [];
			square.split(",").forEach(sq => {
				res.push(V.SquareToCoords(sq));
			});
			return res;
		}
		// Argument is a move:
		const move = moveOrSquare;
		const [sx,sy,ex] = [move.start.x,move.start.y,move.end.x];
		if (this.getPiece(sx,sy) == V.PAWN && Math.abs(sx - ex) >= 2)
		{
			const step = (ex-sx) / Math.abs(ex-sx);
			let res = [{
				x: sx + step,
				y: sy
			}];
			if (sx + 2*step != ex) //3-squares move
			{
				res.push({
					x: sx + 2*step,
					y: sy
				});
			}
			return res;
		}
		return undefined; //default
	}

	getPotentialMovesFrom([x,y])
	{
		switch (this.getPiece(x,y))
		{
			case V.CAMEL:
				return this.getPotentialCamelMoves([x,y]);
			case V.WILDEBEEST:
				return this.getPotentialWildebeestMoves([x,y]);
			default:
				return super.getPotentialMovesFrom([x,y])
		}
	}

	// Pawns jump 2 or 3 squares, and promote to queen or wildebeest
	getPotentialPawnMoves([x,y])
	{
		const color = this.turn;
		let moves = [];
		const [sizeX,sizeY] = [V.size.x,V.size.y];
		const shiftX = (color == "w" ? -1 : 1);
		const startRanks = (color == "w" ? [sizeX-2,sizeX-3] : [1,2]);
		const lastRank = (color == "w" ? 0 : sizeX-1);
		const finalPieces = x + shiftX == lastRank
			? [V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN]
			: [V.PAWN];

		if (this.board[x+shiftX][y] == V.EMPTY)
		{
			// One square forward
			for (let piece of finalPieces)
				moves.push(this.getBasicMove([x,y], [x+shiftX,y], {c:color,p:piece}));
			if (startRanks.includes(x))
			{
				if (this.board[x+2*shiftX][y] == V.EMPTY)
				{
					// Two squares jump
					moves.push(this.getBasicMove([x,y], [x+2*shiftX,y]));
					if (x==startRanks[0] && this.board[x+3*shiftX][y] == V.EMPTY)
					{
						// Three squares jump
						moves.push(this.getBasicMove([x,y], [x+3*shiftX,y]));
					}
				}
			}
		}
		// Captures
		for (let shiftY of [-1,1])
		{
			if (y + shiftY >= 0 && y + shiftY < sizeY
				&& this.board[x+shiftX][y+shiftY] != V.EMPTY
				&& this.canTake([x,y], [x+shiftX,y+shiftY]))
			{
				for (let piece of finalPieces)
				{
					moves.push(this.getBasicMove([x,y], [x+shiftX,y+shiftY],
						{c:color,p:piece}));
				}
			}
		}

		// En passant
		const Lep = this.epSquares.length;
		const epSquare = this.epSquares[Lep-1];
		if (!!epSquare)
		{
			for (let epsq of epSquare)
			{
				// TODO: some redundant checks
				if (epsq.x == x+shiftX && Math.abs(epsq.y - y) == 1)
				{
					var enpassantMove = this.getBasicMove([x,y], [epsq.x,epsq.y]);
					// WARNING: the captured pawn may be diagonally behind us,
					// if it's a 3-squares jump and we take on 1st passing square
					const px = (this.board[x][epsq.y] != V.EMPTY ? x : x - shiftX);
					enpassantMove.vanish.push({
						x: px,
						y: epsq.y,
						p: 'p',
						c: this.getColor(px,epsq.y)
					});
					moves.push(enpassantMove);
				}
			}
		}

		return moves;
	}

	// TODO: wildebeest castle

	getPotentialCamelMoves(sq)
	{
		return this.getSlideNJumpMoves(sq, V.steps[V.CAMEL], "oneStep");
	}

	getPotentialWildebeestMoves(sq)
	{
		return this.getSlideNJumpMoves(
			sq, V.steps[V.KNIGHT].concat(V.steps[V.CAMEL]), "oneStep");
	}

	isAttacked(sq, colors)
	{
		return super.isAttacked(sq, colors)
			|| this.isAttackedByCamel(sq, colors)
			|| this.isAttackedByWildebeest(sq, colors);
	}

	isAttackedByCamel(sq, colors)
	{
		return this.isAttackedBySlideNJump(sq, colors,
			V.CAMEL, V.steps[V.CAMEL], "oneStep");
	}

	isAttackedByWildebeest(sq, colors)
	{
		return this.isAttackedBySlideNJump(sq, colors, V.WILDEBEEST,
			V.steps[V.KNIGHT].concat(V.steps[V.CAMEL]), "oneStep");
	}

  getCurrentScore()
  {
    if (this.atLeastOneMove()) // game not over
      return "*";

		// No valid move: game is lost (stalemate is a win)
		return (this.turn == "w" ? "0-1" : "1-0");
	}

	static get VALUES() {
		return Object.assign(
			ChessRules.VALUES,
			{'c': 3, 'w': 7} //experimental
		);
	}

	static get SEARCH_DEPTH() { return 2; }

	static GenRandInitFen()
	{
		let pieces = { "w": new Array(10), "b": new Array(10) };
		for (let c of ["w","b"])
		{
			let positions = ArrayFun.range(11);

			// Get random squares for bishops + camels (different colors)
			let randIndexes = sample(ArrayFun.range(6), 2)
        .map(i => { return 2*i; });
			let bishop1Pos = positions[randIndexes[0]];
			let camel1Pos = positions[randIndexes[1]];
			// The second bishop (camel) must be on a square of different color
			let randIndexes_tmp = sample(ArrayFun.range(5), 2)
        .map(i => { return 2*i+1; });
			let bishop2Pos = positions[randIndexes_tmp[0]];
			let camel2Pos = positions[randIndexes_tmp[1]];
			for (let idx of randIndexes.concat(randIndexes_tmp)
				.sort((a,b) => { return b-a; })) //largest indices first
			{
				positions.splice(idx, 1);
			}

			let randIndex = randInt(7);
			let knight1Pos = positions[randIndex];
			positions.splice(randIndex, 1);
			randIndex = randInt(6);
			let knight2Pos = positions[randIndex];
			positions.splice(randIndex, 1);

			randIndex = randInt(5);
			let queenPos = positions[randIndex];
			positions.splice(randIndex, 1);

			// Random square for wildebeest
			randIndex = randInt(4);
			let wildebeestPos = positions[randIndex];
			positions.splice(randIndex, 1);

			let rook1Pos = positions[0];
			let kingPos = positions[1];
			let rook2Pos = positions[2];

			pieces[c][rook1Pos] = 'r';
			pieces[c][knight1Pos] = 'n';
			pieces[c][bishop1Pos] = 'b';
			pieces[c][queenPos] = 'q';
			pieces[c][camel1Pos] = 'c';
			pieces[c][camel2Pos] = 'c';
			pieces[c][wildebeestPos] = 'w';
			pieces[c][kingPos] = 'k';
			pieces[c][bishop2Pos] = 'b';
			pieces[c][knight2Pos] = 'n';
			pieces[c][rook2Pos] = 'r';
		}
		return pieces["b"].join("") +
			"/ppppppppppp/11/11/11/11/11/11/PPPPPPPPPPP/" +
			pieces["w"].join("").toUpperCase() +
			" w 0 1111 -";
	}
}