Code reorganization

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

// NOTE: initial setup differs from the original; see
// https://www.chessvariants.com/large.dir/freeling.html
class GrandRules extends ChessRules
{
	static getPpath(b)
	{
		return ([V.MARSHALL,V.CARDINAL].includes(b[1]) ? "Grand/" : "") + b;
	}

	static IsGoodFen(fen)
	{
		if (!ChessRules.IsGoodFen(fen))
			return false;
		const fenParsed = V.ParseFen(fen);
		// 5) Check captures
		if (!fenParsed.captured || !fenParsed.captured.match(/^[0-9]{14,14}$/))
			return false;
		return true;
	}

	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;
	}

	static ParseFen(fen)
	{
		const fenParts = fen.split(" ");
		return Object.assign(
			ChessRules.ParseFen(fen),
			{ captured: fenParts[5] }
		);
	}

	getFen()
	{
		return super.getFen() + " " + this.getCapturedFen();
	}

	getCapturedFen()
	{
		let counts = [...Array(14).fill(0)];
		let i = 0;
		for (let j=0; j<V.PIECES.length; j++)
		{
			if (V.PIECES[j] == V.KING) //no king captured
				continue;
			counts[i] = this.captured["w"][V.PIECES[i]];
			counts[7+i] = this.captured["b"][V.PIECES[i]];
			i++;
		}
		return counts.join("");
	}

	setOtherVariables(fen)
	{
		super.setOtherVariables(fen);
		const fenParsed = V.ParseFen(fen);
		// Initialize captured pieces' counts from FEN
		this.captured =
		{
			"w":
			{
				[V.PAWN]: parseInt(fenParsed.captured[0]),
				[V.ROOK]: parseInt(fenParsed.captured[1]),
				[V.KNIGHT]: parseInt(fenParsed.captured[2]),
				[V.BISHOP]: parseInt(fenParsed.captured[3]),
				[V.QUEEN]: parseInt(fenParsed.captured[4]),
				[V.MARSHALL]: parseInt(fenParsed.captured[5]),
				[V.CARDINAL]: parseInt(fenParsed.captured[6]),
			},
			"b":
			{
				[V.PAWN]: parseInt(fenParsed.captured[7]),
				[V.ROOK]: parseInt(fenParsed.captured[8]),
				[V.KNIGHT]: parseInt(fenParsed.captured[9]),
				[V.BISHOP]: parseInt(fenParsed.captured[10]),
				[V.QUEEN]: parseInt(fenParsed.captured[11]),
				[V.MARSHALL]: parseInt(fenParsed.captured[12]),
				[V.CARDINAL]: parseInt(fenParsed.captured[13]),
			}
		};
	}

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

	static get MARSHALL() { return 'm'; } //rook+knight
	static get CARDINAL() { return 'c'; } //bishop+knight

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

	// 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.MARSHALL:
				return this.getPotentialMarshallMoves([x,y]);
			case V.CARDINAL:
				return this.getPotentialCardinalMoves([x,y]);
			default:
				return super.getPotentialMovesFrom([x,y])
		}
	}

	// Special pawn rules: promotions to captured friendly pieces,
	// optional on ranks 8-9 and mandatory on rank 10.
	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 lastRanks = (color == "w" ? [0,1,2] : [sizeX-1,sizeX-2,sizeX-3]);
		const promotionPieces =
			[V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN,V.MARSHALL,V.CARDINAL];

		// Always x+shiftX >= 0 && x+shiftX < sizeX, because no pawns on last rank
		let finalPieces = undefined;
		if (lastRanks.includes(x + shiftX))
		{
			finalPieces = promotionPieces.filter(p => this.captured[color][p] > 0);
			if (x + shiftX != lastRanks[0])
				finalPieces.push(V.PAWN);
		}
		else
			finalPieces = [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: different castle?

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

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

	isAttacked(sq, colors)
	{
		return super.isAttacked(sq, colors)
			|| this.isAttackedByMarshall(sq, colors)
			|| this.isAttackedByCardinal(sq, colors);
	}

	isAttackedByMarshall(sq, colors)
	{
		return this.isAttackedBySlideNJump(sq, colors, V.MARSHALL, V.steps[V.ROOK])
			|| this.isAttackedBySlideNJump(
				sq, colors, V.MARSHALL, V.steps[V.KNIGHT], "oneStep");
	}

	isAttackedByCardinal(sq, colors)
	{
		return this.isAttackedBySlideNJump(sq, colors, V.CARDINAL, V.steps[V.BISHOP])
			|| this.isAttackedBySlideNJump(
				sq, colors, V.CARDINAL, V.steps[V.KNIGHT], "oneStep");
	}

	updateVariables(move)
	{
		super.updateVariables(move);
		if (move.vanish.length == 2 && move.appear.length == 1)
		{
			// Capture: update this.captured
			this.captured[move.vanish[1].c][move.vanish[1].p]++;
		}
		if (move.vanish[0].p != move.appear[0].p)
		{
			// Promotion: update this.captured
			this.captured[move.vanish[0].c][move.appear[0].p]--;
		}
	}

	unupdateVariables(move)
	{
		super.unupdateVariables(move);
		if (move.vanish.length == 2 && move.appear.length == 1)
			this.captured[move.vanish[1].c][move.vanish[1].p]--;
		if (move.vanish[0].p != move.appear[0].p)
			this.captured[move.vanish[0].c][move.appear[0].p]++;
	}

	static get VALUES()
	{
		return Object.assign(
			ChessRules.VALUES,
			{'c': 5, 'm': 7} //experimental
		);
	}

	static get SEARCH_DEPTH() { return 2; }

	// TODO: this function could be generalized and shared better (how ?!...)
	static GenRandInitFen()
	{
		let pieces = { "w": new Array(10), "b": new Array(10) };
		// Shuffle pieces on first and last rank
		for (let c of ["w","b"])
		{
			let positions = range(10);

			// Get random squares for bishops
			let randIndex = 2 * random(5);
			let bishop1Pos = positions[randIndex];
			// The second bishop must be on a square of different color
			let randIndex_tmp = 2 * random(5) + 1;
			let bishop2Pos = positions[randIndex_tmp];
			// Remove chosen squares
			positions.splice(Math.max(randIndex,randIndex_tmp), 1);
			positions.splice(Math.min(randIndex,randIndex_tmp), 1);

			// Get random squares for knights
			randIndex = random(8);
			let knight1Pos = positions[randIndex];
			positions.splice(randIndex, 1);
			randIndex = random(7);
			let knight2Pos = positions[randIndex];
			positions.splice(randIndex, 1);

			// Get random square for queen
			randIndex = random(6);
			let queenPos = positions[randIndex];
			positions.splice(randIndex, 1);

			// ...random square for marshall
			randIndex = random(5);
			let marshallPos = positions[randIndex];
			positions.splice(randIndex, 1);

			// ...random square for cardinal
			randIndex = random(4);
			let cardinalPos = positions[randIndex];
			positions.splice(randIndex, 1);

			// Rooks and king positions are now fixed, because of the ordering rook-king-rook
			let rook1Pos = positions[0];
			let kingPos = positions[1];
			let rook2Pos = positions[2];

			// Finally put the shuffled pieces in the board array
			pieces[c][rook1Pos] = 'r';
			pieces[c][knight1Pos] = 'n';
			pieces[c][bishop1Pos] = 'b';
			pieces[c][queenPos] = 'q';
			pieces[c][marshallPos] = 'm';
			pieces[c][cardinalPos] = 'c';
			pieces[c][kingPos] = 'k';
			pieces[c][bishop2Pos] = 'b';
			pieces[c][knight2Pos] = 'n';
			pieces[c][rook2Pos] = 'r';
		}
		return pieces["b"].join("") +
			"/pppppppppp/10/10/10/10/10/10/PPPPPPPPPP/" +
			pieces["w"].join("").toUpperCase() +
			" w 1111 - 00000000000000";
	}
}