X-Git-Url: https://git.auder.net/?a=blobdiff_plain;f=public%2Fjavascripts%2Fbase_rules.js;h=79b6a7a3ce468e6f23e64dd798317ff29eb2aaad;hb=dda21a71b6245832a78ca987b14c77176bd15dd6;hp=d4315c73724b5572437e3e7b3203b12bc7fefda4;hpb=c605216162dfc09cbbe61b0969f8890f28625372;p=vchess.git

diff --git a/public/javascripts/base_rules.js b/public/javascripts/base_rules.js
index d4315c73..79b6a7a3 100644
--- a/public/javascripts/base_rules.js
+++ b/public/javascripts/base_rules.js
@@ -124,7 +124,7 @@ class ChessRules
 		return board;
 	}
 
-	// Overridable: flags can change a lot
+	// Extract (relevant) flags from fen
 	setFlags(fen)
 	{
 		// white a-castle, h-castle, black a-castle, h-castle
@@ -137,7 +137,6 @@ class ChessRules
 	///////////////////
 	// GETTERS, SETTERS
 
-	// Simple useful getters
 	static get size() { return [8,8]; }
 	// Two next functions return 'undefined' if called on empty square
 	getColor(i,j) { return this.board[i][j].charAt(0); }
@@ -199,7 +198,7 @@ class ChessRules
 		return undefined; //default
 	}
 
-	// can thing on square1 take thing on square2
+	// Can thing on square1 take thing on square2
 	canTake([x1,y1], [x2,y2])
 	{
 		return this.getColor(x1,y1) != this.getColor(x2,y2);
@@ -276,7 +275,8 @@ class ChessRules
 		{
 			let i = x + step[0];
 			let j = y + step[1];
-			while (i>=0 && i<sizeX && j>=0 && j<sizeY && this.board[i][j] == VariantRules.EMPTY)
+			while (i>=0 && i<sizeX && j>=0 && j<sizeY
+				&& this.board[i][j] == VariantRules.EMPTY)
 			{
 				moves.push(this.getBasicMove([x,y], [i,j]));
 				if (oneStep !== undefined)
@@ -284,23 +284,23 @@ class ChessRules
 				i += step[0];
 				j += step[1];
 			}
-			if (i>=0 && i<8 && j>=0 && j<8 && this.canTake([x,y], [i,j]))
+			if (i>=0 && i<sizeX && j>=0 && j<sizeY && this.canTake([x,y], [i,j]))
 				moves.push(this.getBasicMove([x,y], [i,j]));
 		}
 		return moves;
 	}
 
-	// What are the pawn moves from square x,y considering color "color" ?
+	// What are the pawn moves from square x,y ?
 	getPotentialPawnMoves([x,y])
 	{
 		const color = this.turn;
 		let moves = [];
 		const V = VariantRules;
-		const [sizeX,sizeY] = VariantRules.size;
+		const [sizeX,sizeY] = V.size;
 		const shift = (color == "w" ? -1 : 1);
-		const firstRank = (color == 'w' ? sizeY-1 : 0);
-		const startRank = (color == "w" ? sizeY-2 : 1);
-		const lastRank = (color == "w" ? 0 : sizeY-1);
+		const firstRank = (color == 'w' ? sizeX-1 : 0);
+		const startRank = (color == "w" ? sizeX-2 : 1);
+		const lastRank = (color == "w" ? 0 : sizeX-1);
 
 		if (x+shift >= 0 && x+shift < sizeX && x+shift != lastRank)
 		{
@@ -308,7 +308,7 @@ class ChessRules
 			if (this.board[x+shift][y] == V.EMPTY)
 			{
 				moves.push(this.getBasicMove([x,y], [x+shift,y]));
-				// Next condition because variants with pawns on 1st rank generally allow them to jump
+				// Next condition because variants with pawns on 1st rank allow them to jump
 				if ([startRank,firstRank].includes(x) && this.board[x+2*shift][y] == V.EMPTY)
 				{
 					// Two squares jump
@@ -316,10 +316,16 @@ class ChessRules
 				}
 			}
 			// Captures
-			if (y>0 && this.canTake([x,y], [x+shift,y-1]) && this.board[x+shift][y-1] != V.EMPTY)
+			if (y>0 && this.canTake([x,y], [x+shift,y-1])
+				&& this.board[x+shift][y-1] != V.EMPTY)
+			{
 				moves.push(this.getBasicMove([x,y], [x+shift,y-1]));
-			if (y<sizeY-1 && this.canTake([x,y], [x+shift,y+1]) && this.board[x+shift][y+1] != V.EMPTY)
+			}
+			if (y<sizeY-1 && this.canTake([x,y], [x+shift,y+1])
+				&& this.board[x+shift][y+1] != V.EMPTY)
+			{
 				moves.push(this.getBasicMove([x,y], [x+shift,y+1]));
+			}
 		}
 
 		if (x+shift == lastRank)
@@ -331,10 +337,16 @@ class ChessRules
 				if (this.board[x+shift][y] == V.EMPTY)
 					moves.push(this.getBasicMove([x,y], [x+shift,y], {c:color,p:p}));
 				// Captures
-				if (y>0 && this.canTake([x,y], [x+shift,y-1]) && this.board[x+shift][y-1] != V.EMPTY)
+				if (y>0 && this.canTake([x,y], [x+shift,y-1])
+					&& this.board[x+shift][y-1] != V.EMPTY)
+				{
 					moves.push(this.getBasicMove([x,y], [x+shift,y-1], {c:color,p:p}));
-				if (y<sizeY-1 && this.canTake([x,y], [x+shift,y+1]) && this.board[x+shift][y+1] != V.EMPTY)
+				}
+				if (y<sizeY-1 && this.canTake([x,y], [x+shift,y+1])
+					&& this.board[x+shift][y+1] != V.EMPTY)
+				{
 					moves.push(this.getBasicMove([x,y], [x+shift,y+1], {c:color,p:p}));
+				}
 			});
 		}
 
@@ -417,7 +429,7 @@ class ChessRules
 			let step = finalSquares[castleSide][0] < y ? -1 : 1;
 			for (i=y; i!=finalSquares[castleSide][0]; i+=step)
 			{
-				if (this.isAttacked([x,i], oppCol) || (this.board[x][i] != V.EMPTY &&
+				if (this.isAttacked([x,i], [oppCol]) || (this.board[x][i] != V.EMPTY &&
 					// NOTE: next check is enough, because of chessboard constraints
 					(this.getColor(x,i) != c || ![V.KING,V.ROOK].includes(this.getPiece(x,i)))))
 				{
@@ -492,9 +504,9 @@ class ChessRules
 		const oppCol = this.getOppCol(color);
 		let potentialMoves = [];
 		const [sizeX,sizeY] = VariantRules.size;
-		for (var i=0; i<sizeX; i++)
+		for (let i=0; i<sizeX; i++)
 		{
-			for (var j=0; j<sizeY; j++)
+			for (let j=0; j<sizeY; j++)
 			{
 				// Next condition ... != oppCol is a little HACK to work with checkered variant
 				if (this.board[i][j] != VariantRules.EMPTY && this.getColor(i,j) != oppCol)
@@ -533,7 +545,7 @@ class ChessRules
 		return false;
 	}
 
-	// Check if pieces of color 'colors' are attacking square x,y
+	// Check if pieces of color in array 'colors' are attacking square x,y
 	isAttacked(sq, colors)
 	{
 		return (this.isAttackedByPawn(sq, colors)
@@ -544,17 +556,18 @@ class ChessRules
 			|| this.isAttackedByKing(sq, colors));
 	}
 
-	// Is square x,y attacked by pawns of color c ?
+	// Is square x,y attacked by 'colors' pawns ?
 	isAttackedByPawn([x,y], colors)
 	{
+		const [sizeX,sizeY] = VariantRules.size;
 		for (let c of colors)
 		{
 			let pawnShift = (c=="w" ? 1 : -1);
-			if (x+pawnShift>=0 && x+pawnShift<8)
+			if (x+pawnShift>=0 && x+pawnShift<sizeX)
 			{
 				for (let i of [-1,1])
 				{
-					if (y+i>=0 && y+i<8 && this.getPiece(x+pawnShift,y+i)==VariantRules.PAWN
+					if (y+i>=0 && y+i<sizeY && this.getPiece(x+pawnShift,y+i)==VariantRules.PAWN
 						&& this.getColor(x+pawnShift,y+i)==c)
 					{
 						return true;
@@ -565,28 +578,28 @@ class ChessRules
 		return false;
 	}
 
-	// Is square x,y attacked by rooks of color c ?
+	// Is square x,y attacked by 'colors' rooks ?
 	isAttackedByRook(sq, colors)
 	{
 		return this.isAttackedBySlideNJump(sq, colors,
 			VariantRules.ROOK, VariantRules.steps[VariantRules.ROOK]);
 	}
 
-	// Is square x,y attacked by knights of color c ?
+	// Is square x,y attacked by 'colors' knights ?
 	isAttackedByKnight(sq, colors)
 	{
 		return this.isAttackedBySlideNJump(sq, colors,
 			VariantRules.KNIGHT, VariantRules.steps[VariantRules.KNIGHT], "oneStep");
 	}
 
-	// Is square x,y attacked by bishops of color c ?
+	// Is square x,y attacked by 'colors' bishops ?
 	isAttackedByBishop(sq, colors)
 	{
 		return this.isAttackedBySlideNJump(sq, colors,
 			VariantRules.BISHOP, VariantRules.steps[VariantRules.BISHOP]);
 	}
 
-	// Is square x,y attacked by queens of color c ?
+	// Is square x,y attacked by 'colors' queens ?
 	isAttackedByQueen(sq, colors)
 	{
 		const V = VariantRules;
@@ -594,7 +607,7 @@ class ChessRules
 			V.steps[V.ROOK].concat(V.steps[V.BISHOP]));
 	}
 
-	// Is square x,y attacked by king of color c ?
+	// Is square x,y attacked by 'colors' king(s) ?
 	isAttackedByKing(sq, colors)
 	{
 		const V = VariantRules;
@@ -602,19 +615,22 @@ class ChessRules
 			V.steps[V.ROOK].concat(V.steps[V.BISHOP]), "oneStep");
 	}
 
-	// Generic method for non-pawn pieces ("sliding or jumping"): is x,y attacked by piece != color ?
+	// Generic method for non-pawn pieces ("sliding or jumping"):
+	// is x,y attacked by a piece of color in array 'colors' ?
 	isAttackedBySlideNJump([x,y], colors, piece, steps, oneStep)
 	{
+		const [sizeX,sizeY] = VariantRules.size;
 		for (let step of steps)
 		{
 			let rx = x+step[0], ry = y+step[1];
-			while (rx>=0 && rx<8 && ry>=0 && ry<8 && this.board[rx][ry] == VariantRules.EMPTY
-				&& !oneStep)
+			while (rx>=0 && rx<sizeX && ry>=0 && ry<sizeY
+				&& this.board[rx][ry] == VariantRules.EMPTY && !oneStep)
 			{
 				rx += step[0];
 				ry += step[1];
 			}
-			if (rx>=0 && rx<8 && ry>=0 && ry<8 && this.board[rx][ry] != VariantRules.EMPTY
+			if (rx>=0 && rx<sizeX && ry>=0 && ry<sizeY
+				&& this.board[rx][ry] != VariantRules.EMPTY
 				&& this.getPiece(rx,ry) == piece && colors.includes(this.getColor(rx,ry)))
 			{
 				return true;
@@ -623,22 +639,22 @@ class ChessRules
 		return false;
 	}
 
-	// Is color c under check after move ?
+	// Is current player under check after his move ?
 	underCheck(move)
 	{
 		const color = this.turn;
 		this.play(move);
-		let res = this.isAttacked(this.kingPos[color], this.getOppCol(color));
+		let res = this.isAttacked(this.kingPos[color], [this.getOppCol(color)]);
 		this.undo(move);
 		return res;
 	}
 
-	// On which squares is color c under check (after move) ?
+	// On which squares is opponent under check after our move ?
 	getCheckSquares(move)
 	{
 		this.play(move);
 		const color = this.turn; //opponent
-		let res = this.isAttacked(this.kingPos[color], this.getOppCol(color))
+		let res = this.isAttacked(this.kingPos[color], [this.getOppCol(color)])
 			? [ JSON.parse(JSON.stringify(this.kingPos[color])) ] //need to duplicate!
 			: [ ];
 		this.undo(move);
@@ -694,6 +710,8 @@ class ChessRules
 		}
 	}
 
+	// After move is undo-ed, un-update variables (flags are reset)
+	// TODO: more symmetry, by storing flags increment in move...
 	unupdateVariables(move)
 	{
 		// (Potentially) Reset king position
@@ -704,12 +722,8 @@ class ChessRules
 
 	play(move, ingame)
 	{
-		// DEBUG:
-//		if (!this.states) this.states = [];
-//		if (!ingame) this.states.push(JSON.stringify(this.board));
-
 		if (!!ingame)
-			move.notation = this.getNotation(move);
+			move.notation = [this.getNotation(move), this.getLongNotation(move)];
 
 		move.flags = JSON.stringify(this.flags); //save flags (for undo)
 		this.updateVariables(move);
@@ -725,22 +739,16 @@ class ChessRules
 		this.moves.pop();
 		this.unupdateVariables(move);
 		this.parseFlags(JSON.parse(move.flags));
-
-		// DEBUG:
-//		let state = this.states.pop();
-//		if (JSON.stringify(this.board) != state)
-//			debugger;
 	}
 
 	//////////////
 	// END OF GAME
 
+	// Basic check for 3 repetitions (in the last moves only)
 	checkRepetition()
 	{
-		// Check for 3 repetitions
 		if (this.moves.length >= 8)
 		{
-			// NOTE: crude detection, only moves repetition
 			const L = this.moves.length;
 			if (_.isEqual(this.moves[L-1], this.moves[L-5]) &&
 				_.isEqual(this.moves[L-2], this.moves[L-6]) &&
@@ -753,6 +761,7 @@ class ChessRules
 		return false;
 	}
 
+	// Is game over ? And if yes, what is the score ?
 	checkGameOver()
 	{
 		if (this.checkRepetition())
@@ -770,7 +779,7 @@ class ChessRules
 	{
 		const color = this.turn;
 		// No valid move: stalemate or checkmate?
-		if (!this.isAttacked(this.kingPos[color], this.getOppCol(color)))
+		if (!this.isAttacked(this.kingPos[color], [this.getOppCol(color)]))
 			return "1/2";
 		// OK, checkmate
 		return color == "w" ? "0-1" : "1-0";
@@ -800,13 +809,28 @@ class ChessRules
 		return VariantRules.INFINITY;
 	}
 
+	static get SEARCH_DEPTH() {
+		return 3; //2 for high branching factor, 4 for small (Loser chess)
+	}
+
 	// Assumption: at least one legal move
-	getComputerMove(moves1) //moves1 might be precomputed (Magnetic chess)
+	// NOTE: works also for extinction chess because depth is 3...
+	getComputerMove()
 	{
+		this.shouldReturn = false;
 		const maxeval = VariantRules.INFINITY;
 		const color = this.turn;
-		if (!moves1)
-			moves1 = this.getAllValidMoves();
+		let moves1 = this.getAllValidMoves();
+
+		// Can I mate in 1 ? (for Magnetic & Extinction)
+		for (let i of _.shuffle(_.range(moves1.length)))
+		{
+			this.play(moves1[i]);
+			const finish = (Math.abs(this.evalPosition()) >= VariantRules.THRESHOLD_MATE);
+			this.undo(moves1[i]);
+			if (finish)
+				return moves1[i];
+		}
 
 		// Rank moves using a min-max at depth 2
 		for (let i=0; i<moves1.length; i++)
@@ -834,27 +858,38 @@ class ChessRules
 		}
 		moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
 
-		// Skip depth 3 if we found a checkmate (or if we are checkmated in 1...)
-		if (Math.abs(moves1[0].eval) < VariantRules.THRESHOLD_MATE)
+		let candidates = [0]; //indices of candidates moves
+		for (let j=1; j<moves1.length && moves1[j].eval == moves1[0].eval; j++)
+			candidates.push(j);
+		let currentBest = moves1[_.sample(candidates, 1)];
+
+		// Skip depth 3+ if we found a checkmate (or if we are checkmated in 1...)
+		if (VariantRules.SEARCH_DEPTH >= 3
+			&& Math.abs(moves1[0].eval) < VariantRules.THRESHOLD_MATE)
 		{
-			// TODO: show current analyzed move for depth 3, allow stopping eval (return moves1[0])
 			for (let i=0; i<moves1.length; i++)
 			{
+				if (this.shouldReturn)
+					return currentBest; //depth-2, minimum
 				this.play(moves1[i]);
 				// 0.1 * oldEval : heuristic to avoid some bad moves (not all...)
-				moves1[i].eval = 0.1*moves1[i].eval + this.alphabeta(2, -maxeval, maxeval);
+				moves1[i].eval = 0.1*moves1[i].eval +
+					this.alphabeta(VariantRules.SEARCH_DEPTH-1, -maxeval, maxeval);
 				this.undo(moves1[i]);
 			}
 			moves1.sort( (a,b) => { return (color=="w" ? 1 : -1) * (b.eval - a.eval); });
 		}
+		else
+			return currentBest;
 
-		let candidates = [0]; //indices of candidates moves
+		candidates = [0];
 		for (let j=1; j<moves1.length && moves1[j].eval == moves1[0].eval; j++)
 			candidates.push(j);
 //		console.log(moves1.map(m => { return [this.getNotation(m), m.eval]; }));
 		return moves1[_.sample(candidates, 1)];
 	}
 
+	// TODO: some optimisations, understand why CH get mated in 2
 	alphabeta(depth, alpha, beta)
   {
 		const maxeval = VariantRules.INFINITY;
@@ -902,7 +937,7 @@ class ChessRules
 	{
 		const [sizeX,sizeY] = VariantRules.size;
 		let evaluation = 0;
-		//Just count material for now
+		// Just count material for now
 		for (let i=0; i<sizeX; i++)
 		{
 			for (let j=0; j<sizeY; j++)
@@ -920,7 +955,7 @@ class ChessRules
 	////////////
 	// FEN utils
 
-	// Overridable..
+	// Setup the initial random (assymetric) position
 	static GenRandInitFen()
 	{
 		let pieces = [new Array(8), new Array(8)];
@@ -980,6 +1015,7 @@ class ChessRules
 		return this.getBaseFen() + " " + this.getFlagsFen();
 	}
 
+	// Position part of the FEN string
 	getBaseFen()
 	{
 		let fen = "";
@@ -1013,7 +1049,7 @@ class ChessRules
 		return fen;
 	}
 
-	// Overridable..
+	// Flags part of the FEN string
 	getFlagsFen()
 	{
 		let fen = "";
@@ -1068,6 +1104,16 @@ class ChessRules
 		}
 	}
 
+	// Complete the usual notation, may be required for de-ambiguification
+	getLongNotation(move)
+	{
+		const startSquare =
+			String.fromCharCode(97 + move.start.y) + (VariantRules.size[0]-move.start.x);
+		const finalSquare =
+			String.fromCharCode(97 + move.end.y) + (VariantRules.size[0]-move.end.x);
+		return startSquare + finalSquare; //not encoding move. But short+long is enough
+	}
+
 	// The score is already computed when calling this function
 	getPGN(mycolor, score, fenStart, mode)
 	{
@@ -1082,14 +1128,24 @@ class ChessRules
 		pgn += '[Fen "' + fenStart + '"]<br>';
 		pgn += '[Result "' + score + '"]<br><br>';
 
+		// Standard PGN
 		for (let i=0; i<this.moves.length; i++)
 		{
 			if (i % 2 == 0)
 				pgn += ((i/2)+1) + ".";
-			pgn += this.moves[i].notation + " ";
+			pgn += this.moves[i].notation[0] + " ";
 		}
+		pgn += score + "<br><br>";
 
+		// "Complete moves" PGN (helping in ambiguous cases)
+		for (let i=0; i<this.moves.length; i++)
+		{
+			if (i % 2 == 0)
+				pgn += ((i/2)+1) + ".";
+			pgn += this.moves[i].notation[1] + " ";
+		}
 		pgn += score;
+
 		return pgn;
 	}
 }