| 1 | import { ChessRules } from "@/base_rules"; |
| 2 | import { randInt } from "@/utils/alea"; |
| 3 | |
| 4 | export const VariantRules = class MarseilleRules extends ChessRules |
| 5 | { |
| 6 | static IsGoodEnpassant(enpassant) |
| 7 | { |
| 8 | if (enpassant != "-") |
| 9 | { |
| 10 | const squares = enpassant.split(","); |
| 11 | if (squares.length > 2) |
| 12 | return false; |
| 13 | for (let sq of squares) |
| 14 | { |
| 15 | const ep = V.SquareToCoords(sq); |
| 16 | if (isNaN(ep.x) || !V.OnBoard(ep)) |
| 17 | return false; |
| 18 | } |
| 19 | } |
| 20 | return true; |
| 21 | } |
| 22 | |
| 23 | getTurnFen() |
| 24 | { |
| 25 | return this.turn + this.subTurn; |
| 26 | } |
| 27 | |
| 28 | // There may be 2 enPassant squares (if 2 pawns jump 2 squares in same turn) |
| 29 | getEnpassantFen() |
| 30 | { |
| 31 | const L = this.epSquares.length; |
| 32 | if (this.epSquares[L-1].every(epsq => epsq === undefined)) |
| 33 | return "-"; //no en-passant |
| 34 | let res = ""; |
| 35 | this.epSquares[L-1].forEach(epsq => { |
| 36 | if (!!epsq) |
| 37 | res += V.CoordsToSquare(epsq) + ","; |
| 38 | }); |
| 39 | return res.slice(0,-1); //remove last comma |
| 40 | } |
| 41 | |
| 42 | setOtherVariables(fen) |
| 43 | { |
| 44 | const parsedFen = V.ParseFen(fen); |
| 45 | this.setFlags(parsedFen.flags); |
| 46 | if (parsedFen.enpassant == "-") |
| 47 | this.epSquares = [ [undefined] ]; |
| 48 | else |
| 49 | { |
| 50 | let res = []; |
| 51 | const squares = parsedFen.enpassant.split(","); |
| 52 | for (let sq of squares) |
| 53 | res.push(V.SquareToCoords(sq)); |
| 54 | this.epSquares = [ res ]; |
| 55 | } |
| 56 | this.scanKingsRooks(fen); |
| 57 | // Extract subTurn from turn indicator: "w" (first move), or |
| 58 | // "w1" or "w2" white subturn 1 or 2, and same for black |
| 59 | const fullTurn = V.ParseFen(fen).turn; |
| 60 | this.turn = fullTurn[0]; |
| 61 | this.subTurn = (fullTurn[1] || 0); //"w0" = special code for first move in game |
| 62 | } |
| 63 | |
| 64 | getPotentialPawnMoves([x,y]) |
| 65 | { |
| 66 | const color = this.turn; |
| 67 | let moves = []; |
| 68 | const [sizeX,sizeY] = [V.size.x,V.size.y]; |
| 69 | const shiftX = (color == "w" ? -1 : 1); |
| 70 | const firstRank = (color == 'w' ? sizeX-1 : 0); |
| 71 | const startRank = (color == "w" ? sizeX-2 : 1); |
| 72 | const lastRank = (color == "w" ? 0 : sizeX-1); |
| 73 | const finalPieces = x + shiftX == lastRank |
| 74 | ? [V.ROOK,V.KNIGHT,V.BISHOP,V.QUEEN] |
| 75 | : [V.PAWN]; |
| 76 | |
| 77 | // One square forward |
| 78 | if (this.board[x+shiftX][y] == V.EMPTY) |
| 79 | { |
| 80 | for (let piece of finalPieces) |
| 81 | { |
| 82 | moves.push(this.getBasicMove([x,y], [x+shiftX,y], |
| 83 | {c:color,p:piece})); |
| 84 | } |
| 85 | // Next condition because pawns on 1st rank can generally jump |
| 86 | if ([startRank,firstRank].includes(x) |
| 87 | && this.board[x+2*shiftX][y] == V.EMPTY) |
| 88 | { |
| 89 | // Two squares jump |
| 90 | moves.push(this.getBasicMove([x,y], [x+2*shiftX,y])); |
| 91 | } |
| 92 | } |
| 93 | // Captures |
| 94 | for (let shiftY of [-1,1]) |
| 95 | { |
| 96 | if (y + shiftY >= 0 && y + shiftY < sizeY |
| 97 | && this.board[x+shiftX][y+shiftY] != V.EMPTY |
| 98 | && this.canTake([x,y], [x+shiftX,y+shiftY])) |
| 99 | { |
| 100 | for (let piece of finalPieces) |
| 101 | { |
| 102 | moves.push(this.getBasicMove([x,y], [x+shiftX,y+shiftY], |
| 103 | {c:color,p:piece})); |
| 104 | } |
| 105 | } |
| 106 | } |
| 107 | |
| 108 | // En passant: always OK if subturn 1, |
| 109 | // OK on subturn 2 only if enPassant was played at subturn 1 |
| 110 | // (and if there are two e.p. squares available). |
| 111 | const Lep = this.epSquares.length; |
| 112 | const epSquares = this.epSquares[Lep-1]; //always at least one element |
| 113 | let epSqs = []; |
| 114 | epSquares.forEach(sq => { |
| 115 | if (!!sq) |
| 116 | epSqs.push(sq); |
| 117 | }); |
| 118 | if (epSqs.length == 0) |
| 119 | return moves; |
| 120 | const oppCol = V.GetOppCol(color); |
| 121 | for (let sq of epSqs) |
| 122 | { |
| 123 | if (this.subTurn == 1 || (epSqs.length == 2 && |
| 124 | // Was this en-passant capture already played at subturn 1 ? |
| 125 | // (Or maybe the opponent filled the en-passant square with a piece) |
| 126 | this.board[epSqs[0].x][epSqs[0].y] != V.EMPTY)) |
| 127 | { |
| 128 | if (sq.x == x+shiftX && Math.abs(sq.y - y) == 1 |
| 129 | // Add condition "enemy pawn must be present" |
| 130 | && this.getPiece(x,sq.y) == V.PAWN && this.getColor(x,sq.y) == oppCol) |
| 131 | { |
| 132 | let epMove = this.getBasicMove([x,y], [sq.x,sq.y]); |
| 133 | epMove.vanish.push({ |
| 134 | x: x, |
| 135 | y: sq.y, |
| 136 | p: 'p', |
| 137 | c: oppCol |
| 138 | }); |
| 139 | moves.push(epMove); |
| 140 | } |
| 141 | } |
| 142 | } |
| 143 | |
| 144 | return moves; |
| 145 | } |
| 146 | |
| 147 | play(move) |
| 148 | { |
| 149 | move.flags = JSON.stringify(this.aggregateFlags()); |
| 150 | move.turn = this.turn + this.subTurn; |
| 151 | V.PlayOnBoard(this.board, move); |
| 152 | const epSq = this.getEpSquare(move); |
| 153 | if (this.subTurn == 0) //first move in game |
| 154 | { |
| 155 | this.turn = "b"; |
| 156 | this.subTurn = 1; |
| 157 | this.epSquares.push([epSq]); |
| 158 | } |
| 159 | // Does this move give check on subturn 1? If yes, skip subturn 2 |
| 160 | else if (this.subTurn==1 && this.underCheck(V.GetOppCol(this.turn))) |
| 161 | { |
| 162 | this.turn = V.GetOppCol(this.turn); |
| 163 | this.epSquares.push([epSq]); |
| 164 | move.checkOnSubturn1 = true; |
| 165 | } |
| 166 | else |
| 167 | { |
| 168 | if (this.subTurn == 2) |
| 169 | { |
| 170 | this.turn = V.GetOppCol(this.turn); |
| 171 | let lastEpsq = this.epSquares[this.epSquares.length-1]; |
| 172 | lastEpsq.push(epSq); |
| 173 | } |
| 174 | else |
| 175 | this.epSquares.push([epSq]); |
| 176 | this.subTurn = 3 - this.subTurn; |
| 177 | } |
| 178 | this.updateVariables(move); |
| 179 | } |
| 180 | |
| 181 | undo(move) |
| 182 | { |
| 183 | this.disaggregateFlags(JSON.parse(move.flags)); |
| 184 | V.UndoOnBoard(this.board, move); |
| 185 | if (move.turn[1] == '0' || move.checkOnSubturn1 || this.subTurn == 2) |
| 186 | this.epSquares.pop(); |
| 187 | else //this.subTurn == 1 |
| 188 | { |
| 189 | let lastEpsq = this.epSquares[this.epSquares.length-1]; |
| 190 | lastEpsq.pop(); |
| 191 | } |
| 192 | this.turn = move.turn[0]; |
| 193 | this.subTurn = parseInt(move.turn[1]); |
| 194 | this.unupdateVariables(move); |
| 195 | } |
| 196 | |
| 197 | // NOTE: GenRandInitFen() is OK, |
| 198 | // since at first move turn indicator is just "w" |
| 199 | |
| 200 | static get VALUES() |
| 201 | { |
| 202 | return { |
| 203 | 'p': 1, |
| 204 | 'r': 5, |
| 205 | 'n': 3, |
| 206 | 'b': 3, |
| 207 | 'q': 7, //slightly less than in orthodox game |
| 208 | 'k': 1000 |
| 209 | }; |
| 210 | } |
| 211 | |
| 212 | // No alpha-beta here, just adapted min-max at depth 2(+1) |
| 213 | getComputerMove() |
| 214 | { |
| 215 | if (this.subTurn == 2) |
| 216 | return null; //TODO: imperfect interface setup |
| 217 | |
| 218 | const maxeval = V.INFINITY; |
| 219 | const color = this.turn; |
| 220 | const oppCol = V.GetOppCol(this.turn); |
| 221 | |
| 222 | // Search best (half) move for opponent turn |
| 223 | const getBestMoveEval = () => { |
| 224 | const turnBefore = this.turn + this.subTurn; |
| 225 | let score = this.getCurrentScore(); |
| 226 | if (score != "*") |
| 227 | { |
| 228 | if (score == "1/2") |
| 229 | return 0; |
| 230 | return maxeval * (score == "1-0" ? 1 : -1); |
| 231 | } |
| 232 | let moves = this.getAllValidMoves(); |
| 233 | let res = (oppCol == "w" ? -maxeval : maxeval); |
| 234 | for (let m of moves) |
| 235 | { |
| 236 | this.play(m); |
| 237 | score = this.getCurrentScore(); |
| 238 | // Now turn is oppCol,2 if m doesn't give check |
| 239 | // Otherwise it's color,1. In both cases the next test makes sense |
| 240 | if (score != "*") |
| 241 | { |
| 242 | if (score == "1/2") |
| 243 | res = (oppCol == "w" ? Math.max(res, 0) : Math.min(res, 0)); |
| 244 | else |
| 245 | { |
| 246 | // Found a mate |
| 247 | this.undo(m); |
| 248 | return maxeval * (score == "1-0" ? 1 : -1); |
| 249 | } |
| 250 | } |
| 251 | const evalPos = this.evalPosition(); |
| 252 | res = (oppCol == "w" ? Math.max(res, evalPos) : Math.min(res, evalPos)); |
| 253 | this.undo(m); |
| 254 | } |
| 255 | return res; |
| 256 | }; |
| 257 | |
| 258 | let moves11 = this.getAllValidMoves(); |
| 259 | let doubleMoves = []; |
| 260 | // Rank moves using a min-max at depth 2 |
| 261 | for (let i=0; i<moves11.length; i++) |
| 262 | { |
| 263 | this.play(moves11[i]); |
| 264 | if (this.turn != color) |
| 265 | { |
| 266 | // We gave check with last move: search the best opponent move |
| 267 | doubleMoves.push({moves:[moves11[i]], eval:getBestMoveEval()}); |
| 268 | } |
| 269 | else |
| 270 | { |
| 271 | let moves12 = this.getAllValidMoves(); |
| 272 | for (let j=0; j<moves12.length; j++) |
| 273 | { |
| 274 | this.play(moves12[j]); |
| 275 | doubleMoves.push({ |
| 276 | moves:[moves11[i],moves12[j]], |
| 277 | eval:getBestMoveEval()}); |
| 278 | this.undo(moves12[j]); |
| 279 | } |
| 280 | } |
| 281 | this.undo(moves11[i]); |
| 282 | } |
| 283 | |
| 284 | doubleMoves.sort( (a,b) => { |
| 285 | return (color=="w" ? 1 : -1) * (b.eval - a.eval); }); |
| 286 | let candidates = [0]; //indices of candidates moves |
| 287 | for (let i=1; |
| 288 | i<doubleMoves.length && doubleMoves[i].eval == doubleMoves[0].eval; |
| 289 | i++) |
| 290 | { |
| 291 | candidates.push(i); |
| 292 | } |
| 293 | |
| 294 | const selected = doubleMoves[randInt(candidates.length)].moves; |
| 295 | if (selected.length == 1) |
| 296 | return selected[0]; |
| 297 | return selected; |
| 298 | } |
| 299 | } |