| 1 | import { ChessRules } from "@/base_rules"; |
| 2 | import { ArrayFun } from "@/utils/array"; |
| 3 | import { randInt } from "@/utils/alea"; |
| 4 | |
| 5 | export const VariantRules = class DarkRules extends ChessRules { |
| 6 | // Standard rules, in the shadow |
| 7 | setOtherVariables(fen) { |
| 8 | super.setOtherVariables(fen); |
| 9 | const [sizeX, sizeY] = [V.size.x, V.size.y]; |
| 10 | this.enlightened = { |
| 11 | w: ArrayFun.init(sizeX, sizeY), |
| 12 | b: ArrayFun.init(sizeX, sizeY) |
| 13 | }; |
| 14 | // Setup enlightened: squares reachable by each side |
| 15 | // (TODO: one side would be enough ?) |
| 16 | this.updateEnlightened(); |
| 17 | } |
| 18 | |
| 19 | updateEnlightened() { |
| 20 | for (let i = 0; i < V.size.x; i++) { |
| 21 | for (let j = 0; j < V.size.y; j++) { |
| 22 | this.enlightened["w"][i][j] = false; |
| 23 | this.enlightened["b"][i][j] = false; |
| 24 | } |
| 25 | } |
| 26 | const pawnShift = { w: -1, b: 1 }; |
| 27 | // Initialize with pieces positions (which are seen) |
| 28 | for (let i = 0; i < V.size.x; i++) { |
| 29 | for (let j = 0; j < V.size.y; j++) { |
| 30 | if (this.board[i][j] != V.EMPTY) { |
| 31 | const color = this.getColor(i, j); |
| 32 | this.enlightened[color][i][j] = true; |
| 33 | // Add potential squares visible by "impossible pawn capture" |
| 34 | if (this.getPiece(i, j) == V.PAWN) { |
| 35 | for (let shiftY of [-1, 1]) { |
| 36 | if ( |
| 37 | V.OnBoard(i + pawnShift[color], j + shiftY) && |
| 38 | this.board[i + pawnShift[color]][j + shiftY] == V.EMPTY |
| 39 | ) { |
| 40 | this.enlightened[color][i + pawnShift[color]][ |
| 41 | j + shiftY |
| 42 | ] = true; |
| 43 | } |
| 44 | } |
| 45 | } |
| 46 | } |
| 47 | } |
| 48 | } |
| 49 | const currentTurn = this.turn; |
| 50 | this.turn = "w"; |
| 51 | const movesWhite = this.getAllValidMoves(); |
| 52 | this.turn = "b"; |
| 53 | const movesBlack = this.getAllValidMoves(); |
| 54 | this.turn = currentTurn; |
| 55 | for (let move of movesWhite) |
| 56 | this.enlightened["w"][move.end.x][move.end.y] = true; |
| 57 | for (let move of movesBlack) |
| 58 | this.enlightened["b"][move.end.x][move.end.y] = true; |
| 59 | } |
| 60 | |
| 61 | // Has to be redefined to avoid an infinite loop |
| 62 | getAllValidMoves() { |
| 63 | const color = this.turn; |
| 64 | let potentialMoves = []; |
| 65 | for (let i = 0; i < V.size.x; i++) { |
| 66 | for (let j = 0; j < V.size.y; j++) { |
| 67 | if (this.board[i][j] != V.EMPTY && this.getColor(i, j) == color) |
| 68 | Array.prototype.push.apply( |
| 69 | potentialMoves, |
| 70 | this.getPotentialMovesFrom([i, j]) |
| 71 | ); |
| 72 | } |
| 73 | } |
| 74 | return potentialMoves; //because there are no checks |
| 75 | } |
| 76 | |
| 77 | atLeastOneMove() { |
| 78 | if (this.kingPos[this.turn][0] < 0) return false; |
| 79 | return true; //TODO: is it right? |
| 80 | } |
| 81 | |
| 82 | underCheck() { |
| 83 | return false; //there is no check |
| 84 | } |
| 85 | |
| 86 | getCheckSquares() { |
| 87 | return []; |
| 88 | } |
| 89 | |
| 90 | updateVariables(move) { |
| 91 | super.updateVariables(move); |
| 92 | if (move.vanish.length >= 2 && move.vanish[1].p == V.KING) { |
| 93 | // We took opponent king ! (because if castle vanish[1] is a rook) |
| 94 | this.kingPos[this.turn] = [-1, -1]; |
| 95 | } |
| 96 | |
| 97 | // Update lights for both colors: |
| 98 | this.updateEnlightened(); |
| 99 | } |
| 100 | |
| 101 | unupdateVariables(move) { |
| 102 | super.unupdateVariables(move); |
| 103 | const c = move.vanish[0].c; |
| 104 | const oppCol = V.GetOppCol(c); |
| 105 | if (this.kingPos[oppCol][0] < 0) { |
| 106 | // Last move took opponent's king |
| 107 | for (let psq of move.vanish) { |
| 108 | if (psq.p == "k") { |
| 109 | this.kingPos[oppCol] = [psq.x, psq.y]; |
| 110 | break; |
| 111 | } |
| 112 | } |
| 113 | } |
| 114 | |
| 115 | // Update lights for both colors: |
| 116 | this.updateEnlightened(); |
| 117 | } |
| 118 | |
| 119 | getCurrentScore() { |
| 120 | const color = this.turn; |
| 121 | const kp = this.kingPos[color]; |
| 122 | if (kp[0] < 0) |
| 123 | //king disappeared |
| 124 | return color == "w" ? "0-1" : "1-0"; |
| 125 | if (this.atLeastOneMove()) |
| 126 | // game not over |
| 127 | return "*"; |
| 128 | return "1/2"; //no moves but kings still there (seems impossible) |
| 129 | } |
| 130 | |
| 131 | static get THRESHOLD_MATE() { |
| 132 | return 500; //checkmates evals may be slightly below 1000 |
| 133 | } |
| 134 | |
| 135 | // In this special situation, we just look 1 half move ahead |
| 136 | getComputerMove() { |
| 137 | const maxeval = V.INFINITY; |
| 138 | const color = this.turn; |
| 139 | const oppCol = V.GetOppCol(color); |
| 140 | const pawnShift = color == "w" ? -1 : 1; |
| 141 | |
| 142 | // Do not cheat: the current enlightment is all we can see |
| 143 | const myLight = JSON.parse(JSON.stringify(this.enlightened[color])); |
| 144 | |
| 145 | // Can a slider on (i,j) apparently take my king? |
| 146 | // NOTE: inaccurate because assume yes if some squares are shadowed |
| 147 | const sliderTake = ([i, j], piece) => { |
| 148 | const kp = this.kingPos[color]; |
| 149 | let step = undefined; |
| 150 | if (piece == V.BISHOP) { |
| 151 | if (Math.abs(kp[0] - i) == Math.abs(kp[1] - j)) { |
| 152 | step = [ |
| 153 | (i - kp[0]) / Math.abs(i - kp[0]), |
| 154 | (j - kp[1]) / Math.abs(j - kp[1]) |
| 155 | ]; |
| 156 | } |
| 157 | } else if (piece == V.ROOK) { |
| 158 | if (kp[0] == i) step = [0, (j - kp[1]) / Math.abs(j - kp[1])]; |
| 159 | else if (kp[1] == j) step = [(i - kp[0]) / Math.abs(i - kp[0]), 0]; |
| 160 | } |
| 161 | if (!step) return false; |
| 162 | // Check for obstacles |
| 163 | let obstacle = false; |
| 164 | for ( |
| 165 | let x = kp[0] + step[0], y = kp[1] + step[1]; |
| 166 | x != i && y != j; |
| 167 | x += step[0], y += step[1] |
| 168 | ) { |
| 169 | if (myLight[x][y] && this.board[x][y] != V.EMPTY) { |
| 170 | obstacle = true; |
| 171 | break; |
| 172 | } |
| 173 | } |
| 174 | if (!obstacle) return true; |
| 175 | return false; |
| 176 | }; |
| 177 | |
| 178 | // Do I see something which can take my king ? |
| 179 | const kingThreats = () => { |
| 180 | const kp = this.kingPos[color]; |
| 181 | for (let i = 0; i < V.size.x; i++) { |
| 182 | for (let j = 0; j < V.size.y; j++) { |
| 183 | if ( |
| 184 | myLight[i][j] && |
| 185 | this.board[i][j] != V.EMPTY && |
| 186 | this.getColor(i, j) != color |
| 187 | ) { |
| 188 | switch (this.getPiece(i, j)) { |
| 189 | case V.PAWN: |
| 190 | if (kp[0] + pawnShift == i && Math.abs(kp[1] - j) == 1) |
| 191 | return true; |
| 192 | break; |
| 193 | case V.KNIGHT: |
| 194 | if ( |
| 195 | (Math.abs(kp[0] - i) == 2 && Math.abs(kp[1] - j) == 1) || |
| 196 | (Math.abs(kp[0] - i) == 1 && Math.abs(kp[1] - j) == 2) |
| 197 | ) { |
| 198 | return true; |
| 199 | } |
| 200 | break; |
| 201 | case V.KING: |
| 202 | if (Math.abs(kp[0] - i) == 1 && Math.abs(kp[1] - j) == 1) |
| 203 | return true; |
| 204 | break; |
| 205 | case V.BISHOP: |
| 206 | if (sliderTake([i, j], V.BISHOP)) return true; |
| 207 | break; |
| 208 | case V.ROOK: |
| 209 | if (sliderTake([i, j], V.ROOK)) return true; |
| 210 | break; |
| 211 | case V.QUEEN: |
| 212 | if (sliderTake([i, j], V.BISHOP) || sliderTake([i, j], V.ROOK)) |
| 213 | return true; |
| 214 | break; |
| 215 | } |
| 216 | } |
| 217 | } |
| 218 | } |
| 219 | return false; |
| 220 | }; |
| 221 | |
| 222 | let moves = this.getAllValidMoves(); |
| 223 | for (let move of moves) { |
| 224 | this.play(move); |
| 225 | if (this.kingPos[oppCol][0] >= 0 && kingThreats()) { |
| 226 | // We didn't take opponent king, and our king will be captured: bad |
| 227 | move.eval = -maxeval; |
| 228 | } |
| 229 | this.undo(move); |
| 230 | |
| 231 | if (move.eval) continue; |
| 232 | |
| 233 | move.eval = 0; //a priori... |
| 234 | |
| 235 | // Can I take something ? If yes, do it if it seems good... |
| 236 | if (move.vanish.length == 2 && move.vanish[1].c != color) { |
| 237 | //avoid castle |
| 238 | const myPieceVal = V.VALUES[move.appear[0].p]; |
| 239 | const hisPieceVal = V.VALUES[move.vanish[1].p]; |
| 240 | if (myPieceVal <= hisPieceVal) move.eval = hisPieceVal - myPieceVal + 2; |
| 241 | //favor captures |
| 242 | else { |
| 243 | // Taking a pawn with minor piece, |
| 244 | // or minor piece or pawn with a rook, |
| 245 | // or anything but a queen with a queen, |
| 246 | // or anything with a king. |
| 247 | // ==> Do it at random, although |
| 248 | // this is clearly inferior to what a human can deduce... |
| 249 | move.eval = Math.random() < 0.5 ? 1 : -1; |
| 250 | } |
| 251 | } |
| 252 | } |
| 253 | |
| 254 | // TODO: also need to implement the case when an opponent piece (in light) |
| 255 | // is threatening something - maybe not the king, but e.g. pawn takes rook. |
| 256 | |
| 257 | moves.sort((a, b) => b.eval - a.eval); |
| 258 | let candidates = [0]; |
| 259 | for (let j = 1; j < moves.length && moves[j].eval == moves[0].eval; j++) |
| 260 | candidates.push(j); |
| 261 | return moves[candidates[randInt(candidates.length)]]; |
| 262 | } |
| 263 | }; |