| 1 | import { ChessRules } from "@/base_rules"; |
| 2 | |
| 3 | export const VariantRules = class ShatranjRules extends ChessRules { |
| 4 | static get HasFlags() { |
| 5 | return false; |
| 6 | } |
| 7 | |
| 8 | static get HasEnpassant() { |
| 9 | return false; |
| 10 | } |
| 11 | |
| 12 | static get ElephantSteps() { |
| 13 | return [ |
| 14 | [-2, -2], |
| 15 | [-2, 2], |
| 16 | [2, -2], |
| 17 | [2, 2] |
| 18 | ]; |
| 19 | } |
| 20 | |
| 21 | static GenRandInitFen(randomness) { |
| 22 | // Remove castle flags and en-passant indication |
| 23 | return ChessRules.GenRandInitFen(randomness).slice(0, -7); |
| 24 | } |
| 25 | |
| 26 | getPotentialPawnMoves([x, y]) { |
| 27 | const color = this.turn; |
| 28 | let moves = []; |
| 29 | const [sizeX, sizeY] = [V.size.x, V.size.y]; |
| 30 | const shiftX = color == "w" ? -1 : 1; |
| 31 | const startRank = color == "w" ? sizeX - 2 : 1; |
| 32 | const lastRank = color == "w" ? 0 : sizeX - 1; |
| 33 | // Promotion in minister (queen) only: |
| 34 | const finalPiece = x + shiftX == lastRank ? V.QUEEN : V.PAWN; |
| 35 | |
| 36 | if (this.board[x + shiftX][y] == V.EMPTY) { |
| 37 | // One square forward |
| 38 | moves.push( |
| 39 | this.getBasicMove([x, y], [x + shiftX, y], { |
| 40 | c: color, |
| 41 | p: finalPiece |
| 42 | }) |
| 43 | ); |
| 44 | } |
| 45 | // Captures |
| 46 | for (let shiftY of [-1, 1]) { |
| 47 | if ( |
| 48 | y + shiftY >= 0 && |
| 49 | y + shiftY < sizeY && |
| 50 | this.board[x + shiftX][y + shiftY] != V.EMPTY && |
| 51 | this.canTake([x, y], [x + shiftX, y + shiftY]) |
| 52 | ) { |
| 53 | moves.push( |
| 54 | this.getBasicMove([x, y], [x + shiftX, y + shiftY], { |
| 55 | c: color, |
| 56 | p: finalPiece |
| 57 | }) |
| 58 | ); |
| 59 | } |
| 60 | } |
| 61 | |
| 62 | return moves; |
| 63 | } |
| 64 | |
| 65 | getPotentialBishopMoves(sq) { |
| 66 | let moves = this.getSlideNJumpMoves(sq, V.ElephantSteps, "oneStep"); |
| 67 | // Complete with "repositioning moves": like a queen, without capture |
| 68 | let repositioningMoves = this.getSlideNJumpMoves( |
| 69 | sq, |
| 70 | V.steps[V.BISHOP], |
| 71 | "oneStep" |
| 72 | ).filter(m => m.vanish.length == 1); |
| 73 | return moves.concat(repositioningMoves); |
| 74 | } |
| 75 | |
| 76 | getPotentialQueenMoves(sq) { |
| 77 | // Diagonal capturing moves |
| 78 | let captures = this.getSlideNJumpMoves( |
| 79 | sq, |
| 80 | V.steps[V.BISHOP], |
| 81 | "oneStep" |
| 82 | ).filter(m => m.vanish.length == 2); |
| 83 | return captures.concat( |
| 84 | // Orthogonal non-capturing moves |
| 85 | this.getSlideNJumpMoves( |
| 86 | sq, |
| 87 | V.steps[V.ROOK], |
| 88 | "oneStep" |
| 89 | ).filter(m => m.vanish.length == 1) |
| 90 | ); |
| 91 | } |
| 92 | |
| 93 | getPotentialKingMoves(sq) { |
| 94 | return this.getSlideNJumpMoves( |
| 95 | sq, |
| 96 | V.steps[V.ROOK].concat(V.steps[V.BISHOP]), |
| 97 | "oneStep" |
| 98 | ); |
| 99 | } |
| 100 | |
| 101 | isAttackedByBishop(sq, colors) { |
| 102 | return this.isAttackedBySlideNJump( |
| 103 | sq, |
| 104 | colors, |
| 105 | V.BISHOP, |
| 106 | V.ElephantSteps, |
| 107 | "oneStep" |
| 108 | ); |
| 109 | } |
| 110 | |
| 111 | isAttackedByQueen(sq, colors) { |
| 112 | return this.isAttackedBySlideNJump( |
| 113 | sq, |
| 114 | colors, |
| 115 | V.QUEEN, |
| 116 | V.steps[V.BISHOP], |
| 117 | "oneStep" |
| 118 | ); |
| 119 | } |
| 120 | |
| 121 | getCurrentScore() { |
| 122 | const color = this.turn; |
| 123 | const getScoreLost = () => { |
| 124 | // Result if I lose: |
| 125 | return color == "w" ? "0-1" : "1-0"; |
| 126 | }; |
| 127 | if (!this.atLeastOneMove()) |
| 128 | // No valid move: I lose (this includes checkmate) |
| 129 | return getScoreLost(); |
| 130 | // Win if the opponent has no pieces left (except king), |
| 131 | // and cannot bare king on the next move. |
| 132 | let piecesLeft = { |
| 133 | // No need to remember all pieces' squares: |
| 134 | // variable only used if just one remaining piece. |
| 135 | "w": {count: 0, square: null}, |
| 136 | "b": {count: 0, square: null} |
| 137 | }; |
| 138 | outerLoop: for (let i=0; i<V.size.x; i++) { |
| 139 | for (let j=0; j<V.size.y; j++) { |
| 140 | if (this.board[i][j] != V.EMPTY && this.getPiece(i,j) != V.KING) { |
| 141 | const sqCol = this.getColor(i,j); |
| 142 | piecesLeft[sqCol].count++; |
| 143 | piecesLeft[sqCol].square = [i,j]; |
| 144 | } |
| 145 | } |
| 146 | } |
| 147 | if (Object.values(piecesLeft).every(v => v.count > 0)) |
| 148 | return "*"; |
| 149 | // No pieces left for some side: if both kings are bare, it's a draw |
| 150 | if (Object.values(piecesLeft).every(v => v.count == 0)) |
| 151 | return "1/2"; |
| 152 | if (piecesLeft[color].count > 0) |
| 153 | // He could have drawn, but didn't take my last piece... |
| 154 | return color == "w" ? "1-0" : "0-1"; |
| 155 | const oppCol = V.GetOppCol(color); |
| 156 | if (piecesLeft[oppCol].count >= 2) |
| 157 | // 2 enemy units or more: I lose |
| 158 | return getScoreLost(); |
| 159 | // I don't have any piece, my opponent have one: can I take it? |
| 160 | if (this.isAttacked(piecesLeft[oppCol].square, [color])) |
| 161 | // Yes! But I still need to take it |
| 162 | return "*"; |
| 163 | // No :( |
| 164 | return getScoreLost(); |
| 165 | } |
| 166 | |
| 167 | static get VALUES() { |
| 168 | return { |
| 169 | p: 1, |
| 170 | r: 5, |
| 171 | n: 3, |
| 172 | b: 3, |
| 173 | q: 3, |
| 174 | k: 1000 |
| 175 | }; |
| 176 | } |
| 177 | }; |