| 1 | import { ChessRules } from "@/base_rules"; |
| 2 | import { ArrayFun } from "@/utils/array"; |
| 3 | import { randInt } from "@/utils/alea"; |
| 4 | |
| 5 | export const VariantRules = class GrasshopperRules extends ChessRules { |
| 6 | static get HasEnpassant() { |
| 7 | return false; |
| 8 | } |
| 9 | |
| 10 | static get GRASSHOPPER() { |
| 11 | return "g"; |
| 12 | } |
| 13 | |
| 14 | static get PIECES() { |
| 15 | return ChessRules.PIECES.concat([V.GRASSHOPPER]); |
| 16 | } |
| 17 | |
| 18 | getPpath(b) { |
| 19 | return (b[1] == V.GRASSHOPPER ? "Grasshopper/" : "") + b; |
| 20 | } |
| 21 | |
| 22 | getPotentialMovesFrom([x, y]) { |
| 23 | switch (this.getPiece(x, y)) { |
| 24 | case V.GRASSHOPPER: |
| 25 | return this.getPotentialGrasshopperMoves([x, y]); |
| 26 | default: |
| 27 | return super.getPotentialMovesFrom([x, y]); |
| 28 | } |
| 29 | } |
| 30 | |
| 31 | getPotentialPawnMoves([x, y]) { |
| 32 | const color = this.turn; |
| 33 | let moves = []; |
| 34 | const [sizeX, sizeY] = [V.size.x, V.size.y]; |
| 35 | const shiftX = color == "w" ? -1 : 1; |
| 36 | const lastRank = color == "w" ? 0 : sizeX - 1; |
| 37 | |
| 38 | const finalPieces = |
| 39 | x + shiftX == lastRank |
| 40 | ? [V.ROOK, V.KNIGHT, V.BISHOP, V.QUEEN, V.GRASSHOPPER] |
| 41 | : [V.PAWN]; |
| 42 | if (this.board[x + shiftX][y] == V.EMPTY) { |
| 43 | // One square forward |
| 44 | for (let piece of finalPieces) { |
| 45 | moves.push( |
| 46 | this.getBasicMove([x, y], [x + shiftX, y], { |
| 47 | c: color, |
| 48 | p: piece |
| 49 | }) |
| 50 | ); |
| 51 | } |
| 52 | // No 2-squares jump |
| 53 | } |
| 54 | // Captures |
| 55 | for (let shiftY of [-1, 1]) { |
| 56 | if ( |
| 57 | y + shiftY >= 0 && |
| 58 | y + shiftY < sizeY && |
| 59 | this.board[x + shiftX][y + shiftY] != V.EMPTY && |
| 60 | this.canTake([x, y], [x + shiftX, y + shiftY]) |
| 61 | ) { |
| 62 | for (let piece of finalPieces) { |
| 63 | moves.push( |
| 64 | this.getBasicMove([x, y], [x + shiftX, y + shiftY], { |
| 65 | c: color, |
| 66 | p: piece |
| 67 | }) |
| 68 | ); |
| 69 | } |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | return moves; |
| 74 | } |
| 75 | |
| 76 | getPotentialGrasshopperMoves([x, y]) { |
| 77 | let moves = []; |
| 78 | // Look in every direction until an obstacle (to jump) is met |
| 79 | for (const step of V.steps[V.ROOK].concat(V.steps[V.BISHOP])) { |
| 80 | let i = x + step[0]; |
| 81 | let j = y + step[1]; |
| 82 | while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) { |
| 83 | i += step[0]; |
| 84 | j += step[1]; |
| 85 | } |
| 86 | // Move is valid if the next square is empty or occupied by enemy |
| 87 | const nextSq = [i+step[0], j+step[1]]; |
| 88 | if (V.OnBoard(nextSq[0], nextSq[1]) && this.canTake([x, y], nextSq)) |
| 89 | moves.push(this.getBasicMove([x, y], nextSq)); |
| 90 | } |
| 91 | return moves; |
| 92 | } |
| 93 | |
| 94 | isAttacked(sq, color) { |
| 95 | return ( |
| 96 | super.isAttacked(sq, color) || |
| 97 | this.isAttackedByGrasshopper(sq, color) |
| 98 | ); |
| 99 | } |
| 100 | |
| 101 | isAttackedByGrasshopper([x, y], color) { |
| 102 | // Reversed process: is there an adjacent obstacle, |
| 103 | // and a grasshopper next in the same line? |
| 104 | for (const step of V.steps[V.ROOK].concat(V.steps[V.BISHOP])) { |
| 105 | const nextSq = [x+step[0], y+step[1]]; |
| 106 | if ( |
| 107 | V.OnBoard(nextSq[0], nextSq[1]) && |
| 108 | this.board[nextSq[0]][nextSq[1]] != V.EMPTY |
| 109 | ) { |
| 110 | let i = nextSq[0] + step[0]; |
| 111 | let j = nextSq[1] + step[1]; |
| 112 | while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) { |
| 113 | i += step[0]; |
| 114 | j += step[1]; |
| 115 | } |
| 116 | if ( |
| 117 | V.OnBoard(i, j) && |
| 118 | this.getPiece(i, j) == V.GRASSHOPPER && |
| 119 | this.getColor(i, j) == color |
| 120 | ) { |
| 121 | return true; |
| 122 | } |
| 123 | } |
| 124 | } |
| 125 | return false; |
| 126 | } |
| 127 | |
| 128 | static get VALUES() { |
| 129 | return Object.assign( |
| 130 | // TODO: grasshoppers power decline with less pieces on board... |
| 131 | { g: 2 }, |
| 132 | ChessRules.VALUES |
| 133 | ); |
| 134 | } |
| 135 | |
| 136 | static get SEARCH_DEPTH() { |
| 137 | return 2; |
| 138 | } |
| 139 | |
| 140 | static GenRandInitFen(randomness) { |
| 141 | return ChessRules.GenRandInitFen(randomness) |
| 142 | .slice(0, -2) |
| 143 | .replace( |
| 144 | "/pppppppp/8/8/8/8/PPPPPPPP/", |
| 145 | "/gggggggg/pppppppp/8/8/PPPPPPPP/GGGGGGGG/" |
| 146 | ); |
| 147 | } |
| 148 | }; |