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1 | import { ChessRules } from "@/base_rules"; |
2 | ||
a4eca0dc | 3 | export const VariantRules = class ShatranjRules extends ChessRules { |
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4 | static get HasFlags() { |
5 | return false; | |
6 | } | |
7 | ||
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8 | static get HasCastle() { |
9 | return false; | |
10 | } | |
11 | ||
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12 | static get HasEnpassant() { |
13 | return false; | |
14 | } | |
15 | ||
16 | static get ElephantSteps() { | |
17 | return [ | |
18 | [-2, -2], | |
19 | [-2, 2], | |
20 | [2, -2], | |
21 | [2, 2] | |
22 | ]; | |
23 | } | |
24 | ||
7ba4a5bc | 25 | static GenRandInitFen(randomness) { |
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26 | // Remove castle flags and en-passant indication |
27 | return ChessRules.GenRandInitFen(randomness).slice(0, -7); | |
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28 | } |
29 | ||
30 | getPotentialPawnMoves([x, y]) { | |
31 | const color = this.turn; | |
32 | let moves = []; | |
33 | const [sizeX, sizeY] = [V.size.x, V.size.y]; | |
34 | const shiftX = color == "w" ? -1 : 1; | |
35 | const startRank = color == "w" ? sizeX - 2 : 1; | |
36 | const lastRank = color == "w" ? 0 : sizeX - 1; | |
37 | // Promotion in minister (queen) only: | |
38 | const finalPiece = x + shiftX == lastRank ? V.QUEEN : V.PAWN; | |
39 | ||
40 | if (this.board[x + shiftX][y] == V.EMPTY) { | |
41 | // One square forward | |
42 | moves.push( | |
43 | this.getBasicMove([x, y], [x + shiftX, y], { | |
44 | c: color, | |
45 | p: finalPiece | |
46 | }) | |
47 | ); | |
48 | } | |
49 | // Captures | |
50 | for (let shiftY of [-1, 1]) { | |
51 | if ( | |
52 | y + shiftY >= 0 && | |
53 | y + shiftY < sizeY && | |
54 | this.board[x + shiftX][y + shiftY] != V.EMPTY && | |
55 | this.canTake([x, y], [x + shiftX, y + shiftY]) | |
56 | ) { | |
57 | moves.push( | |
58 | this.getBasicMove([x, y], [x + shiftX, y + shiftY], { | |
59 | c: color, | |
60 | p: finalPiece | |
61 | }) | |
62 | ); | |
63 | } | |
64 | } | |
65 | ||
66 | return moves; | |
67 | } | |
68 | ||
69 | getPotentialBishopMoves(sq) { | |
70 | let moves = this.getSlideNJumpMoves(sq, V.ElephantSteps, "oneStep"); | |
71 | // Complete with "repositioning moves": like a queen, without capture | |
72 | let repositioningMoves = this.getSlideNJumpMoves( | |
73 | sq, | |
74 | V.steps[V.BISHOP], | |
75 | "oneStep" | |
76 | ).filter(m => m.vanish.length == 1); | |
77 | return moves.concat(repositioningMoves); | |
78 | } | |
79 | ||
80 | getPotentialQueenMoves(sq) { | |
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81 | // Diagonal capturing moves |
82 | let captures = this.getSlideNJumpMoves( | |
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83 | sq, |
84 | V.steps[V.BISHOP], | |
85 | "oneStep" | |
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86 | ).filter(m => m.vanish.length == 2); |
87 | return captures.concat( | |
88 | // Orthogonal non-capturing moves | |
89 | this.getSlideNJumpMoves( | |
90 | sq, | |
91 | V.steps[V.ROOK], | |
92 | "oneStep" | |
93 | ).filter(m => m.vanish.length == 1) | |
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94 | ); |
95 | } | |
96 | ||
68e19a44 | 97 | isAttackedByBishop(sq, color) { |
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98 | return this.isAttackedBySlideNJump( |
99 | sq, | |
68e19a44 | 100 | color, |
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101 | V.BISHOP, |
102 | V.ElephantSteps, | |
103 | "oneStep" | |
104 | ); | |
105 | } | |
106 | ||
68e19a44 | 107 | isAttackedByQueen(sq, color) { |
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108 | return this.isAttackedBySlideNJump( |
109 | sq, | |
68e19a44 | 110 | color, |
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111 | V.QUEEN, |
112 | V.steps[V.BISHOP], | |
113 | "oneStep" | |
114 | ); | |
115 | } | |
116 | ||
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117 | getCurrentScore() { |
118 | const color = this.turn; | |
119 | const getScoreLost = () => { | |
120 | // Result if I lose: | |
121 | return color == "w" ? "0-1" : "1-0"; | |
122 | }; | |
123 | if (!this.atLeastOneMove()) | |
124 | // No valid move: I lose (this includes checkmate) | |
125 | return getScoreLost(); | |
126 | // Win if the opponent has no pieces left (except king), | |
127 | // and cannot bare king on the next move. | |
128 | let piecesLeft = { | |
129 | // No need to remember all pieces' squares: | |
130 | // variable only used if just one remaining piece. | |
131 | "w": {count: 0, square: null}, | |
132 | "b": {count: 0, square: null} | |
133 | }; | |
134 | outerLoop: for (let i=0; i<V.size.x; i++) { | |
135 | for (let j=0; j<V.size.y; j++) { | |
136 | if (this.board[i][j] != V.EMPTY && this.getPiece(i,j) != V.KING) { | |
137 | const sqCol = this.getColor(i,j); | |
138 | piecesLeft[sqCol].count++; | |
139 | piecesLeft[sqCol].square = [i,j]; | |
140 | } | |
141 | } | |
142 | } | |
143 | if (Object.values(piecesLeft).every(v => v.count > 0)) | |
144 | return "*"; | |
145 | // No pieces left for some side: if both kings are bare, it's a draw | |
146 | if (Object.values(piecesLeft).every(v => v.count == 0)) | |
147 | return "1/2"; | |
148 | if (piecesLeft[color].count > 0) | |
149 | // He could have drawn, but didn't take my last piece... | |
150 | return color == "w" ? "1-0" : "0-1"; | |
151 | const oppCol = V.GetOppCol(color); | |
152 | if (piecesLeft[oppCol].count >= 2) | |
153 | // 2 enemy units or more: I lose | |
154 | return getScoreLost(); | |
155 | // I don't have any piece, my opponent have one: can I take it? | |
68e19a44 | 156 | if (this.isAttacked(piecesLeft[oppCol].square, color)) |
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157 | // Yes! But I still need to take it |
158 | return "*"; | |
159 | // No :( | |
160 | return getScoreLost(); | |
161 | } | |
162 | ||
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163 | static get VALUES() { |
164 | return { | |
165 | p: 1, | |
166 | r: 5, | |
167 | n: 3, | |
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168 | b: 3, |
169 | q: 3, | |
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170 | k: 1000 |
171 | }; | |
172 | } | |
173 | }; |