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1 | import { ChessRules, PiPo, Move } from "@/base_rules"; |
2 | ||
32f6285e | 3 | export class EnpassantRules extends ChessRules { |
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4 | static IsGoodEnpassant(enpassant) { |
5 | if (enpassant != "-") { | |
6 | const squares = enpassant.split(","); | |
7 | for (let sq of squares) { | |
8 | const ep = V.SquareToCoords(sq); | |
9 | if (isNaN(ep.x) || !V.OnBoard(ep)) return false; | |
10 | } | |
11 | } | |
12 | return true; | |
13 | } | |
14 | ||
15 | getEpSquare(moveOrSquare) { | |
16 | if (!moveOrSquare) return undefined; | |
17 | if (typeof moveOrSquare === "string") { | |
18 | const square = moveOrSquare; | |
19 | if (square == "-") return undefined; | |
20 | let res = []; | |
21 | square.split(",").forEach(sq => { | |
22 | res.push(V.SquareToCoords(sq)); | |
23 | }); | |
24 | return res; | |
25 | } | |
26 | // Argument is a move: all intermediate squares are en-passant candidates, | |
27 | // except if the moving piece is a king. | |
28 | const move = moveOrSquare; | |
29 | const piece = move.appear[0].p; | |
30 | if (piece == V.KING || | |
31 | ( | |
32 | Math.abs(move.end.x-move.start.x) <= 1 && | |
33 | Math.abs(move.end.y-move.start.y) <= 1 | |
34 | ) | |
35 | ) { | |
36 | return undefined; | |
37 | } | |
38 | const delta = [move.end.x-move.start.x, move.end.y-move.start.y]; | |
39 | let step = undefined; | |
40 | if (piece == V.KNIGHT) { | |
41 | const divisor = Math.min(Math.abs(delta[0]), Math.abs(delta[1])); | |
42 | step = [delta[0]/divisor || 0, delta[1]/divisor || 0]; | |
43 | } else { | |
44 | step = [delta[0]/Math.abs(delta[0]) || 0, delta[1]/Math.abs(delta[1]) || 0]; | |
45 | } | |
46 | let res = []; | |
47 | for ( | |
48 | let [x,y] = [move.start.x+step[0],move.start.y+step[1]]; | |
49 | x != move.end.x || y != move.end.y; | |
50 | x += step[0], y += step[1] | |
51 | ) { | |
52 | res.push({x:x, y:y}); | |
53 | } | |
54 | // Add final square to know which piece is taken en passant: | |
55 | res.push(move.end); | |
56 | return res; | |
57 | } | |
58 | ||
59 | getEnpassantFen() { | |
60 | const L = this.epSquares.length; | |
61 | if (!this.epSquares[L - 1]) return "-"; //no en-passant | |
62 | let res = ""; | |
63 | this.epSquares[L - 1].forEach(sq => { | |
64 | res += V.CoordsToSquare(sq) + ","; | |
65 | }); | |
66 | return res.slice(0, -1); //remove last comma | |
67 | } | |
68 | ||
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69 | getPotentialMovesFrom([x, y]) { |
70 | let moves = super.getPotentialMovesFrom([x,y]); | |
71 | // Add en-passant captures from this square: | |
72 | const L = this.epSquares.length; | |
73 | if (!this.epSquares[L - 1]) return moves; | |
74 | const squares = this.epSquares[L - 1]; | |
75 | const S = squares.length; | |
76 | // Object describing the removed opponent's piece: | |
77 | const pipoV = new PiPo({ | |
78 | x: squares[S-1].x, | |
79 | y: squares[S-1].y, | |
80 | c: V.GetOppCol(this.turn), | |
81 | p: this.getPiece(squares[S-1].x, squares[S-1].y) | |
82 | }); | |
83 | // Check if existing non-capturing moves could also capture en passant | |
84 | moves.forEach(m => { | |
85 | if ( | |
86 | m.appear[0].p != V.PAWN && //special pawn case is handled elsewhere | |
87 | m.vanish.length <= 1 && | |
88 | [...Array(S-1).keys()].some(i => { | |
89 | return m.end.x == squares[i].x && m.end.y == squares[i].y; | |
90 | }) | |
91 | ) { | |
92 | m.vanish.push(pipoV); | |
93 | } | |
94 | }); | |
95 | // Special case of the king knight's movement: | |
96 | if (this.getPiece(x, y) == V.KING) { | |
97 | V.steps[V.KNIGHT].forEach(step => { | |
98 | const endX = x + step[0]; | |
99 | const endY = y + step[1]; | |
100 | if ( | |
101 | V.OnBoard(endX, endY) && | |
102 | [...Array(S-1).keys()].some(i => { | |
103 | return endX == squares[i].x && endY == squares[i].y; | |
104 | }) | |
105 | ) { | |
106 | let enpassantMove = this.getBasicMove([x, y], [endX, endY]); | |
107 | enpassantMove.vanish.push(pipoV); | |
108 | moves.push(enpassantMove); | |
109 | } | |
110 | }); | |
111 | } | |
112 | return moves; | |
113 | } | |
114 | ||
32f6285e | 115 | getEnpassantCaptures([x, y], shiftX) { |
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116 | const Lep = this.epSquares.length; |
117 | const squares = this.epSquares[Lep - 1]; | |
32f6285e | 118 | let moves = []; |
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119 | if (!!squares) { |
120 | const S = squares.length; | |
121 | const taken = squares[S-1]; | |
122 | const pipoV = new PiPo({ | |
123 | x: taken.x, | |
124 | y: taken.y, | |
125 | p: this.getPiece(taken.x, taken.y), | |
126 | c: this.getColor(taken.x, taken.y) | |
127 | }); | |
128 | [...Array(S-1).keys()].forEach(i => { | |
129 | const sq = squares[i]; | |
130 | if (sq.x == x + shiftX && Math.abs(sq.y - y) == 1) { | |
131 | let enpassantMove = this.getBasicMove([x, y], [sq.x, sq.y]); | |
132 | enpassantMove.vanish.push(pipoV); | |
133 | moves.push(enpassantMove); | |
134 | } | |
135 | }); | |
136 | } | |
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137 | return moves; |
138 | } | |
139 | ||
140 | // Remove the "onestep" condition: knight promote to knightrider: | |
7d8bf63e BA |
141 | getPotentialKnightMoves(sq) { |
142 | return this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT]); | |
143 | } | |
144 | ||
a97bdbda BA |
145 | filterValid(moves) { |
146 | const filteredMoves = super.filterValid(moves); | |
147 | // If at least one full move made, everything is allowed: | |
148 | if (this.movesCount >= 2) | |
149 | return filteredMoves; | |
150 | // Else, forbid captures: | |
151 | return filteredMoves.filter(m => m.vanish.length == 1); | |
152 | } | |
153 | ||
68e19a44 | 154 | isAttackedByKnight(sq, color) { |
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155 | return this.isAttackedBySlideNJump( |
156 | sq, | |
68e19a44 | 157 | color, |
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158 | V.KNIGHT, |
159 | V.steps[V.KNIGHT] | |
160 | ); | |
161 | } | |
162 | ||
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163 | static get SEARCH_DEPTH() { |
164 | return 2; | |
165 | } | |
166 | ||
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167 | static get VALUES() { |
168 | return { | |
169 | p: 1, | |
170 | r: 5, | |
171 | n: 4, | |
172 | b: 3, | |
173 | q: 9, | |
174 | k: 1000 | |
175 | }; | |
176 | } | |
177 | }; |