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1 | import { ChessRules, PiPo, Move } from "@/base_rules"; |
2 | ||
32f6285e | 3 | export class EnpassantRules extends ChessRules { |
7d8bf63e BA |
4 | static IsGoodEnpassant(enpassant) { |
5 | if (enpassant != "-") { | |
6 | const squares = enpassant.split(","); | |
472c0c4f | 7 | if (squares.length > 2) return false; |
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8 | for (let sq of squares) { |
9 | const ep = V.SquareToCoords(sq); | |
10 | if (isNaN(ep.x) || !V.OnBoard(ep)) return false; | |
11 | } | |
12 | } | |
13 | return true; | |
14 | } | |
15 | ||
16 | getEpSquare(moveOrSquare) { | |
17 | if (!moveOrSquare) return undefined; | |
18 | if (typeof moveOrSquare === "string") { | |
19 | const square = moveOrSquare; | |
20 | if (square == "-") return undefined; | |
472c0c4f BA |
21 | // Expand init + dest squares into a full path: |
22 | const init = V.SquareToCoords(square.substr(0, 2)); | |
23 | let newPath = [init]; | |
24 | if (square.length == 2) return newPath; | |
25 | const dest = V.SquareToCoords(square.substr(2)); | |
26 | const delta = ['x', 'y'].map(i => Math.abs(dest[i] - init[i])); | |
27 | // Check if it's a knight(rider) movement: | |
28 | let step = [0, 0]; | |
29 | if (delta[0] > 0 && delta[1] > 0 && delta[0] != delta[1]) { | |
30 | // Knightrider | |
31 | const minShift = Math.min(delta[0], delta[1]); | |
32 | step[0] = (dest.x - init.x) / minShift; | |
33 | step[1] = (dest.y - init.y) / minShift; | |
34 | } else { | |
35 | // "Sliders" | |
36 | step = ['x', 'y'].map((i, idx) => { | |
37 | return (dest[i] - init[i]) / delta[idx] || 0 | |
38 | }); | |
39 | } | |
40 | let x = init.x + step[0], | |
41 | y = init.y + step[1]; | |
42 | while (x != dest.x || y != dest.y) { | |
43 | newPath.push({ x: x, y: y }); | |
44 | x += step[0]; | |
45 | y += step[1]; | |
46 | } | |
47 | newPath.push(dest); | |
48 | return newPath; | |
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49 | } |
50 | // Argument is a move: all intermediate squares are en-passant candidates, | |
51 | // except if the moving piece is a king. | |
52 | const move = moveOrSquare; | |
53 | const piece = move.appear[0].p; | |
54 | if (piece == V.KING || | |
55 | ( | |
56 | Math.abs(move.end.x-move.start.x) <= 1 && | |
57 | Math.abs(move.end.y-move.start.y) <= 1 | |
58 | ) | |
59 | ) { | |
60 | return undefined; | |
61 | } | |
62 | const delta = [move.end.x-move.start.x, move.end.y-move.start.y]; | |
63 | let step = undefined; | |
64 | if (piece == V.KNIGHT) { | |
65 | const divisor = Math.min(Math.abs(delta[0]), Math.abs(delta[1])); | |
66 | step = [delta[0]/divisor || 0, delta[1]/divisor || 0]; | |
67 | } else { | |
2c5d7b20 BA |
68 | step = [ |
69 | delta[0]/Math.abs(delta[0]) || 0, | |
70 | delta[1]/Math.abs(delta[1]) || 0 | |
71 | ]; | |
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72 | } |
73 | let res = []; | |
74 | for ( | |
75 | let [x,y] = [move.start.x+step[0],move.start.y+step[1]]; | |
76 | x != move.end.x || y != move.end.y; | |
77 | x += step[0], y += step[1] | |
78 | ) { | |
472c0c4f | 79 | res.push({ x: x, y: y }); |
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80 | } |
81 | // Add final square to know which piece is taken en passant: | |
82 | res.push(move.end); | |
83 | return res; | |
84 | } | |
85 | ||
86 | getEnpassantFen() { | |
87 | const L = this.epSquares.length; | |
88 | if (!this.epSquares[L - 1]) return "-"; //no en-passant | |
472c0c4f BA |
89 | const epsq = this.epSquares[L - 1]; |
90 | if (epsq.length <= 2) return epsq.map(V.CoordsToSquare).join(""); | |
91 | // Condensate path: just need initial and final squares: | |
92 | return V.CoordsToSquare(epsq[0]) + V.CoordsToSquare(epsq[epsq.length - 1]); | |
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93 | } |
94 | ||
a97bdbda BA |
95 | getPotentialMovesFrom([x, y]) { |
96 | let moves = super.getPotentialMovesFrom([x,y]); | |
97 | // Add en-passant captures from this square: | |
98 | const L = this.epSquares.length; | |
99 | if (!this.epSquares[L - 1]) return moves; | |
100 | const squares = this.epSquares[L - 1]; | |
101 | const S = squares.length; | |
102 | // Object describing the removed opponent's piece: | |
103 | const pipoV = new PiPo({ | |
104 | x: squares[S-1].x, | |
105 | y: squares[S-1].y, | |
106 | c: V.GetOppCol(this.turn), | |
107 | p: this.getPiece(squares[S-1].x, squares[S-1].y) | |
108 | }); | |
109 | // Check if existing non-capturing moves could also capture en passant | |
110 | moves.forEach(m => { | |
111 | if ( | |
112 | m.appear[0].p != V.PAWN && //special pawn case is handled elsewhere | |
113 | m.vanish.length <= 1 && | |
114 | [...Array(S-1).keys()].some(i => { | |
115 | return m.end.x == squares[i].x && m.end.y == squares[i].y; | |
116 | }) | |
117 | ) { | |
118 | m.vanish.push(pipoV); | |
119 | } | |
120 | }); | |
121 | // Special case of the king knight's movement: | |
122 | if (this.getPiece(x, y) == V.KING) { | |
123 | V.steps[V.KNIGHT].forEach(step => { | |
124 | const endX = x + step[0]; | |
125 | const endY = y + step[1]; | |
126 | if ( | |
127 | V.OnBoard(endX, endY) && | |
128 | [...Array(S-1).keys()].some(i => { | |
129 | return endX == squares[i].x && endY == squares[i].y; | |
130 | }) | |
131 | ) { | |
132 | let enpassantMove = this.getBasicMove([x, y], [endX, endY]); | |
133 | enpassantMove.vanish.push(pipoV); | |
134 | moves.push(enpassantMove); | |
135 | } | |
136 | }); | |
137 | } | |
138 | return moves; | |
139 | } | |
140 | ||
32f6285e | 141 | getEnpassantCaptures([x, y], shiftX) { |
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142 | const Lep = this.epSquares.length; |
143 | const squares = this.epSquares[Lep - 1]; | |
32f6285e | 144 | let moves = []; |
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145 | if (!!squares) { |
146 | const S = squares.length; | |
147 | const taken = squares[S-1]; | |
148 | const pipoV = new PiPo({ | |
149 | x: taken.x, | |
150 | y: taken.y, | |
151 | p: this.getPiece(taken.x, taken.y), | |
152 | c: this.getColor(taken.x, taken.y) | |
153 | }); | |
154 | [...Array(S-1).keys()].forEach(i => { | |
155 | const sq = squares[i]; | |
156 | if (sq.x == x + shiftX && Math.abs(sq.y - y) == 1) { | |
157 | let enpassantMove = this.getBasicMove([x, y], [sq.x, sq.y]); | |
158 | enpassantMove.vanish.push(pipoV); | |
159 | moves.push(enpassantMove); | |
160 | } | |
161 | }); | |
162 | } | |
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163 | return moves; |
164 | } | |
165 | ||
166 | // Remove the "onestep" condition: knight promote to knightrider: | |
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167 | getPotentialKnightMoves(sq) { |
168 | return this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT]); | |
169 | } | |
170 | ||
a97bdbda BA |
171 | filterValid(moves) { |
172 | const filteredMoves = super.filterValid(moves); | |
173 | // If at least one full move made, everything is allowed: | |
174 | if (this.movesCount >= 2) | |
175 | return filteredMoves; | |
176 | // Else, forbid captures: | |
177 | return filteredMoves.filter(m => m.vanish.length == 1); | |
178 | } | |
179 | ||
68e19a44 | 180 | isAttackedByKnight(sq, color) { |
7d8bf63e BA |
181 | return this.isAttackedBySlideNJump( |
182 | sq, | |
68e19a44 | 183 | color, |
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184 | V.KNIGHT, |
185 | V.steps[V.KNIGHT] | |
186 | ); | |
187 | } | |
188 | ||
b83a675a BA |
189 | static get SEARCH_DEPTH() { |
190 | return 2; | |
191 | } | |
192 | ||
7d8bf63e BA |
193 | static get VALUES() { |
194 | return { | |
195 | p: 1, | |
196 | r: 5, | |
197 | n: 4, | |
198 | b: 3, | |
199 | q: 9, | |
200 | k: 1000 | |
201 | }; | |
202 | } | |
203 | }; |