Generalize pawn movements: cleaner and smaller code
[vchess.git] / client / src / variants / Circular.js
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1import { ChessRules, PiPo, Move } from "@/base_rules";
2import { ArrayFun } from "@/utils/array";
32f6285e 3import { shuffle } from "@/utils/alea";
e3e2cc44 4
32f6285e 5export class CircularRules extends ChessRules {
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6 static get HasCastle() {
7 return false;
8 }
9
71ef1664 10 static get HasEnpassant() {
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11 return false;
12 }
13
71ef1664 14 static get CanFlip() {
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15 return false;
16 }
17
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18 setFlags(fenflags) {
19 this.pawnFlags = {
20 w: [...Array(8).fill(true)], //pawns can move 2 squares?
21 b: [...Array(8).fill(true)]
22 };
23 for (let c of ["w", "b"]) {
24 for (let i = 0; i < 8; i++)
25 this.pawnFlags[c][i] = fenflags.charAt((c == "w" ? 0 : 8) + i) == "1";
26 }
27 }
28
29 aggregateFlags() {
30 return this.pawnFlags;
31 }
32
33 disaggregateFlags(flags) {
34 this.pawnFlags = flags;
35 }
e3e2cc44 36
7ba4a5bc 37 static GenRandInitFen(randomness) {
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38 if (randomness == 0)
39 return "8/8/pppppppp/rnbqkbnr/8/8/PPPPPPPP/RNBQKBNR w 0 1111111111111111";
40
e3e2cc44 41 let pieces = { w: new Array(8), b: new Array(8) };
32f6285e 42 // Shuffle pieces on first and last rank
e3e2cc44 43 for (let c of ["w", "b"]) {
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44 if (c == 'b' && randomness == 1) {
45 pieces['b'] = pieces['w'];
46 break;
47 }
48
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49 // Get random squares for every piece, totally freely
50 let positions = shuffle(ArrayFun.range(8));
51 const composition = ['b', 'b', 'r', 'r', 'n', 'n', 'k', 'q'];
52 const rem2 = positions[0] % 2;
53 if (rem2 == positions[1] % 2) {
54 // Fix bishops (on different colors)
55 for (let i=2; i<8; i++) {
56 if (positions[i] % 2 != rem2)
57 [positions[1], positions[i]] = [positions[i], positions[1]];
58 }
59 }
60 for (let i = 0; i < 8; i++) pieces[c][positions[i]] = composition[i];
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61 }
62 return (
71ef1664 63 "8/8/pppppppp/" +
e3e2cc44 64 pieces["b"].join("") +
71ef1664 65 "/8/8/PPPPPPPP/" +
e3e2cc44 66 pieces["w"].join("").toUpperCase() +
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67 // 16 flags: can pawns advance 2 squares?
68 " w 0 1111111111111111"
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69 );
70 }
71
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72 // Output basically x % 8 (circular board)
73 static ComputeX(x) {
74 let res = x % V.size.x;
75 if (res < 0)
76 res += V.size.x;
77 return res;
78 }
79
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80 getSlideNJumpMoves([x, y], steps, oneStep) {
81 let moves = [];
82 outerLoop: for (let step of steps) {
71ef1664 83 let i = V.ComputeX(x + step[0]);
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84 let j = y + step[1];
85 while (V.OnBoard(i, j) && this.board[i][j] == V.EMPTY) {
86 moves.push(this.getBasicMove([x, y], [i, j]));
87 if (oneStep !== undefined) continue outerLoop;
71ef1664 88 i = V.ComputeX(i + step[0]);
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89 j += step[1];
90 }
91 if (V.OnBoard(i, j) && this.canTake([x, y], [i, j]))
92 moves.push(this.getBasicMove([x, y], [i, j]));
93 }
94 return moves;
95 }
96
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97 getPotentialPawnMoves([x, y]) {
98 const color = this.turn;
99 let moves = [];
100 const [sizeX, sizeY] = [V.size.x, V.size.y];
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101 // All pawns go in the same direction!
102 const shiftX = -1;
103 const startRank = color == "w" ? sizeX - 2 : 2;
104
105 // One square forward
106 const nextRow = V.ComputeX(x + shiftX);
107 if (this.board[nextRow][y] == V.EMPTY) {
108 moves.push(this.getBasicMove([x, y], [nextRow, y]));
109 if (
110 x == startRank &&
111 this.pawnFlags[color][y] &&
112 this.board[x + 2 * shiftX][y] == V.EMPTY
113 ) {
114 // Two squares jump
115 moves.push(this.getBasicMove([x, y], [x + 2 * shiftX, y]));
e3e2cc44 116 }
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117 }
118 // Captures
119 for (let shiftY of [-1, 1]) {
120 if (
121 y + shiftY >= 0 &&
122 y + shiftY < sizeY &&
123 this.board[nextRow][y + shiftY] != V.EMPTY &&
124 this.canTake([x, y], [nextRow, y + shiftY])
125 ) {
126 moves.push(this.getBasicMove([x, y], [nextRow, y + shiftY]));
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127 }
128 }
129
130 return moves;
131 }
132
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133 filterValid(moves) {
134 const filteredMoves = super.filterValid(moves);
135 // If at least one full move made, everything is allowed:
9842aca2 136 if (this.movesCount >= 2) return filteredMoves;
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137 // Else, forbid check:
138 const oppCol = V.GetOppCol(this.turn);
139 return filteredMoves.filter(m => {
140 this.play(m);
141 const res = !this.underCheck(oppCol);
142 this.undo(m);
143 return res;
144 });
145 }
146
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147 isAttackedByPawn([x, y], color) {
148 // pawn shift is always 1 (all pawns go the same way)
149 const attackerRow = V.ComputeX(x + 1);
150 for (let i of [-1, 1]) {
151 if (
152 y + i >= 0 &&
153 y + i < V.size.y &&
154 this.getPiece(attackerRow, y + i) == V.PAWN &&
155 this.getColor(attackerRow, y + i) == color
156 ) {
157 return true;
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158 }
159 }
160 return false;
161 }
162
68e19a44 163 isAttackedBySlideNJump([x, y], color, piece, steps, oneStep) {
e3e2cc44 164 for (let step of steps) {
71ef1664 165 let rx = V.ComputeX(x + step[0]),
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166 ry = y + step[1];
167 while (V.OnBoard(rx, ry) && this.board[rx][ry] == V.EMPTY && !oneStep) {
71ef1664 168 rx = V.ComputeX(rx + step[0]);
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169 ry += step[1];
170 }
171 if (
172 V.OnBoard(rx, ry) &&
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173 this.getPiece(rx, ry) == piece &&
174 this.getColor(rx, ry) == color
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175 ) {
176 return true;
177 }
178 }
179 return false;
180 }
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181
182 getFlagsFen() {
183 // Return pawns flags
184 let flags = "";
185 for (let c of ["w", "b"]) {
186 for (let i = 0; i < 8; i++) flags += this.pawnFlags[c][i] ? "1" : "0";
187 }
188 return flags;
189 }
190
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191 postPlay(move) {
192 super.postPlay(move);
71ef1664 193 const c = move.vanish[0].c;
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194 const secondRank = { "w": 6, "b": 2 };
195 if (move.vanish[0].p == V.PAWN && secondRank[c] == move.start.x)
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196 // This move turns off a 2-squares pawn flag
197 this.pawnFlags[c][move.start.y] = false;
198 }
199
200 static get VALUES() {
201 return {
202 p: 1,
203 r: 5,
204 n: 3,
205 b: 4,
206 q: 10,
207 k: 1000
208 };
209 }
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210
211 static get SEARCH_DEPTH() {
212 return 2;
213 }
e3e2cc44 214};