Improve Bario rules description about castling
[vchess.git] / client / src / variants / Cannibal.js
1 import { ChessRules, Move, PiPo } from "@/base_rules";
2
3 export class CannibalRules extends ChessRules {
4
5 static get KING_CODE() {
6 return {
7 'p': 's',
8 'r': 'u',
9 'n': 'o',
10 'b': 'c',
11 'q': 't'
12 };
13 }
14
15 static get KING_DECODE() {
16 return {
17 's': 'p',
18 'u': 'r',
19 'o': 'n',
20 'c': 'b',
21 't': 'q'
22 };
23 }
24
25 // Kings may be disguised:
26 getPiece(x, y) {
27 const piece = this.board[x][y].charAt(1);
28 if (Object.keys(V.KING_DECODE).includes(piece))
29 return V.KING_DECODE[piece];
30 return piece;
31 }
32
33 getPpath(b) {
34 return (Object.keys(V.KING_DECODE).includes(b[1]) ? "Cannibal/" : "") + b;
35 }
36
37 static IsGoodPosition(position) {
38 if (position.length == 0) return false;
39 const rows = position.split("/");
40 if (rows.length != V.size.x) return false;
41 let kings = { "w": 0, "b": 0 };
42 const allPiecesCodes = V.PIECES.concat(Object.keys(V.KING_DECODE));
43 const kingBlackCodes = Object.keys(V.KING_DECODE).concat(['k']);
44 const kingWhiteCodes =
45 Object.keys(V.KING_DECODE).map(k => k.toUpperCase()).concat(['K']);
46 for (let row of rows) {
47 let sumElts = 0;
48 for (let i = 0; i < row.length; i++) {
49 if (kingBlackCodes.includes(row[i])) kings['b']++;
50 else if (kingWhiteCodes.includes(row[i])) kings['w']++;
51 if (allPiecesCodes.includes(row[i].toLowerCase())) sumElts++;
52 else {
53 const num = parseInt(row[i], 10);
54 if (isNaN(num)) return false;
55 sumElts += num;
56 }
57 }
58 if (sumElts != V.size.y) return false;
59 }
60 // Both kings should be on board, only one of each color:
61 if (Object.values(kings).some(v => v != 1)) return false;
62 return true;
63 }
64
65 // Kings may be disguised:
66 setOtherVariables(fen) {
67 super.setOtherVariables(fen);
68 const rows = V.ParseFen(fen).position.split("/");
69 if (this.kingPos["w"][0] < 0 || this.kingPos["b"][0] < 0) {
70 for (let i = 0; i < rows.length; i++) {
71 let k = 0; //column index on board
72 for (let j = 0; j < rows[i].length; j++) {
73 const piece = rows[i].charAt(j);
74 if (Object.keys(V.KING_DECODE).includes(piece.toLowerCase())) {
75 const color = (piece.charCodeAt(0) <= 90 ? 'w' : 'b');
76 this.kingPos[color] = [i, k];
77 } else {
78 const num = parseInt(rows[i].charAt(j), 10);
79 if (!isNaN(num)) k += num - 1;
80 }
81 k++;
82 }
83 }
84 }
85 }
86
87 // Trim all non-capturing moves
88 static KeepCaptures(moves) {
89 return moves.filter(m => m.vanish.length == 2 && m.appear.length == 1);
90 }
91
92 // Stop at the first capture found (if any)
93 atLeastOneCapture() {
94 const color = this.turn;
95 const oppCol = V.GetOppCol(color);
96 for (let i = 0; i < V.size.x; i++) {
97 for (let j = 0; j < V.size.y; j++) {
98 if (
99 this.board[i][j] != V.EMPTY &&
100 this.getColor(i, j) != oppCol &&
101 this.filterValid(this.getPotentialMovesFrom([i, j])).some(m =>
102 // Warning: discard castle moves
103 m.vanish.length == 2 && m.appear.length == 1)
104 ) {
105 return true;
106 }
107 }
108 }
109 return false;
110 }
111
112 // Because of the disguised kings, getPiece() could be wrong:
113 // use board[x][y][1] instead (always valid).
114 getBasicMove([sx, sy], [ex, ey], tr) {
115 let mv = super.getBasicMove([sx, sy], [ex, ey], tr);
116
117 if (this.board[ex][ey] != V.EMPTY) {
118 // If the captured piece has a different nature: take it as well
119 if (mv.vanish[0].p != mv.vanish[1].p) {
120 if (
121 mv.vanish[0].p == V.KING ||
122 Object.keys(V.KING_DECODE).includes(mv.vanish[0].p)
123 ) {
124 mv.appear[0].p = V.KING_CODE[mv.vanish[1].p];
125 }
126 else mv.appear[0].p = mv.vanish[1].p;
127 }
128 }
129 else if (!!tr && mv.vanish[0].p != V.PAWN)
130 // Special case of a non-capturing king-as-pawn promotion
131 mv.appear[0].p = V.KING_CODE[tr.p];
132
133 return mv;
134 }
135
136 getPotentialMovesFrom([x, y]) {
137 const piece = this.board[x][y].charAt(1);
138 if (Object.keys(V.KING_DECODE).includes(piece))
139 return super.getPotentialMovesFrom([x, y], V.KING_DECODE[piece]);
140 return super.getPotentialMovesFrom([x, y], piece);
141 }
142
143 addPawnMoves([x1, y1], [x2, y2], moves) {
144 let finalPieces = [V.PAWN];
145 const color = this.turn;
146 const lastRank = (color == "w" ? 0 : V.size.x - 1);
147 if (x2 == lastRank) {
148 if (this.board[x2][y2] != V.EMPTY)
149 // Cannibal rules: no choice if capture
150 finalPieces = [this.getPiece(x2, y2)];
151 else finalPieces = V.PawnSpecs.promotions;
152 }
153 let tr = null;
154 for (let piece of finalPieces) {
155 tr = (piece != V.PAWN ? { c: color, p: piece } : null);
156 moves.push(this.getBasicMove([x1, y1], [x2, y2], tr));
157 }
158 }
159
160 getPossibleMovesFrom(sq) {
161 let moves = this.filterValid(this.getPotentialMovesFrom(sq));
162 const captureMoves = V.KeepCaptures(moves);
163 if (captureMoves.length > 0) return captureMoves;
164 if (this.atLeastOneCapture()) return [];
165 return moves;
166 }
167
168 getAllValidMoves() {
169 const moves = super.getAllValidMoves();
170 if (moves.some(m => m.vanish.length == 2 && m.appear.length == 1))
171 return V.KeepCaptures(moves);
172 return moves;
173 }
174
175 postPlay(move) {
176 const c = V.GetOppCol(this.turn);
177 const piece = move.appear[0].p;
178 // Update king position + flags
179 if (piece == V.KING || Object.keys(V.KING_DECODE).includes(piece)) {
180 this.kingPos[c][0] = move.appear[0].x;
181 this.kingPos[c][1] = move.appear[0].y;
182 this.castleFlags[c] = [V.size.y, V.size.y];
183 }
184 // Next call is still required because the king may eat an opponent's rook
185 // TODO: castleFlags will be turned off twice then.
186 super.updateCastleFlags(move, piece);
187 }
188
189 postUndo(move) {
190 // (Potentially) Reset king position
191 const c = this.getColor(move.start.x, move.start.y);
192 const piece = move.appear[0].p;
193 if (piece == V.KING || Object.keys(V.KING_DECODE).includes(piece))
194 this.kingPos[c] = [move.start.x, move.start.y];
195 }
196
197 static get VALUES() {
198 return {
199 p: 1,
200 r: 5,
201 n: 3,
202 b: 3,
203 q: 9,
204 k: 5
205 };
206 }
207
208 getNotation(move) {
209 let notation = super.getNotation(move);
210 const lastRank = (move.appear[0].c == "w" ? 0 : 7);
211 if (
212 move.end.x != lastRank &&
213 this.getPiece(move.start.x, move.start.y) == V.PAWN &&
214 move.vanish.length == 2 &&
215 move.appear[0].p != V.PAWN
216 ) {
217 // Fix "promotion" (transform indicator) from base_rules notation
218 notation = notation.slice(0, -2);
219 }
220 return notation;
221 }
222
223 };