--- /dev/null
+import { ChessRules, PiPo, Move } from "@/base_rules";
+
+export const VariantRules = class Allmate2Rules extends ChessRules {
+ static get HasEnpassant() {
+ return false;
+ }
+
+ getCheckSquares() {
+ // No notion of check
+ return [];
+ }
+
+ static GenRandInitFen() {
+ return ChessRules.GenRandInitFen().replace(/ -$/, "");
+ }
+
+ getPotentialMovesFrom([x, y]) {
+ let moves = super.getPotentialMovesFrom([x, y]);
+ // Remove standard captures (without removing castling):
+ moves = moves.filter(m => {
+ return m.vanish.length == 1 || m.appear.length == 2;
+ });
+
+ // Augment moves with "mate-captures":
+ // TODO: this is coded in a highly inefficient way...
+ const color = this.turn;
+ const oppCol = V.GetOppCol(this.turn);
+ moves.forEach(m => {
+ this.play(m);
+
+ // 1) What is attacked?
+ let attacked = {};
+ for (let i=0; i<V.size.x; i++) {
+ for (let j=0; j<V.size.y; j++) {
+ if (this.getColor(i,j) == oppCol && this.isAttacked([i,j], [color]))
+ attacked[i+"_"+j] = [i,j];
+ }
+ }
+
+ // 2) Among attacked pieces, which cannot escape capture?
+ // --> without (normal-)capturing: difference with Allmate variant
+ // Avoid "oppMoves = this.getAllValidMoves();" => infinite recursion
+ outerLoop: for (let i=0; i<V.size.x; i++) {
+ for (let j=0; j<V.size.y; j++) {
+ if (this.getColor(i,j) == oppCol) {
+ let oppMoves = [];
+ switch (this.getPiece(i, j)) {
+ case V.PAWN:
+ oppMoves = this.getPotentialPawnMoves([i, j]);
+ break;
+ case V.ROOK:
+ oppMoves = this.getPotentialRookMoves([i, j]);
+ break;
+ case V.KNIGHT:
+ oppMoves = this.getPotentialKnightMoves([i, j]);
+ break;
+ case V.BISHOP:
+ oppMoves = this.getPotentialBishopMoves([i, j]);
+ break;
+ case V.QUEEN:
+ oppMoves = this.getPotentialQueenMoves([i, j]);
+ break;
+ case V.KING:
+ oppMoves = this.getPotentialKingMoves([i, j]);
+ break;
+ }
+ for (let om of oppMoves) {
+ if (om.vanish.length == 2 && om.appear.length == 1)
+ // Skip captures: forbidden in this mode
+ continue;
+ V.PlayOnBoard(this.board, om);
+ Object.values(attacked).forEach(sq => {
+ const origSq = [sq[0], sq[1]];
+ if (om.start.x == sq[0] && om.start.y == sq[1])
+ // Piece moved:
+ sq = [om.appear[0].x, om.appear[0].y];
+ if (!this.isAttacked(sq, [color]))
+ delete attacked[origSq[0]+"_"+origSq[1]];
+ });
+ V.UndoOnBoard(this.board, om);
+ if (Object.keys(attacked).length == 0)
+ // No need to explore more moves
+ break outerLoop;
+ }
+ }
+ }
+ }
+
+ // 3) Add mate-captures:
+ Object.values(attacked).forEach(sq => {
+ m.vanish.push(new PiPo({
+ x: sq[0],
+ y: sq[1],
+ c: oppCol,
+ p: this.getPiece(sq[0], sq[1])
+ }));
+ });
+
+ this.undo(m);
+ });
+
+ return moves;
+ }
+
+ // No "under check" conditions in castling
+ getCastleMoves([x, y]) {
+ const c = this.getColor(x, y);
+ if (x != (c == "w" ? V.size.x - 1 : 0) || y != this.INIT_COL_KING[c])
+ return []; //x isn't first rank, or king has moved (shortcut)
+
+ // Castling ?
+ const oppCol = V.GetOppCol(c);
+ let moves = [];
+ let i = 0;
+ // King, then rook:
+ const finalSquares = [
+ [2, 3],
+ [V.size.y - 2, V.size.y - 3]
+ ];
+ castlingCheck: for (
+ let castleSide = 0;
+ castleSide < 2;
+ castleSide++ //large, then small
+ ) {
+ if (!this.castleFlags[c][castleSide]) continue;
+ // If this code is reached, rooks and king are on initial position
+
+ // Nothing on the path of the king ? (and no checks)
+ const finDist = finalSquares[castleSide][0] - y;
+ let step = finDist / Math.max(1, Math.abs(finDist));
+ for (let i = y; i != finalSquares[castleSide][0]; i += step) {
+ if (
+ this.board[x][i] != V.EMPTY &&
+ // NOTE: next check is enough, because of chessboard constraints
+ (this.getColor(x, i) != c ||
+ ![V.KING, V.ROOK].includes(this.getPiece(x, i)))
+ ) {
+ continue castlingCheck;
+ }
+ }
+
+ // Nothing on the path to the rook?
+ step = castleSide == 0 ? -1 : 1;
+ for (i = y + step; i != this.INIT_COL_ROOK[c][castleSide]; i += step) {
+ if (this.board[x][i] != V.EMPTY) continue castlingCheck;
+ }
+ const rookPos = this.INIT_COL_ROOK[c][castleSide];
+
+ // Nothing on final squares, except maybe king and castling rook?
+ for (i = 0; i < 2; i++) {
+ if (
+ this.board[x][finalSquares[castleSide][i]] != V.EMPTY &&
+ this.getPiece(x, finalSquares[castleSide][i]) != V.KING &&
+ finalSquares[castleSide][i] != rookPos
+ ) {
+ continue castlingCheck;
+ }
+ }
+
+ // If this code is reached, castle is valid
+ moves.push(
+ new Move({
+ appear: [
+ new PiPo({ x: x, y: finalSquares[castleSide][0], p: V.KING, c: c }),
+ new PiPo({ x: x, y: finalSquares[castleSide][1], p: V.ROOK, c: c })
+ ],
+ vanish: [
+ new PiPo({ x: x, y: y, p: V.KING, c: c }),
+ new PiPo({ x: x, y: rookPos, p: V.ROOK, c: c })
+ ],
+ end:
+ Math.abs(y - rookPos) <= 2
+ ? { x: x, y: rookPos }
+ : { x: x, y: y + 2 * (castleSide == 0 ? -1 : 1) }
+ })
+ );
+ }
+
+ return moves;
+ }
+
+ // TODO: allow pieces to "commit suicide"? (Currently yes except king)
+ filterValid(moves) {
+ // Remove moves which let the king mate-captured:
+ if (moves.length == 0) return [];
+ const color = this.turn;
+ const oppCol = V.GetOppCol(color);
+ return moves.filter(m => {
+ let res = true;
+ this.play(m);
+ if (this.underCheck(color)) {
+ res = false;
+ const attacked = this.kingPos[color];
+ // Try to find a move to escape check
+ // TODO: very inefficient method.
+ outerLoop: for (let i=0; i<V.size.x; i++) {
+ for (let j=0; j<V.size.y; j++) {
+ if (this.getColor(i,j) == color) {
+ let emoves = [];
+ // Artficial turn change to "play twice":
+ this.turn = color;
+ switch (this.getPiece(i, j)) {
+ case V.PAWN:
+ emoves = this.getPotentialPawnMoves([i, j]);
+ break;
+ case V.ROOK:
+ emoves = this.getPotentialRookMoves([i, j]);
+ break;
+ case V.KNIGHT:
+ emoves = this.getPotentialKnightMoves([i, j]);
+ break;
+ case V.BISHOP:
+ emoves = this.getPotentialBishopMoves([i, j]);
+ break;
+ case V.QUEEN:
+ emoves = this.getPotentialQueenMoves([i, j]);
+ break;
+ case V.KING:
+ emoves = this.getPotentialKingMoves([i, j]);
+ break;
+ }
+ this.turn = oppCol;
+ for (let em of emoves) {
+ V.PlayOnBoard(this.board, em);
+ let sq = attacked;
+ if (em.start.x == attacked[0] && em.start.y == attacked[1])
+ // King moved:
+ sq = [em.appear[0].x, em.appear[0].y];
+ if (!this.isAttacked(sq, [oppCol]))
+ res = true;
+ V.UndoOnBoard(this.board, em);
+ if (res)
+ // No need to explore more moves
+ break outerLoop;
+ }
+ }
+ }
+ }
+ }
+ this.undo(m);
+ return res;
+ });
+ }
+
+ updateVariables(move) {
+ super.updateVariables(move);
+ const color = V.GetOppCol(this.turn);
+ if (move.vanish.length >= 2 && move.appear.length == 1) {
+ move.vanish.forEach(v => {
+ if (v.c == color)
+ return;
+ // Did opponent king disappeared?
+ if (v.p == V.KING)
+ this.kingPos[this.turn] = [-1, -1];
+ // Or maybe a rook?
+ else if (v.p == V.ROOK) {
+ if (v.y < this.INIT_COL_KING[v.c])
+ this.castleFlags[v.c][0] = false;
+ else
+ // v.y > this.INIT_COL_KING[v.c]
+ this.castleFlags[v.c][1] = false;
+ }
+ });
+ }
+ }
+
+ unupdateVariables(move) {
+ super.unupdateVariables(move);
+ const color = this.turn;
+ if (move.vanish.length >= 2 && move.appear.length == 1) {
+ // Did opponent king disappeared?
+ const psq = move.vanish.find(v => v.p == V.KING && v.c != color)
+ if (psq)
+ this.kingPos[psq.c] = [psq.x, psq.y];
+ }
+ }
+
+ getCurrentScore() {
+ const color = this.turn;
+ const kp = this.kingPos[color];
+ if (kp[0] < 0)
+ // King disappeared
+ return color == "w" ? "0-1" : "1-0";
+ if (this.atLeastOneMove())
+ return "*";
+ // Kings still there, no moves:
+ return "1/2";
+ }
+
+ static get SEARCH_DEPTH() {
+ return 2;
+ }
+
+ getNotation(move) {
+ let notation = super.getNotation(move);
+ // Add a capture mark (not describing what is captured...):
+ if (move.vanish.length > 1 && move.appear.length == 1) {
+ if (notation.match(/^[a-h]x/))
+ // Pawn capture: remove initial "b" in bxc4 for example
+ notation = notation.substr(1);
+ notation = notation.replace("x","") + "X";
+ }
+ return notation;
+ }
+};
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