+ updateCastleFlags(move, piece) {
+ const c = this.turn;
+ const firstRank = (c == "w" ? 7 : 0);
+ if (piece == V.KING && move.appear.length > 0)
+ this.castleFlags[c] = [V.size.y, V.size.y];
+ else if (
+ move.start.x == firstRank &&
+ this.castleFlags[c].includes(move.start.y)
+ ) {
+ const flagIdx = (move.start.y == this.castleFlags[c][0] ? 0 : 1);
+ this.castleFlags[c][flagIdx] = V.size.y;
+ }
+ else if (
+ move.end.x == firstRank &&
+ this.castleFlags[c].includes(move.end.y)
+ ) {
+ // Move to our rook: necessary normal piece, to union, releasing
+ // (or the rook was moved before!)
+ const flagIdx = (move.end.y == this.castleFlags[c][0] ? 0 : 1);
+ this.castleFlags[c][flagIdx] = V.size.y;
+ }
+ }
+
+ prePlay(move) {
+ // Easier before move is played in this case (flags are saved)
+ const c = this.turn;
+ const L = this.lastMoveEnd.length;
+ const lm = this.lastMoveEnd[L-1];
+ const piece = (!!lm ? lm.p : move.vanish[0].p);
+ if (piece == V.KING)
+ this.kingPos[c] = [move.appear[0].x, move.appear[0].y];
+ this.updateCastleFlags(move, piece);
+ const pawnFirstRank = (c == 'w' ? 6 : 1);
+ if (move.start.x == pawnFirstRank)
+ // This move (potentially) turns off a 2-squares pawn flag
+ this.pawnFlags[c][move.start.y] = false;
+ }
+