--- /dev/null
+import { ChessRules } from "@/base_rules";
+import { ArrayFun } from "@/utils/array";
+import { randInt, shuffle } from "@/utils/alea";
+
+export const VariantRules = class RoyalraceRules extends ChessRules {
+ static get HasFlags() {
+ return false;
+ }
+
+ static get HasEnpassant() {
+ return false;
+ }
+
+ static get CanFlip() {
+ return false;
+ }
+
+ static get size() {
+ return { x: 11, y: 11 };
+ }
+
+ static GenRandInitFen() {
+ let pieces = { w: new Array(10), b: new Array(10) };
+ // Shuffle pieces on first and second rank
+ for (let c of ["w", "b"]) {
+ // Reserve 4 and 5 which are pawns positions
+ let positions = ArrayFun.range(10).filter(i => i != 4 && i != 5);
+
+ // Get random squares for bishops
+ let randIndex = 2 * randInt(4);
+ const bishop1Pos = positions[randIndex];
+ // The second bishop must be on a square of different color
+ let randIndex_tmp = 2 * randInt(4) + 1;
+ const bishop2Pos = positions[randIndex_tmp];
+ // Remove chosen squares
+ positions.splice(Math.max(randIndex, randIndex_tmp), 1);
+ positions.splice(Math.min(randIndex, randIndex_tmp), 1);
+
+ // Place the king at random on (remaining squares of) first row
+ let maxIndex = 4;
+ if (positions[maxIndex-1] >= 4)
+ maxIndex--;
+ if (positions[maxIndex-1] >= 4)
+ maxIndex--;
+ randIndex = randInt(maxIndex);
+ const kingPos = positions[randIndex];
+ positions.splice(randIndex, 1);
+
+ // Get random squares for knights
+ randIndex = randInt(5);
+ const knight1Pos = positions[randIndex];
+ positions.splice(randIndex, 1);
+ randIndex = randInt(4);
+ const knight2Pos = positions[randIndex];
+ positions.splice(randIndex, 1);
+
+ // Get random squares for rooks
+ randIndex = randInt(3);
+ const rook1Pos = positions[randIndex];
+ positions.splice(randIndex, 1);
+ randIndex = randInt(2);
+ const rook2Pos = positions[randIndex];
+ positions.splice(randIndex, 1);
+
+ // Queen position is now determined,
+ // because pawns are not placed at random
+ const queenPos = positions[0];
+
+ // Finally put the shuffled pieces in the board array
+ pieces[c][rook1Pos] = "r";
+ pieces[c][knight1Pos] = "n";
+ pieces[c][bishop1Pos] = "b";
+ pieces[c][queenPos] = "q";
+ pieces[c][kingPos] = "k";
+ pieces[c][bishop2Pos] = "b";
+ pieces[c][knight2Pos] = "n";
+ pieces[c][rook2Pos] = "r";
+ pieces[c][4] = "p";
+ pieces[c][5] = "p";
+ }
+ const whiteFen = pieces["w"].join("").toUpperCase();
+ const blackFen = pieces["b"].join("");
+ return (
+ "11/11/11/11/11/11/11/11/11/" +
+ whiteFen.substr(5).split("").reverse().join("") +
+ "1" +
+ blackFen.substr(5).split("").reverse().join("") +
+ "/" +
+ whiteFen.substr(0,5) + "1" + blackFen.substr(0,5) +
+ " w 0"
+ );
+ }
+
+ getPotentialPawnMoves([x, y]) {
+ // Normal moves (as a rook)
+ let moves =
+ this.getSlideNJumpMoves([x, y], V.steps[V.ROOK]).filter(m => {
+ // Remove captures. Alt: redefine canTake
+ return m.vanish.length == 1;
+ });
+
+ // Captures
+ const shiftX = -1;
+ for (let shiftY of [-1, 1]) {
+ if (
+ V.OnBoard(x + shiftX, y + shiftY) &&
+ this.board[x + shiftX][y + shiftY] != V.EMPTY &&
+ this.canTake([x, y], [x + shiftX, y + shiftY])
+ ) {
+ moves.push(this.getBasicMove([x, y], [x + shiftX, y + shiftY]));
+ }
+ }
+
+ return moves;
+ }
+
+ getPotentialKnightMoves(sq) {
+ // Knight becomes knightrider:
+ return this.getSlideNJumpMoves(sq, V.steps[V.KNIGHT]);
+ }
+
+ // What are the king moves from square x,y ?
+ getPotentialKingMoves(sq) {
+ return this.getSlideNJumpMoves(
+ sq,
+ V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
+ "oneStep"
+ );
+ }
+
+ filterValid(moves) {
+ if (moves.length == 0) return [];
+ const color = this.turn;
+ const oppCol = V.GetOppCol(color);
+ return moves.filter(m => {
+ this.play(m);
+ // Giving check is forbidden as well:
+ const res = !this.underCheck(color) && !this.underCheck(oppCol);
+ this.undo(m);
+ return res;
+ });
+ }
+
+ isAttackedByPawn([x, y], colors) {
+ const pawnShift = 1;
+ if (x + pawnShift < V.size.x) {
+ for (let c of colors) {
+ for (let i of [-1, 1]) {
+ if (
+ y + i >= 0 &&
+ y + i < V.size.y &&
+ this.getPiece(x + pawnShift, y + i) == V.PAWN &&
+ this.getColor(x + pawnShift, y + i) == c
+ ) {
+ return true;
+ }
+ }
+ }
+ }
+ return false;
+ }
+
+ isAttackedByKnight(sq, colors) {
+ return this.isAttackedBySlideNJump(
+ sq,
+ colors,
+ V.KNIGHT,
+ V.steps[V.KNIGHT]
+ );
+ }
+
+ getCurrentScore() {
+ // Turn has changed:
+ const color = V.GetOppCol(this.turn);
+ if (this.kingPos[color][0] == 0)
+ // The opposing edge is reached!
+ return color == "w" ? "1-0" : "0-1";
+ return "*";
+ }
+
+ static get SEARCH_DEPTH() {
+ return 2;
+ }
+
+ static get VALUES() {
+ return {
+ p: 2,
+ r: 5,
+ n: 3,
+ b: 3,
+ q: 9,
+ k: 1000
+ };
+ }
+
+ evalPosition() {
+ // Count material:
+ let evaluation = super.evalPosition();
+ // Ponder with king position:
+ return evaluation/5 + this.kingPos["b"][0] - this.kingPos["w"][0];
+ }
+
+ getNotation(move) {
+ // Since pawns are much more mobile, treat them as other pieces:
+ return (
+ move.vanish[0].p.toUpperCase() +
+ (move.vanish.length > move.appear.length ? "x" : "") +
+ V.CoordsToSquare(move.end)
+ );
+ }
+};
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