Fix suggestion for Chaturanga, renamed into Shatranj

[vchess.git] / client / src / variants / Shatranj.js

diff --git a/client/src/variants/Shatranj.js b/client/src/variants/Shatranj.js
new file mode 100644 (file)
index 0000000..e2e0c79
--- /dev/null
+++ b/client/src/variants/Shatranj.js
@@ -0,0 +1,124 @@
+// TODO: bishop OK, but queen should move vertical/horizontal and capture diagonally.
+// ==> then the pawn promotion is a real promotion (enhancement).
+
+import { ChessRules } from "@/base_rules";
+
+export const VariantRules = class ShatranjRules extends ChessRules {
+  static get HasFlags() {
+    return false;
+  }
+
+  static get HasEnpassant() {
+    return false;
+  }
+
+  static get ElephantSteps() {
+    return [
+      [-2, -2],
+      [-2, 2],
+      [2, -2],
+      [2, 2]
+    ];
+  }
+
+  static GenRandInitFen() {
+    return ChessRules.GenRandInitFen().replace("w 1111 -", "w");
+  }
+
+  getPotentialPawnMoves([x, y]) {
+    const color = this.turn;
+    let moves = [];
+    const [sizeX, sizeY] = [V.size.x, V.size.y];
+    const shiftX = color == "w" ? -1 : 1;
+    const startRank = color == "w" ? sizeX - 2 : 1;
+    const lastRank = color == "w" ? 0 : sizeX - 1;
+    // Promotion in minister (queen) only:
+    const finalPiece = x + shiftX == lastRank ? V.QUEEN : V.PAWN;
+
+    if (this.board[x + shiftX][y] == V.EMPTY) {
+      // One square forward
+      moves.push(
+        this.getBasicMove([x, y], [x + shiftX, y], {
+          c: color,
+          p: finalPiece
+        })
+      );
+    }
+    // Captures
+    for (let shiftY of [-1, 1]) {
+      if (
+        y + shiftY >= 0 &&
+        y + shiftY < sizeY &&
+        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], {
+            c: color,
+            p: finalPiece
+          })
+        );
+      }
+    }
+
+    return moves;
+  }
+
+  getPotentialBishopMoves(sq) {
+    let moves = this.getSlideNJumpMoves(sq, V.ElephantSteps, "oneStep");
+    // Complete with "repositioning moves": like a queen, without capture
+    let repositioningMoves = this.getSlideNJumpMoves(
+      sq,
+      V.steps[V.BISHOP],
+      "oneStep"
+    ).filter(m => m.vanish.length == 1);
+    return moves.concat(repositioningMoves);
+  }
+
+  getPotentialQueenMoves(sq) {
+    return this.getSlideNJumpMoves(
+      sq,
+      V.steps[V.BISHOP],
+      "oneStep"
+    );
+  }
+
+  getPotentialKingMoves(sq) {
+    return this.getSlideNJumpMoves(
+      sq,
+      V.steps[V.ROOK].concat(V.steps[V.BISHOP]),
+      "oneStep"
+    );
+  }
+
+  isAttackedByBishop(sq, colors) {
+    return this.isAttackedBySlideNJump(
+      sq,
+      colors,
+      V.BISHOP,
+      V.ElephantSteps,
+      "oneStep"
+    );
+  }
+
+  isAttackedByQueen(sq, colors) {
+    return this.isAttackedBySlideNJump(
+      sq,
+      colors,
+      V.QUEEN,
+      V.steps[V.BISHOP],
+      "oneStep"
+    );
+  }
+
+  static get VALUES() {
+    return {
+      p: 1,
+      r: 5,
+      n: 3,
+      b: 2.5,
+      q: 2,
+      k: 1000
+    };
+  }
+};