From bfbb9ef404cefa3c5e0b20fb9e94336050e1e743 Mon Sep 17 00:00:00 2001
From: Sage Vaillancourt <sagev9000@tutanota.com>
Date: Wed, 30 Dec 2020 22:50:07 -0500
Subject: [PATCH] Added castling

---
 src/index.js | 42 +++++++++++++++++++++++++++++++++++++-----
 1 file changed, 37 insertions(+), 5 deletions(-)

diff --git a/src/index.js b/src/index.js
index 25cc578..fc9a91b 100644
--- a/src/index.js
+++ b/src/index.js
@@ -285,18 +285,38 @@ class Board extends React.Component {
       [[1, 1], [1, -1], [-1, 1], [-1, -1], [0, 1], [0, -1], [1, 0], [-1, 0]]
         .forEach(delta => tryAddMove(x + delta[0], y + delta[1]));
       if (piece.moves === 0) {
-        const [x, y] = this.getXandY(this.findIndex(piece));
+        const kingIndex = this.findIndex(piece);
+        const [x, y] = this.getXandY(kingIndex);
+
         let leftRook = this.pieceAt(0, y);
         if(isRook(leftRook) && leftRook.moves === 0) {
-          // Check if between space puts king in check
           // Check if spaces between rook and king are empty
-          // add move(x: x - 2, y, castle: [x, y])
+          if(this.pieceAt(1, y) == null &&
+            this.pieceAt(2, y) == null &&
+            this.pieceAt(3, y) == null) {
+            // Check if between space puts king in check
+            let board = this.clone();
+            board.state.squares[board.getIndex(x - 1, y)] = piece;
+            board.state.squares[kingIndex] = null;
+            if(board.inCheck(piece) == null) {
+              moves.push({x: x - 2, y, castle: [x - 1, y]});
+            }
+          }
         }
+
         let rightRook = this.pieceAt(7, y);
         if(isRook(rightRook) && rightRook.moves === 0) {
-          // Check if between space puts king in check
           // Check if spaces between rook and king are empty
-          // add move(x: x + 2, y, castle: [x, y])
+          if(this.pieceAt(5, y) == null &&
+            this.pieceAt(6, y) == null) {
+            // Check if between space puts king in check
+            let board = this.clone();
+            board.state.squares[board.getIndex(x + 1, y)] = piece;
+            board.state.squares[kingIndex] = null;
+            if(board.inCheck(piece) == null) {
+              moves.push({x: x + 2, y, castle: [x + 1, y]});
+            }
+          }
         }
       }
     }
@@ -411,6 +431,18 @@ class Board extends React.Component {
       if (move.passant) {
         squares[this.getIndex(move.passant.x, move.passant.y)] = null;
       }
+      if (move.castle) {
+        // .castle holds the position where the rook should end up
+        // King moved left
+        const rookX = move.castle[0] > move.x ? 0 : 7;
+        console.log("Replace ");
+        console.log(move.castle);
+        console.log("With ");
+        console.log([rookX, move.castle[1]]);
+        squares[this.getIndex(move.castle[0], move.castle[1])] =
+          squares[this.getIndex(rookX, move.castle[1])];
+        squares[this.getIndex(rookX, move.castle[1])] = null;
+      }
       // Remove existing passantable states
       squares.forEach(square => {
         if (square) {