feat: add castle

1 files changed, 76 insertions, 3 deletions

diff --git a/src/main.c b/src/main.c
index acfc37e..52724cf 100644
--- a/src/main.c
+++ b/src/main.c
@@ -2,6 +2,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <time.h>
+#include <stdlib.h>
 
 #include "config.h"
 #include "pieces.h"
@@ -171,7 +172,36 @@ int validate_move(int move[2], int color, int* board) {
     legal_move++;
   }
 
-  return -5;
+  // Handle castling
+  if ((piece & NO_COLOR) == KING) {
+    if (piece % 2 == WHITE && origin == 4) {
+      if (destination == 2) {
+        for (int i = 1; i < 4; i++) {
+          if (board[i] != EMPTY) return -5;
+        }
+        return 0;
+      } else if (destination == 6) {
+        for (int i = 5; i < 7; i++) {
+          if (board[i] != EMPTY) return -5;
+        }
+        return 0;
+      }
+    } else if (piece % 2 == BLACK && origin == 116) {
+      if (destination == 114) {
+        for (int i = 114; i < 116; i++) {
+          if (board[i] != EMPTY) return -5;
+        }
+        return 0;
+      } else if (destination == 118) {
+        for (int i = 117; i < 119; i++) {
+          if (board[i] != EMPTY) return -5;
+        }
+        return 0;
+      }
+    }
+  }
+
+  return -6;
 }
 
 char* VALIDATION_ERRORS[] = {
@@ -180,6 +210,7 @@ char* VALIDATION_ERRORS[] = {
   "opponent piece on origin square",
   "trying to capture your own piece",
   "move is not allowed",
+  "castle is not allowed",
 };
 
 int apply_move(int move[2], int* board) {
@@ -195,6 +226,27 @@ int apply_move(int move[2], int* board) {
     // printf("Captured %s\n", pieces[target_piece]);
   }
 
+  if ((piece & NO_COLOR) == KING && abs(destination - origin) == 2) {
+    // CASTLE!
+    if (destination == 2) {
+      int rook = board[0];
+      board[0] = EMPTY;
+      board[3] = rook;
+    } else if (destination == 6) {
+      int rook = board[7];
+      board[7] = EMPTY;
+      board[5] = rook;
+    } else if (destination == 114) {
+      int rook = board[112];
+      board[112] = EMPTY;
+      board[115] = rook;
+    } else if (destination == 118) {
+      int rook = board[119];
+      board[119] = EMPTY;
+      board[117] = rook;
+    }
+  }
+
   return target_piece;
 }
 
@@ -205,6 +257,27 @@ void reverse_move(int move[2], int captured_piece, int* board) {
 
   board[origin] = piece;
   board[destination] = captured_piece;
+
+  if ((piece & NO_COLOR) == KING && abs(destination - origin) == 2) {
+    // CASTLE!
+    if (destination == 2) {
+      int rook = board[3];
+      board[3] = EMPTY;
+      board[0] = rook;
+    } else if (destination == 6) {
+      int rook = board[5];
+      board[5] = EMPTY;
+      board[7] = rook;
+    } else if (destination == 114) {
+      int rook = board[115];
+      board[115] = EMPTY;
+      board[112] = rook;
+    } else if (destination == 118) {
+      int rook = board[117];
+      board[117] = EMPTY;
+      board[119] = rook;
+    }
+  }
 }
 
 
@@ -244,7 +317,7 @@ int compute_material_advantage(int* board, int color) {
         int sign = (piece % 2 == color) ? 1 : -1;
         switch (piece & NO_COLOR) {
           case KING:
-            counter += 1000 * sign;
+            counter += INFINITY * sign;
             break;
           case PAWN:
            counter += evaluate_pawn(piece, rank) * sign;
@@ -407,7 +480,7 @@ int main() {
   int color = WHITE;
 
   while (1) {
-    if (color == WHITE) {
+    if (color == BLACK) {
       printf("Current score is %i\n", compute_score(board));
       printf("White coverage: %i, black coverage: %i\n", compute_coverage(board, WHITE), compute_coverage(board, BLACK));
       printf("Enter a move for %s:\n", COLORS[color]);