Add 'in check' logic

src/board_state.rs

@@ -75,23 +75,38 @@ impl BoardState {
             }
         }
 
-        if (moving_color == Color::White && proposed.is_white_in_check())
-            || (moving_color == Color::Black && proposed.is_black_in_check())
-        {
+        if proposed.is_in_check(moving_color) {
             return;
         }
 
         *self = proposed;
     }
 
-    // TODO: this
-    fn is_black_in_check(&self) -> bool {
-        false
-    }
+    fn is_in_check(&self, color: Color) -> bool {
+        let mut tmp_board = self.clone();
 
-    // TODO: this
-    fn is_white_in_check(&self) -> bool {
-        false
+        let king = Piece {
+            kind: PieceKind::King,
+            color: color.clone(),
+        };
+
+        let king_opt = self
+            .inner
+            .iter()
+            .find(|(_, piece_state)| piece_state.piece == king);
+
+        if let Some((king_coords, _)) = king_opt {
+            self.inner
+                .iter()
+                .filter(|(_, piece_state)| piece_state.piece.color != color)
+                .any(|(coords, piece_state)| {
+                    piece_state
+                        .clone()
+                        .can_move_to(coords, king_coords, &mut tmp_board)
+                })
+        } else {
+            false
+        }
     }
 }