Add move generation for castling

src/board.rs

@@ -5,7 +5,7 @@ use crate::attack::{
     get_bishop_attacks, get_king_attacks, get_knight_attacks, get_pawn_attacks, get_queen_attacks,
     get_rook_attacks,
 };
-use crate::game::State;
+use crate::game::{CastlingRights, State};
 
 #[derive(Debug, PartialEq, Eq)]
 pub struct Board {
@@ -128,7 +128,82 @@ impl Board {
             Kind::Bishop => bishop_pseudo_moves(pieces, all_occupancies, own_occupancies),
             Kind::Rook => rook_pseudo_moves(pieces, all_occupancies, own_occupancies),
             Kind::Queen => queen_pseudo_moves(pieces, all_occupancies, own_occupancies),
-            Kind::King => king_pseudo_moves(pieces, own_occupancies),
+            Kind::King => king_pseudo_moves(
+                pieces,
+                all_occupancies,
+                own_occupancies,
+                self.castling_ability(color),
+                color,
+            ),
+        }
+    }
+
+    fn castling_ability(&self, color: Color) -> CastlingRights {
+        match (
+            self.castling_from_fen(color),
+            self.castling_pseudo_safety(color),
+        ) {
+            (CastlingRights::Both, _) => self.castling_pseudo_safety(color),
+            (CastlingRights::Short, CastlingRights::Short) => CastlingRights::Short,
+            (CastlingRights::Long, CastlingRights::Long) => CastlingRights::Long,
+            _ => CastlingRights::None,
+        }
+    }
+
+    const fn castling_from_fen(&self, color: Color) -> CastlingRights {
+        let castling_fen = self.state.get_castling_ability();
+
+        let black_king_and_queen = (castling_fen >> 2) & 0b11 == 0b11;
+        let black_king = (castling_fen >> 3) & 1 == 1;
+        let black_queen = (castling_fen >> 2) & 1 == 1;
+        let white_king_and_queen = castling_fen & 0b11 == 0b11;
+        let white_king = (castling_fen >> 1) & 1 == 1;
+        let white_queen = castling_fen & 1 == 1;
+
+        match color {
+            Color::White => match (white_king_and_queen, white_king, white_queen) {
+                (true, _, _) => CastlingRights::Both,
+                (_, true, _) => CastlingRights::Short,
+                (_, _, true) => CastlingRights::Long,
+                _ => CastlingRights::None,
+            },
+            Color::Black => match (black_king_and_queen, black_king, black_queen) {
+                (true, _, _) => CastlingRights::Both,
+                (_, true, _) => CastlingRights::Short,
+                (_, _, true) => CastlingRights::Long,
+                _ => CastlingRights::None,
+            },
+        }
+    }
+
+    fn castling_pseudo_safety(&self, color: Color) -> CastlingRights {
+        match color {
+            Color::White => {
+                if self.is_attacked(4, Color::Black) {
+                    return CastlingRights::None;
+                }
+                let d1_attacked = self.is_attacked(3, Color::Black);
+                let f1_attacked = self.is_attacked(5, Color::Black);
+                match (d1_attacked, f1_attacked) {
+                    (true, true) => CastlingRights::None,
+                    (true, false) => CastlingRights::Short,
+                    (false, true) => CastlingRights::Long,
+                    (false, false) => CastlingRights::Both,
+                }
+            }
+            Color::Black => {
+                if self.is_attacked(60, Color::White) {
+                    return CastlingRights::None;
+                }
+                let d8_attacked = self.is_attacked(59, Color::White);
+                let f8_attacked = self.is_attacked(61, Color::White);
+                match (d8_attacked, f8_attacked) {
+                    (true, true) => CastlingRights::None,
+                    (true, false) => CastlingRights::Short,
+                    (false, true) => CastlingRights::Long,
+                    (false, false) => CastlingRights::Both,
+                }
+            }
         }
     }
 }