Add minimax and adapt UCI tests

src/search/minimax.rs

@@ -0,0 +1,87 @@
+use crate::{
+    board::{
+        board::Color,
+        game::Game,
+        history::{History, MoveParameters},
+    },
+    evaluation::evaluation::evaluate_position,
+    movegen::r#move::Move,
+};
+
+pub fn minimax(game: &mut Game, depth: u8) -> (Option<Move>, i32) {
+    let color = game.current_player();
+
+    if depth == 0 {
+        return (None, evaluate_position(&game.board, color));
+    }
+
+    let mut history = History::new();
+    let mut best_move: Option<Move> = None;
+    let (mut best_score, mate_score) = match color {
+        Color::White => (-100000, -49000 - depth as i32),
+        Color::Black => (100000, 49000 + depth as i32),
+    };
+
+    let moves = game.board.pseudo_moves_all(color);
+    let mut legal_moves = 0;
+
+    for mv in moves {
+        history.push_move_parameters(MoveParameters::build(&game.board, &mv));
+        game.board.make_move(&mv);
+
+        if !game.board.king_under_check(color) {
+            legal_moves += 1;
+            let (_, node_score) = minimax(game, depth - 1);
+            match color {
+                Color::White => {
+                    if best_score < node_score {
+                        best_score = node_score;
+                        best_move = Some(mv);
+                    }
+                }
+                Color::Black => {
+                    if best_score > node_score {
+                        best_score = node_score;
+                        best_move = Some(mv);
+                    }
+                }
+            }
+        }
+        game.board
+            .unmake_move(history.pop_move_parameters().expect("Empty history stack"));
+    }
+
+    if legal_moves == 0 {
+        if game.board.king_under_check(color) {
+            return (None, mate_score);
+        } else {
+            return (None, 0);
+        }
+    }
+    (best_move, best_score)
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::board::{fen::from_fen, square::Square};
+    use crate::movegen::attack::init_attacks;
+    use crate::movegen::r#move::Move;
+    use crate::search::minimax::minimax;
+
+    const FEN_MATE_IN_1: &str = "8/8/8/8/8/4q1k1/8/5K2 b - - 0 1";
+
+    #[test]
+    fn test_minimax() -> Result<(), String> {
+        init_attacks();
+        let mut game = from_fen(FEN_MATE_IN_1)?;
+
+        let e3f2 = Move::new(Square::E3, Square::F2);
+
+        assert_eq!(e3f2, minimax(&mut game, 2).0.unwrap());
+        assert_eq!(e3f2, minimax(&mut game, 3).0.unwrap());
+        assert_eq!(e3f2, minimax(&mut game, 4).0.unwrap());
+        assert_eq!(e3f2, minimax(&mut game, 5).0.unwrap());
+
+        Ok(())
+    }
+}

src/search/mod.rs

@@ -1,2 +1,2 @@
+pub mod minimax;
 pub mod perft;
-pub mod search;

src/search/search.rs

@@ -1,42 +0,0 @@
-use crate::board::game::Game;
-
-pub fn search(game: &mut Game, depth: u8) {
-    if depth == 0 {
-        return;
-    }
-
-    let color = game.current_player();
-    let pseudo_moves = game.board.pseudo_moves_all(color);
-
-    for mv in pseudo_moves {
-        let original_board = game.board.clone();
-        game.board.make_move(&mv);
-
-        if game.board.king_under_check(color) {
-            game.board = original_board;
-            continue;
-        }
-
-        search(game, depth - 1);
-        game.board = original_board;
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::board::fen::from_fen;
-
-    const FEN_QUIET: [&str; 2] = [
-        "rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1",
-        "rnbqkbnr/ppp2ppp/4p3/3pN3/3P4/8/PPP1PPPP/RNBQKB1R w KQkq - 0 1",
-    ];
-
-    #[test]
-    fn test_search() -> Result<(), String> {
-        let _game = from_fen(FEN_QUIET[0])?;
-
-        //TODO:
-
-        Ok(())
-    }
-}