Add minimax and adapt UCI tests

src/board/history.rs

@@ -46,15 +46,24 @@ impl MoveParameters {
         }
     }
 
-    pub fn add_move(&mut self, mv: Move) {
+    pub fn build(board: &Board, mv: &Move) -> Self {
+        let mut move_parameters = Self::new();
+        move_parameters.add_move(*mv);
+        move_parameters.add_irreversible_parameters(board.state);
+        move_parameters.add_capture_and_promotion_piece(board, *mv, board.state.current_player());
+
+        move_parameters
+    }
+
+    fn add_move(&mut self, mv: Move) {
         self.mv = Some(mv)
     }
 
-    pub fn add_captured_piece(&mut self, board: &Board, dst: usize, color: Color) {
+    fn add_captured_piece(&mut self, board: &Board, dst: usize, color: Color) {
         self.captured_piece = board.piece_type_at(dst, color);
     }
 
-    pub fn add_promoted_piece(&mut self, promote: Promote) {
+    fn add_promoted_piece(&mut self, promote: Promote) {
         self.promoted_piece = Some(promote.into_piece_type())
     }
 

src/interface/uci.rs

@@ -3,7 +3,7 @@ use std::{
     str::SplitWhitespace,
 };
 
-use crate::{board::game::Game, board::square::Square, movegen::r#move::Move, search::search};
+use crate::{board::game::Game, movegen::r#move::Move, search};
 
 #[derive(PartialEq, Eq, Debug)]
 pub enum Command {
@@ -91,7 +91,11 @@ pub fn uci_position(position: &mut SplitWhitespace) -> Result<Game, String> {
     let state = position.next().ok_or("Expected startpos or fen")?;
     let mut game = match state {
         "startpos" => Game::new(),
-        "fen" => Game::new_from_fen(position.next().ok_or("Expected fen string")?)?,
+        "fen" => {
+            let fen_parts: Vec<&str> = position.take_while(|&part| part != "moves").collect();
+            let fen = fen_parts.join(" ");
+            Game::new_from_fen(&fen)?
+        }
         _ => return Err("Expected startpos or fen".to_string()),
     };
 
@@ -128,9 +132,11 @@ pub fn uci_go(go: &mut SplitWhitespace, game: &mut Game) -> Result<Move, String>
             _ => (),
         }
     }
-    search::search(game, params.depth.unwrap_or(MAX_DEPTH));
-
-    Ok(Move::new(Square::B8, Square::C6))
+    Ok(
+        search::minimax::minimax(game, params.depth.unwrap_or(MAX_DEPTH))
+            .0
+            .expect("No move selected"),
+    )
 }
 
 pub fn uci_loop<R: BufRead, W: Write>(input: R, mut output: W) -> Result<(), String> {
@@ -171,9 +177,9 @@ mod tests {
     use std::io::Cursor;
 
     use crate::{
-        board::{fen::from_fen, game::Game, square::Square},
+        board::{fen::from_fen, square::Square},
         interface::uci::{parse_command, Command},
-        movegen::r#move::Move,
+        movegen::{attack::init_attacks, r#move::Move},
     };
 
     use super::uci_go;
@@ -204,22 +210,27 @@ mod tests {
         Ok(())
     }
 
+    const FEN_MATE_IN_1: &str = "8/8/8/8/8/4q1k1/8/5K2 b - - 0 1";
+
     #[test]
     fn test_uci_go() -> Result<(), String> {
-        let mut game = Game::new();
+        init_attacks();
+        let mut game = from_fen(FEN_MATE_IN_1)?;
         let command_go = "go depth 4";
         let mut parts = command_go.split_whitespace();
         let response = uci_go(&mut parts, &mut game)?;
 
-        assert_eq!(Move::new(Square::B8, Square::C6), response);
+        assert_eq!(Move::new(Square::E3, Square::F2), response);
+
         Ok(())
     }
 
     #[test]
     fn test_uci_loop() -> Result<(), String> {
+        init_attacks();
         let commands = b"uci\n\
             ucinewgame\n\
-            position startpos moves e2e4 e7e5\n\
+            position fen 8/8/8/8/8/4q1k1/8/5K2 b - - 0 1\n\
             go\n\
             quit";
         let input = Cursor::new(commands);
@@ -232,7 +243,7 @@ mod tests {
             uciok\n\
             Clear cache\n\
             Initialized position\n\
-            bestmove b8c6\n";
+            bestmove e3f2\n";
         let actual_response = String::from_utf8(output).expect("Invalid UTF-8 in output");
 
         assert_eq!(expected_response, actual_response);

src/movegen/move.rs

@@ -131,7 +131,7 @@ impl Board {
             Color::Black => (
                 &mut self.black_pieces,
                 &mut self.white_pieces,
-                Some(mv.src - 8),
+                Some(mv.src.saturating_sub(8)),
             ),
         };
         let pawn_move = Self::is_pawn_move(mv.src, &own_pieces[PieceType::Pawn]);

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(())
-    }
-}