use crate::{
    board::game::Game,
    evaluation::{MAX_SCORE, MIN_SCORE},
    movegen::r#move::Move,
};

use super::{
    negamax,
    time::{soft_limit, TimeInfo},
};

pub fn iterative_deepening(
    game: &mut Game,
    max_depth: u8,
    remaining_time: u128,
) -> anyhow::Result<Option<Move>> {
    let (mut best_move, mut best_score) = (None, MIN_SCORE);
    let time = std::time::Instant::now();

    for depth in 1..=max_depth {
        if soft_limit(&time, remaining_time, best_score) {
            return Ok(best_move);
        }

        let score = negamax::negamax(
            game,
            MIN_SCORE,
            MAX_SCORE,
            depth,
            0,
            &TimeInfo::new(time, remaining_time),
        );

        if score.is_err() {
            break;
        }

        best_score = score?;
        best_move = game.tt.lookup(game.hash).and_then(|entry| entry.mv);
    }
    Ok(best_move)
}

#[cfg(test)]
mod tests {
    use crate::{
        board::fen::from_fen,
        movegen::attack_generator::init_attacks,
        search::{iterative_deepening, MAX_DEPTH, REMAINING_TIME_DEFAULT},
    };

    const FEN: &str = "1r2k2r/2P1pq1p/2npb3/1p3ppP/p3P3/P2B1Q2/1P1PNPP1/R3K2R w KQk g6 0 1";

    #[test]
    fn test_iterative_deepening() -> anyhow::Result<()> {
        init_attacks();
        let mut game = from_fen(FEN).unwrap();
        let time_now = std::time::Instant::now();

        iterative_deepening::iterative_deepening(&mut game, MAX_DEPTH, REMAINING_TIME_DEFAULT)?;

        dbg!(time_now.elapsed());

        Ok(())
    }
}