use crate::{
    agent::{Agent, RandomAgent},
    complexagent::ComplexAgent,
    game_inner::GameInner,
    logic::FutureMoveConfig,
    repr::{Piece, Winner},
};
use rayon::iter::{IntoParallelIterator, ParallelIterator};
use skillratings::{
    elo::{elo, EloConfig, EloRating},
    Outcomes, Rating,
};

pub fn run() {
    const FMV_BASE: FutureMoveConfig = FutureMoveConfig {
        max_depth: 20,
        min_arena_depth: 14,
        top_k_children: 2,
        up_to_minus: 10,
        max_arena_size: 5_000_000,
        do_not_prune: false,
        print: false,
    };

    let mut arena = PlayerArena::new(vec![
        (
            "RandomAgent".into(),
            Box::new(|piece| Box::new(RandomAgent::new(piece))),
        ),
        (
            "ComplexAgentD5".into(),
            Box::new(|piece| {
                Box::new(ComplexAgent::new(
                    piece,
                    FutureMoveConfig {
                        max_depth: 5,
                        ..FMV_BASE
                    },
                ))
            }),
        ),
        (
            "ComplexAgentD6".into(),
            Box::new(|piece| {
                Box::new(ComplexAgent::new(
                    piece,
                    FutureMoveConfig {
                        max_depth: 6,
                        ..FMV_BASE
                    },
                ))
            }),
        ),
        (
            "ComplexAgentD7".into(),
            Box::new(|piece| {
                Box::new(ComplexAgent::new(
                    piece,
                    FutureMoveConfig {
                        max_depth: 7,
                        ..FMV_BASE
                    },
                ))
            }),
        ),
    ]);

    arena.play(
        &(0..arena.players.len())
            .zip([0].into_iter().cycle())
            .filter(|(i, j)| i != j)
            .collect::<Vec<_>>()
            .repeat(20),
    );

    println!("{}", arena);
}

pub struct PlayerArena {
    /// Name, Creator, Elo
    players: Vec<(String, Box<dyn Fn(Piece) -> Box<dyn Agent>>, EloRating)>,
}

impl std::fmt::Display for PlayerArena {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        let mut players_i: Vec<usize> = (0..self.players.len()).collect();
        players_i.sort_by_key(|&i| -(self.players[i].2.rating() * 100.0) as i64);

        for i in players_i {
            writeln!(
                f,
                "({:.2}): {}",
                self.players[i].2.rating(),
                self.players[i].0
            )?;
        }

        Ok(())
    }
}

impl PlayerArena {
    pub fn new(players: Vec<(String, Box<dyn Fn(Piece) -> Box<dyn Agent>>)>) -> Self {
        Self {
            players: players
                .into_iter()
                .zip([EloRating::new()].into_iter().cycle())
                .map(|((a, b), c)| (a, b, c))
                .collect(),
        }
    }

    fn play(&mut self, pairs: &[(usize, usize)]) {
        pairs
            .into_iter()
            .map(|&(i, j)| {
                (
                    (i, j),
                    Self::create_agents(&self.players[i].1, &self.players[j].1),
                )
            })
            .collect::<Vec<_>>()
            // after the agents are created, we can multithread the games being played
            .into_par_iter()
            .map(|((i, j), (p1, p2))| (i, j, Self::play_two_inner(p1, p2)))
            .collect::<Vec<_>>()
            // collect and process the outcomes of all the games
            .into_iter()
            .for_each(|(i, j, o)| self.process_outcome(i, j, &o));
    }

    fn prop_arena(&mut self) {
        self.play(
            &(0..self.players.len())
                .flat_map(|i| {
                    (0..self.players.len())
                        .map(move |j| (i, j))
                        .filter(|(i, j)| i != j)
                        .collect::<Vec<_>>()
                })
                .collect::<Vec<_>>(),
        );
    }

    fn process_outcome(&mut self, player1: usize, player2: usize, outcome: &Outcomes) {
        let (np1, np2) = elo(
            &self.players[player1].2,
            &self.players[player2].2,
            outcome,
            &EloConfig::new(),
        );
        self.players[player1].2 = np1;
        self.players[player2].2 = np2;
    }

    fn create_agents(
        player_1_fn: &Box<dyn Fn(Piece) -> Box<dyn Agent>>,
        player_2_fn: &Box<dyn Fn(Piece) -> Box<dyn Agent>>,
    ) -> (Box<dyn Agent>, Box<dyn Agent>) {
        (player_1_fn(Piece::Black), player_2_fn(Piece::White))
    }

    fn play_two_inner(player_1: Box<dyn Agent>, player_2: Box<dyn Agent>) -> Outcomes {
        let result = GameInner::new(player_1, player_2, false).loop_until_result();

        match result {
            Winner::Player(piece) => match piece {
                Piece::Black => Outcomes::WIN,
                Piece::White => Outcomes::LOSS,
            },
            Winner::Tie => Outcomes::DRAW,
            Winner::None => panic!("somehow met None"),
        }
    }
}