use crate::{
    agent::Agent,
    complexagent::ComplexAgent,
    game_inner::GameInner,
    logic::{ChildrenEvalMethod, FutureMoveConfig},
    repr::{Board, Piece, Winner},
};
use indicatif::{ParallelProgressIterator, ProgressBar, ProgressDrawTarget, ProgressStyle};
use rand::seq::SliceRandom;
use rayon::iter::{IntoParallelIterator, ParallelIterator};
use skillratings::{
    elo::{elo, EloConfig, EloRating},
    Outcomes, Rating,
};
use std::num::NonZero;

type AgentMaker = Box<dyn Fn(Piece) -> Box<dyn Agent>>;

#[allow(dead_code)]
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: usize::MAX,
        do_prune: false,
        print: false,
        children_eval_method: ChildrenEvalMethod::AverageDivDepth,
    };

    let configs = [6]
        .into_iter()
        .map(move |d| FutureMoveConfig {
            max_depth: d,
            ..FMV_BASE
        })
        .flat_map(move |prev_c| {
            // create children which enable, and disable pruning
            [true, false].map(move |do_prune| FutureMoveConfig { do_prune, ..prev_c })
        })
        .filter(move |move_c| {
            if move_c.do_prune {
                move_c.max_depth >= 8
            } else {
                move_c.max_depth < 8
            }
        })
        // .flat_map(move |prev_c| {
        //     [
        //         ChildrenEvalMethod::Average,
        //         ChildrenEvalMethod::AverageDivDepth,
        //     ]
        //     .map(move |children_strat| FutureMoveConfig {
        //         children_eval_method: children_strat,
        //         ..prev_c
        //     })
        // });
        .flat_map(move |prev_c| {
            if !prev_c.do_prune {
                // do not bother making configs when pruning is disabled
                // as top_k_children does nothing when pruning is skipped
                return vec![prev_c];
            }

            // different values of top_k_children
            [1, 2, 3]
                .map(move |top_k_children| FutureMoveConfig {
                    top_k_children,
                    ..prev_c
                })
                .to_vec()
        })
        .flat_map(move |prev_c| {
            if !prev_c.do_prune {
                // do not bother making configs when pruning is disabled
                return vec![prev_c];
            }

            // different values to be subtracted from max_depth
            // to become min_arena_depth
            [1, 2, 3]
                .into_iter()
                .filter(|&x| x <= prev_c.max_depth)
                .map(move |ad_offset| FutureMoveConfig {
                    min_arena_depth: prev_c.max_depth - ad_offset,
                    ..prev_c
                })
                .collect()
        })
        .flat_map(move |prev_c| {
            if !prev_c.do_prune {
                // do not bother making configs when pruning is disabled
                return vec![prev_c];
            }

            // different values of up_to_minus
            [prev_c.max_depth, 1, 2, 3]
                .into_iter()
                .filter(|&x| x <= prev_c.max_depth)
                .map(move |up_to_minus| FutureMoveConfig {
                    up_to_minus,
                    ..prev_c
                })
                .collect()
        });

    let vec: Vec<(String, AgentMaker)> = configs
        .into_iter()
        .map(move |config| -> (String, AgentMaker) {
            (
                format!("{}", config),
                Box::new(move |piece| Box::new(ComplexAgent::new(piece, config))),
            )
        })
        .collect();

    let mut arena = PlayerArena::new(vec);

    arena.prop_arena(100);

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

pub struct PlayerArena {
    /// Name, Creator Function, Elo
    players: Vec<(String, AgentMaker, 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, AgentMaker)>) -> Self {
        Self {
            players: players
                .into_iter()
                .zip([EloRating::new()].into_iter().cycle())
                // flatten tuple
                .map(|((a, b), c)| (a, b, c))
                .collect(),
        }
    }

    fn play(&mut self, pairs: &[(usize, usize)]) {
        let mut created_pairs = pairs
            .iter()
            .map(|&(i, j)| {
                (
                    (i, j),
                    Self::create_agents(&self.players[i].1, &self.players[j].1),
                )
            })
            .collect::<Vec<_>>();

        // shuffle for consistency
        created_pairs.shuffle(&mut rand::rng());

        let num = created_pairs.len();

        let (sender, receiver) = crossbeam_channel::unbounded();

        let term = console::Term::stdout();

        // Spawn parallel processing in a dedicated thread
        let processing_thread = {
            let sender = sender.clone();
            let term = term.clone();

            std::thread::spawn(move || {
                rayon::ThreadPoolBuilder::new()
                    .num_threads(
                        std::thread::available_parallelism()
                            .map(NonZero::get)
                            .expect("unable to get number of threads"),
                    )
                    .build_global()
                    .unwrap();

                created_pairs
                    .into_par_iter()
                    .progress_with({
                        let a = ProgressBar::new(num as u64).with_style(
                            ProgressStyle::with_template(
                                "[{elapsed_precise}] {pos:>7}/{len:7} ETA: {eta}",
                            )
                            .expect("invalid ProgressStyle"),
                        );
                        a.set_draw_target(ProgressDrawTarget::term(term, 5));
                        a
                    })
                    .progress_with_style(
                        ProgressStyle::with_template(
                            "[{elapsed_precise}] {pos:>7}/{len:7} ETA: {eta}",
                        )
                        .expect("invalid ProgressStyle"),
                    )
                    .map(|((i, j), (p1, p2))| (i, j, Self::play_two_inner(p1, p2)))
                    .for_each(|(i, j, o)| {
                        sender.send((i, j, o)).expect("Failed to send result");
                    });
            })
        };

        // Immediately drop our copy of the sender so the channel closes properly
        drop(sender);

        // Process results on main thread as they arrive
        let mut received_num = 0;
        while let Ok((i, j, o)) = receiver.recv() {
            self.process_outcome(i, j, &o);
            received_num += 1;

            term.clear_last_lines(self.players.len())
                .expect("unable to clear prev lines");
            term.write_str(format!("{}", self).as_str())
                .expect("unable to write leaderboard");

            // break if all pairs were recieved
            if received_num == num {
                break;
            }
        }

        // Ensure parallel thread completes
        processing_thread
            .join()
            .expect("Processing thread panicked");
    }

    fn prop_arena(&mut self, n: usize) {
        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<_>>()
                .repeat(n),
        );
    }

    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: &AgentMaker,
        player_2_fn: &AgentMaker,
    ) -> (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,
            Board::random(rand::random_range(3..=7)),
        )
        .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"),
        }
    }
}