// Copyright (C) 2022 tslil clingman
//
// This file is part of srchr.
//
// srchr is free software: you can redistribute it and/or modify it under the
// terms of the GNU General Public License as published by the Free Software
// Foundation, either version 3 of the License, or (at your option) any later
// version.
//
// srchr is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
// A PARTICULAR PURPOSE. See the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License along with
// srchr. If not, see <https://www.gnu.org/licenses/>.

mod config;
mod corpus;
mod evaluation;
mod layout;
mod output;

use rayon::prelude::*;

use rand::prelude::*;
use rand_pcg::*;

use config::*;
use corpus::*;
use evaluation::*;
use layout::*;

use std::time::Instant;

struct Tournament<'a> {
    rngs: Vec<Pcg64>,
    top_prelayouts: Vec<(Prelayout, f32)>,
    corpus: &'a Corpus,
}

impl<'a> Tournament<'a> {
    fn new_from_seed_prelayout(seed_prelayout: &Prelayout, corpus: &'a Corpus) -> Tournament<'a> {
        let mut rngs: Vec<Pcg64> = Vec::new();
        for _ in 0..NUM_CONTESTANTS {
            rngs.push(Pcg64::from_entropy());
        }

        let mut top_prelayouts: Vec<(Prelayout, f32)> = Vec::new();
        let score = prelayout_fitness(&corpus, &seed_prelayout);
        for _ in 0..NUM_PERSIST {
            top_prelayouts.push((seed_prelayout.clone(), score));
        }

        Tournament {
            rngs,
            top_prelayouts,
            corpus,
        }
    }

    fn run_round(&mut self) -> Option<Prelayout> {
        let rngs = &mut self.rngs;

        let mut tournament = rngs
            .into_par_iter()
            .map(|mut rng| {
                let layout = Prelayout::new_random_from(
                    &self.top_prelayouts[rng.gen_range(0..NUM_PERSIST)].0,
                    &mut rng,
                );
                return (layout, prelayout_fitness(&self.corpus, &layout));
            })
            .collect::<Vec<(Prelayout, f32)>>();

        let best = self.top_prelayouts[0].1;
        tournament.append(&mut self.top_prelayouts);
        tournament.sort_by(|(_, lscore), (_, rscore)| {
            if lscore < rscore {
                std::cmp::Ordering::Less
            } else {
                std::cmp::Ordering::Greater
            }
        });

        let result;
        if tournament[0].1 + 1e-7 < best {
            result = Some(tournament[0].0);
        } else {
            result = None;
        }

        for i in 0..NUM_PERSIST {
            self.top_prelayouts.push(tournament[i]);
        }

        result
    }
}

fn main() {
    let corpus;
    if LOAD_STATS {
        corpus = Corpus::load_from_json_file(STATS_FILE_NAME).unwrap();
    } else {
        corpus = Corpus::load_from_text_file(CORPUS_FILE_NAME).unwrap();
    }

    let seed_layout = Layout::from_verbose(STARTING_LAYOUT_STRING).unwrap();
    let seed_evl = Evaluation::evaluate_layout(&corpus, &seed_layout);
    let seed_prelayout = seed_layout.as_prelayout();

    println!("Starting with\n{}{}", seed_layout, seed_evl);

    let mut tournament = Tournament::new_from_seed_prelayout(&seed_prelayout, &corpus);

    let mut count: usize = 0;
    let mut current = Instant::now();
    loop {
        let improvement = tournament.run_round();

        if let Some(prelayout) = improvement {
            let layout = Layout::from_prelayout(&prelayout, &corpus);
            let evl = Evaluation::evaluate_layout(&corpus, &layout);
            println!("\n================================================================================\n\n{}{}",
                 layout, evl
            );
        }

        count += 1;
        if count > 65535 {
            let duration = current.elapsed();
            let rps = count as f32 / duration.as_millis() as f32 * 1000.0;
            eprint!(
                "\u{001b}[2K\u{001b}[1000D{} layouts/s and {} tournaments/s",
                rps * NUM_CONTESTANTS as f32,
                rps
            );
            current = Instant::now();
            count = 0;
        }
    }
}