use search::apply_move;
use bitboard::Bitboard;
use game::Game;
use search::*;
use movegen::*;
use evaluate::PosValue;
use log::{info};
use std::time::{Duration, Instant};
use std::collections::{VecDeque, HashMap};
use zobrist::ZobristTable;
use hash::Cache;

use std::thread::sleep_ms;
use std::sync::mpsc::{Receiver, Sender};

pub enum EngineMsg {
    SetBoard(Game),
    SetPiece(Bitboard),
    Search(SearchInfo),
    Ping,
    Stop,
    NewGame,
    GetState,
    GetInfo,
}

pub enum SearchInfo {
    Depth(isize),
    Movetime(isize),
    Time {
        wtime: isize,
        btime: isize,
        winc: isize,
        binc: isize,
        movestogo: isize
    },
    Infinite,

}

pub enum InterfaceMsg {
}

pub struct Engine {
    game: Game,
    messages: VecDeque<EngineMsg>,
    r: Receiver<EngineMsg>,
    s: Sender<InterfaceMsg>,
    hash: Cache,
    zobrist_table: ZobristTable
}

impl Engine {
    pub fn new(r: Receiver<EngineMsg>, s: Sender<InterfaceMsg>) -> Self {
        let mut eng = Engine {
            game: Game::default(),
            messages: VecDeque::new(),
            r, s,
            hash: Cache::new(),
            zobrist_table: ZobristTable::new()
        };
        eng.game.zobrist = Some(eng.game.calculate_zobrist(&eng.zobrist_table));
        eng
    }

    pub fn run(&mut self) {
        while let Some(msg) = self.dequeue_message() {
            match msg {
                EngineMsg::SetBoard(g) => {
                    self.game = g;
                },
                EngineMsg::Search(ref info) => {
                    self.start_search(info);
                }
                _ => {}
            }
        }
    }

    /**
     * blocks until a message is available
     */
    fn dequeue_message(&mut self) -> Option<EngineMsg> {
        if self.messages.is_empty() {
            self.r.recv().ok()
        }
        else {
            self.messages.pop_front()
        }
    }

    fn start_search(&mut self, si: &SearchInfo) {
        match si {
            SearchInfo::Depth(depth) => {
                let receiver = &mut self.r;
                let messages = &mut self.messages;
                let mut check_fn = || -> bool {
                    if let Ok(msg) = receiver.try_recv() {
                        if let EngineMsg::Stop = msg {
                            return true;
                        }
                        else {
                            messages.push_back(msg);
                        }
                    }
                    return false;
                };
                let mut sc = SearchControl{ nodes: 0, check: &mut check_fn };
                let before = Instant::now();
                let search_result = search(&self.game, &mut sc, &mut self.hash, *depth as i32);

                if let SearchResult::Finished(best_move, best_val) = search_result {
                    let time = before.elapsed();
                    let nps = (sc.nodes as f64 / time.as_millis() as f64 * 1000.0) as i64;
                    info!("bestmove {}", best_move.to_string());
                    info!("searched {} nodes in {} ms ({} nodes/s)", sc.nodes, time.as_millis(), (sc.nodes as f64 / time.as_millis() as f64 * 1000.0) as i64);
    
                    println!("info nps {}", nps.to_string());
                    println!("bestmove {}", best_move.to_string());
                }
            },
            SearchInfo::Movetime(millis) => {
                let before = Instant::now();
                let mut depth = 1;
                let receiver = &mut self.r;
                let messages = &mut self.messages;
                let mut check_fn = || -> bool {
                    if let Ok(msg) = receiver.try_recv() {
                        if let EngineMsg::Stop = msg {
                            return true;
                        }
                        else {
                            messages.push_back(msg);
                        }
                    }
                    if before.elapsed() > Duration::from_millis(*millis as _) {
                        return true;
                    }
                    return false;
                };

                let mut sc = SearchControl{ nodes: 0, check: &mut check_fn };
                let mut best_move = Move::default();
                let mut best_val: PosValue = i32::max_value() as _;
                loop {
                    let search_result = search(&mut self.game, &mut sc, &mut self.hash, depth as i32);
                    if let SearchResult::Finished(bm, bv) = search_result {
                        info!("depth: {} bm: {}, bv: {}", depth, bm.to_string(), bv);
                        best_move = bm;
                        best_val = bv;
    
                        let elapsed = before.elapsed();
                        let nodes = sc.nodes;
                        let nps = (nodes as f64 / elapsed.as_nanos() as f64 * 1000000000.0) as i64;
                        let cp = best_val as i64;
                        println!("info depth {} score cp {} time {} nodes {} nps {} pv {}", depth, cp, elapsed.as_millis(), nodes, nps, best_move.to_string());
                        info!("info depth {} score cp {} time {} nodes {} nps {} pv {}", depth, cp, elapsed.as_millis(), nodes, nps, best_move.to_string());
                        depth += 1;
                    }
                    else if let SearchResult::Mate(bm, in_turns) = search_result {
                        best_move = bm;
                        let elapsed = before.elapsed();
                        let nodes = sc.nodes;
                        let nps = (nodes as f64 / elapsed.as_nanos() as f64 * 1000000000.0) as i64;
                        let pv = best_val as i64;
                        println!("info depth {} score mate {} time {} nodes {} nps {} pv {}", depth, in_turns, elapsed.as_millis(), nodes, nps, bm.to_string());
                        info!("info depth {} score mate {} time {} nodes {} nps {} pv {}", depth, pv, elapsed.as_millis(), nodes, nps, bm.to_string());
                        break;
                    }
                    else {
                        break;
                    }
                }
                info!("bestmove {}", best_move.to_string());

                println!("bestmove {}", best_move.to_string());
            },
            _ => {}
        }
    }
}

/*

fn dequeue_message(queue: &mut VecDeque<EngineMsg>, r: &Receiver<EngineMsg>) -> Option<EngineMsg> {
    if queue.is_empty() {
        r.recv().ok()
    }
    else {
        queue.pop_front()
    }
}

pub fn run_engine(r: Receiver<EngineMsg>, _s: Sender<InterfaceMsg>) {
    let mut game = Game::default();
    let mut messages: VecDeque<EngineMsg> = VecDeque::new();
    loop {
        let msg = dequeue_message(&mut messages, &r).unwrap();

        match msg {
            EngineMsg::SetBoard(g) => {
                game = g;
            },
            EngineMsg::SetPiece(_) => { println!("SetPiece") },
            EngineMsg::Search(info) => {

                match info {
                    SearchInfo::Depth(depth) => {
                        let mut check_fn = || -> bool {
                            if let Ok(msg) = r.try_recv() {
                                if let EngineMsg::Stop = msg {
                                    return true;
                                }
                                else {
                                    messages.push_back(msg);
                                }
                            }
                            return false;
                        };
                        let mut sc = SearchControl{ nodes: 0, check: &mut check_fn };
                        let before = Instant::now();
                        let best_move = search(&game, &mut sc, depth as i32);

                        let time = before.elapsed();
                        let nps = (sc.nodes as f64 / time.as_millis() as f64 * 1000.0) as i64;
                        info!("bestmove {}", best_move.to_string());
                        info!("searched {} nodes in {} ms ({} nodes/s)", sc.nodes, time.as_millis(), (sc.nodes as f64 / time.as_millis() as f64 * 1000.0) as i64);

                        println!("info nps {}", nps.to_string());
                        println!("bestmove {}", best_move.to_string());
                    },
                    SearchInfo::Movetime(millis) => {
                        let before = Instant::now();
                        let mut depth = 1;
                        let mut check_fn = || -> bool {
                            if let Ok(msg) = r.try_recv() {
                                if let EngineMsg::Stop = msg {
                                    return true;
                                }
                                else {
                                    messages.push_back(msg);
                                }
                            }
                            if before.elapsed() > Duration::from_millis(millis as _) {
                                return true;
                            }
                            return false;
                        };

                        let mut sc = SearchControl{ nodes: 0, check: &mut check_fn };
                        let mut best_move = Move::default();
                        loop {
                            let bm = search(&game, &mut sc, depth as i32);
                            if bm != Move::default() {
                                best_move = bm;
                            }
                            else {
                                break;
                            }
                            depth += 1;
                        }

                        println!("bestmove {}", best_move.to_string());
                    },
                    _ => {}
                }
            },
            EngineMsg::Ping => { println!("Ping") },
            EngineMsg::Stop => { println!("Stop") },
            EngineMsg::NewGame => {
                //println!("NewGame")
            },
            EngineMsg::GetState => { println!("GetState") },
            EngineMsg::GetInfo => { println!("GetInfo") },
        }

        //println!("{}", game.beautiful_print());

        //let moves = generate_moves(&game, WHITE);
    }
}

*/