use crate::game::{Board, Cell};
use crate::player::Player;

pub struct Engine {
    players: Vec<Box<dyn Player>>,
    turn: usize,
    board: Board,
    x: usize,
}

impl Engine {
    pub fn new(p1: Box<dyn Player>, p2: Box<dyn Player>) -> Engine {
        let board = Board::new();
        Engine {
            players: vec![p1, p2],
            turn: 0,
            board: board,
            x: 0,
        }
    }

    pub fn run(&mut self) -> Result<(), Box<dyn std::error::Error>> {
        loop {
            // setup new game for players
            self.players[self.x].start_new_game(Cell::X)?;
            self.players[(self.x + 1) % 2].start_new_game(Cell::O)?;

            // reset board
            self.board.reset();
            self.turn = self.x;

            // run game
            self.run_single_game()?;

            // switch sides
            self.x = (self.x + 1) % 2;
        }
    }

    fn run_single_game(&mut self) -> Result<(), Box<dyn std::error::Error>> {
        loop {
            // request move from player, fail if there is error
            let m = self.players[self.turn].request_move(&self.board)?;
            let next = (self.turn + 1) % 2;

            if !self.board.is_valid_move(&m) {
                continue;
            }

            // apply move
            self.board.apply(m)?;

            // check if there is a winner
            if let Some(_winner) = self.board.has_winner() {
                self.players[self.turn].message("You win!")?;
                self.players[next].message("You loose!")?;
                break;
            }

            if !self.board.valid_moves_available() {
                self.players[self.turn].message("It's a draw!")?;
                self.players[next].message("It's a draw!")?;
                break;
            }

            self.turn = next
        }

        Ok(())
    }
}