// A game is a self-contained struct that holds everything that an instance of
// Tetris needs to run, except for something to tick the time forward.

use crate::playfield::PlayField;
use crate::srs::RotationSystem;
use crate::srs::SRS;
use crate::tetromino::Position;
use crate::Renderable;
use crate::TICKS_PER_SECOND;
use log::trace;
use sdl2::{render::Canvas, video::Window};
use std::fmt;

// I think this was correct, can't find source
const LINE_CLEAR_DELAY: u64 = TICKS_PER_SECOND as u64 * 41 / 60;

// Logic is based on 60 ticks / second
pub struct Game {
    playfield: PlayField,
    rotation_system: SRS,
    level: u8,
    score: u32,
    tick: u64,
    next_gravity_tick: u64,
    next_lock_tick: u64,
    next_spawn_tick: u64,
    is_game_over: bool,
}

impl fmt::Debug for Game {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        writeln!(f, "level: {}, points: {}", self.level, self.score)?;
        writeln!(f, "tick: {}", self.tick)?;
        write!(f, "{:?}", self.playfield)
    }
}

impl Default for Game {
    fn default() -> Self {
        Game {
            playfield: PlayField::new(),
            rotation_system: SRS::default(),
            level: 1,
            score: 0,
            tick: 0,
            next_gravity_tick: 60,
            next_lock_tick: 0,
            next_spawn_tick: 0,
            is_game_over: false,
        }
    }
}

pub trait Tickable {
    fn tick(&mut self);
}

impl Tickable for Game {
    fn tick(&mut self) {
        if self.is_game_over() {
            return;
        }

        self.tick += 1;
        match self.tick {
            t if t == self.next_spawn_tick => self.spawn_tetromino(),
            t if t == self.next_lock_tick => {
                self.try_lock_tetromino();
            }
            t if t == self.next_gravity_tick => {
                self.playfield.tick_gravity();
                if !self.playfield.can_active_piece_move_down() {
                    self.update_lock_tick();
                }
                self.update_gravity_tick();
            }
            _ => (),
        }
    }
}

impl Game {
    pub fn is_game_over(&self) -> bool {
        self.is_game_over || !self.playfield.is_active_piece_in_valid_position()
    }

    fn update_gravity_tick(&mut self) {
        self.next_gravity_tick = (-1 as i64) as u64; //self.tick + TICKS_PER_SECOND as u64;
    }

    fn update_lock_tick(&mut self) {
        self.next_lock_tick = self.tick + TICKS_PER_SECOND as u64 / 2;
    }

    fn spawn_tetromino(&mut self) {
        self.playfield.spawn_tetromino();
        self.playfield.tick_gravity();
        self.update_gravity_tick();
    }

    /// Returns if some lines were cleared
    fn clear_lines(&mut self) -> bool {
        // todo: award points based on how lines were cleared
        return false;
    }

    fn try_lock_tetromino(&mut self) -> bool {
        // It's possible that the player moved the piece in the meantime.
        if !self.playfield.can_active_piece_move_down() {
            let positions = self.playfield.lock_active_piece();
            self.is_game_over =
                self.is_game_over || positions.iter().all(|Position { x: _, y }| *y < 20);
            if self.clear_lines() {
                self.next_spawn_tick = self.tick + LINE_CLEAR_DELAY;
            } else {
                self.spawn_tetromino();
            }
            true
        } else {
            false
        }
    }
}

impl Renderable for Game {
    fn render(&self, canvas: &mut Canvas<Window>) -> Result<(), String> {
        self.playfield.render(canvas)
    }
}

pub trait Controllable {
    fn move_left(&mut self);
    fn move_right(&mut self);
    fn move_down(&mut self);
    fn rotate_left(&mut self);
    fn rotate_right(&mut self);
    fn hard_drop(&mut self);
    fn hold(&mut self);
}

impl Controllable for Game {
    fn move_left(&mut self) {
        self.playfield.move_offset(-1, 0);
        self.update_lock_tick();
    }
    fn move_right(&mut self) {
        self.playfield.move_offset(1, 0);
        self.update_lock_tick();
    }
    fn move_down(&mut self) {
        if self.playfield.move_offset(0, 1) {
            self.score += 1;
            self.update_gravity_tick();
            self.update_lock_tick();
        }
    }
    fn rotate_left(&mut self) {
        match self.rotation_system.rotate_left(&self.playfield) {
            Ok(Position { x, y }) => {
                let mut active_piece = self.playfield.active_piece.unwrap().clone();
                active_piece.position = active_piece.position.offset(x, y);
                active_piece.rotate_left();
                self.playfield.active_piece = Some(active_piece);
                self.update_lock_tick();
            }
            Err(_) => (),
        }
    }
    fn rotate_right(&mut self) {
        match self.rotation_system.rotate_right(&self.playfield) {
            Ok(Position { x, y }) => {
                let mut active_piece = self.playfield.active_piece.unwrap().clone();
                active_piece.position = active_piece.position.offset(x, y);
                active_piece.rotate_right();
                self.playfield.active_piece = Some(active_piece);
                self.update_lock_tick();
            }
            Err(_) => (),
        }
    }
    fn hard_drop(&mut self) {
        while self.playfield.can_active_piece_move_down() {
            self.score += 2;
            self.playfield.move_offset(0, 1);
        }

        if !self.try_lock_tetromino() {
            println!("couldn't lock tetromino despite hard dropping!");
        }
    }

    fn hold(&mut self) {
        // if self.can_swap_hold {
        //     match self.hold_piece {
        //         None => {
        //             self.hold_piece = Some(self.active_piece);
        //             self.get_new_piece();
        //         }
        //         Some(piece) => {
        //             self.hold_piece = Some(self.active_piece);
        //             self.active_piece = piece;
        //             self.reset_position();
        //         }
        //     }

        //     self.can_swap_hold = false;
        // }
    }
}