use crate::constants;
use bevy::prelude::*;
use rand::{
    distributions::{Distribution, Standard},
    Rng,
};

#[derive(Debug, PartialEq, Clone, Copy)]
pub enum Occupant {
    None,
    Green,
    Yellow,
    Red,
    Blue,
    Explosion,
}

impl Default for Occupant {
    fn default() -> Occupant {
        Occupant::None
    }
}

impl Occupant {
    pub fn to_index(&self) -> u32 {
        match self {
            Occupant::Green => constants::TILESHEET_GREEN,
            Occupant::Yellow => constants::TILESHEET_YELLOW,
            Occupant::Red => constants::TILESHEET_RED,
            Occupant::Blue => constants::TILESHEET_BLUE,
            Occupant::Explosion => constants::TILESHEET_EXPLOSION1,
            Occupant::None => constants::TILESHEET_NONE1,
        }
    }
}

impl Distribution<Occupant> for Standard {
    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> Occupant {
        match rng.gen_range(0..=3) {
            0 => Occupant::Green,
            1 => Occupant::Yellow,
            2 => Occupant::Blue,
            3 => Occupant::Red,
            _ => Occupant::None,
        }
    }
}

#[derive(Debug, Clone, Default, Copy)]
pub struct Cell {
    pub x: usize,
    pub y: usize,
    pub occupant: Occupant,
    pub selected: bool,
    pub hovered: bool,
}

impl Cell {
    pub fn new(x: usize, y: usize) -> Cell {
        Cell {
            x,
            y,
            occupant: Occupant::None,
            selected: false,
            hovered: false,
        }
    }
}

pub fn insert(mut q: Query<(&mut Cell, &mut TextureAtlasSprite)>) {
    for (mut cell, mut sprite) in q.iter_mut() {
        if cell.occupant == Occupant::None && cell.y == constants::GRID_SIZE - 1 {
            cell.occupant = rand::random();
            sprite.index = cell.occupant.to_index();
        }
    }
}

pub fn start_explosion(mut commands: Commands, mut q: Query<(Entity, &Cell), Without<Timer>>) {
    for (entity, cell) in q.iter_mut() {
        if cell.occupant == Occupant::Explosion {
            commands
                .entity(entity)
                .insert(Timer::from_seconds(0.1, true));
        }
    }
}

pub fn check(mut q: Query<(&mut Cell, &mut TextureAtlasSprite)>) {
    let mut cells = [[Cell::default(); constants::GRID_SIZE]; constants::GRID_SIZE];
    for (cell, _) in q.iter_mut() {
        cells[cell.x][cell.y] = *cell;
    }

    let mut last = Occupant::None;
    let mut connected = Vec::new();

    for (i, row) in cells.iter().enumerate() {
        let mut c = Vec::new();
        for (j, _) in row.iter().enumerate() {
            if cells[i][j].occupant == last && last != Occupant::None && last != Occupant::Explosion
            {
                c.push((i, j));
                c.push((i, j - 1));
            } else {
                connected.push(c.clone());
                c.clear();
            }
            last = cells[i][j].occupant;
        }
        connected.push(c);
        last = Occupant::None;
    }

    for (i, row) in cells.iter().enumerate() {
        let mut c = Vec::new();
        for (j, _) in row.iter().enumerate() {
            if cells[j][i].occupant == last && last != Occupant::None && last != Occupant::Explosion
            {
                c.push((j, i));
                c.push((j - 1, i));
            } else {
                connected.push(c.clone());
                c.clear();
            }
            last = cells[j][i].occupant;
        }
        connected.push(c);
        last = Occupant::None;
    }

    connected = connected.into_iter().filter(|c| c.len() > 4).collect();

    for c in connected.iter() {
        for (i, j) in c.iter() {
            for (mut cell, mut sprite) in q.iter_mut() {
                if &cell.x == i && &cell.y == j && cell.occupant != Occupant::Explosion {
                    cell.occupant = Occupant::Explosion;
                    sprite.index = cell.occupant.to_index();
                }
            }
        }
    }
}

pub fn falling(mut q: Query<(&mut Cell, &mut TextureAtlasSprite)>) {
    let mut have_gems = Vec::new();
    for (cell, _sprite) in q.iter_mut() {
        if cell.occupant != Occupant::None {
            have_gems.push(*cell);
        }
    }

    let mut moved_gems = Vec::new();
    for (mut cell, mut sprite) in q.iter_mut() {
        if cell.occupant == Occupant::None {
            if let Some(c) = have_gems
                .iter()
                .find(|&c| (c.x, c.y) == (cell.x, cell.y + 1))
            {
                cell.occupant = c.occupant;
                sprite.index = cell.occupant.to_index();
                moved_gems.push(c);
            }
        }
    }

    for (mut cell, mut sprite) in q.iter_mut() {
        if moved_gems.iter().any(|c| (c.x, c.y) == (cell.x, cell.y)) {
            cell.occupant = Occupant::None;
            sprite.index = cell.occupant.to_index();
        }
    }
}