use std::collections::HashMap;

use crate::{
    config::CHUNK_SIZE,
    sim::{cell::Cell, chunk::Chunk},
};

pub struct World {
    pub chunks: Vec<Chunk>,
    // TODO FxHashMap?
    pub chunk_position_to_chunk_idx: HashMap<(i32, i32), usize>,
}

impl World {
    #[inline]
    pub fn split_game_position(x: i32, y: i32) -> ((i32, i32), (u8, u8)) {
        (
            (
                // TODO is this cast expensive?
                x.div_euclid(CHUNK_SIZE as i32),
                y.div_euclid(CHUNK_SIZE as i32),
            ),
            (
                x.rem_euclid(CHUNK_SIZE as i32) as u8,
                y.rem_euclid(CHUNK_SIZE as i32) as u8,
            ),
        )
    }

    // VERY EXPENSIVE
    pub fn get_cell_from_game_position(&self, x: i32, y: i32) -> Option<Cell> {
        let ((cx, cy), (dx, dy)) = World::split_game_position(x, y);
        self.chunk_position_to_chunk_idx
            .get(&(cx, cy))
            .map(|&idx| self.chunks[idx].get_cell_at_local_position(dx, dy))
    }

    // VERY EXPENSIVE
    pub fn set_cell_from_game_position(
        &mut self,
        x: i32,
        y: i32,
        cell: Cell,
        sleeping: bool,
    ) -> () {
        let ((cx, cy), (dx, dy)) = World::split_game_position(x, y);
        if let Some(&idx) = self.chunk_position_to_chunk_idx.get(&(cx, cy)) {
            self.chunks[idx].set_cell_at_local_position(dx, dy, cell);
            // this is a temporary hack
            self.chunks[idx].sleeping = sleeping;
        }
    }

    pub fn insert(&mut self, x: i32, y: i32, chunk: Chunk) -> () {
        self.chunk_position_to_chunk_idx
            .insert((x, y), self.chunks.len());
        self.chunks.push(chunk);
    }

    pub fn from_default_size() -> Self {
        let mut world = World {
            chunks: Vec::new(),
            chunk_position_to_chunk_idx: HashMap::new(),
        };

        for y in -10..10 {
            for x in -50..50 {
                world.insert(x, y, Chunk::void());
            }
        }

        world
    }
}