use std::{
	fmt::Debug,
	ops::{Div, Index, IndexMut, Rem},
};

use itertools::iproduct;

pub const BLOCKS_PER_CHUNK: u8 = 16;

/// A block X coordinate relative to a chunk
#[derive(Debug, Clone, Copy)]
pub struct BlockX(pub u8);

/// A block Y coordinate relative to a chunk section
#[derive(Debug, Clone, Copy)]
pub struct BlockY(pub u8);

/// A block Z coordinate relative to a chunk
#[derive(Debug, Clone, Copy)]
pub struct BlockZ(pub u8);

#[derive(Clone, Copy)]
pub struct BlockCoords {
	pub x: BlockX,
	pub y: BlockY,
	pub z: BlockZ,
}

impl BlockCoords {
	pub fn offset(&self) -> usize {
		const N: usize = BLOCKS_PER_CHUNK as usize;
		let x = self.x.0 as usize;
		let y = self.y.0 as usize;
		let z = self.z.0 as usize;
		((y * N) + z) * N + x
	}
}

impl Debug for BlockCoords {
	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
		write!(f, "({}, {}, {})", self.x.0, self.y.0, self.z.0)
	}
}

/// A section Y coordinate
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
pub struct SectionY(pub i32);

pub const CHUNKS_PER_REGION: u8 = 32;

/// A chunk X coordinate relative to a region
#[derive(Debug, Clone, Copy)]
pub struct ChunkX(pub u8);

/// A chunk Z coordinate relative to a region
#[derive(Debug, Clone, Copy)]
pub struct ChunkZ(pub u8);

/// A pair of chunk coordinates relative to a region
#[derive(Clone, Copy)]
pub struct ChunkCoords {
	pub x: ChunkX,
	pub z: ChunkZ,
}

impl Debug for ChunkCoords {
	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
		write!(f, "({}, {})", self.x.0, self.z.0)
	}
}

#[derive(Debug, Clone, Copy, Default)]
pub struct ChunkArray<T>(pub [[T; CHUNKS_PER_REGION as usize]; CHUNKS_PER_REGION as usize]);

impl<T> ChunkArray<T> {
	pub fn keys() -> impl Iterator<Item = ChunkCoords> {
		iproduct!(0..CHUNKS_PER_REGION, 0..CHUNKS_PER_REGION).map(|(z, x)| ChunkCoords {
			x: ChunkX(x),
			z: ChunkZ(z),
		})
	}

	pub fn values(&self) -> impl Iterator<Item = &T> {
		Self::keys().map(|k| &self[k])
	}

	pub fn iter(&self) -> impl Iterator<Item = (ChunkCoords, &T)> {
		Self::keys().map(|k| (k, &self[k]))
	}
}

impl<T> Index<ChunkCoords> for ChunkArray<T> {
	type Output = T;

	fn index(&self, index: ChunkCoords) -> &Self::Output {
		&self.0[index.z.0 as usize][index.x.0 as usize]
	}
}

impl<T> IndexMut<ChunkCoords> for ChunkArray<T> {
	fn index_mut(&mut self, index: ChunkCoords) -> &mut Self::Output {
		&mut self.0[index.z.0 as usize][index.x.0 as usize]
	}
}

pub trait DivRem<Rhs> {
	type DivOutput;
	type RemOutput;

	fn div_rem(self, rhs: Rhs) -> (Self::DivOutput, Self::RemOutput);
}

impl<Lhs, Rhs> DivRem<Rhs> for Lhs
where
	Self: Div<Rhs>,
	Self: Rem<Rhs>,
	Self: Copy,
	Rhs: Copy,
{
	type DivOutput = <Self as Div<Rhs>>::Output;
	type RemOutput = <Self as Rem<Rhs>>::Output;

	fn div_rem(self, rhs: Rhs) -> (Self::DivOutput, Self::RemOutput) {
		(self / rhs, self % rhs)
	}
}