use std::collections::BTreeMap;

use anyhow::{bail, Context, Result};

use super::{
	de,
	section::{OldSection, PaletteSection, PaletteSectionBiomes},
};
use crate::types::*;

pub enum Chunk<'a> {
	V1_18 {
		section_map: BTreeMap<SectionY, (PaletteSection<'a>, PaletteSectionBiomes<'a>)>,
	},
	V1_13 {
		section_map: BTreeMap<SectionY, PaletteSection<'a>>,
		biomes: &'a de::BiomesOld,
	},
	Old {
		section_map: BTreeMap<SectionY, OldSection<'a>>,
		biomes: &'a de::BiomesOld,
	},
	Empty,
}

impl<'a> Chunk<'a> {
	pub fn new(data: &'a de::Chunk) -> Result<Self> {
		let data_version = data.data_version.unwrap_or_default();

		match &data.chunk {
			de::ChunkVariants::V1_18 { sections } => Self::new_v1_18(data_version, sections),
			de::ChunkVariants::Old { level } => Self::new_old(data_version, level),
		}
	}

	fn new_v1_18(data_version: u32, sections: &'a Vec<de::SectionV1_18>) -> Result<Self> {
		let mut section_map = BTreeMap::new();

		for section in sections {
			section_map.insert(
				SectionY(section.y),
				(
					PaletteSection::new(
						data_version,
						section.block_states.data.as_ref(),
						&section.block_states.palette,
					)
					.with_context(|| format!("Failed to load section at Y={}", section.y))?,
					PaletteSectionBiomes::new(
						section.biomes.data.as_ref(),
						&section.biomes.palette,
					)
					.with_context(|| format!("Failed to load section biomes at Y={}", section.y))?,
				),
			);
		}

		Ok(Chunk::V1_18 { section_map })
	}

	fn new_old(data_version: u32, level: &'a de::LevelOld) -> Result<Self> {
		let mut section_map_v1_13 = BTreeMap::new();
		let mut section_map_old = BTreeMap::new();

		for section in &level.sections {
			match &section.section {
				de::SectionOldVariants::V1_13 {
					block_states,
					palette,
				} => {
					section_map_v1_13.insert(
						SectionY(section.y.into()),
						PaletteSection::new(data_version, Some(block_states), palette)
							.with_context(|| {
								format!("Failed to load section at Y={}", section.y)
							})?,
					);
				}
				de::SectionOldVariants::Old { blocks, data } => {
					section_map_old.insert(
						SectionY(section.y.into()),
						OldSection::new(blocks, data).with_context(|| {
							format!("Failed to load section at Y={}", section.y)
						})?,
					);
				}
				de::SectionOldVariants::Empty {} => {}
			}
		}

		// TODO Check biomes length
		let biomes = level.biomes.as_ref().context("Invalid biome data");

		Ok(
			match (section_map_v1_13.is_empty(), section_map_old.is_empty()) {
				(true, true) => Chunk::Empty,
				(false, true) => Chunk::V1_13 {
					section_map: section_map_v1_13,
					biomes: biomes?,
				},
				(true, false) => Chunk::Old {
					section_map: section_map_old,
					biomes: biomes?,
				},
				(false, false) => {
					bail!("Mixed section versions");
				}
			},
		)
	}
}