use std::path::{Path, PathBuf};

use anyhow::{Context, Result};
use clap::Parser;

use minedmap::{resource, world};

#[derive(Debug, Parser)]
struct Args {
	/// Minecraft save directory
	savedir: PathBuf,
}

/// Type with methods for processing the regions of a Minecraft save directory
struct RegionProcessor {
	block_types: resource::BlockTypeMap,
}

impl RegionProcessor {
	fn new() -> Self {
		RegionProcessor {
			block_types: resource::block_types(),
		}
	}

	/// Parses a filename in the format r.X.Z.mca into the contained X and Z values
	fn parse_region_filename(path: &Path) -> Option<(i32, i32)> {
		let file_name = path.file_name()?.to_str()?;
		let parts: Vec<_> = file_name.split('.').collect();
		let &["r", x, z, "mca"] = parts.as_slice() else {
			return None;
		};

		Some((x.parse().ok()?, z.parse().ok()?))
	}

	/// Processes a single region file
	fn process_region(&self, path: &Path, _x: i32, _z: i32) -> Result<()> {
		minedmap::io::region::from_file(path)?.foreach_chunk(|coords, data: world::de::Chunk| {
			let chunk = match world::chunk::Chunk::new(&data) {
				Ok(chunk) => chunk,
				Err(err) => {
					eprintln!("Chunk {:?}: {}", coords, err);
					return Ok(());
				}
			};

			match world::layer::top_layer(&chunk, &self.block_types) {
				Ok(_) => {}
				Err(err) => println!("{:?}", err),
			};
			Ok(())
		})
	}

	/// Iterates over all region files of a Minecraft save directory
	fn process_region_dir(&self, regiondir: &Path) -> Result<()> {
		let read_dir = regiondir
			.read_dir()
			.with_context(|| format!("Failed to read directory {}", regiondir.display()))?;

		for entry in read_dir.filter_map(|entry| entry.ok()).filter(|entry| {
			// We are only interested in regular files
			entry
				.file_type()
				.map(|file_type| file_type.is_file())
				.unwrap_or_default()
		}) {
			let path = entry.path();
			let Some((x, z)) = Self::parse_region_filename(&path) else {
			continue;
		};

			if let Err(err) = self.process_region(&path, x, z) {
				eprintln!("Failed to process region r.{}.{}.mca: {}", x, z, err);
			}
		}

		Ok(())
	}
}

fn main() -> Result<()> {
	let args = Args::parse();

	let regiondir: PathBuf = [&args.savedir, Path::new("region")].iter().collect();

	let region_processor = RegionProcessor::new();
	region_processor.process_region_dir(&regiondir)?;

	Ok(())
}