use pile_config::Label;
use std::{
	collections::HashMap,
	path::Component,
	sync::{Arc, OnceLock},
};

use crate::{
	extract::traits::ObjectExtractor,
	value::{Item, PileValue},
};

pub struct FsExtractor {
	item: Item,
	output: OnceLock<HashMap<Label, PileValue>>,
}

impl FsExtractor {
	pub fn new(item: &Item) -> Self {
		Self {
			item: item.clone(),
			output: OnceLock::new(),
		}
	}

	fn get_inner(&self) -> Result<&HashMap<Label, PileValue>, std::io::Error> {
		if let Some(x) = self.output.get() {
			return Ok(x);
		}

		let Item::File { path, .. } = &self.item else {
			return Ok(self.output.get_or_init(HashMap::new));
		};

		#[expect(clippy::unwrap_used)]
		let output = HashMap::from([
			(
				Label::new("extension").unwrap(),
				path.extension()
					.and_then(|x| x.to_str())
					.map(|x| PileValue::String(Arc::new(x.into())))
					.unwrap_or(PileValue::Null),
			),
			(
				Label::new("path").unwrap(),
				path.to_str()
					.map(|x| PileValue::String(Arc::new(x.into())))
					.unwrap_or(PileValue::Null),
			),
			(
				Label::new("segments").unwrap(),
				path.components()
					.map(|x| match x {
						Component::CurDir => Some(".".to_owned()),
						Component::Normal(x) => x.to_str().map(|x| x.to_owned()),
						Component::ParentDir => Some("..".to_owned()),
						Component::RootDir => Some("/".to_owned()),
						Component::Prefix(x) => x.as_os_str().to_str().map(|x| x.to_owned()),
					})
					.map(|x| x.map(|x| PileValue::String(Arc::new(x.into()))))
					.collect::<Option<Vec<_>>>()
					.map(|v| PileValue::Array(Arc::new(v)))
					.unwrap_or(PileValue::Null),
			),
		]);

		return Ok(self.output.get_or_init(|| output));
	}
}

#[async_trait::async_trait]
impl ObjectExtractor for FsExtractor {
	async fn field(
		&self,
		name: &Label,
		args: Option<&str>,
	) -> Result<Option<PileValue>, std::io::Error> {
		if args.is_some() {
			return Ok(None);
		}

		Ok(self.get_inner()?.get(name).cloned())
	}

	async fn fields(&self) -> Result<Vec<Label>, std::io::Error> {
		Ok(self.get_inner()?.keys().cloned().collect())
	}
}