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

use crate::{FileItem, Item, PileValue, extract::Extractor};

fn toml_to_pile<I: Item>(value: toml::Value) -> PileValue<'static, I> {
	match value {
		toml::Value::String(s) => PileValue::String(s.into()),
		toml::Value::Integer(i) => PileValue::String(i.to_string().into()),
		toml::Value::Float(f) => PileValue::String(f.to_string().into()),
		toml::Value::Boolean(b) => PileValue::String(b.to_string().into()),
		toml::Value::Datetime(d) => PileValue::String(d.to_string().into()),
		toml::Value::Array(a) => PileValue::Array(a.into_iter().map(toml_to_pile).collect()),
		toml::Value::Table(_) => PileValue::Null,
	}
}

pub struct SidecarExtractor<'a> {
	item: &'a FileItem,
	output: OnceLock<HashMap<Label, PileValue<'a, FileItem>>>,
}

impl<'a> SidecarExtractor<'a> {
	pub fn new(item: &'a FileItem) -> Self {
		Self {
			item,
			output: OnceLock::new(),
		}
	}

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

		let sidecar_file = self.item.path.with_extension("toml");

		if !(sidecar_file.is_file() && self.item.sidecar) {
			return Ok(self.output.get_or_init(HashMap::new));
		}

		let sidecar = std::fs::read(&sidecar_file)?;
		let sidecar: toml::Value = match toml::from_slice(&sidecar) {
			Ok(x) => x,
			Err(_) => return Ok(self.output.get_or_init(HashMap::new)),
		};

		let output: HashMap<Label, PileValue<'_, FileItem>> = match sidecar {
			toml::Value::Table(t) => t
				.into_iter()
				.filter_map(|(k, v)| Label::new(&k).map(|label| (label, toml_to_pile(v))))
				.collect(),
			_ => HashMap::new(),
		};

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

impl Extractor<FileItem> for SidecarExtractor<'_> {
	fn field<'a>(
		&'a self,
		name: &Label,
	) -> Result<Option<&'a PileValue<'a, FileItem>>, std::io::Error> {
		Ok(self.get_inner()?.get(name))
	}

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