pile/crates/pile-value/src/extract/item/flac.rs

use mime::Mime;
use pile_config::Label;
use pile_flac::{FlacBlock, FlacReader};
use std::{
	collections::HashMap,
	io::BufReader,
	sync::{Arc, OnceLock},
};

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

pub struct FlacImagesExtractor {
	item: Item,
}

impl FlacImagesExtractor {
	pub fn new(item: &Item) -> Self {
		Self { item: item.clone() }
	}

	async fn get_images(&self) -> Result<Vec<PileValue>, std::io::Error> {
		let reader = SyncReadBridge::new_current(self.item.read().await?);
		let raw_images = tokio::task::spawn_blocking(move || {
			let reader = FlacReader::new(BufReader::new(reader));
			let mut images: Vec<(Mime, Vec<u8>)> = Vec::new();
			for block in reader {
				match block.map_err(|e| std::io::Error::new(std::io::ErrorKind::InvalidData, e))? {
					FlacBlock::Picture(picture) => {
						images.push((picture.mime, picture.img_data));
					}
					FlacBlock::AudioFrame(_) => break,
					_ => {}
				}
			}
			Ok::<_, std::io::Error>(images)
		})
		.await
		.map_err(std::io::Error::other)??;

		Ok(raw_images
			.into_iter()
			.map(|(mime, data)| PileValue::Blob {
				mime,
				bytes: Arc::new(data),
			})
			.collect())
	}
}

#[async_trait::async_trait]
impl ListExtractor for FlacImagesExtractor {
	async fn get<'a>(&'a self, idx: usize) -> Result<Option<PileValue>, std::io::Error> {
		Ok(self.get_images().await?.into_iter().nth(idx))
	}

	async fn len(&self) -> Result<usize, std::io::Error> {
		Ok(self.get_images().await?.len())
	}
}

pub struct FlacExtractor {
	item: Item,
	output: OnceLock<HashMap<Label, PileValue>>,
	images: Option<PileValue>,
}

impl FlacExtractor {
	pub fn new(item: &Item) -> Self {
		let is_flac = match item {
			Item::File { path, .. } => path.to_str().unwrap_or_default().ends_with(".flac"),
			Item::S3 { key, .. } => key.ends_with(".flac"),
		};

		let images =
			is_flac.then(|| PileValue::ListExtractor(Arc::new(FlacImagesExtractor::new(item))));

		Self {
			item: item.clone(),
			output: OnceLock::new(),
			images,
		}
	}

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

		let key = match &self.item {
			Item::File { path, .. } => path.to_str().unwrap_or_default().to_owned(),
			Item::S3 { key, .. } => key.to_string(),
		};

		if !key.ends_with(".flac") {
			let _ = self.output.set(HashMap::new());
			#[expect(clippy::unwrap_used)]
			return Ok(self.output.get().unwrap());
		}

		let reader = SyncReadBridge::new_current(self.item.read().await?);
		let raw_tags = tokio::task::spawn_blocking(move || {
			let reader = FlacReader::new(BufReader::new(reader));
			let mut tags: Vec<(String, String)> = Vec::new();
			for block in reader {
				match block.map_err(|e| std::io::Error::new(std::io::ErrorKind::InvalidData, e))? {
					FlacBlock::VorbisComment(comment) => {
						for (k, v) in comment.comment.comments {
							tags.push((k.to_string().to_lowercase(), v.into()));
						}
					}
					FlacBlock::AudioFrame(_) => break,
					_ => {}
				}
			}
			Ok::<_, std::io::Error>(tags)
		})
		.await
		.map_err(std::io::Error::other)??;

		let mut output: HashMap<Label, Vec<PileValue>> = HashMap::new();
		for (k, v) in raw_tags {
			if let Some(label) = Label::new(k) {
				output
					.entry(label)
					.or_default()
					.push(PileValue::String(Arc::new(v.into())));
			}
		}
		let output: HashMap<Label, PileValue> = output
			.into_iter()
			.map(|(k, v)| (k, PileValue::Array(Arc::new(v))))
			.collect();

		let _ = self.output.set(output);
		#[expect(clippy::unwrap_used)]
		return Ok(self.output.get().unwrap());
	}
}

#[async_trait::async_trait]
impl ObjectExtractor for FlacExtractor {
	async fn field(&self, name: &Label) -> Result<Option<PileValue>, std::io::Error> {
		if name.as_str() == "images"
			&& let Some(ref images) = self.images
		{
			return Ok(Some(images.clone()));
		}
		Ok(self.get_inner().await?.get(name).cloned())
	}

	async fn fields(&self) -> Result<Vec<Label>, std::io::Error> {
		let mut fields = self.get_inner().await?.keys().cloned().collect::<Vec<_>>();
		if self.images.is_some() {
			#[expect(clippy::unwrap_used)]
			fields.push(Label::new("images").unwrap());
		}
		Ok(fields)
	}
}