Extractor rewrite

crates/pile-value/src/extract/item/epub/epub_meta.rs

@@ -0,0 +1,95 @@
+use epub::doc::EpubDoc;
+use pile_config::Label;
+use std::{
+	collections::HashMap,
+	sync::{Arc, OnceLock},
+};
+use tracing::trace;
+
+use crate::{
+	extract::traits::ObjectExtractor,
+	value::{Item, PileValue, SyncReadBridge},
+};
+
+pub struct EpubMetaExtractor {
+	item: Item,
+	output: OnceLock<HashMap<Label, PileValue>>,
+}
+
+impl EpubMetaExtractor {
+	pub fn new(item: &Item) -> Self {
+		Self {
+			item: item.clone(),
+			output: OnceLock::new(),
+		}
+	}
+
+	async fn get_inner(&self) -> Result<&HashMap<Label, PileValue>, std::io::Error> {
+		if let Some(x) = self.output.get() {
+			return Ok(x);
+		}
+
+		let key = self.item.key();
+		let ext = key.as_str().rsplit('.').next();
+		if !matches!(ext, Some("epub")) {
+			return Ok(self.output.get_or_init(HashMap::new));
+		}
+
+		let reader = SyncReadBridge::new_current(self.item.read().await?);
+		let raw_meta = tokio::task::spawn_blocking(move || {
+			let doc = EpubDoc::from_reader(reader)
+				.map_err(|e| std::io::Error::new(std::io::ErrorKind::InvalidData, e.to_string()))?;
+
+			let fields: &[&'static str] = &[
+				"title",
+				"creator",
+				"description",
+				"language",
+				"publisher",
+				"date",
+				"subject",
+				"identifier",
+			];
+
+			let meta: Vec<(&'static str, Option<String>)> =
+				fields.iter().map(|&key| (key, doc.mdata(key))).collect();
+
+			Ok::<_, std::io::Error>(meta)
+		})
+		.await
+		.map_err(std::io::Error::other)?;
+
+		let raw_meta = match raw_meta {
+			Ok(x) => x,
+			Err(error) => {
+				trace!(message = "Could not process epub", ?error, key = ?self.item.key());
+				return Ok(self.output.get_or_init(HashMap::new));
+			}
+		};
+
+		let mut output: HashMap<Label, PileValue> = HashMap::new();
+
+		#[expect(clippy::unwrap_used)]
+		for (key, val) in raw_meta {
+			let label = Label::new(key).unwrap();
+			let value = match val {
+				Some(s) => PileValue::String(Arc::new(s.into())),
+				None => PileValue::Null,
+			};
+			output.insert(label, value);
+		}
+
+		return Ok(self.output.get_or_init(|| output));
+	}
+}
+
+#[async_trait::async_trait]
+impl ObjectExtractor for EpubMetaExtractor {
+	async fn field(&self, name: &Label) -> Result<Option<PileValue>, std::io::Error> {
+		Ok(self.get_inner().await?.get(name).cloned())
+	}
+
+	async fn fields(&self) -> Result<Vec<Label>, std::io::Error> {
+		Ok(self.get_inner().await?.keys().cloned().collect())
+	}
+}