Files
pile/crates/pile-value/src/extract/item/epub/epub_meta.rs
2026-03-16 09:56:46 -07:00

96 lines
2.3 KiB
Rust

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())
}
}