{chapter.title}

use anyhow::{Context, Result}; use ogrim::{Document, xml}; use quick_xml::events::{BytesStart, Event}; use quick_xml::{Reader, Writer}; use relative_path::{RelativePath, RelativePathBuf}; use std::collections::HashMap; use std::io::{BufRead, Write}; use url::Url; use crate::models::{Chapter, EpubResponse, FileEntry}; /// Checks if a tag is a standard HTML void element that shouldn't have a closing tag. fn is_html_void_tag(name: &[u8]) -> bool { matches!( name, b"area" | b"base" | b"br" | b"col" | b"embed" | b"hr" | b"img" | b"input" | b"link" | b"meta" | b"param" | b"source" | b"track" | b"wbr" ) } /// Processes the fragment and outputs a complete, EPUB-ready XHTML document. pub fn build_epub_chapter( epub_data: &EpubResponse, chapter: &Chapter, chapter_dir: &RelativePath, fragment_input: R, url_to_file: &HashMap<&Url, &FileEntry>, url_path_to_local: &HashMap<&str, &RelativePathBuf>, mut out: &mut W, ) -> Result<()> { // EPUB XHTML Boilerplate wrapper. // EPUBs strictly require the w3 and idpf namespaces to validate properly. let wrapper_xhtml = xml!( {chapter.title} {|doc| make_stylesheet_links(doc, chapter, chapter_dir, url_to_file)} ); let wrapper_suffix = ""; let wrapper_prefix = wrapper_xhtml .as_str() .strip_suffix(wrapper_suffix) .context("Wrapper must end with ")?; // Write wrapper prefix to output first. out.write_all(wrapper_prefix.as_bytes())?; out.write_all(b"\n")?; // Setup the XML Reader and Writer. let mut reader = Reader::from_reader(fragment_input); // Preserve spacing for EPUB text formatting. reader.config_mut().trim_text(false); // Fragments could have unmatched tags - tell the parser not to panic if so. reader.config_mut().check_end_names = false; let mut writer = Writer::new(&mut out); // Loop through the XML events and rewrite tags. let mut buffer = Vec::new(); loop { match reader.read_event_into(&mut buffer) { Ok(Event::Start(tag_data)) => { // If it is a void tag, convert it to a self-closing XML tag. let tag_type = if is_html_void_tag(tag_data.name().as_ref()) { Event::Empty } else { Event::Start }; writer.write_event(tag_type(rewrite_attributes( &tag_data, url_path_to_local, chapter_dir, )))?; } Ok(Event::Empty(tag_data)) => { // If tags are already empty, leave them as-is. writer.write_event(Event::Empty(rewrite_attributes( &tag_data, url_path_to_local, chapter_dir, )))?; } Ok(Event::End(tag_data)) => { // Silently drop closing tags for void elements if they exist (e.g. ). if !is_html_void_tag(tag_data.name().as_ref()) { writer.write_event(Event::End(tag_data))?; } } Ok(Event::Eof) => break, Ok(tag_data) => writer.write_event(tag_data)?, // Pass through text, comments, etc. unmodified. Err(e) => anyhow::bail!(e), } } // Finish by flushing wrapper suffix to output. out.write_all(b"\n")?; out.write_all(wrapper_suffix.as_bytes())?; Ok(()) } /// Helper function add link elements for stylesheets to an xml Document. fn make_stylesheet_links( doc: &mut Document, chapter: &Chapter, chapter_dir: &RelativePath, url_to_file: &HashMap<&Url, &FileEntry>, ) { chapter .related_assets .stylesheets .iter() .filter_map(|u| url_to_file.get(u)) .for_each(|e| { let rel_path = chapter_dir.relative(&e.full_path); xml!(doc, ); }) } /// Helper function to inspect tags and rewrite the elements' attributes. fn rewrite_attributes<'a>( tag_data: &BytesStart<'a>, url_path_to_local: &HashMap<&str, &RelativePathBuf>, chapter_dir: &RelativePath, ) -> BytesStart<'static> { let name = String::from_utf8_lossy(tag_data.name().as_ref()).into_owned(); let mut new_elem = BytesStart::new(name); for attr in tag_data.attributes().filter_map(Result::ok) { let key = attr.key.as_ref(); // Intercept element attributes which could contain links to resources. if matches!( (tag_data.name().as_ref(), key), (b"img", b"src") | (b"source", b"src") | (b"video", b"src") | (b"audio", b"src") | (b"a", b"href") | (b"link", b"href") | (b"object", b"data") | (b"embed", b"src") | (b"iframe", b"src") | (b"track", b"src") ) { let url = String::from_utf8_lossy(&attr.value); // If we have a local path, inject it instead of the absolute URL. if let Some(local_path) = url_path_to_local.get(url.as_ref()) { let key = String::from_utf8_lossy(key); new_elem.push_attribute((key.as_ref(), chapter_dir.relative(local_path).as_str())); continue; } } // Keep all other attributes intact. new_elem.push_attribute(attr); } new_elem }