{chapter.title}

use anyhow::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::Cursor; 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: &str, url_to_file: &HashMap<&Url, &FileEntry>, url_path_to_local: &HashMap<&str, &RelativePathBuf>, ) -> Result { // Setup the XML Reader and Writer. let mut reader = Reader::from_str(fragment); // 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(Cursor::new(Vec::new())); // Loop through the XML events and rewrite tags. loop { match reader.read_event() { 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), } } // Extract the modified fragment let processed_fragment = String::from_utf8(writer.into_inner().into_inner())?; // Wrap in EPUB XHTML Boilerplate. // EPUBs strictly require the w3 and idpf namespaces to validate properly. let full_xhtml = xml!( {chapter.title} {|doc| make_stylesheet_links(doc, chapter, chapter_dir, url_to_file)} {processed_fragment} ); Ok(full_xhtml.into_string()) } /// 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 tags with a "src" attribute. if tag_data.name().as_ref() == b"img" && key == 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()) { new_elem.push_attribute(("src", chapter_dir.relative(local_path).as_str())); continue; } } // Keep all other attributes intact. new_elem.push_attribute(attr); } new_elem }