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|
use anyhow::{Context, Result};
use ogrim::{Document, xml};
use quick_xml::events::{BytesEnd, BytesStart, BytesText, 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<R: BufRead, W: Write>(
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!(
<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml" xmlns:epub="http://www.idpf.org/2007/ops"
lang={epub_data.language} xml:lang={epub_data.language}>
<head>
<title>{chapter.title}</title>
{|doc| make_stylesheet_links(doc, chapter, chapter_dir, url_to_file)}
</head>
<body>
</body>
</html>
);
let wrapper_suffix = "</body></html>";
let wrapper_prefix = wrapper_xhtml
.as_str()
.strip_suffix(wrapper_suffix)
.context("Wrapper must end with </body></html>")?;
// 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. <img></img>).
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(())
}
/// Processes the fragment and outputs a complete, EPUB-ready XHTML document.
pub fn write_modified_opf<R: BufRead, W: Write>(
opf_input: R,
mut out: &mut W,
description: &str,
) -> Result<()> {
// Setup the XML Reader and Writer.
let mut reader = Reader::from_reader(opf_input);
// Preserve spacing for easier diffs.
reader.config_mut().trim_text(false);
let mut writer = Writer::new(&mut out);
// Loop through the XML events and check tags.
let mut buffer = Vec::new();
let mut desc_found = false;
loop {
match reader.read_event_into(&mut buffer) {
Ok(Event::Start(tag_data)) => {
// Simply record if dc:description found.
if tag_data.name().as_ref() == b"dc:description" {
desc_found = true;
}
// Then pass through unmodified.
writer.write_event(Event::Start(tag_data))?;
}
Ok(Event::End(tag_data)) => {
// Write description if end of metadata is reached without finding one.
if tag_data.name().as_ref() == b"metadata" && !desc_found {
writer.write_event(Event::Start(BytesStart::new("dc:description")))?;
writer.write_event(Event::Text(BytesText::new(description)))?;
writer.write_event(Event::End(BytesEnd::new("dc:description")))?;
}
// Pass through unmodified.
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),
}
}
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,
<link rel="stylesheet" type={e.media_type} href={rel_path} />
);
})
}
/// 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
}
|
