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using System;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
using System.Xml.Linq;
using VersOne.Epub.Environment;
using VersOne.Epub.Options;
using VersOne.Epub.Schema;
using VersOne.Epub.Utils;
namespace VersOne.Epub.Internal
{
internal class Epub3NavDocumentReader
{
private readonly EpubReaderOptions epubReaderOptions;
public Epub3NavDocumentReader(EpubReaderOptions? epubReaderOptions = null)
{
this.epubReaderOptions = epubReaderOptions ?? new EpubReaderOptions();
}
public async Task<Epub3NavDocument?> ReadEpub3NavDocumentAsync(IZipFile epubFile, string contentDirectoryPath, EpubPackage package)
{
EpubManifestItem navManifestItem = package.Manifest.Items.Find(item => item.Properties != null && item.Properties.Contains(EpubManifestProperty.NAV));
if (navManifestItem == null)
{
if (package.EpubVersion == EpubVersion.EPUB_2)
{
return null;
}
else
{
throw new Epub3NavException("EPUB parsing error: NAV item not found in EPUB manifest.");
}
}
string navFileEntryPath = ContentPathUtils.Combine(contentDirectoryPath, navManifestItem.Href);
IZipFileEntry navFileEntry = epubFile.GetEntry(navFileEntryPath) ??
throw new Epub3NavException($"EPUB parsing error: navigation file {navFileEntryPath} not found in the EPUB file.");
if (navFileEntry.Length > Int32.MaxValue)
{
throw new Epub3NavException($"EPUB parsing error: navigation file {navFileEntryPath} is larger than 2 GB.");
}
XDocument navDocument;
using (Stream containerStream = navFileEntry.Open())
{
navDocument = await XmlUtils.LoadDocumentAsync(containerStream, epubReaderOptions.XmlReaderOptions).ConfigureAwait(false);
}
XNamespace xhtmlNamespace = navDocument.Root.Name.Namespace;
XElement htmlNode = navDocument.Element(xhtmlNamespace + "html") ?? throw new Epub3NavException("EPUB parsing error: navigation file does not contain html element.");
XElement bodyNode = htmlNode.Element(xhtmlNamespace + "body") ?? throw new Epub3NavException("EPUB parsing error: navigation file does not contain body element.");
List<Epub3Nav> navs = new();
ReadEpub3NavsWithinContainerElement(bodyNode, navs);
return new(navFileEntryPath, navs);
}
private static void ReadEpub3NavsWithinContainerElement(XElement containerElement, List<Epub3Nav> resultNavs)
{
foreach (XElement childElement in containerElement.Elements())
{
if (childElement.GetLowerCaseLocalName() == "nav")
{
Epub3Nav? epub3Nav = ReadEpub3Nav(childElement);
if (epub3Nav != null)
{
resultNavs.Add(epub3Nav);
}
}
else
{
ReadEpub3NavsWithinContainerElement(childElement, resultNavs);
}
}
}
private static Epub3Nav? ReadEpub3Nav(XElement navNode)
{
Epub3StructuralSemanticsProperty? type = null;
bool isHidden = false;
string? head = null;
Epub3NavOl? ol = null;
foreach (XAttribute navNodeAttribute in navNode.Attributes())
{
string attributeValue = navNodeAttribute.Value;
switch (navNodeAttribute.GetLowerCaseLocalName())
{
case "type":
type = Epub3StructuralSemanticsPropertyParser.ParseProperty(attributeValue);
break;
case "hidden":
isHidden = true;
break;
}
}
if (type == null)
{
return null;
}
foreach (XElement navChildNode in navNode.Elements())
{
switch (navChildNode.GetLowerCaseLocalName())
{
case "h1":
case "h2":
case "h3":
case "h4":
case "h5":
case "h6":
head = navChildNode.Value.Trim();
break;
case "ol":
ol = ReadEpub3NavOl(navChildNode);
break;
}
}
if (ol == null)
{
throw new Epub3NavException("EPUB parsing error: 'nav' element in the navigation file does not contain a required 'ol' element.");
}
return new(type, isHidden, head, ol);
}
private static Epub3NavOl ReadEpub3NavOl(XElement epub3NavOlNode)
{
bool isHidden = false;
List<Epub3NavLi> lis = new();
foreach (XAttribute navOlNodeAttribute in epub3NavOlNode.Attributes())
{
switch (navOlNodeAttribute.GetLowerCaseLocalName())
{
case "hidden":
isHidden = true;
break;
}
}
foreach (XElement navOlChildNode in epub3NavOlNode.Elements())
{
switch (navOlChildNode.GetLowerCaseLocalName())
{
case "li":
Epub3NavLi epub3NavLi = ReadEpub3NavLi(navOlChildNode);
lis.Add(epub3NavLi);
break;
}
}
return new(isHidden, lis);
}
private static Epub3NavLi ReadEpub3NavLi(XElement epub3NavLiNode)
{
Epub3NavAnchor? anchor = null;
Epub3NavSpan? span = null;
Epub3NavOl? childOl = null;
foreach (XElement navLiChildNode in epub3NavLiNode.Elements())
{
switch (navLiChildNode.GetLowerCaseLocalName())
{
case "a":
Epub3NavAnchor epub3NavAnchor = ReadEpub3NavAnchor(navLiChildNode);
anchor = epub3NavAnchor;
break;
case "span":
Epub3NavSpan epub3NavSpan = ReadEpub3NavSpan(navLiChildNode);
span = epub3NavSpan;
break;
case "ol":
Epub3NavOl epub3NavOl = ReadEpub3NavOl(navLiChildNode);
childOl = epub3NavOl;
break;
}
}
if (anchor == null && span == null)
{
throw new Epub3NavException("EPUB parsing error: 'li' element in the navigation file must contain either an 'a' element or a 'span' element.");
}
return new(anchor, span, childOl);
}
private static Epub3NavAnchor ReadEpub3NavAnchor(XElement epub3NavAnchorNode)
{
string? href = null;
string text;
string? title = null;
string? alt = null;
Epub3StructuralSemanticsProperty? type = null;
foreach (XAttribute navAnchorNodeAttribute in epub3NavAnchorNode.Attributes())
{
string attributeValue = navAnchorNodeAttribute.Value;
switch (navAnchorNodeAttribute.GetLowerCaseLocalName())
{
case "href":
href = Uri.UnescapeDataString(attributeValue);
break;
case "title":
title = attributeValue;
break;
case "alt":
alt = attributeValue;
break;
case "type":
type = Epub3StructuralSemanticsPropertyParser.ParseProperty(attributeValue);
break;
}
}
text = epub3NavAnchorNode.Value.Trim();
return new(href, text, title, alt, type);
}
private static Epub3NavSpan ReadEpub3NavSpan(XElement epub3NavSpanNode)
{
string text;
string? title = null;
string? alt = null;
foreach (XAttribute navSpanNodeAttribute in epub3NavSpanNode.Attributes())
{
string attributeValue = navSpanNodeAttribute.Value;
switch (navSpanNodeAttribute.GetLowerCaseLocalName())
{
case "title":
title = attributeValue;
break;
case "alt":
alt = attributeValue;
break;
}
}
text = epub3NavSpanNode.Value.Trim();
return new(text, title, alt);
}
}
}
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