private static async Task<EpubNavigationPoint> ReadNavigationPointAsync(XmlReader reader)
{
EpubNavigationPoint result = new EpubNavigationPoint();
//we have to skip first entry as it could be empty after new sub-reader created
if (reader.NodeType == XmlNodeType.None) await reader.ReadAsync();
//Now the pointer should point to the <navPoint> itself
while (reader.MoveToNextAttribute()) //Doing this we just passing through <navPoint> tag
{
switch (reader.LocalName.ToLowerInvariant()) //We have to collect all possible attributes from the <navPoint>
{
case "id":
result.Id = reader.Value;
break;
case "class":
result.Class = reader.Value;
break;
case "playorder":
result.PlayOrder = reader.Value;
break;
}
}
if (String.IsNullOrWhiteSpace(result.Id))
throw new Exception("Incorrect EPUB navigation point: point ID is missing");
result.NavigationLabels = new List<EpubNavigationLabel>();
result.ChildNavigationPoints = new List<EpubNavigationPoint>();
// We need to make sure that we will return pointer back to <navPoint> entry after reading all attributes
reader.MoveToElement();
//Now we are looking for subnodes - navLabel, content and sub-navPoints
while (await reader.ReadAsync())
{
if (reader.NodeType != XmlNodeType.EndElement)
switch (reader.LocalName.ToLowerInvariant())
{
case "navlabel":
EpubNavigationLabel navigationLabel = await ReadNavigationLabelAsync(reader);// Adding label to collection
result.NavigationLabels.Add(navigationLabel);
break;
case "content":
EpubNavigationContent content = await ReadNavigationContentAsync(reader); //Adding content to collection
result.Content = content;
break;
case "navpoint": //Yeep. Looks like we found a <navPoint> sub-node
XmlReader subTree = reader.ReadSubtree(); //Cooking a separate sub-reader scope for this node to separate it from the others siblings
EpubNavigationPoint childNavigationPoint = await ReadNavigationPointAsync(subTree);// I hate recursion...
//Adding a child to a collection
result.ChildNavigationPoints.Add(childNavigationPoint);
subTree.Dispose();
break;
}
};
return result;
}
private static EpubNavigationPoint ReadNavigationPoint(XmlNode navigationPointNode)
{
EpubNavigationPoint result = new EpubNavigationPoint();
foreach (XmlAttribute navigationPointNodeAttribute in navigationPointNode.Attributes)
{
string attributeValue = navigationPointNodeAttribute.Value;
switch (navigationPointNodeAttribute.Name.ToLowerInvariant())
{
case "id":
result.Id = attributeValue;
break;
case "class":
result.Class = attributeValue;
break;
case "playOrder":
result.PlayOrder = attributeValue;
break;
}
}
if (String.IsNullOrWhiteSpace(result.Id))
throw new Exception("Incorrect EPUB navigation point: point ID is missing");
result.NavigationLabels = new List<EpubNavigationLabel>();
result.ChildNavigationPoints = new List<EpubNavigationPoint>();
foreach (XmlNode navigationPointChildNode in navigationPointNode.ChildNodes)
switch (navigationPointChildNode.LocalName.ToLowerInvariant())
{
case "navlabel":
EpubNavigationLabel navigationLabel = ReadNavigationLabel(navigationPointChildNode);
result.NavigationLabels.Add(navigationLabel);
break;
case "content":
EpubNavigationContent content = ReadNavigationContent(navigationPointChildNode);
result.Content = content;
break;
case "navpoint":
EpubNavigationPoint childNavigationPoint = ReadNavigationPoint(navigationPointChildNode);
result.ChildNavigationPoints.Add(childNavigationPoint);
break;
}
if (!result.NavigationLabels.Any())
throw new Exception(String.Format("EPUB parsing error: navigation point {0} should contain at least one navigation label", result.Id));
if (result.Content == null)
throw new Exception(String.Format("EPUB parsing error: navigation point {0} should contain content", result.Id));
return result;
}