FeedCenter/Application/FeedParsers/RdfParser.cs

using FeedCenter.Xml;
using Serilog;
using System.Xml;

namespace FeedCenter.FeedParsers;

internal class RdfParser : FeedParserBase
{
    public RdfParser(Feed feed) : base(feed) { }

    public override FeedReadResult ParseFeed(string feedText)
    {
        try
        {
            // Create the XML document
            var document = new XmlDocument { XmlResolver = null };

            // Load the XML document from the text
            document.LoadXml(feedText);

            // Create the namespace manager
            var namespaceManager = document.GetAllNamespaces();

            // Get the root node
            XmlNode rootNode = document.DocumentElement;

            // If we didn't find a root node then bail
            if (rootNode == null)
                return FeedReadResult.UnknownError;

            // Get the channel node
            var channelNode = rootNode.SelectSingleNode("default:channel", namespaceManager);

            if (channelNode == null)
                return FeedReadResult.InvalidXml;

            // Loop over all nodes in the channel node
            foreach (XmlNode node in channelNode.ChildNodes)
            {
                // Handle each node that we find
                switch (node.Name)
                {
                    case "title":
                        Feed.Title = System.Net.WebUtility.HtmlDecode(node.InnerText).Trim();
                        break;

                    case "link":
                        Feed.Link = node.InnerText.Trim();
                        break;

                    case "description":
                        Feed.Description = node.InnerText;
                        break;
                }
            }

            // Initialize the sequence number for items
            var sequence = 0;

            // Loop over all nodes in the channel node
            foreach (XmlNode node in rootNode.ChildNodes)
            {
                // Handle each node that we find
                switch (node.Name)
                {
                    case "item":
                        HandleFeedItem(node, ref sequence);
                        break;
                }
            }

            return FeedReadResult.Success;
        }
        catch (XmlException xmlException)
        {
            Log.Logger.Error(xmlException, "Exception: {0}", feedText);

            return FeedReadResult.InvalidXml;
        }
    }

    protected override FeedItem ParseFeedItem(XmlNode node)
    {
        // Create a new feed item
        var feedItem = FeedItem.Create();

        // Loop over all nodes in the feed node
        foreach (XmlNode childNode in node.ChildNodes)
        {
            // Handle each node that we find
            switch (childNode.Name.ToLower())
            {
                case "title":
                    feedItem.Title = System.Net.WebUtility.HtmlDecode(childNode.InnerText).Trim();
                    break;

                case "link":
                    feedItem.Link = childNode.InnerText.Trim();

                    // RDF doesn't have a GUID node so we'll just use the link
                    feedItem.Guid = feedItem.Link;

                    break;

                case "description":
                    feedItem.Description = System.Net.WebUtility.HtmlDecode(childNode.InnerText);
                    break;
            }
        }

        return feedItem;
    }
}