RssParser.cs

//
// RssParser.cs
//
// Author:
//       Alan McGovern <alan@xamarin.com>
//
// Copyright 2011, Xamarin Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.

using System;
using System.Linq;
using System.Xml.Linq;
using System.Collections.Generic;

namespace LazyTableImages {

	public static class RssParser {

		// These are used to select the correct nodes and attributes from the Rss feed
		static readonly XName FeedElement = XName.Get ("feed", "http://www.w3.org/2005/Atom");
		static readonly XName EntryElement = XName.Get ("entry", "http://www.w3.org/2005/Atom");
		static readonly XName AppUrlElement = XName.Get ("id", "http://www.w3.org/2005/Atom");

		static readonly XName AppNameElement = XName.Get ("name", "https://rss.itunes.apple.com");
		static readonly XName ArtistElement = XName.Get ("artist", "https://rss.itunes.apple.com");
		static readonly XName ImageUrlElement = XName.Get ("image", "https://rss.itunes.apple.com");

		static readonly XName HeightAttribute = XName.Get ("height", "");

		public static List<App> Parse (string xml)
		{
			// Open the xml
			var doc = XDocument.Parse (xml);

			// We want to convert all the raw Xml nodes called 'entry' which
			// are in that namespace into instances of the 'App' class so they
			// can be displayed easily in the table.
			return doc.Element (FeedElement) // Select the 'feed' node.
				.Elements (EntryElement)     // Select all children with the name 'entry'.
				.Select (XmlElementToApp)    // Convert the 'entry' nodes to instances of the App class.
				.ToList ();                  // Return as a List<App>.
		}

		static App XmlElementToApp (XElement entry)
		{
			// Select an image node
			var imageUrlNode = entry.Elements (ImageUrlElement).FirstOrDefault ();

			// Parse the rest of the apps information from the XElement and
			// return the App instance.
			return new App {
				Name = entry.Element (AppNameElement).Value,
				Url = new Uri (entry.Element (AppUrlElement).Value),
				Artist = entry.Element (ArtistElement).Value,
				ImageUrl = new Uri (imageUrlNode.Value)
			};
		}
	}
}