using System;
using System.IO;
using System.Collections;
using System.Xml.XPath;


namespace blurxml
{
	//////////////////////////////////////////////////////////////////////////////////////////////////////////
	//  HEADLINE CLASS
	//  represents a newsfeed headline (story title and url)
	//////////////////////////////////////////////////////////////////////////////////////////////////////////
	public class Headline
	{
		private string title;
		private string link;
	
		public Headline( )
		{
			title = null;
			link = null;
		}
		public Headline( string title, string link )
		{
			this.title = title;
			this.link = link;
		}
		public string Link
		{
			get{ return link; }
			set{ link = value; }
		}
		public string Title
		{
			get{ return title; } 
			set{ title = value; }
		}
	}//Headline class


	//////////////////////////////////////////////////////////////////////////////////////////////////////////
	//  NEWSFEED STRUCT
	//  represents a newsfeed (url, and processing specifics)
	////////////////////////////////////////////////////////////////////////////////////////////////////////// 
	public struct Newsfeed
	{
		private string siteurl;
		private string link;
		private string title;
		private string xpath;

		public Newsfeed( string url, string title, string link, string xpath )
		{
			this.siteurl = url;
			this.title = title;
			this.link = link;
			this.xpath = xpath;
		}
		public string Url
		{
			get{ return siteurl; }
			set{ siteurl = value; }
		}
		public string Link
		{
			get{ return link; }
			set{ link = value; }
		}
		public string Title
		{
			get{ return title; }
			set{ title = value; }
		}
		public string XPath
		{
			get{ return xpath; }
			set{ xpath = value; }
		}
	}//struct newsfeed

	//////////////////////////////////////////////////////////////////////////////////////////////////////////
	// HEADLINEFILTER CLASS
	// Operates on Headline arrays and maintains an internal list of the already processed headlines
	//////////////////////////////////////////////////////////////////////////////////////////////////////////
	public class HeadlineFilter
	{
		Headline[] current;

		public HeadlineFilter( Headline[] seed )
		{
			current = seed;
		}
	
		public Headline[] filter_for_new( Headline[] newest )
		{
			if( current == null )
			{
				current = newest;
				Console.WriteLine("current was null");
				return current;
			}
		
			Headline[] tmp = new Headline[ newest.Length ]; //worst-case: all are new
			bool contained = false;
			int fresh = 0;
		
			for( int i = 0; i < newest.Length; i++ )
			{
				for( int j = 0; j < current.Length; j++ )
				{
					if( String.Compare(newest[i].Title , current[j].Title) == 0 )
					{
						contained = true;
					}
				}//for j
				if( contained == false )
				{
					tmp[fresh] = newest[i];
					fresh++;
				}
				contained = false;
			}//for i
			Headline[] filtered = new Headline[ fresh ];
			Array.Copy( tmp , filtered , fresh );
			this.current = (Headline[] )newest.Clone(); //now *this* is the last array of Headlines we looked at
			return filtered;
		}


	}





	//////////////////////////////////////////////////////////////////////////////////////////////////////////
	// RSSREADER CLASS
	// Reads in and operates on the RSS XML feed
	//////////////////////////////////////////////////////////////////////////////////////////////////////////
	public class RSSReader
	{
		public Newsfeed slashdot;
		public Newsfeed wirednews;
		public Newsfeed anandtech;
		public Newsfeed newsforge;
		
	
		public RSSReader( )
		{
			//testing...
			//slashdot = new Newsfeed( "http://spinlock/slashdot.xml",
			//	"title","url","/backslash/story" );
			slashdot = new Newsfeed( "http://slashdot.org/slashdot.xml",
				"title","url","/backslash/story" );
		
			wirednews = new Newsfeed("http://www.wired.com/news_drop/netcenter/netcenter.rdf",
				"title","link","/rss/channel/item");
		
			anandtech = new Newsfeed( "http://www.newsisfree.com/HPE/xml/feeds/61/161.xml",
				"title","link","/rss/channel/item");
		
			newsforge = new Newsfeed( "http://newsforge.com/newsforge.xml",
				"title","url","/backslash/story" );

		

		}

	
	
		public Headline grab_headline_from_node( XPathNavigator nav , Newsfeed feed )
		{
			XPathNodeIterator iter = nav.SelectDescendants( XPathNodeType.Element, false);
			Headline headline = new Headline( );
		
			while( iter.MoveNext() )
			{
				string name = iter.Current.Name;
				
				if( name == feed.Title )
				{
					headline.Title = iter.Current.Value;
				}			
				if( name == feed.Link )
				{
					headline.Link = iter.Current.Value;
				}
							
			}
			return headline;
		}

	
	
		public Headline[] process_feed( Newsfeed feed )
		{
			int i = 0;
			Headline[] headlines = new Headline[ 15 ]; //RSS has maximum of 15 <item>'s per <channel>
			try
			{	
				XPathDocument xpdoc = new XPathDocument( feed.Url );
				XPathNavigator nav = xpdoc.CreateNavigator( );
				XPathNodeIterator iter = nav.Select( feed.XPath );
				for( i = 0; iter.MoveNext() ; i++ )
				{
					headlines[i] = grab_headline_from_node( iter.Current, feed );
				}
			
			}
			catch( Exception ex )
			{
				Console.WriteLine( ex.Message.ToString() );
			}
			Headline[] actual = new Headline[ i ];
			Array.Copy( headlines , actual , i );
			return actual;
		}
	
	
/*	
		public static void Main( )
		{	
			//  usage:
			 //		create a Headline array to store the headlines
			 //		create an RSSReader instance
			 //		call process_feed on any of the built-in websites, and grab the returned array
			 //			you can check how many headlines you have by calling .Length on the array
			 //
			Headline[] hlns;
			RSSReader xrr = new RSSReader( );                     // need one RSSReader
			HeadlineFilter filter;
			Newsfeed feed = new Newsfeed("c:\\program files\\bsnews\\headlines.xml",
				"title","link","/headlines/headline");
			
			hlns = xrr.process_feed( feed );
			foreach( Headline h in hlns )
				Console.WriteLine(h.Title+" :: "+h.Link );
		}

			// EXAMPLE 1 : SLASHDOT
			Console.WriteLine("//// Slashdot ////");             // THE ONLY PARTS THAT CHANGE:
			hlns = xrr.process_feed( xrr.slashdot );             // process slashdot
			Console.WriteLine( hlns.Length.ToString() );
			filter = new HeadlineFilter( hlns );
			foreach( Headline h in hlns )
				Console.WriteLine(h.Title+" :: "+h.Link );
		
			//NOW FILTER THE RESULTS (we're checking again soon, so they'll prolly be the same)
			//now filter slashdot by checking the website again and using it as input to the filter
			Headline[] filtered = filter.filter_for_new( xrr.process_feed(xrr.slashdot));
			foreach( Headline h in filtered )
				Console.WriteLine(h.Title+"  "+h.Link);
				
		
			// EXAMPLE 2 : ANANDTECH
			Console.WriteLine("//// Anandtech News ////");
			hlns = xrr.process_feed( xrr.anandtech );            // process anandtech
			Console.WriteLine( hlns.Length.ToString() );
			foreach( Headline h in hlns )
				Console.WriteLine(h.Title+" :: "+h.Link );
			// EXAMPLE 3 : NEWSFORGE
			Console.WriteLine("//// Newsforge ////");            // process Newsforge
			hlns = xrr.process_feed( xrr.newsforge );
			Console.WriteLine( hlns.Length.ToString() );
			foreach( Headline h in hlns )
				Console.WriteLine(h.Title+" :: "+h.Link );
		
		}
*/



	
	} 
}//blurxml namespace