//All contents copyright Logical Expressions, Inc. 2004

using System;
using System.Web;
using System.Xml;
using System.Configuration;
using System.IO;
using System.Data;
using System.Data.OleDb;
using System.Collections;

namespace LEI.RssLib
{
	public class RssHandler : IHttpHandler {

		public void ProcessRequest(HttpContext context) {
			// Get the file name from the query string and see if the file is in the cache:
			string fileName = Path.GetFileName(context.Request.Path);
			string cachedChan = context.Cache[fileName] as String;
			if( cachedChan == null ) {
				// The file is not in the cache.
				// Verify that the profile folder has been configured:
				string profileFolder = ConfigurationSettings.AppSettings["profileFolder"];
				if( profileFolder == null ) {
					context.Response.StatusCode = 404;
					context.Response.End();
					return;
				}
				// Verify that you have a profile for the requested feed:
				string profilePath = profileFolder + "\\" + fileName;
				if( !File.Exists(profilePath) ) {
					context.Response.StatusCode = 404;
					context.Response.End();
					return;
				}
				// 
				RssChannel chan = new RssChannel(profilePath);
				cachedChan = chan.GetResponse();
				double cacheTimeout;
				string appCacheTimeout = ConfigurationSettings.AppSettings["cacheTimeout"];
				if( appCacheTimeout == null )
					cacheTimeout = 15;
				else
					cacheTimeout = double.Parse(appCacheTimeout);
				context.Cache.Insert(fileName, cachedChan, null, DateTime.Now.AddMinutes(cacheTimeout), TimeSpan.Zero);
			}
			context.Response.ContentType = "text/xml";
			context.Response.Write(cachedChan);
		}

		public bool IsReusable {
			get {
				return true;
			}
		}

	}

	internal class RssChannel {
		private string _title;
		private string _link;
		private string _description;
		private string _language;
		private string _itemSql;
		private string _itemConn;
		private string _profilePath;
		private string _linkFormat;
		private string _guidFormat;
		private string _guidIsPermanent;
		private ArrayList _items;

		public RssChannel(string profilePath) {
			_profilePath = profilePath;
			Load();
		}
		
		public string ItemConn {
			get { return( _itemConn ); }
			set { _itemConn = value; }
		}
		
		public string ItemSql {
			get { return( _itemSql ); }
			set { _itemSql = value; }
		}

		public string Title {
			get { return( _title ); }
			set { _title = value; }
		}
		
		public string Link {
			get { return( _link ); }
			set { _link = value; }
		}
		
		public string Description {
			get { return( _description ); }
			set { _description = value; }
		}
		
		public string Language {
			get { return( _language ); }
			set { _language = value; }
		}

		public RssItem this[int index] {
			get {
				if( index < _items.Count)
					return( (RssItem) _items[index] );
				return( null );
			}
		}

		public string GetResponse() {
			XmlElement workNode;
			XmlElement itemNode;
			XmlAttribute workAttr;
			RssItem thisItem;
			XmlDocument rssDoc = new XmlDocument();
			// Create the rss document node and set the version attribute:
			XmlElement docNode = rssDoc.CreateElement("rss");
			XmlAttribute attr = rssDoc.CreateAttribute("version");
			attr.Value = "2.0";
			docNode.Attributes.Append(attr);
			rssDoc.AppendChild(docNode);
			// Create the channel element and its subelements:
			XmlElement chanNode = rssDoc.CreateElement("channel");
			docNode.AppendChild(chanNode);
			workNode = rssDoc.CreateElement("title");
			workNode.InnerText = _title;
			chanNode.AppendChild(workNode);
			workNode = rssDoc.CreateElement("link");
			workNode.InnerText = _link;
			chanNode.AppendChild(workNode);
			workNode = rssDoc.CreateElement("description");
			workNode.InnerText = _description;
			chanNode.AppendChild(workNode);
			workNode = rssDoc.CreateElement("language");
			workNode.InnerText = _language;
			chanNode.AppendChild(workNode);
			// Append item nodes to the channel:
			for( int index=0; index < _items.Count; index++ ) {
				thisItem = (RssItem) _items[index];
				itemNode = rssDoc.CreateElement("item");
				chanNode.AppendChild(itemNode);
				workNode = rssDoc.CreateElement("title");
				workNode.InnerText = thisItem.Title;
				itemNode.AppendChild(workNode);
				workNode = rssDoc.CreateElement("description");
				workNode.InnerText = thisItem.Description;
				itemNode.AppendChild(workNode);
				workNode = rssDoc.CreateElement("link");
				workNode.InnerText = thisItem.Link;
				itemNode.AppendChild(workNode);
				workNode = rssDoc.CreateElement("pubDate");
				workNode.InnerText = thisItem.PubDate;
				itemNode.AppendChild(workNode);
				workNode = rssDoc.CreateElement("guid");
				workAttr = rssDoc.CreateAttribute("isPermaLink");
				workAttr.Value = _guidIsPermanent;
				workNode.Attributes.Append(workAttr);
				workNode.InnerText = thisItem.GUID;
				itemNode.AppendChild(workNode);
			}
			return( rssDoc.OuterXml );
		}

		private void Load() {
			_items = new ArrayList();
			XmlDocument profile = new XmlDocument();
			// The profile is an xml document that provides configuration 
			// data for the feed. Load the file into an XmlDocument object:
			try {
				profile.Load(_profilePath);
			}
			catch (Exception e) {
				HttpContext.Current.Response.Write(string.Format("<p>{0}: {1}</p>", e.Message, _profilePath));
				return;
			}
			// Set channel properties from the profile:
			_title = profile.SelectSingleNode("/RssProfile/Title").InnerText;
			_link = profile.SelectSingleNode("/RssProfile/Link").InnerText;
			_description = profile.SelectSingleNode("/RssProfile/Description").InnerText;
			_language = profile.SelectSingleNode("/RssProfile/Language").InnerText;
			_itemConn = profile.SelectSingleNode("/RssProfile/ItemConnection").InnerText;
			_itemSql = profile.SelectSingleNode("/RssProfile/ItemSql").InnerText;
			_linkFormat = profile.SelectSingleNode("/RssProfile/LinkFormat").InnerText;
			_guidFormat = profile.SelectSingleNode("/RssProfile/GUIDFormat").InnerText;
			_guidIsPermanent = profile.SelectSingleNode("/RssProfile/GUIDIsPermanent").InnerText;
			// Retrieve items from the database:
			OleDbConnection conn = new OleDbConnection(_itemConn);
			IDbCommand cmd = new OleDbCommand(_itemSql);
			try {
				conn.Open();
				cmd.Connection = conn;
				IDataReader reader = cmd.ExecuteReader();
				while( reader.Read() ) {
					RssItem thisItem = new RssItem(reader, _linkFormat, _guidFormat);
					_items.Add(thisItem);
				}
				reader.Close();
				reader.Dispose();
				conn.Close();
			}
			finally {
				conn.Dispose();
			}
		}

		internal class RssItem {
			private string _title;
			private string _description;
			private string _link;
			private string _pubDate;
			private string _guid;

			internal RssItem( IDataReader reader, string linkFormat, string guidFormat ) {
				string itemId;
				itemId = reader[0].ToString();
				_title = reader[1].ToString();
				_description = reader[2].ToString();
				_pubDate = reader[3].ToString();
				// The linkFormat argument provides the URL of the 
				// item's document.
				_link = string.Format(linkFormat, itemId);
				// The guidFormat argument provides the string that uniquely identifies
				// the item for RSS readers.
				_guid = string.Format(guidFormat, itemId);
			}

			public string Title {
				get { return( _title ); }
				set { _title = value; }
			}

			public string Description 
			{
				get { return( _description ); }
				set { _description = value; }
			}

			public string Link 
			{
				get { return( _link ); }
				set { _link = value; }
			}

			public string PubDate 
			{
				get { return( _pubDate ); }
				set { _pubDate= value; }
			}

			public string GUID {
				get { return( _guid ); }
				set { _guid = value; }
			}

		}

	}
}