using System;
using System.Collections;
using System.Web;
using System.Text;
using System.IO;
using System.Xml;
using System.Text.RegularExpressions;

using Cuyahoga.Core;
using Cuyahoga.Core.Domain;
using Cuyahoga.Core.Service;
using Cuyahoga.Core.Util;
using Cuyahoga.Web.Util;

namespace Cuyahoga.Web
{
    /// <summary>
    /// Summary description for Rss.
    /// </summary>
    public class Rdf : System.Web.UI.Page
    {
        private CoreRepository _coreRepository;

        private void Page_Load(object sender, System.EventArgs e)
        {
            Context.Response.Clear();
            Context.Response.ContentType = "application/rdf+xml";
            Context.Response.ContentEncoding = Encoding.UTF8;

            if (Context.Request.QueryString["SectionId"] != null)
            {
                int sectionId = Int32.Parse(Context.Request.QueryString["SectionId"]);
                string pathInfo = Context.Request.PathInfo;
                string cacheKey = String.Format("RDF_{0}_{1}", sectionId, pathInfo);
                string content = null;

                if (Context.Cache[cacheKey] == null)
                {
                    // Get the data for the RSS feed because it's not in the cache yet.
                    // Use the same cache duration for the RSS feed as the Section.
                    this._coreRepository = (CoreRepository)HttpContext.Current.Items["CoreRepository"];
                    Section section = (Section)this._coreRepository.GetObjectById(typeof(Section), sectionId);
                    section.SessionFactoryRebuilt += new EventHandler(Section_SessionFactoryRebuilt);
                    ModuleBase module = section.CreateModule(UrlHelper.GetUrlFromSection(section));
                    // Create event handlers for NHibernate-related events that can occur in the module.

                    module.ModulePathInfo = pathInfo;
                    ISyndicatable syndicatableModule = module as ISyndicatable;
                    if (syndicatableModule != null)
                    {
                        RssChannel channel = syndicatableModule.GetRssFeed();
                        // Rss feed writer code from http://aspnet.4guysfromrolla.com/articles/021804-1.aspx
                        // Use an XmlTextWriter to write the XML data to a string...
                        StringWriter sw = new StringWriter();
                        XmlTextWriter writer = new XmlTextWriter(sw);
                        writer.Formatting = Formatting.Indented;

                        // write out 
                        writer.WriteStartElement("rdf:RDF");
                        writer.WriteAttributeString("xmlns", "http://purl.org/rss/1.0/");
                        writer.WriteAttributeString("xmlns:rdf", "http://www.w3.org/1999/02/22-rdf-syntax-ns#");
                        writer.WriteAttributeString("xmlns:dc", "http://purl.org/dc/elements/1.1/");
                        writer.WriteAttributeString("xmlns:sy", "http://purl.org/rss/1.0/modules/syndication/");
                        writer.WriteAttributeString("xmlns:admin", "http://webns.net/mvcb/");

                        // write out 
                        writer.WriteStartElement("channel");
                        writer.WriteAttributeString("rdf:about", Util.UrlHelper.GetSiteUrl());

                        // write out -level elements
                        writer.WriteElementString("title", channel.Title);
                        writer.WriteElementString("link", Util.UrlHelper.GetFullUrlFromSection(section) + pathInfo);
                        writer.WriteElementString("description", channel.Description);
                        writer.WriteElementString("dc:date", channel.PubDate.ToUniversalTime().ToString("s") + "-06:00");
                        //writer.WriteElementString("lastBuildDate", channel.LastBuildDate.ToUniversalTime().ToString("r"));

                        writer.WriteStartElement("admin:generatorAgent"); //, channel.Generator);
                        writer.WriteAttributeString("rdf:resource", "http://www.cuyahoga-project.org");
                        writer.WriteEndElement();

                        writer.WriteElementString("sy:updatePeriod", "hourly");
                        writer.WriteElementString("sy:updateFrequency", "1");

                        //write items list for channel description
                        writer.WriteStartElement("items");
                        writer.WriteStartElement("rdf:Seq");
                        foreach (RssItem item in channel.RssItems)
                        {
                            writer.WriteStartElement("rdf:li");
                            writer.WriteAttributeString("rdf:resource", Util.UrlHelper.GetFullUrlFromSection(section) + "/" + item.ItemId);
                            writer.WriteEndElement();
                        }
                        writer.WriteEndElement();
                        writer.WriteEndElement();

                        //close channel tag
                        writer.WriteEndElement();


                        // Regular expression to find relative urls
                        string expression = String.Format(@"=[""']{0}", UrlHelper.GetApplicationPath());
                        Regex regExUrl = new Regex(expression, RegexOptions.Singleline | RegexOptions.CultureInvariant | RegexOptions.Compiled);

                        //write each item
                        foreach (RssItem item in channel.RssItems)
                        {
                            // replace inline relative hyperlinks with full hyperlinks
                            if (item.Description != null)
                            {
                                item.Description = regExUrl.Replace(item.Description, String.Format(@"=""{0}/", UrlHelper.GetSiteUrl()));
                            }

                            // write out 
                            writer.WriteStartElement("item");

                            // write out -level information
                            writer.WriteAttributeString("rdf:about", Util.UrlHelper.GetFullUrlFromSection(section) + "/" + item.ItemId);

                            writer.WriteElementString("title", item.Title);
                            // TODO: Only supports ID's in the pathinfo now...
                            writer.WriteElementString("link", Util.UrlHelper.GetFullUrlFromSection(section) + "/" + item.ItemId);
                            writer.WriteElementString("description", item.Description);
                            writer.WriteElementString("dc:creator", item.Author);
                            writer.WriteElementString("dc:date", item.PubDate.ToUniversalTime().ToString("s") + "-06:00");
                            writer.WriteElementString("dc:subject", item.Category);

                            // write out 
                            writer.WriteEndElement();
                        }

                        // write out 
                        //writer.WriteEndElement();

                        // write out
                        writer.WriteEndElement();

                        content = sw.ToString();
                        // save the string in the cache
                        Cache.Insert(cacheKey, content, null, DateTime.Now.AddSeconds(section.CacheDuration), TimeSpan.Zero);

                        writer.Close();
                    }
                    else
                    {
                        throw new Exception(String.Format("The module {0} doesn't implement ISyndicatable", module.GetType().FullName));
                    }
                }
                else
                {
                    content = Context.Cache[cacheKey].ToString();
                }
                Context.Response.Write(content);
            }

            Context.Response.End();
        }

        #region Web Form Designer generated code
        override protected void OnInit(EventArgs e)
        {
            //
            // CODEGEN: This call is required by the ASP.NET Web Form Designer.
            //
            InitializeComponent();
            base.OnInit(e);
        }

        /// <summary>
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// </summary>
        private void InitializeComponent()
        {
            this.Load += new System.EventHandler(this.Page_Load);
        }
        #endregion

        private void Section_SessionFactoryRebuilt(object sender, EventArgs e)
        {
            // The SessionFactory was rebuilt, so the current NHibernate Session has become invalid.
            // This is handled by a simple reload of the page. 
            // TODO: handle more elegantly?
            if (Context.Items["VirtualUrl"] != null)
            {
                Context.Response.Redirect(Context.Items["VirtualUrl"].ToString());
            }
            else
            {
                Context.Response.Redirect(Context.Request.RawUrl);
            }
        }
    }
}