using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Configuration;
using CodeCafe.Web;
using System.IO;
using System.Security;
using System.Xml;

/// <summary>
/// Summary description for RSSGenerator
/// </summary>
public struct FeedItem
{
  public string Title;
  public string Link;
  public string Description;
  public DateTime PubDate;
}

public class RSSGenerator
{
  protected string RSSFile = "";
  protected List<FeedItem> Feed = new List<FeedItem>();
  protected string RSSFilename = "";

  private string[] ShortMonth = new string[12] { "jan", "feb", "mar", "apr", "may", "jun", "jul", "aug", "sep", "oct", "nov", "dec" };
 
  public string Title
  { get; set; }

  public string Description
  { get; set; }

  public string WebsiteURL
  { get; set; }

  public string RSSFileURL
  { get; set; }

  public int MaxFeeds
  { get; set; }
  

  /****************************************************************************************************/
  /// <summary>
  /// Initializes a new instance of the <see cref="RSSGenerator"/> class.
  /// </summary>
  /// <param name="filename">The filename.</param>
  public RSSGenerator(string filename)
	{
    RSSFilename = AddServerPath(filename);
    //todo: check if file exists - if it does then load default values from the file
    LoadDefaultValues();
    LoadExistingFeedItems();
	}

  /****************************************************************************************************/
  /// <summary>
  /// Loads the default values from web.config .
  /// </summary>
  protected void LoadDefaultValues()
  {
    if (!string.IsNullOrEmpty(ConfigurationManager.AppSettings.Get("RSSTitle")))
      Title = ConfigurationManager.AppSettings.Get("RSSTitle");

    if (!string.IsNullOrEmpty(ConfigurationManager.AppSettings.Get("RSSDescription")))
      Description = ConfigurationManager.AppSettings.Get("RSSDescription");

    if (!string.IsNullOrEmpty(ConfigurationManager.AppSettings.Get("RSSWebsiteURL")))
      WebsiteURL = ConfigurationManager.AppSettings.Get("RSSWebsiteURL");

    if (!string.IsNullOrEmpty(ConfigurationManager.AppSettings.Get("RSSFileURL")))
      RSSFileURL = ConfigurationManager.AppSettings.Get("RSSFileURL");

    if (!string.IsNullOrEmpty(ConfigurationManager.AppSettings.Get("RSSMaxFeeds")))
      MaxFeeds = Utils.StrToIntDef(ConfigurationManager.AppSettings.Get("RSSMaxFeeds"), 10);
    else
      MaxFeeds = 10;
    
    //<add key="RSSTitle" value="Pharmaceutical Blue Book" />
    //<add key="RSSDescription" value="Up-to-date pricing for Medicines and Scheduled Substances." />
    //<add key="RSSWebsiteURL" value="http://www.pbb.co.za" />
    //<add key="RSSFileURL" value="http://www.pbb.co.za/rss/updates.xml" />
    //<add key="RSSMaxFeeds" value="10" />
  }

  /****************************************************************************************************/
  /// <summary>
  /// Gets the month.
  /// </summary>
  /// <param name="MonthVal">The month val.</param>
  /// <returns></returns>
  private int GetMonth(string MonthVal)
  {
    int result = DateTime.Today.Month;
    for (int i = 0; i < 12; i++)
    {
      if (MonthVal.ToLower().Equals(ShortMonth[i]))
      {
        result = i + 1;
        break;
      }
    }
    return result;
  }

  /****************************************************************************************************/
  /// <summary>
  /// Converts to date time.
  /// </summary>
  /// <param name="RSSDate">The RSS date.</param>
  /// <returns></returns>
  private DateTime ConvertToDateTime(string RSSDate)
  {
    DateTime result = DateTime.Now;
    //Sun, 27 Mar 2011 18:33:22 +0100
    int day;
    int month;
    int year;

    int hour;
    int min;
    int sec;

    day = Utils.StrToIntDef(RSSDate.Substring(5, 2).Trim(), result.Day);
    month = GetMonth(RSSDate.Substring(8, 3).Trim());
    year = Utils.StrToIntDef(RSSDate.Substring(12, 4).Trim(), result.Year);

    hour = Utils.StrToIntDef(RSSDate.Substring(17, 2).Trim(), result.Hour);
    min = Utils.StrToIntDef(RSSDate.Substring(20, 2).Trim(), result.Minute);
    sec = Utils.StrToIntDef(RSSDate.Substring(23, 2).Trim(), result.Second);

    result = new DateTime(year, month, day, hour, min, sec);

    return result;
  }

  /****************************************************************************************************/
  /// <summary>
  /// Loads the existing feed items.
  /// </summary>
  private void LoadExistingFeedItems()
  {
    if (File.Exists(RSSFilename))
    {
      try
      {
        string xmlData = Utils.LoadFile(RSSFilename);
        XmlTextReader reader = new XmlTextReader(new StringReader(xmlData));
        FeedItem item = new FeedItem();
        while (reader.Read())
        {
          switch (reader.NodeType)
          {
            case XmlNodeType.Element:
              if (reader.Name.ToLower().Equals("item"))
                item = new FeedItem();

              if (reader.Name.ToLower().Equals("title"))
              {
                if (reader.Read())
                  if (reader.NodeType == XmlNodeType.Text)
                    item.Title = reader.Value;
              }

              if (reader.Name.ToLower().Equals("link"))
              {
                if (reader.Read())
                  if (reader.NodeType == XmlNodeType.Text)
                    item.Link = reader.Value;
              }

              if (reader.Name.ToLower().Equals("description"))
              {
                if (reader.Read())
                  if (reader.NodeType == XmlNodeType.Text)
                    item.Description = reader.Value;
              }

              if (reader.Name.ToLower().Equals("pubdate"))
              {
                if (reader.Read())
                  if (reader.NodeType == XmlNodeType.Text)
                  {
                    item.PubDate = ConvertToDateTime(reader.Value);
                  }
              }
              break;
            case XmlNodeType.Text:
              break;
            case XmlNodeType.EndElement:
              if (reader.Name.ToLower().Equals("item"))
              {
                Feed.Add(item);
              }
              break;
          }
        }
      }
      catch (Exception)
      {
      }
    }
  }

  /****************************************************************************************************/

  private bool ItemExists(FeedItem check)
  {
    bool result = false;
    foreach (FeedItem item in Feed)
    {
      result = item.Title.Equals(check.Title) && item.Description.Equals(check.Description) && item.Link.Equals(check.Link);
      if (result)    
        break;
    }
    return result;
  }

  /****************************************************************************************************/
  /// <summary>
  /// Adds an item to the feed.
  /// </summary>
  /// <param name="item">The item.</param>
  public void AddFeedItem(FeedItem item)
  {
    if(!ItemExists(item))
      Feed.Add(item);
  }

  /****************************************************************************************************/
  /// <summary>
  /// Exports the RSS File.
  /// </summary>
  public void ExportRSS()
  {
    AddRSSHeader();
    ListFeeds();
    AddRSSFooter();
    if (File.Exists(RSSFilename))
      File.Delete(RSSFilename);

    Utils.SaveFile(RSSFilename, RSSFile);
  }
  
  /****************************************************************************************************/
  /// <summary>
  /// Lists the feeds.
  /// </summary>
  private void ListFeeds()
  {
    Feed.Sort(delegate(FeedItem item1, FeedItem item2) { return item2.PubDate.CompareTo(item1.PubDate); }); //sort descending
    int idx = 1;

    foreach (FeedItem item in Feed)
    {
      if (idx < MaxFeeds)
      {
        RSSFile += "\t\t<item>\n";
        RSSFile += "\t\t\t<title>" + SecurityElement.Escape(item.Title) + "</title>\n";
        RSSFile += "\t\t\t<link>" + SecurityElement.Escape(item.Link) + "</link>\n";
        RSSFile += "\t\t\t<description>" + SecurityElement.Escape(item.Description) + "</description>\n";
        RSSFile += "\t\t\t<pubDate>" + item.PubDate.ToString("ddd, dd MMM yyyy HH:mm:ss") + " +0200</pubDate>\n";
        RSSFile += "\t\t</item>\n";
      }
      idx++;
    }
  }

  /****************************************************************************************************/
  /// <summary>
  /// Adds the RSS header.
  /// </summary>
  private void AddRSSHeader()
  {
    //e.g. http://www.freemarketfoundation.com/DynamicData/fmfpodcast.xml
    RSSFile += "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
    RSSFile += "<rss version=\"2.0\" xml:lang=\"en-US\" xmlns:atom=\"http://www.w3.org/2005/Atom\">\n";
    RSSFile += "\t<channel>\n";
    RSSFile += "\t\t<atom:link href=\"" + RSSFileURL + "\" rel=\"self\" type=\"application/rss+xml\" />\n";
    RSSFile += "\t\t<title>" + Title + "</title>\n";
    RSSFile += "\t\t<description>" + Description + "</description>\n";
    RSSFile += "\t\t<link>" + WebsiteURL + "</link>\n";
    RSSFile += "\t\t<lastBuildDate>" + DateTime.Now.ToString("ddd, dd MMM yyyy HH:mm:ss") + " +0200</lastBuildDate>\n";
    RSSFile += "\t\t<generator>Code Cafe RSS Feed Generator 1.0.0</generator>\n";
  }

  /****************************************************************************************************/
  /// <summary>
  /// Adds the RSS footer.
  /// </summary>
  private void AddRSSFooter()
  {
    RSSFile += "\t</channel>\n";
    RSSFile += "</rss>\n";
  }

  /*****************************************************************************************************/
  /// <summary>
  /// Adds the server path.
  /// </summary>
  /// <param name="Filename">The filename.</param>
  /// <returns></returns>
  private string AddServerPath(string Filename)
  {
    string result = Filename;
    if (Filename.StartsWith("~/"))
      result = System.Web.HttpContext.Current.Server.MapPath(Filename);
    return result;
  }

}