using System;
using System.Collections.Generic;
using System.IO;
using System.Text;
using System.Linq;
using System.Text.RegularExpressions;
using System.Threading;
using System.Windows.Threading;
using Ticker.Models;
using Ticker.Helper;

namespace Ticker.Animation
{
  public class FeedManager
  {
    private static int FEED_DEFAULT_INTERVAL_MINUTES=1;
    private static String FEED_CACHE_FILE_NAME="feedcache.txt";
    private readonly Dictionary<string, FeedItem> feedItems = new Dictionary<string, FeedItem>();
    private DispatcherTimer dispatcherTimer = new DispatcherTimer(); 
    public event EventHandler<ItemEventArgs<FeedItem>> NewFeedItem;
    public delegate List<FeedItem> GetFeedItemsEventHandler();
    public event GetFeedItemsEventHandler FeedSourceEventHandler;
    private bool stop = false;
    private bool isInit=true;
    public FeedManager()
    {                                                                                                                
      ReadCache();
      dispatcherTimer.Tick += DispatcherTimer_Tick;
      dispatcherTimer.Interval = new TimeSpan(0, FEED_DEFAULT_INTERVAL_MINUTES, 0);
    }
    public virtual void Dispose()
    {
      Stop();
    }
    public void MarkFeedAsRead(FeedItem item)
    {
      if(!feedItems.ContainsKey(item.Guid))return;
      feedItems[item.Guid].Read = true;
      WriteCache(item);
    }
    public int GetFeedItemCount()
    {
      int count=0;
      lock(feedItems)
      {
        if(null==feedItems||0==feedItems.Count)return count;
        List<FeedItem> feedItemsList=new List<FeedItem>(feedItems.Values);
        count=(from FeedItem feedItem in feedItemsList where feedItem.Read==false select feedItem).Count();
      }
      return count;
    }
    private void DispatcherTimer_Tick(object sender, EventArgs e)
    {
      Go();
    }
    public int FeedIntervalMinutes
    {
      get{return dispatcherTimer.Interval.Minutes;}
      set{dispatcherTimer.Interval=new TimeSpan(0,value,0);}
    }
    public void Start()
    {
      stop = false;
      Go();
      dispatcherTimer.Start();
    }
    public void Stop()
    {
      if(stop)return;
      if(null!=dispatcherTimer)dispatcherTimer.Stop();
      stop = true;
    }
    private void Go()
    {
      if(stop)return;
      if(isInit)
      {
        isInit=false;
        AddOpeningBanner();
      }
      ThreadPool.QueueUserWorkItem(LoadFeed,null);
    }
// ***************************************************************************************************************************************************
// *************************************************************************** F E E D  C A C H E ****************************************************
// ***************************************************************************************************************************************************
    private void ReadCache()
    {
      lock(feedItems)
      {
        feedItems.Clear();
        List<FeedItem> cacheItems=FeedSerializer.Deserialize(FEED_CACHE_FILE_NAME);
        foreach(FeedItem feedItem in cacheItems)
        {
          if(!feedItems.ContainsKey(feedItem.Guid))feedItems.Add(feedItem.Guid,feedItem);
        }
      }
    }
    private void WriteCache(FeedItem feedItem)
    {
      lock(feedItems)
      {
        List<FeedItem> cacheItems=new List<FeedItem>(feedItems.Values);
        FeedSerializer.Serialize(FEED_CACHE_FILE_NAME,DateTime.Today,feedItem);
      }
    }
// ***************************************************************************************************************************************************
    private void AddOpeningBanner()
    {
      FeedItem feedItem=new FeedItem();
      DateTime today=DateTime.Now;
      feedItem.Description="TradeBlotter";
      feedItem.Title=today.ToLongDateString()+" "+today.ToLongTimeString();
      feedItem.Guid=today.ToLongTimeString();
      feedItem.Link="https://www.time.gov/";
      feedItem.Source="";
      feedItem.PubDate=today.ToLongDateString();
      feedItems.Add(feedItem.Guid,feedItem);
      if (NewFeedItem != null) NewFeedItem(this, new ItemEventArgs<FeedItem>(feedItem));
    }
    private void LoadFeed(object state)
    {
      try
      {
        List<FeedItem> newFeedItems=null;
        if(null==FeedSourceEventHandler)return;
        newFeedItems=FeedSourceEventHandler();
        if(null==newFeedItems||0==newFeedItems.Count)return;
        foreach (FeedItem item in newFeedItems)
        {
          if (stop) return;
          if (feedItems.ContainsKey(item.Guid)) continue;
          item.Title = Clean(item.Title).Replace("\r","").Replace("\n","");
          item.Description = Clean(item.Description);
          lock (feedItems)
          {
            feedItems.Add(item.Guid, item);    
          }
          if (NewFeedItem != null) NewFeedItem(this, new ItemEventArgs<FeedItem>(item));
        }
      }
      catch(Exception)
      {
      }
    }
    private static string Clean(string input)
    {
      string output = input.Trim();
      output = output.Replace("&#39;", "'");
      output = output.Replace("&amp;", "&");
      output = output.Replace("&quot;", "\"");
      output = output.Replace("&nbsp;", " ");
      output = RemoveHTMLTags(output);
      return output;
    }
    private static string RemoveHTMLTags(string text)
    {
      string regularExpressionString = "<.+?>";
      Regex r = new Regex(regularExpressionString, RegexOptions.Singleline);
      return r.Replace(text, "");
    }
  }
}