using System;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Ink;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;

using System.Windows.Data;
using System.Globalization;
using System.Text.RegularExpressions;

namespace SwtorNews
{
    public class RssTextTrimmer : IValueConverter
    {

        // Clean up text fields from each SyndicationItem. 
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value == null) return null;

            int maxLength = 200;
            int strLength = 0;
            string fixedString = "";

            // Remove HTML tags and newline characters from the text, and decode HTML encoded characters. 
            // This is a basic method. Additional code would be needed to more thoroughly  
            // remove certain elements, such as embedded Javascript. 

            // Remove HTML tags. 
            fixedString = Regex.Replace(value.ToString(), "<[^>]+>", string.Empty);

            // Remove newline characters.
            fixedString = fixedString.Replace("\r", "").Replace("\n", "");

            // Remove encoded HTML characters.
            fixedString = HttpUtility.HtmlDecode(fixedString);

            strLength = fixedString.ToString().Length;

            // Some feed management tools include an image tag in the Description field of an RSS feed, 
            // so even if the Description field (and thus, the Summary property) is not populated, it could still contain HTML. 
            // Due to this, after we strip tags from the string, we should return null if there is nothing left in the resulting string. 
            if (strLength == 0)
            {
                return null;
            }

            // Truncate the text if it is too long. 
            else if (strLength >= maxLength)
            {
                fixedString = fixedString.Substring(0, maxLength);

                // Unless we take the next step, the string truncation could occur in the middle of a word.
                // Using LastIndexOf we can find the last space character in the string and truncate there. 
                fixedString = fixedString.Substring(0, fixedString.LastIndexOf(" "));
            }

            fixedString += "...";

            return fixedString;
        }

        // This code sample does not use TwoWay binding, so we do not need to flesh out ConvertBack.  
        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }

    }
}