using System;
using System.Collections;
using System.Collections.Generic;
using System.Runtime.Serialization;

namespace Website
{
    [DataContract]
    public class FeedItem
    {
        public const int MAX_SUMMARY_LENGTH = 250;
        public const string SUMMARY_FORMAT = "{0}... <a href='{1}'>[more]</a>";

        [DataMember]
        public string Title { get; private set; }
        [DataMember]
        public string Link { get; private set; }
        [DataMember]
        public string Text { get; private set; }
        
        public string Summary
        {
            get 
            {
                if(string.IsNullOrEmpty(Text)) 
                    return string.Empty;

                var text = RemoveHtml(Text);

                return text.Length < MAX_SUMMARY_LENGTH ? text :
                    string.Format(SUMMARY_FORMAT, text.Substring(0, MAX_SUMMARY_LENGTH), Link);
            }
        }

        [DataMember]
        public DateTime? PostDate { get; private set; }

        public FeedItem()
        {
        }

        public FeedItem(string title, string link, string text, string pubDate) 
            : this(title, link, text, (DateTime?)null)
        {
            DateTime postDate;
            DateTime.TryParse(pubDate, out postDate);
            PostDate = (postDate == default(DateTime)) ? (DateTime?)null : postDate;
        }

        public FeedItem(string title, string link, string text, DateTime? postDate)
        {
            Title = title;
            Link = link;
            Text = text;
            PostDate = postDate;
        }

        public override string ToString()
        {
            return (PostDate.HasValue) ?
                string.Format("{0:D}: {1}", PostDate.Value, Title) :
                Title;
        }

        private static string RemoveHtml(string text)
        {
            return System.Text.RegularExpressions.Regex.Replace(text, "<[^>]*>", "");
        }
    }

    [DataContract]
    public class FeedItemCollection : IEnumerable<FeedItem>
    {
        [DataMember]
        private readonly IEnumerable<FeedItem> items;

        public FeedItemCollection(IEnumerable<FeedItem> items)
        {
            this.items = items;
        }

        public IEnumerator<FeedItem> GetEnumerator()
        {
            return items.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }
    }
}