using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Xml.Linq;
using Luticate2.Utils.Dbo.Result;
using VDS.RDF;
using WebApiWebSem.Dbo.Feed;

namespace WebApiWebSem.DataAccess
{
    public class FeedDataAccess
    {
        public LuResult<IList<FeedDbo>> Parse(string url)
        {
            try
            {
                using (var client = new HttpClient())
                {
                    var request = new HttpRequestMessage(HttpMethod.Get, url);

                    var responseTask = client.SendAsync(request);
                    responseTask.Wait();
                    using (var response = responseTask.Result)
                    {
                        var streamTask = response.Content.ReadAsStreamAsync();
                        streamTask.Wait();
                        using (var stream = streamTask.Result)
                        {
                            var doc = XDocument.Load(stream);
                            var entries = from item in doc.Root.Descendants()
                                    .First(i => i.Name.LocalName == "channel")
                                    .Elements()
                                    .Where(i => i.Name.LocalName == "item")
                                select new FeedDbo
                                {
                                    Content = item.Elements().First(i => i.Name.LocalName == "description").Value,
                                    Link = item.Elements().First(i => i.Name.LocalName == "link").Value,
                                    PublishDate = ParseDate(
                                        item.Elements().First(i => i.Name.LocalName == "pubDate").Value),
                                    Title = item.Elements().First(i => i.Name.LocalName == "title").Value
                                };
                            return LuResult<IList<FeedDbo>>.Ok(entries.ToList());
                        }
                    }
                }
            }
            catch (Exception e)
            {
                return LuResult<IList<FeedDbo>>.Error(LuStatus.BackendError, e, "Failed to read remote RSS feed");
            }
        }

        private DateTime ParseDate(string date)
        {
            DateTime result;
            if (DateTime.TryParse(date, out result))
                return result;
            return DateTime.MinValue;
        }
    }
}