using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using Argotic.Common;
using Argotic.Syndication;
using Serilog;
using SharpRss.Models;

namespace SharpRss.Services
{
    /// <summary>
    /// Managing RSS feeds and categories.
    /// </summary>
    public class RssService
    {
        public RssService()
        {
            SetupTestCategoriesAndFeedsAsync();
        }

        public async Task<HashSet<object>> GetCategoriesAndFeedsAsync()
        {
            HashSet<object> items = new HashSet<object>();
            items.UnionWith(await GetCategoriesAsync());
            items.UnionWith(await GetUngroupedFeedsAsync());
            return items;
        }

        public async Task<CategoryModel?> CreateCategoryAsync(CategoryModel category) =>
            await DbAccess.SetCategoryAsync(category);
		public async Task<HashSet<CategoryModel>> GetCategoriesAsync() => await DbAccess.GetCategoriesAsync();
        public async Task<bool> AddSubscriptionAsync(string url, CategoryModel? category = null)
        {
            var syndication = SyndicationManager.CreateSyndication(url);
            if (!syndication.Fetched)
            {
                Log.Debug("Failed to fetch syndication feed!");
                return false;
            }
            if (category != null)
                syndication.Category = category;
            try
            {
                await DbAccess.SetSyndicationAsync(syndication);
            }
            catch (Exception e)
            {
                Log.Error(e,"Error adding feed: {FeedUrl} to database!", url);
            }
            return true;
        }
        public async Task UpdateFeeds()
        {
            Log.Verbose("Fetching feeds...");
            var feeds = await GetFeedsAsync();
        }
        public async Task<HashSet<FeedModel>> GetFeedsAsync(string? categoryId = null) => await DbAccess.GetFeedsAsync(categoryId == null ? null : new[]{ categoryId });
        public async Task<HashSet<FeedModel>> GetUngroupedFeedsAsync() => await DbAccess.GetFeedsAsync(new []{""});
        public async Task<HashSet<FeedItemModel>> GetFeedItemsAsync(string feedId, string? groupId = null) => await GetFeedItemsFromFeedsAsync(new[] { feedId }, groupId);
        public async Task<HashSet<FeedItemModel>> GetFeedItemsFromFeedsAsync(string[] feedIds, string? groupId = null)
        {
            var items =  await DbAccess.GetFeedItemsAsync(feedIds);
            return items;
        }
        
        
        
        private static FeedModel FromResource(ISyndicationResource resource)
        {
            FeedModel model = new FeedModel();
            switch (resource.Format)
            {
                case SyndicationContentFormat.Rss:
                    RssFeed rssFeed = (RssFeed)resource;
                    model.FeedType = rssFeed.Format.ToString();
                    model.Title = rssFeed.Channel.Title;
                    model.Description = rssFeed.Channel.Description;
                    model.Copyright = rssFeed.Channel.Copyright;
                    model.EncodedUrl = rssFeed.Channel.SelfLink.ToString();
                    model.ImageUrl = rssFeed.Channel.Image?.Url.ToString() ?? string.Empty;
                    model.Language = rssFeed.Channel.Language?.ToString();
                    break;
                case SyndicationContentFormat.Atom:
                    AtomFeed atomFeed = (AtomFeed)resource;
                    break;
                default:
                    Log.Information("Feed implementation missing!");
                    break;
            }
            return model;
        }
        private GenericSyndicationFeed? CreateFeed(string url)
        {
            Uri feedUri = new Uri(url);
            Log.Verbose("Checking feed: {FeedUrl}", feedUri.ToString());
            if (!SyndicationDiscoveryUtility.UriExists(feedUri))
            {
                Log.Warning("Feed: {FeedUri} does not exists!", feedUri.ToString());
                return null;
            }
            Log.Verbose("Fetching feed: {FeedUrl}", feedUri.ToString());
            return GenericSyndicationFeed.Create(new Uri(url));
        }
        private async void SetupTestCategoriesAndFeedsAsync()
        {
            /*CategoryModel? newsCategory = await CreateCategoryAsync(new CategoryModel() { Name = "News" });
            if (newsCategory != null)
            {
                await AddSubscriptionAsync("https://www.nu.nl/rss/Algemeen", newsCategory);
                await AddSubscriptionAsync("https://www.nasa.gov/rss/dyn/breaking_news.rss", newsCategory);
                await AddSubscriptionAsync("http://news.google.com/?output=atom", newsCategory);
                await AddSubscriptionAsync("https://www.ad.nl/home/rss.xml", newsCategory);
            }

            CategoryModel? techCategory = await CreateCategoryAsync(new CategoryModel() { Name = "Tech" });
            if (techCategory != null)
            {
                await AddSubscriptionAsync("https://itsfoss.com/feed", techCategory);
                await AddSubscriptionAsync("http://fedoramagazine.org/feed/", techCategory);
                await AddSubscriptionAsync("https://arstechnica.com/feed/", techCategory);
                await AddSubscriptionAsync("https://feeds.arstechnica.com/arstechnica/gadgets", techCategory);
            }

            CategoryModel? youtubeCategory = await CreateCategoryAsync(new CategoryModel() { Name = "YouTube" });
            if (youtubeCategory != null)
            {
                await AddSubscriptionAsync("https://www.youtube.com/feeds/videos.xml?channel_id=UCXuqSBlHAE6Xw-yeJA0Tunw", youtubeCategory);
                await AddSubscriptionAsync("https://www.youtube.com/feeds/videos.xml?channel_id=UC1Et9K-hHf-P_LzQkE_Q3Jw", youtubeCategory);
                await AddSubscriptionAsync("https://www.youtube.com/feeds/videos.xml?channel_id=UCsXVk37bltHxD1rDPwtNM8Q", youtubeCategory);
            }
            
            await AddSubscriptionAsync("http://www.digitaleoverheid.nl/feed/");
            await AddSubscriptionAsync("http://www.digitaleoverheid.nl/agenda/feed/");
            await AddSubscriptionAsync("https://feeds.rijksoverheid.nl/nieuws.rss");
            await AddSubscriptionAsync("https://nl.wikipedia.org/w/index.php?title=Speciaal:RecenteWijzigingen&feed=atom");
            await AddSubscriptionAsync("https://feeds.aivd.nl/nieuws.rss");
            await AddSubscriptionAsync("https://blogs.microsoft.com/feed");
            await AddSubscriptionAsync("https://www.europarl.europa.eu/rss/doc/top-stories/nl.xml");*/
        }
    }
}