using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Argotic.Common;
using Argotic.Syndication;
using Microsoft.Data.Sqlite;
using Serilog;
using SharpRss.Models;

namespace SharpRss.Services
{
    /// <summary>
    /// Managing RSS feeds and groups.
    /// </summary>
    public class RssService : IDisposable
    {
        public RssService()
        {
            SetupTestGroupsAndFeedsAsync();
        }

        public async Task<HashSet<object>> GetGroupsFeedsAsync()
        {
            HashSet<object> items = new HashSet<object>();
            items.UnionWith(await GetGroupsAsync());
            items.UnionWith(await GetUngroupedFeedsAsync());
            return items;
        }
        public async Task<bool> CreateGroupAsync(CategoryModel group) => await DbAccess.SetGroupAsync(group);
		public async Task<HashSet<CategoryModel>> GetGroupsAsync() => await DbAccess.GetGroupsAsync();
        
        //TODO: Rework this!
        // Subscribe to a feed.
        public async Task<bool> AddSubscriptionAsync(string url, CategoryModel? group = null)
        {
            // Check for valid feed url
            bool validate = SyndicationDiscoveryUtility.UriExists(new Uri(url));
            if (!validate) return false;
            // Check if feed exists in db
            FeedModel? dbFeed = await DbAccess.GetFeedAsync(url);
            if (dbFeed == null)
            {
                GenericSyndicationFeed genFeed = new GenericSyndicationFeed();
                switch (genFeed.Format)
                {
                    case SyndicationContentFormat.Rss:
                        RssFeed rssFeed = (RssFeed)genFeed.Resource;
                        break;
                    case SyndicationContentFormat.Atom:
                        AtomFeed atomFeed = (AtomFeed)genFeed.Resource;
                        break;
                    default:
                        Log.Information("Feed implementation missing!");
                        break;
                }
            }
            // Update feed if newer
            // Update/fetch items

            return false;
        }
        private static FeedModel FromResource(ISyndicationResource resource)
        {
            FeedModel model = new FeedModel("");
            switch (resource)
            {
                case RssFeed rssFeed:
                    //TODO: From feed to model
                    break;
            }
            return model;
        }

        public async Task UpdateFeeds()
        {
            Log.Verbose("Fetching feeds...");
            var feeds = await GetFeedsAsync();
        }

        public async Task<HashSet<FeedModel>> GetFeedsAsync(string? groupId = null) => await DbAccess.GetFeedsAsync(groupId);
        public async Task<HashSet<FeedModel>> GetUngroupedFeedsAsync() => await DbAccess.GetFeedsAsync("");

        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 async Task<int> AddFeedItems(IList<FeedItem> items, FeedModel feedModel)
		{
            int result = 0;
            if (!items.Any())
                return result;
            HashSet<FeedItemModel> itemModels = new HashSet<FeedItemModel>();
            // TODO: implement!!!
            result = await DbAccess.SetFeedItemsAsync(itemModels);
			return result;
		}*/

        /*private IList<FeedItemModel> ConstructFeedItems(IList<FeedItem> items, FeedModel feed)
        {
            IList<FeedItemModel> itemModels = new List<FeedItemModel>();
            if (!items.Any())
                return itemModels;
            foreach (FeedItem item in items)
            {
                itemModels.Add(new FeedItemModel()
                {
                    Id = item.Id,
                    FeedId = feed.Id,
                    Title = item.Title,
                    Description = item.Description,
                    Link = item.Link,
                    LastUpdated = DateTimeOffset.Now,
                    PublishingDate = item.PublishingDate != null ? new DateTimeOffset((DateTime)item.PublishingDate) : null,
                    Author = item.Author,
                    Categories = item.Categories.ToArray(),
                    Content = item.Content
                });
            }
            return itemModels;
        }*/

        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 SetupTestGroupsAndFeedsAsync()
        {
            //TODO: Make multiple adding of feed to a transaction, now throws an exception.
            /*var groupRes = await CreateGroupAsync(new GroupModel() { Name = "Test" });
            groupRes = await CreateGroupAsync(new GroupModel() { Name = "News" });
            groupRes = await CreateGroupAsync(new GroupModel() { Name = "Tech" });
            groupRes = await CreateGroupAsync(new GroupModel() { Name = "Science" });*/
            /*Log.Verbose("Fetching feeds...");
            var groups = await GetGroupsAsync();
            GroupModel testGroup = groups.Single(x => x.Name == "Test");
            try
            {
                var res = await AddFeed("http://fedoramagazine.org/feed/", testGroup);
                res = await AddFeed("https://www.nasa.gov/rss/dyn/breaking_news.rss", testGroup);
                res = await AddFeed("https://journals.plos.org/plosone/feed/atom", testGroup);
                res = await AddFeed("https://itsfoss.com/feed", testGroup);
                res = await AddFeed("https://advisories.ncsc.nl/rss/advisories", testGroup);
            }
            catch (Exception e)
            {
                Log.Error(e, "Error fetching feeds!");
                throw;
            }*/
            var groups = await GetGroupsAsync();
            CategoryModel testGroup = groups.Single(x => x.Name == "News");
            /*await AddFeedsAsync(new[]
            {
                "https://www.nu.nl/rss/Algemeen",
                "https://www.nu.nl/rss/Economie",
                "https://www.nu.nl/rss/Sport",
                "http://news.google.com/?output=atom"
            }, testGroup);*/
        }

        public void Dispose()
        {
        }
    }
}