using NLog;
using Sony.Filtr.Spotify.Artists;
using Sony.Filtr.SpotifyWebAPI;
using Sony.Filtr.Utility.Extensions;
using System;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace Sony.Filtr.Tasks.Tasks.Spotify
{
    public class ScrapeArtistListenersTask : IScheduledTask
    {
        private readonly SpotifyArtistMonthlyListenerManager _spotifyArtistMonthlyListenerManager;
        private readonly SpotifyArtistManager _spotifyArtistManager;
        private readonly Logger _logger;
        private readonly InternalSpotifyApiClient _internalSpotifyApiClient;

        public ScrapeArtistListenersTask(SpotifyArtistMonthlyListenerManager spotifyArtistMonthlyListenerManager, SpotifyArtistManager spotifyArtistManager)
        {
            _spotifyArtistMonthlyListenerManager = spotifyArtistMonthlyListenerManager;
            _spotifyArtistManager = spotifyArtistManager;
            _logger = LogManager.GetLogger("ScrapeArtistListeners");
            _internalSpotifyApiClient = new InternalSpotifyApiClient(_logger);
        }

        public async Task<ScheduledTaskLog> ExecuteAsync(Guid scheduledTaskLogId)
        {

            var date = DateTime.Today;

            var existingEntries = _spotifyArtistMonthlyListenerManager.GetEntries(date);
            var existingArtistIds = existingEntries.Select(p => p.ArtistId);

            var popularArtistIds = await _spotifyArtistManager.GetArtistIdsWithMinimumFollowerCountAsync(1000);

            var errorsWhileFetchingCount = 0;
            var artistIdsToFetch = popularArtistIds.Except(existingArtistIds).ToList();
            if (artistIdsToFetch.Any())
            {
                _logger.Debug($"Will fetch info for {artistIdsToFetch.Count} artists");

                await artistIdsToFetch.ForEachAsync(5, async artistId =>
                {
                    _logger.Debug($"Getting info for {artistId}");

                    try
                    {
                        var artistInfo = await _internalSpotifyApiClient.GetArtistInfoAsync(artistId);
                        if (artistInfo?.artistInsights != null)
                        {
                            _logger.Debug($"Saving info for {artistId}");
                            await _spotifyArtistMonthlyListenerManager.SaveMonthlyListenersAsync(artistId, date, artistInfo.artistInsights.monthly_listeners, artistInfo.artistInsights.monthly_listeners_delta);
                        }
                        else
                        {
                            _logger.Error($"No data for fetch on { artistId }");
                        }
                    }
                    catch (Exception e)
                    {
                        _logger.Error(e, $"Error while scraping data for artist with ID { artistId }");
                        Interlocked.Increment(ref errorsWhileFetchingCount);
                    }
                });

                if (errorsWhileFetchingCount > 0)
                    _logger.Warn($"{ errorsWhileFetchingCount } errors occured while fetching individual artists' info.");
            }

            return null;
        }
    }
}