using System;
using System.Collections.Generic;
using System.Linq;
using NLog;
using NzbDrone.Common.Messaging;
using NzbDrone.Core.Configuration;
using NzbDrone.Core.Download;
using NzbDrone.Core.MediaFiles.Events;
using NzbDrone.Core.MetadataSource;
using NzbDrone.Core.Model;
using NzbDrone.Core.Tv.Events;

namespace NzbDrone.Core.Tv
{
    public interface IEpisodeService
    {
        Episode GetEpisode(int id);
        Episode GetEpisode(int seriesId, int seasonNumber, int episodeNumber, bool useScene = false);
        Episode GetEpisode(int seriesId, DateTime date);
        List<Episode> GetEpisodeBySeries(int seriesId);
        List<Episode> GetEpisodesBySeason(int seriesId, int seasonNumber);
        List<Episode> EpisodesWithoutFiles(bool includeSpecials);
        List<Episode> GetEpisodesByFileId(int episodeFileId);
        List<Episode> EpisodesWithFiles();
        void RefreshEpisodeInfo(Series series);
        void UpdateEpisode(Episode episode);
        List<int> GetEpisodeNumbersBySeason(int seriesId, int seasonNumber);
        void SetEpisodeIgnore(int episodeId, bool isIgnored);
        bool IsFirstOrLastEpisodeOfSeason(int episodeId);
        void SetPostDownloadStatus(List<int> episodeIds, PostDownloadStatusType postDownloadStatus);
        void UpdateEpisodes(List<Episode> episodes);
        List<Episode> EpisodesBetweenDates(DateTime start, DateTime end);
    }

    public class EpisodeService : IEpisodeService,
        IHandle<EpisodeGrabbedEvent>,
        IHandle<EpisodeFileDeletedEvent>,
        IHandle<EpisodeFileAddedEvent>,
    IHandleAsync<SeriesDeletedEvent>,
        IHandleAsync<SeriesAddedEvent>
    {

        private static readonly Logger logger = LogManager.GetCurrentClassLogger();

        private readonly IProvideEpisodeInfo _episodeInfoProxy;
        private readonly ISeasonRepository _seasonRepository;
        private readonly IEpisodeRepository _episodeRepository;
        private readonly IMessageAggregator _messageAggregator;
        private readonly IConfigService _configService;
        private readonly ISeriesService _seriesService;
        private readonly Logger _logger;

        public EpisodeService(IProvideEpisodeInfo episodeInfoProxy, ISeasonRepository seasonRepository,
                              IEpisodeRepository episodeRepository, IMessageAggregator messageAggregator,
                              IConfigService configService, ISeriesService seriesService, Logger logger)
        {
            _episodeInfoProxy = episodeInfoProxy;
            _seasonRepository = seasonRepository;
            _episodeRepository = episodeRepository;
            _messageAggregator = messageAggregator;
            _configService = configService;
            _seriesService = seriesService;
            _logger = logger;
        }


        public Episode GetEpisode(int id)
        {
            return _episodeRepository.Get(id);
        }

        public Episode GetEpisode(int seriesId, int seasonNumber, int episodeNumber, bool useSceneNumbering = false)
        {
            if (useSceneNumbering)
            {
                return _episodeRepository.GetEpisodeBySceneNumbering(seriesId, seasonNumber, episodeNumber);
            }
            return _episodeRepository.Get(seriesId, seasonNumber, episodeNumber);
        }

        public Episode GetEpisode(int seriesId, DateTime date)
        {
            return _episodeRepository.Get(seriesId, date);
        }

        public List<Episode> GetEpisodeBySeries(int seriesId)
        {
            return _episodeRepository.GetEpisodes(seriesId).ToList();
        }

        public List<Episode> GetEpisodesBySeason(int seriesId, int seasonNumber)
        {
            return _episodeRepository.GetEpisodes(seriesId, seasonNumber);
        }

        public List<Episode> EpisodesWithoutFiles(bool includeSpecials)
        {
            var episodes = _episodeRepository.EpisodesWithoutFiles(includeSpecials);

            return LinkSeriesToEpisodes(episodes);
        }

        public List<Episode> GetEpisodesByFileId(int episodeFileId)
        {
            return _episodeRepository.GetEpisodeByFileId(episodeFileId);
        }

        public List<Episode> EpisodesWithFiles()
        {
            return _episodeRepository.EpisodesWithFiles();
        }

        public void RefreshEpisodeInfo(Series series)
        {
            logger.Trace("Starting episode info refresh for series: {0}", series.Title.WithDefault(series.Id));
            var successCount = 0;
            var failCount = 0;

            var tvdbEpisodes = _episodeInfoProxy.GetEpisodeInfo(series.TvdbId);

            var seriesEpisodes = GetEpisodeBySeries(series.Id);
            var updateList = new List<Episode>();
            var newList = new List<Episode>();

            foreach (var episode in tvdbEpisodes.OrderBy(e => e.SeasonNumber).ThenBy(e => e.EpisodeNumber))
            {
                try
                {
                    logger.Trace("Updating info for [{0}] - S{1:00}E{2:00}", series.Title, episode.SeasonNumber, episode.EpisodeNumber);

                    //first check using tvdbId, this should cover cases when and episode number in a season is changed

                    var episodes = seriesEpisodes.Where(e => e.TvDbEpisodeId == episode.TvDbEpisodeId).ToList();
                    var episodeToUpdate = seriesEpisodes.SingleOrDefault(e => e.TvDbEpisodeId == episode.TvDbEpisodeId);

                    //not found, try using season/episode number
                    if (episodeToUpdate == null)
                    {
                        episodeToUpdate = seriesEpisodes.SingleOrDefault(e => e.SeasonNumber == episode.SeasonNumber && e.EpisodeNumber == episode.EpisodeNumber);
                    }

                    if (episodeToUpdate == null)
                    {
                        episodeToUpdate = new Episode();
                        newList.Add(episodeToUpdate);

                        //If it is Episode Zero Ignore it (specials, sneak peeks.)
                        if (episode.EpisodeNumber == 0 && episode.SeasonNumber != 1)
                        {
                            episodeToUpdate.Ignored = true;
                        }
                        else
                        {
                            episodeToUpdate.Ignored = _seasonRepository.IsIgnored(series.Id, episode.SeasonNumber);
                        }
                    }
                    else
                    {
                        updateList.Add(episodeToUpdate);
                    }

                    if ((episodeToUpdate.EpisodeNumber != episode.EpisodeNumber ||
                         episodeToUpdate.SeasonNumber != episode.SeasonNumber) &&
                        episodeToUpdate.EpisodeFileId > 0)
                    {
                        logger.Info("Unlinking episode file because TheTVDB changed the episode number...");
                        episodeToUpdate.EpisodeFile = null;
                    }

                    episodeToUpdate.SeriesId = series.Id;
                    episodeToUpdate.Series = series;
                    episodeToUpdate.TvDbEpisodeId = episode.TvDbEpisodeId;
                    episodeToUpdate.EpisodeNumber = episode.EpisodeNumber;
                    episodeToUpdate.SeasonNumber = episode.SeasonNumber;
                    episodeToUpdate.AbsoluteEpisodeNumber = episode.AbsoluteEpisodeNumber;
                    episodeToUpdate.Title = episode.Title;
                    episodeToUpdate.Overview = episode.Overview;
                    episodeToUpdate.AirDate = episode.AirDate;

                    if (!String.IsNullOrWhiteSpace(series.AirTime) && episodeToUpdate.AirDate.HasValue)
                    {
                        episodeToUpdate.AirDate = episodeToUpdate.AirDate.Value.Add(Convert.ToDateTime(series.AirTime).TimeOfDay)
                                                                               .AddHours(series.UtcOffset * -1);
                    }

                    successCount++;
                }
                catch (Exception e)
                {
                    logger.FatalException(String.Format("An error has occurred while updating episode info for series {0}", series.Title), e);
                    failCount++;
                }
            }

            var allEpisodes = new List<Episode>();
            allEpisodes.AddRange(newList);
            allEpisodes.AddRange(updateList);

            var groups = allEpisodes.GroupBy(e => new { e.SeriesId, e.AirDate }).Where(g => g.Count() > 1).ToList();

            foreach (var group in groups)
            {
                int episodeCount = 0;
                foreach (var episode in group.OrderBy(e => e.SeasonNumber).ThenBy(e => e.EpisodeNumber))
                {
                    episode.AirDate = episode.AirDate.Value.AddMinutes(episode.Series.Runtime * episodeCount);
                    episodeCount++;
                }
            }

            _episodeRepository.InsertMany(newList);
            _episodeRepository.UpdateMany(updateList);

            if (newList.Any())
            {
                _messageAggregator.PublishEvent(new EpisodeInfoAddedEvent(newList));
            }

            if (updateList.Any())
            {
                _messageAggregator.PublishEvent(new EpisodeInfoUpdatedEvent(updateList));
            }

            if (failCount != 0)
            {
                logger.Info("Finished episode refresh for series: {0}. Successful: {1} - Failed: {2} ",
                            series.Title, successCount, failCount);
            }
            else
            {
                logger.Info("Finished episode refresh for series: {0}.", series.Title);
            }

            DeleteEpisodesNotInTvdb(series, tvdbEpisodes);
        }

        public void UpdateEpisode(Episode episode)
        {
            _episodeRepository.Update(episode);
        }

        public List<int> GetEpisodeNumbersBySeason(int seriesId, int seasonNumber)
        {
            return GetEpisodesBySeason(seriesId, seasonNumber).Select(c => c.Id).ToList();
        }

        public void SetEpisodeIgnore(int episodeId, bool isIgnored)
        {
            var episode = _episodeRepository.Get(episodeId);
            _episodeRepository.SetIgnoreFlat(episode, isIgnored);

            logger.Info("Ignore flag for Episode:{0} was set to {1}", episodeId, isIgnored);
        }

        public bool IsFirstOrLastEpisodeOfSeason(int episodeId)
        {
            var episode = GetEpisode(episodeId);
            var seasonEpisodes = GetEpisodesBySeason(episode.SeriesId, episode.SeasonNumber);


            //Ensure that this is either the first episode
            //or is the last episode in a season that has 10 or more episodes
            if (seasonEpisodes.First().EpisodeNumber == episode.EpisodeNumber || (seasonEpisodes.Count() >= 10 && seasonEpisodes.Last().EpisodeNumber == episode.EpisodeNumber))
                return true;

            return false;
        }

        public void SetPostDownloadStatus(List<int> episodeIds, PostDownloadStatusType postDownloadStatus)
        {
            if (episodeIds.Count == 0) throw new ArgumentException("episodeIds should contain one or more episode ids.");


            foreach (var episodeId in episodeIds)
            {
                var episode = _episodeRepository.Get(episodeId);
                episode.PostDownloadStatus = postDownloadStatus;
                _episodeRepository.Update(episode);
            }


            logger.Trace("Updating PostDownloadStatus for {0} episode(s) to {1}", episodeIds.Count, postDownloadStatus);
        }

        public void UpdateEpisodes(List<Episode> episodes)
        {
            _episodeRepository.UpdateMany(episodes);
        }

        public List<Episode> EpisodesBetweenDates(DateTime start, DateTime end)
        {
            var episodes = _episodeRepository.EpisodesBetweenDates(start.ToUniversalTime(), end.ToUniversalTime());

            return LinkSeriesToEpisodes(episodes);
        }

        public void Handle(EpisodeGrabbedEvent message)
        {
            foreach (var episode in message.Episode.Episodes)
            {
                logger.Trace("Marking episode {0} as fetched.", episode.Id);
                episode.GrabDate = DateTime.UtcNow;
                _episodeRepository.Update(episode);
            }
        }

        public void HandleAsync(SeriesDeletedEvent message)
        {
            var episodes = GetEpisodeBySeries(message.Series.Id);
            _episodeRepository.DeleteMany(episodes);
        }

        public void Handle(EpisodeFileDeletedEvent message)
        {
            foreach (var episode in GetEpisodesByFileId(message.EpisodeFile.Id))
            {
                _logger.Trace("Detaching episode {0} from file.", episode.Id);
                episode.EpisodeFile = null;
                episode.Ignored = _configService.AutoIgnorePreviouslyDownloadedEpisodes;
                episode.GrabDate = null;
                episode.PostDownloadStatus = PostDownloadStatusType.Unknown;
                UpdateEpisode(episode);
            }
        }

        public void HandleAsync(SeriesAddedEvent message)
        {
            RefreshEpisodeInfo(message.Series);
        }

        public void Handle(EpisodeFileAddedEvent message)
        {
            foreach (var episode in message.EpisodeFile.Episodes.Value)
            {
                _episodeRepository.SetFileId(episode.Id, message.EpisodeFile.Id);
                _episodeRepository.SetPostDownloadStatus(episode.Id, PostDownloadStatusType.NoError);
                _logger.Debug("Linking [{0}] > [{1}]", message.EpisodeFile.Path, episode);
            }
        }

        private void DeleteEpisodesNotInTvdb(Series series, IEnumerable<Episode> tvdbEpisodes)
        {
            //Todo: This will not work as currently implemented - what are we trying to do here?
            return;
            logger.Trace("Starting deletion of episodes that no longer exist in TVDB: {0}", series.Title.WithDefault(series.Id));
            foreach (var episode in tvdbEpisodes)
            {
                _episodeRepository.Delete(episode.Id);
            }

            logger.Trace("Deleted episodes that no longer exist in TVDB for {0}", series.Id);
        }

        private List<Episode> LinkSeriesToEpisodes(List<Episode> episodes)
        {
            var series = _seriesService.GetSeriesInList(episodes.Select(e => e.SeriesId).Distinct());

            episodes.ForEach(e =>
            {
                e.Series = series.SingleOrDefault(s => s.Id == e.SeriesId);
            });

            return episodes;
        }
    }
}