using System;
using System.Collections.Generic;
using System.Linq;
using NLog;
using NzbDrone.Common.Crypto;
using NzbDrone.Common.Extensions;
using NzbDrone.Core.Configuration;
using NzbDrone.Core.CustomFormats;
using NzbDrone.Core.DecisionEngine;
using NzbDrone.Core.Indexers;
using NzbDrone.Core.Jobs;
using NzbDrone.Core.Languages;
using NzbDrone.Core.Messaging.Events;
using NzbDrone.Core.Movies;
using NzbDrone.Core.Movies.Events;
using NzbDrone.Core.Parser;
using NzbDrone.Core.Parser.Model;
using NzbDrone.Core.Profiles.Delay;
using NzbDrone.Core.Qualities;

namespace NzbDrone.Core.Download.Pending
{
    public interface IPendingReleaseService
    {
        void Add(DownloadDecision decision, PendingReleaseReason reason);
        void AddMany(List<Tuple<DownloadDecision, PendingReleaseReason>> decisions);
        List<ReleaseInfo> GetPending();
        List<RemoteMovie> GetPendingRemoteMovies(int movieId);
        List<Queue.Queue> GetPendingQueue();
        Queue.Queue FindPendingQueueItem(int queueId);
        void RemovePendingQueueItems(int queueId);
        RemoteMovie OldestPendingRelease(int movieId);
    }

    public class PendingReleaseService : IPendingReleaseService,
                                         IHandle<MovieGrabbedEvent>,
                                         IHandle<MoviesDeletedEvent>,
                                         IHandle<RssSyncCompleteEvent>
    {
        private readonly IIndexerStatusService _indexerStatusService;
        private readonly IPendingReleaseRepository _repository;
        private readonly IMovieService _movieService;
        private readonly IParsingService _parsingService;
        private readonly IDelayProfileService _delayProfileService;
        private readonly ITaskManager _taskManager;
        private readonly IConfigService _configService;
        private readonly ICustomFormatCalculationService _formatCalculator;
        private readonly IEventAggregator _eventAggregator;
        private readonly Logger _logger;

        public PendingReleaseService(IIndexerStatusService indexerStatusService,
                                     IPendingReleaseRepository repository,
                                     IMovieService movieService,
                                     IParsingService parsingService,
                                     IDelayProfileService delayProfileService,
                                     ITaskManager taskManager,
                                     IConfigService configService,
                                     ICustomFormatCalculationService formatCalculator,
                                     IEventAggregator eventAggregator,
                                     Logger logger)
        {
            _indexerStatusService = indexerStatusService;
            _repository = repository;
            _movieService = movieService;
            _parsingService = parsingService;
            _delayProfileService = delayProfileService;
            _taskManager = taskManager;
            _configService = configService;
            _formatCalculator = formatCalculator;
            _eventAggregator = eventAggregator;
            _logger = logger;
        }

        public void Add(DownloadDecision decision, PendingReleaseReason reason)
        {
            AddMany(new List<Tuple<DownloadDecision, PendingReleaseReason>> { Tuple.Create(decision, reason) });
        }

        public void AddMany(List<Tuple<DownloadDecision, PendingReleaseReason>> decisions)
        {
            foreach (var movieDecisions in decisions.GroupBy(v => v.Item1.RemoteMovie.Movie.Id))
            {
                var movie = movieDecisions.First().Item1.RemoteMovie.Movie;
                var alreadyPending = _repository.AllByMovieId(movie.Id);

                foreach (var pair in movieDecisions)
                {
                    var decision = pair.Item1;
                    var reason = pair.Item2;

                    var existingReports = alreadyPending ?? Enumerable.Empty<PendingRelease>();

                    var matchingReports = existingReports.Where(MatchingReleasePredicate(decision.RemoteMovie.Release)).ToList();

                    if (matchingReports.Any())
                    {
                        var matchingReport = matchingReports.First();

                        if (matchingReport.Reason != reason)
                        {
                            _logger.Debug("The release {0} is already pending with reason {1}, changing to {2}", decision.RemoteMovie, matchingReport.Reason, reason);
                            matchingReport.Reason = reason;
                            _repository.Update(matchingReport);
                        }
                        else
                        {
                            _logger.Debug("The release {0} is already pending with reason {1}, not adding again", decision.RemoteMovie, reason);
                        }

                        if (matchingReports.Count > 1)
                        {
                            _logger.Debug("The release {0} had {1} duplicate pending, removing duplicates.", decision.RemoteMovie, matchingReports.Count - 1);

                            foreach (var duplicate in matchingReports.Skip(1))
                            {
                                _repository.Delete(duplicate.Id);
                                alreadyPending.Remove(duplicate);
                            }
                        }

                        continue;
                    }

                    _logger.Debug("Adding release {0} to pending releases with reason {1}", decision.RemoteMovie, reason);
                    Insert(decision, reason);
                }
            }
        }

        public List<ReleaseInfo> GetPending()
        {
            var releases = _repository.All().Select(p => p.Release).ToList();

            if (releases.Any())
            {
                releases = FilterBlockedIndexers(releases);
            }

            return releases;
        }

        private List<ReleaseInfo> FilterBlockedIndexers(List<ReleaseInfo> releases)
        {
            var blockedIndexers = new HashSet<int>(_indexerStatusService.GetBlockedProviders().Select(v => v.ProviderId));

            return releases.Where(release => !blockedIndexers.Contains(release.IndexerId)).ToList();
        }

        public List<RemoteMovie> GetPendingRemoteMovies(int movieId)
        {
            return IncludeRemoteMovies(_repository.AllByMovieId(movieId)).Select(v => v.RemoteMovie).ToList();
        }

        public List<Queue.Queue> GetPendingQueue()
        {
            var queued = new List<Queue.Queue>();

            var nextRssSync = new Lazy<DateTime>(() => _taskManager.GetNextExecution(typeof(RssSyncCommand)));

            var pendingReleases = IncludeRemoteMovies(_repository.WithoutFallback());

            foreach (var pendingRelease in pendingReleases)
            {
                if (pendingRelease.RemoteMovie != null)
                {
                    pendingRelease.RemoteMovie.CustomFormats = _formatCalculator.ParseCustomFormat(pendingRelease.ParsedMovieInfo, pendingRelease.RemoteMovie.Movie);

                    var ect = pendingRelease.Release.PublishDate.AddMinutes(GetDelay(pendingRelease.RemoteMovie));

                    if (ect < nextRssSync.Value)
                    {
                        ect = nextRssSync.Value;
                    }
                    else
                    {
                        ect = ect.AddMinutes(_configService.RssSyncInterval);
                    }

                    var timeleft = ect.Subtract(DateTime.UtcNow);

                    if (timeleft.TotalSeconds < 0)
                    {
                        timeleft = TimeSpan.Zero;
                    }

                    var queue = new Queue.Queue
                    {
                        Id = GetQueueId(pendingRelease, pendingRelease.RemoteMovie.Movie),
                        Movie = pendingRelease.RemoteMovie.Movie,
                        Quality = pendingRelease.RemoteMovie.ParsedMovieInfo?.Quality ?? new QualityModel(),
                        Languages = pendingRelease.RemoteMovie.ParsedMovieInfo?.Languages ?? new List<Language>(),
                        Title = pendingRelease.Title,
                        Size = pendingRelease.RemoteMovie.Release.Size,
                        Sizeleft = pendingRelease.RemoteMovie.Release.Size,
                        RemoteMovie = pendingRelease.RemoteMovie,
                        Timeleft = timeleft,
                        EstimatedCompletionTime = ect,
                        Status = pendingRelease.Reason.ToString(),
                        Protocol = pendingRelease.RemoteMovie.Release.DownloadProtocol,
                        Indexer = pendingRelease.RemoteMovie.Release.Indexer
                    };

                    queued.Add(queue);
                }
            }

            // Return best quality release for each movie
            var deduped = queued.GroupBy(q => q.Movie.Id).Select(g =>
            {
                var movies = g.First().Movie;

                return g.OrderByDescending(e => e.Quality, new QualityModelComparer(movies.Profile))
                        .ThenBy(q => PrioritizeDownloadProtocol(q.Movie, q.Protocol))
                        .First();
            });

            return deduped.ToList();
        }

        public Queue.Queue FindPendingQueueItem(int queueId)
        {
            return GetPendingQueue().SingleOrDefault(p => p.Id == queueId);
        }

        public void RemovePendingQueueItems(int queueId)
        {
            var targetItem = FindPendingRelease(queueId);
            var movieReleases = _repository.AllByMovieId(targetItem.MovieId);

            var releasesToRemove = movieReleases.Where(c => c.ParsedMovieInfo.PrimaryMovieTitle == targetItem.ParsedMovieInfo.PrimaryMovieTitle);

            _repository.DeleteMany(releasesToRemove.Select(c => c.Id));
        }

        public RemoteMovie OldestPendingRelease(int movieId)
        {
            var movieReleases = GetPendingReleases(movieId);

            return movieReleases.Select(r => r.RemoteMovie)
                                 .OrderByDescending(p => p.Release.AgeHours)
                                 .FirstOrDefault();
        }

        private List<PendingRelease> GetPendingReleases()
        {
            return IncludeRemoteMovies(_repository.All().ToList());
        }

        private List<PendingRelease> GetPendingReleases(int movieId)
        {
            return IncludeRemoteMovies(_repository.AllByMovieId(movieId).ToList());
        }

        private List<PendingRelease> IncludeRemoteMovies(List<PendingRelease> releases, Dictionary<string, RemoteMovie> knownRemoteMovies = null)
        {
            var result = new List<PendingRelease>();

            var movieMap = new Dictionary<int, Movie>();

            if (knownRemoteMovies != null)
            {
                foreach (var movie in knownRemoteMovies.Values.Select(v => v.Movie))
                {
                    if (!movieMap.ContainsKey(movie.Id))
                    {
                        movieMap[movie.Id] = movie;
                    }
                }
            }

            foreach (var movie in _movieService.GetMovies(releases.Select(v => v.MovieId).Distinct().Where(v => !movieMap.ContainsKey(v))))
            {
                movieMap[movie.Id] = movie;
            }

            foreach (var release in releases)
            {
                var movie = movieMap.GetValueOrDefault(release.MovieId);

                // Just in case the series was removed, but wasn't cleaned up yet (housekeeper will clean it up)
                if (movie == null)
                {
                    return null;
                }

                release.RemoteMovie = new RemoteMovie
                {
                    Movie = movie,
                    ParsedMovieInfo = release.ParsedMovieInfo,
                    Release = release.Release
                };

                result.Add(release);
            }

            return result;
        }

        private void Insert(DownloadDecision decision, PendingReleaseReason reason)
        {
            var release = new PendingRelease
            {
                MovieId = decision.RemoteMovie.Movie.Id,
                ParsedMovieInfo = decision.RemoteMovie.ParsedMovieInfo,
                Release = decision.RemoteMovie.Release,
                Title = decision.RemoteMovie.Release.Title,
                Added = DateTime.UtcNow,
                Reason = reason
            };

            if (release.ParsedMovieInfo == null)
            {
                _logger.Warn("Pending release {0} does not have ParsedMovieInfo, will cause issues.", release.Title);
            }

            _repository.Insert(release);

            _eventAggregator.PublishEvent(new PendingReleasesUpdatedEvent());
        }

        private void Delete(PendingRelease pendingRelease)
        {
            _repository.Delete(pendingRelease);
            _eventAggregator.PublishEvent(new PendingReleasesUpdatedEvent());
        }

        private static Func<PendingRelease, bool> MatchingReleasePredicate(ReleaseInfo release)
        {
            return p => p.Title == release.Title &&
                   p.Release.PublishDate == release.PublishDate &&
                   p.Release.Indexer == release.Indexer;
        }

        private int GetDelay(RemoteMovie remoteMovie)
        {
            var delayProfile = _delayProfileService.AllForTags(remoteMovie.Movie.Tags).OrderBy(d => d.Order).First();
            var delay = delayProfile.GetProtocolDelay(remoteMovie.Release.DownloadProtocol);
            var minimumAge = _configService.MinimumAge;

            return new[] { delay, minimumAge }.Max();
        }

        private void RemoveGrabbed(RemoteMovie remoteMovie)
        {
            var pendingReleases = GetPendingReleases(remoteMovie.Movie.Id);

            var existingReports = pendingReleases.Where(r => r.RemoteMovie.Movie.Id == remoteMovie.Movie.Id)
                                                             .ToList();

            if (existingReports.Empty())
            {
                return;
            }

            var profile = remoteMovie.Movie.Profile;

            foreach (var existingReport in existingReports)
            {
                var compare = new QualityModelComparer(profile).Compare(remoteMovie.ParsedMovieInfo.Quality,
                                                                        existingReport.RemoteMovie.ParsedMovieInfo.Quality);

                // Only remove lower/equal quality pending releases
                // It is safer to retry these releases on the next round than remove it and try to re-add it (if its still in the feed)
                if (compare >= 0)
                {
                    _logger.Debug("Removing previously pending release, as it was grabbed.");
                    Delete(existingReport);
                }
            }
        }

        private void RemoveRejected(List<DownloadDecision> rejected)
        {
            _logger.Debug("Removing failed releases from pending");
            var pending = GetPendingReleases();

            foreach (var rejectedRelease in rejected)
            {
                var matching = pending.Where(MatchingReleasePredicate(rejectedRelease.RemoteMovie.Release));

                foreach (var pendingRelease in matching)
                {
                    _logger.Debug("Removing previously pending release, as it has now been rejected.");
                    Delete(pendingRelease);
                }
            }
        }

        private PendingRelease FindPendingRelease(int queueId)
        {
            return GetPendingReleases().First(p => queueId == GetQueueId(p, p.RemoteMovie.Movie));
        }

        private int GetQueueId(PendingRelease pendingRelease, Movie movie)
        {
            return HashConverter.GetHashInt31(string.Format("pending-{0}-movie{1}", pendingRelease.Id, movie.Id));
        }

        private int PrioritizeDownloadProtocol(Movie movie, DownloadProtocol downloadProtocol)
        {
            var delayProfile = _delayProfileService.BestForTags(movie.Tags);

            if (downloadProtocol == delayProfile.PreferredProtocol)
            {
                return 0;
            }

            return 1;
        }

        public void Handle(MoviesDeletedEvent message)
        {
            _repository.DeleteByMovieIds(message.Movies.Select(m => m.Id).ToList());
        }

        public void Handle(MovieGrabbedEvent message)
        {
            RemoveGrabbed(message.Movie);
        }

        public void Handle(RssSyncCompleteEvent message)
        {
            RemoveRejected(message.ProcessedDecisions.Rejected);
        }
    }
}