using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using NLog;
using NzbDrone.Common.Disk;
using NzbDrone.Common.Extensions;
using NzbDrone.Common.Instrumentation.Extensions;
using NzbDrone.Core.MediaFiles.Commands;
using NzbDrone.Core.MediaFiles.Events;
using NzbDrone.Core.Messaging.Commands;
using NzbDrone.Core.Messaging.Events;
using NzbDrone.Core.Music;
using NzbDrone.Core.Organizer;

namespace NzbDrone.Core.MediaFiles
{
    public interface IRenameTrackFileService
    {
        List<RenameTrackFilePreview> GetRenamePreviews(int artistId);
        List<RenameTrackFilePreview> GetRenamePreviews(int artistId, int albumId);
    }

    public class RenameTrackFileService : IRenameTrackFileService, IExecute<RenameFilesCommand>, IExecute<RenameArtistCommand>
    {
        private readonly IArtistService _artistService;
        private readonly IAlbumService _albumService;
        private readonly IMediaFileService _mediaFileService;
        private readonly IMoveTrackFiles _trackFileMover;
        private readonly IEventAggregator _eventAggregator;
        private readonly ITrackService _trackService;
        private readonly IBuildFileNames _filenameBuilder;
        private readonly IDiskProvider _diskProvider;
        private readonly Logger _logger;

        public RenameTrackFileService(IArtistService artistService,
                                        IAlbumService albumService,
                                        IMediaFileService mediaFileService,
                                        IMoveTrackFiles trackFileMover,
                                        IEventAggregator eventAggregator,
                                        ITrackService trackService,
                                        IBuildFileNames filenameBuilder,
                                        IDiskProvider diskProvider,
                                        Logger logger)
        {
            _artistService = artistService;
            _albumService = albumService;
            _mediaFileService = mediaFileService;
            _trackFileMover = trackFileMover;
            _eventAggregator = eventAggregator;
            _trackService = trackService;
            _filenameBuilder = filenameBuilder;
            _diskProvider = diskProvider;
            _logger = logger;
        }

        public List<RenameTrackFilePreview> GetRenamePreviews(int artistId)
        {
            var artist = _artistService.GetArtist(artistId);
            var tracks = _trackService.GetTracksByArtist(artistId);
            var files = _mediaFileService.GetFilesByArtist(artistId);

            return GetPreviews(artist, tracks, files)
                .OrderByDescending(e => e.AlbumId)
                .ThenByDescending(e => e.TrackNumbers.First())
                .ToList();
        }

        public List<RenameTrackFilePreview> GetRenamePreviews(int artistId, int albumId)
        {
            var artist = _artistService.GetArtist(artistId);
            var tracks = _trackService.GetTracksByAlbum(albumId);
            var files = _mediaFileService.GetFilesByAlbum(albumId);

            return GetPreviews(artist, tracks, files)
                .OrderByDescending(e => e.TrackNumbers.First()).ToList();
        }

        private IEnumerable<RenameTrackFilePreview> GetPreviews(Artist artist, List<Track> tracks, List<TrackFile> files)
        {
            foreach (var f in files)
            {
                var file = f;
                var tracksInFile = tracks.Where(e => e.TrackFileId == file.Id).ToList();
                var trackFilePath = file.Path;

                if (!tracksInFile.Any())
                {
                    _logger.Warn("File ({0}) is not linked to any tracks", trackFilePath);
                    continue;
                }

                var album = _albumService.GetAlbum(tracksInFile.First().AlbumId);
                var newPath = _filenameBuilder.BuildTrackFilePath(tracksInFile, artist, album, file, Path.GetExtension(trackFilePath));

                if (!trackFilePath.PathEquals(newPath, StringComparison.Ordinal))
                {
                    yield return new RenameTrackFilePreview
                    {
                        ArtistId = artist.Id,
                        AlbumId = album.Id,
                        TrackNumbers = tracksInFile.Select(e => e.AbsoluteTrackNumber).ToList(),
                        TrackFileId = file.Id,
                        ExistingPath = file.Path,
                        NewPath = newPath
                    };
                }
            }
        }

        private void RenameFiles(List<TrackFile> trackFiles, Artist artist)
        {
            var renamed = new List<RenamedTrackFile>();

            foreach (var trackFile in trackFiles)
            {
                var previousPath = trackFile.Path;

                try
                {
                    _logger.Debug("Renaming track file: {0}", trackFile);
                    _trackFileMover.MoveTrackFile(trackFile, artist);

                    _mediaFileService.Update(trackFile);

                    renamed.Add(new RenamedTrackFile
                    {
                        TrackFile = trackFile,
                        PreviousPath = previousPath
                    });

                    _logger.Debug("Renamed track file: {0}", trackFile);

                    _eventAggregator.PublishEvent(new TrackFileRenamedEvent(artist, trackFile, previousPath));
                }
                catch (FileAlreadyExistsException ex)
                {
                    _logger.Warn("File not renamed, there is already a file at the destination: {0}", ex.Filename);
                }
                catch (SameFilenameException ex)
                {
                    _logger.Debug("File not renamed, source and destination are the same: {0}", ex.Filename);
                }
                catch (Exception ex)
                {
                    _logger.Error(ex, "Failed to rename file {0}", previousPath);
                }
            }

            if (renamed.Any())
            {
                _eventAggregator.PublishEvent(new ArtistRenamedEvent(artist, renamed));

                _logger.Debug("Removing Empty Subfolders from: {0}", artist.Path);
                _diskProvider.RemoveEmptySubfolders(artist.Path);
            }
        }

        public void Execute(RenameFilesCommand message)
        {
            var artist = _artistService.GetArtist(message.ArtistId);
            var trackFiles = _mediaFileService.Get(message.Files);

            _logger.ProgressInfo("Renaming {0} files for {1}", trackFiles.Count, artist.Name);
            RenameFiles(trackFiles, artist);
            _logger.ProgressInfo("Selected track files renamed for {0}", artist.Name);

            _eventAggregator.PublishEvent(new RenameCompletedEvent());
        }

        public void Execute(RenameArtistCommand message)
        {
            _logger.Debug("Renaming all files for selected artist");
            var artistToRename = _artistService.GetArtists(message.ArtistIds);

            foreach (var artist in artistToRename)
            {
                var trackFiles = _mediaFileService.GetFilesByArtist(artist.Id);
                _logger.ProgressInfo("Renaming all files in artist: {0}", artist.Name);
                RenameFiles(trackFiles, artist);
                _logger.ProgressInfo("All track files renamed for {0}", artist.Name);
            }

            _eventAggregator.PublishEvent(new RenameCompletedEvent());
        }
    }
}