using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using NLog;
using NzbDrone.Common;
using NzbDrone.Common.Eventing;
using NzbDrone.Core.Configuration;
using NzbDrone.Core.Download;
using NzbDrone.Core.MediaFiles;
using NzbDrone.Core.Organizer;
using NzbDrone.Core.Tv;
using NzbDrone.Core.Model;

namespace NzbDrone.Core.Providers
{
    public class DiskScanProvider
    {
        private static readonly Logger Logger = LogManager.GetCurrentClassLogger();
        private static readonly string[] MediaExtensions = new[] { ".mkv", ".avi", ".wmv", ".mp4", ".mpg", ".mpeg", ".xvid", ".flv", ".mov", ".rm", ".rmvb", ".divx", ".dvr-ms", ".ts", ".ogm", ".m4v", ".strm" };
        private readonly DiskProvider _diskProvider;
        private readonly IEpisodeService _episodeService;
        private readonly IMediaFileService _mediaFileService;
        private readonly IConfigService _configService;
        private readonly IBuildFileNames _buildFileNames;
        private readonly RecycleBinProvider _recycleBinProvider;
        private readonly MediaInfoProvider _mediaInfoProvider;
        private readonly ISeriesRepository _seriesRepository;
        private readonly IEventAggregator _eventAggregator;

        public DiskScanProvider(DiskProvider diskProvider, IEpisodeService episodeService, IMediaFileService mediaFileService, IConfigService configService, IBuildFileNames buildFileNames,
                                RecycleBinProvider recycleBinProvider, MediaInfoProvider mediaInfoProvider, ISeriesRepository seriesRepository, IEventAggregator eventAggregator)
        {
            _diskProvider = diskProvider;
            _episodeService = episodeService;
            _mediaFileService = mediaFileService;
            _configService = configService;
            _buildFileNames = buildFileNames;
            _recycleBinProvider = recycleBinProvider;
            _mediaInfoProvider = mediaInfoProvider;
            _seriesRepository = seriesRepository;
            _eventAggregator = eventAggregator;
        }

        public DiskScanProvider()
        {
        }

        /// <summary>
        ///   Scans the specified series folder for media files
        /// </summary>
        /// <param name = "series">The series to be scanned</param>
        public virtual List<EpisodeFile> Scan(Series series)
        {
            return Scan(series, series.Path);
        }

        /// <summary>
        ///   Scans the specified series folder for media files
        /// </summary>
        /// <param name = "series">The series to be scanned</param>
        /// <param name="path">Path to scan</param>
        public virtual List<EpisodeFile> Scan(Series series, string path)
        {
            if (!_diskProvider.FolderExists(path))
            {
                Logger.Warn("Series folder doesn't exist: {0}", path);
                return new List<EpisodeFile>();
            }

            if (_episodeService.GetEpisodeBySeries(series.Id).Count == 0)
            {
                Logger.Debug("Series {0} has no episodes. skipping", series.Title);
                return new List<EpisodeFile>();
            }

            var seriesFile = _mediaFileService.GetFilesBySeries(series.Id);
            CleanUp(seriesFile);

            var mediaFileList = GetVideoFiles(path);
            var importedFiles = new List<EpisodeFile>();

            foreach (var filePath in mediaFileList)
            {
                var file = ImportFile(series, filePath);
                if (file != null)
                {
                    importedFiles.Add(file);
                }
            }

            //Todo: Find the "best" episode file for all found episodes and import that one
            //Todo: Move the episode linking to here, instead of import (or rename import)

            series.LastDiskSync = DateTime.Now;
            _seriesRepository.Update(series);

            return importedFiles;
        }

        public virtual EpisodeFile ImportFile(Series series, string filePath)
        {
            Logger.Trace("Importing file to database [{0}]", filePath);

            if (_mediaFileService.Exists(filePath))
            {
                Logger.Trace("[{0}] already exists in the database. skipping.", filePath);
                return null;
            }

            var parseResult = Parser.ParsePath(filePath);

            if (parseResult == null)
                return null;

            var size = _diskProvider.GetSize(filePath);
            var runTime = _mediaInfoProvider.GetRunTime(filePath);

            if (series.SeriesTypes == SeriesTypes.Daily || parseResult.SeasonNumber > 0)
            {
                if (size < Constants.IgnoreFileSize && runTime < 180)
                {
                    Logger.Trace("[{0}] appears to be a sample. skipping.", filePath);
                    return null;
                }
            }

            if (!_diskProvider.IsChildOfPath(filePath, series.Path))
                parseResult.SceneSource = true;

            parseResult.SeriesTitle = series.Title; //replaces the nasty path as title to help with logging
            parseResult.Series = series;

            var episodes = _episodeService.GetEpisodesByParseResult(parseResult);

            if (episodes.Count <= 0)
            {
                Logger.Debug("Can't find any matching episodes in the database. Skipping {0}", filePath);
                return null;
            }

            //Make sure this file is an upgrade for ALL episodes already on disk
            if (episodes.All(e => e.EpisodeFile == null || e.EpisodeFile.QualityModel <= parseResult.Quality))
            {
                Logger.Debug("Deleting the existing file(s) on disk to upgrade to: {0}", filePath);
                //Do the delete for files where there is already an episode on disk
                episodes.Where(e => e.EpisodeFile != null).Select(e => e.EpisodeFile.Path).Distinct().ToList().ForEach(p => _recycleBinProvider.DeleteFile(p));
            }

            else
            {
                //Skip this file because its not an upgrade
                Logger.Trace("This file isn't an upgrade for all episodes. Skipping {0}", filePath);
                return null;
            }

            var episodeFile = new EpisodeFile();
            episodeFile.DateAdded = DateTime.Now;
            episodeFile.SeriesId = series.Id;
            episodeFile.Path = filePath.NormalizePath();
            episodeFile.Size = size;
            episodeFile.Quality = parseResult.Quality.Quality;
            episodeFile.Proper = parseResult.Quality.Proper;
            episodeFile.SeasonNumber = parseResult.SeasonNumber;
            episodeFile.SceneName = Path.GetFileNameWithoutExtension(filePath.NormalizePath());
            episodeFile.ReleaseGroup = parseResult.ReleaseGroup;

            //Todo: We shouldn't actually import the file until we confirm its the only one we want.
            //Todo: Separate episodeFile creation from importing (pass file to import to import)
            _mediaFileService.Add(episodeFile);

            //Link file to all episodes
            foreach (var ep in episodes)
            {
                ep.EpisodeFile = episodeFile;
                ep.PostDownloadStatus = PostDownloadStatusType.NoError;
                _episodeService.UpdateEpisode(ep);
                Logger.Debug("Linking [{0}] > [{1}]", filePath, ep);
            }

            return episodeFile;
        }

        public virtual EpisodeFile MoveEpisodeFile(EpisodeFile episodeFile, bool newDownload = false)
        {
            if (episodeFile == null)
                throw new ArgumentNullException("episodeFile");

            var series = _seriesRepository.Get(episodeFile.SeriesId);
            var episodes = _episodeService.GetEpisodesByFileId(episodeFile.Id);
            string newFileName = _buildFileNames.BuildFilename(episodes, series, episodeFile);
            var newFile = _buildFileNames.BuildFilePath(series, episodes.First().SeasonNumber, newFileName, Path.GetExtension(episodeFile.Path));

            //Only rename if existing and new filenames don't match
            if (DiskProvider.PathEquals(episodeFile.Path, newFile))
            {
                Logger.Debug("Skipping file rename, source and destination are the same: {0}", episodeFile.Path);
                return null;
            }

            if (!_diskProvider.FileExists(episodeFile.Path))
            {
                Logger.Error("Episode file path does not exist, {0}", episodeFile.Path);
                return null;
            }

            _diskProvider.CreateDirectory(new FileInfo(newFile).DirectoryName);

            Logger.Debug("Moving [{0}] > [{1}]", episodeFile.Path, newFile);
            _diskProvider.MoveFile(episodeFile.Path, newFile);

            //Wrapped in Try/Catch to prevent this from causing issues with remote NAS boxes, the move worked, which is more important.
            try
            {
                _diskProvider.InheritFolderPermissions(newFile);
            }
            catch (UnauthorizedAccessException ex)
            {
                Logger.Debug("Unable to apply folder permissions to: ", newFile);
                Logger.TraceException(ex.Message, ex);
            }

            episodeFile.Path = newFile;
            _mediaFileService.Update(episodeFile);

            var parseResult = Parser.ParsePath(episodeFile.Path);
            parseResult.Series = series;
            parseResult.Quality = new QualityModel { Quality = episodeFile.Quality, Proper = episodeFile.Proper };
            parseResult.Episodes = episodes;


            if (newDownload)
            {
                _eventAggregator.Publish(new EpisodeDownloadedEvent(parseResult));
            }

            return episodeFile;
        }

        /// <summary>
        ///   Removes files that no longer exist on disk from the database
        /// </summary>
        /// <param name = "files">list of files to verify</param>
        public virtual void CleanUp(IList<EpisodeFile> files)
        {
            foreach (var episodeFile in files)
            {
                try
                {
                    if (!_diskProvider.FileExists(episodeFile.Path))
                    {
                        Logger.Trace("File [{0}] no longer exists on disk. removing from db", episodeFile.Path);

                        //Set the EpisodeFileId for each episode attached to this file to 0
                        foreach (var episode in _episodeService.GetEpisodesByFileId(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;
                            _episodeService.UpdateEpisode(episode);
                        }

                        //Delete it from the DB
                        Logger.Trace("Removing EpisodeFile from DB.");
                        _mediaFileService.Delete(episodeFile.Id);
                    }
                }
                catch (Exception ex)
                {
                    var message = String.Format("Unable to cleanup EpisodeFile in DB: {0}", episodeFile.Id);
                    Logger.ErrorException(message, ex);
                }
            }
        }

        public virtual void CleanUpDropFolder(string path)
        {
            //Todo: We should rename files before importing them to prevent this issue from ever happening

            var filesOnDisk = GetVideoFiles(path);

            foreach (var file in filesOnDisk)
            {
                try
                {
                    var episodeFile = _mediaFileService.GetFileByPath(file);

                    if (episodeFile != null)
                    {
                        Logger.Trace("[{0}] was imported but not moved, moving it now", file);

                        MoveEpisodeFile(episodeFile, true);
                    }

                }
                catch (Exception ex)
                {
                    Logger.WarnException("Failed to move epiosde file from drop folder: " + file, ex);
                    throw;
                }
            }
        }

        public virtual List<string> GetVideoFiles(string path, bool allDirectories = true)
        {
            Logger.Debug("Scanning '{0}' for video files", path);

            var searchOption = allDirectories ? SearchOption.AllDirectories : SearchOption.TopDirectoryOnly;
            var filesOnDisk = _diskProvider.GetFiles(path, searchOption);

            var mediaFileList = filesOnDisk.Where(c => MediaExtensions.Contains(Path.GetExtension(c).ToLower())).ToList();

            Logger.Trace("{0} video files were found in {1}", mediaFileList.Count, path);
            return mediaFileList;
        }
    }
}