using System;
using System.Collections.Generic;
using System.Linq;
using NLog;
using NzbDrone.Common;
using NzbDrone.Common.Disk;
using NzbDrone.Core.Configuration;
using NzbDrone.Core.History;
using NzbDrone.Core.MediaFiles;
using NzbDrone.Core.MediaFiles.EpisodeImport;
using NzbDrone.Core.Messaging.Events;
using System.IO;

namespace NzbDrone.Core.Download
{
    public interface ICompletedDownloadService
    {
        void CheckForCompletedItem(IDownloadClient downloadClient, TrackedDownload trackedDownload, List<History.History> grabbedHistory, List<History.History> importedHistory);
    }

    public class CompletedDownloadService : ICompletedDownloadService
    {
        private readonly IEventAggregator _eventAggregator;
        private readonly IConfigService _configService;
        private readonly IDiskProvider _diskProvider;
        private readonly IDownloadedEpisodesImportService _downloadedEpisodesImportService;
        private readonly IHistoryService _historyService;
        private readonly Logger _logger;

        public CompletedDownloadService(IEventAggregator eventAggregator,
                                     IConfigService configService,
                                     IDiskProvider diskProvider,
                                     IDownloadedEpisodesImportService downloadedEpisodesImportService,
                                     IHistoryService historyService,
                                     Logger logger)
        {
            _eventAggregator = eventAggregator;
            _configService = configService;
            _diskProvider = diskProvider;
            _downloadedEpisodesImportService = downloadedEpisodesImportService;
            _historyService = historyService;
            _logger = logger;
        }

        private List<History.History> GetHistoryItems(List<History.History> grabbedHistory, string downloadClientId)
        {
            return grabbedHistory.Where(h => downloadClientId.Equals(h.Data.GetValueOrDefault(DownloadTrackingService.DOWNLOAD_CLIENT_ID)))
                                 .ToList();
        }

        public void CheckForCompletedItem(IDownloadClient downloadClient, TrackedDownload trackedDownload, List<History.History> grabbedHistory, List<History.History> importedHistory)
        {
            if (!_configService.EnableCompletedDownloadHandling)
            {
                return;
            }

            if (trackedDownload.DownloadItem.Status == DownloadItemStatus.Completed && trackedDownload.State == TrackedDownloadState.Downloading)
            {
                var grabbedItems = GetHistoryItems(grabbedHistory, trackedDownload.DownloadItem.DownloadClientId);

                if (!grabbedItems.Any() && trackedDownload.DownloadItem.Category.IsNullOrWhiteSpace())
                {
                    UpdateStatusMessage(trackedDownload, LogLevel.Debug, "Download wasn't grabbed by drone or not in a category, ignoring download.");
                    return;
                }

                var importedItems = GetHistoryItems(importedHistory, trackedDownload.DownloadItem.DownloadClientId);

                if (importedItems.Any())
                {
                    trackedDownload.State = TrackedDownloadState.Imported;

                    UpdateStatusMessage(trackedDownload, LogLevel.Debug, "Already added to history as imported.");
                }
                else
                {
                    string downloadedEpisodesFolder = _configService.DownloadedEpisodesFolder;
                    string downloadItemOutputPath = trackedDownload.DownloadItem.OutputPath;
                    if (downloadItemOutputPath.IsNullOrWhiteSpace())
                    {
                        UpdateStatusMessage(trackedDownload, LogLevel.Warn, "Download doesn't contain intermediate path, ignoring download.");
                        return;
                    }

                    if (!downloadedEpisodesFolder.IsNullOrWhiteSpace() && (downloadedEpisodesFolder.PathEquals(downloadItemOutputPath) || downloadedEpisodesFolder.IsParentPath(downloadItemOutputPath)))
                    {
                        UpdateStatusMessage(trackedDownload, LogLevel.Warn, "Intermediate Download path inside drone factory, ignoring download.");
                        return;
                    }

                    if (_diskProvider.FolderExists(trackedDownload.DownloadItem.OutputPath))
                    {
                        var importResults = _downloadedEpisodesImportService.ProcessFolder(new DirectoryInfo(trackedDownload.DownloadItem.OutputPath), trackedDownload.DownloadItem);

                        ProcessImportResults(trackedDownload, importResults);
                    }
                    else if (_diskProvider.FileExists(trackedDownload.DownloadItem.OutputPath))
                    {
                        var importResults = _downloadedEpisodesImportService.ProcessFile(new FileInfo(trackedDownload.DownloadItem.OutputPath), trackedDownload.DownloadItem);

                        ProcessImportResults(trackedDownload, importResults);
                    }
                    else
                    {
                        if (grabbedItems.Any())
                        {
                            var episodeIds = trackedDownload.DownloadItem.RemoteEpisode.Episodes.Select(v => v.Id).ToList();

                            // Check if we can associate it with a previous drone factory import.
                            importedItems = importedHistory.Where(v => v.Data.GetValueOrDefault(DownloadTrackingService.DOWNLOAD_CLIENT_ID) == null &&
                                                                  episodeIds.Contains(v.EpisodeId) && 
                                                                  v.Data.GetValueOrDefault("droppedPath") != null &&
                                                                  new FileInfo(v.Data["droppedPath"]).Directory.Name == grabbedItems.First().SourceTitle
                                                                  ).ToList();
                            if (importedItems.Count == 1)
                            {
                                var importedFile = new FileInfo(importedItems.First().Data["droppedPath"]);

                                if (importedFile.Directory.Name == grabbedItems.First().SourceTitle)
                                {
                                    trackedDownload.State = TrackedDownloadState.Imported;

                                    importedItems.First().Data[DownloadTrackingService.DOWNLOAD_CLIENT] = grabbedItems.First().Data[DownloadTrackingService.DOWNLOAD_CLIENT];
                                    importedItems.First().Data[DownloadTrackingService.DOWNLOAD_CLIENT_ID] = grabbedItems.First().Data[DownloadTrackingService.DOWNLOAD_CLIENT_ID];
                                    _historyService.UpdateHistoryData(importedItems.First().Id, importedItems.First().Data);

                                    UpdateStatusMessage(trackedDownload, LogLevel.Debug, "Intermediate Download path does not exist, but found probable drone factory ImportEvent.");
                                    return;
                                }
                            }
                        }

                        UpdateStatusMessage(trackedDownload, LogLevel.Error, "Intermediate Download path does not exist: {0}", trackedDownload.DownloadItem.OutputPath);
                        return;
                    }
                }
            }

            if (_configService.RemoveCompletedDownloads && trackedDownload.State == TrackedDownloadState.Imported && !trackedDownload.DownloadItem.IsReadOnly)
            {
                try
                {
                    _logger.Debug("[{0}] Removing completed download from history.", trackedDownload.DownloadItem.Title);
                    downloadClient.RemoveItem(trackedDownload.DownloadItem.DownloadClientId);

                    if (_diskProvider.FolderExists(trackedDownload.DownloadItem.OutputPath))
                    {
                        _logger.Debug("Removing completed download directory: {0}", trackedDownload.DownloadItem.OutputPath);
                        _diskProvider.DeleteFolder(trackedDownload.DownloadItem.OutputPath, true);
                    }
                    else if (_diskProvider.FileExists(trackedDownload.DownloadItem.OutputPath))
                    {
                        _logger.Debug("Removing completed download file: {0}", trackedDownload.DownloadItem.OutputPath);
                        _diskProvider.DeleteFile(trackedDownload.DownloadItem.OutputPath);
                    }

                    trackedDownload.State = TrackedDownloadState.Removed;
                }
                catch (NotSupportedException)
                {
                    UpdateStatusMessage(trackedDownload, LogLevel.Debug, "Removing item not supported by your download client.");
                }
            }
        }

        private void UpdateStatusMessage(TrackedDownload trackedDownload, LogLevel logLevel, String message, params object[] args)
        {
            var statusMessage = String.Format(message, args);
            var logMessage = String.Format("[{0}] {1}", trackedDownload.DownloadItem.Title, statusMessage);

            if (trackedDownload.StatusMessage != statusMessage)
            {
                trackedDownload.HasError = logLevel >= LogLevel.Warn;
                trackedDownload.StatusMessage = statusMessage;
                _logger.Log(logLevel, logMessage);
            }
            else
            {
                _logger.Debug(logMessage);
            }
        }

        private void ProcessImportResults(TrackedDownload trackedDownload, List<ImportResult> importResults)
        {
            if (importResults.Empty())
            {
                UpdateStatusMessage(trackedDownload, LogLevel.Error, "No files found are eligible for import in {0}", trackedDownload.DownloadItem.OutputPath);
            }
            else if (importResults.All(v => v.Result == ImportResultType.Imported || v.Result == ImportResultType.Rejected))
            {
                UpdateStatusMessage(trackedDownload, LogLevel.Info, "Imported {0} files.", importResults.Count(v => v.Result == ImportResultType.Imported));

                trackedDownload.State = TrackedDownloadState.Imported;
            }
            else
            {
                var errors = importResults
                    .Where(v => v.Result == ImportResultType.Skipped || v.Result == ImportResultType.Rejected)
                    .Select(v => v.Errors.Aggregate(Path.GetFileName(v.ImportDecision.LocalEpisode.Path), (a, r) => a + "\r\n- " + r))
                    .Aggregate("Failed to import:", (a, r) => a + "\r\n" + r);

                UpdateStatusMessage(trackedDownload, LogLevel.Error, errors);
            }
        }
    }
}