using MediaBrowser.Common.Kernel;
using MediaBrowser.Common.Plugins;
using MediaBrowser.Common.ScheduledTasks;
using MediaBrowser.Common.Security;
using MediaBrowser.Common.Updates;
using MediaBrowser.Controller.Drawing;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.IO;
using MediaBrowser.Controller.Library;
using MediaBrowser.Controller.Localization;
using MediaBrowser.Controller.MediaInfo;
using MediaBrowser.Controller.Persistence;
using MediaBrowser.Controller.Playback;
using MediaBrowser.Controller.Plugins;
using MediaBrowser.Controller.Providers;
using MediaBrowser.Controller.Resolvers;
using MediaBrowser.Controller.Updates;
using MediaBrowser.Controller.Weather;
using MediaBrowser.Model.Configuration;
using MediaBrowser.Model.Logging;
using MediaBrowser.Model.Serialization;
using MediaBrowser.Model.System;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace MediaBrowser.Controller
{
    /// <summary>
    /// Class Kernel
    /// </summary>
    public class Kernel : BaseKernel<ServerConfiguration, IServerApplicationPaths>
    {
        /// <summary>
        /// Gets the instance.
        /// </summary>
        /// <value>The instance.</value>
        public static Kernel Instance { get; private set; }

        /// <summary>
        /// Gets the library manager.
        /// </summary>
        /// <value>The library manager.</value>
        public LibraryManager LibraryManager { get; private set; }

        /// <summary>
        /// Gets the image manager.
        /// </summary>
        /// <value>The image manager.</value>
        public ImageManager ImageManager { get; private set; }

        /// <summary>
        /// Gets the user manager.
        /// </summary>
        /// <value>The user manager.</value>
        public UserManager UserManager { get; private set; }

        /// <summary>
        /// Gets the FFMPEG controller.
        /// </summary>
        /// <value>The FFMPEG controller.</value>
        public FFMpegManager FFMpegManager { get; private set; }

        /// <summary>
        /// Gets the installation manager.
        /// </summary>
        /// <value>The installation manager.</value>
        public InstallationManager InstallationManager { get; private set; }

        /// <summary>
        /// Gets or sets the file system manager.
        /// </summary>
        /// <value>The file system manager.</value>
        public FileSystemManager FileSystemManager { get; private set; }

        /// <summary>
        /// Gets the provider manager.
        /// </summary>
        /// <value>The provider manager.</value>
        public ProviderManager ProviderManager { get; private set; }

        /// <summary>
        /// Gets the user data manager.
        /// </summary>
        /// <value>The user data manager.</value>
        public UserDataManager UserDataManager { get; private set; }

        /// <summary>
        /// The _users
        /// </summary>
        private IEnumerable<User> _users;
        /// <summary>
        /// The _user lock
        /// </summary>
        private object _usersSyncLock = new object();
        /// <summary>
        /// The _users initialized
        /// </summary>
        private bool _usersInitialized;
        /// <summary>
        /// Gets the users.
        /// </summary>
        /// <value>The users.</value>
        public IEnumerable<User> Users
        {
            get
            {
                // Call ToList to exhaust the stream because we'll be iterating over this multiple times
                LazyInitializer.EnsureInitialized(ref _users, ref _usersInitialized, ref _usersSyncLock, UserManager.LoadUsers);
                return _users;
            }
            internal set
            {
                _users = value;

                if (value == null)
                {
                    _usersInitialized = false;
                }
            }
        }

        /// <summary>
        /// The _root folder
        /// </summary>
        private AggregateFolder _rootFolder;
        /// <summary>
        /// The _root folder sync lock
        /// </summary>
        private object _rootFolderSyncLock = new object();
        /// <summary>
        /// The _root folder initialized
        /// </summary>
        private bool _rootFolderInitialized;
        /// <summary>
        /// Gets the root folder.
        /// </summary>
        /// <value>The root folder.</value>
        public AggregateFolder RootFolder
        {
            get
            {
                LazyInitializer.EnsureInitialized(ref _rootFolder, ref _rootFolderInitialized, ref _rootFolderSyncLock, LibraryManager.CreateRootFolder);
                return _rootFolder;
            }
            private set
            {
                _rootFolder = value;

                if (value == null)
                {
                    _rootFolderInitialized = false;
                }
            }
        }

        /// <summary>
        /// Gets the kernel context.
        /// </summary>
        /// <value>The kernel context.</value>
        public override KernelContext KernelContext
        {
            get { return KernelContext.Server; }
        }

        /// <summary>
        /// Gets the list of Localized string files
        /// </summary>
        /// <value>The string files.</value>
        public IEnumerable<LocalizedStringData> StringFiles { get; private set; }

        /// <summary>
        /// Gets the list of plugin configuration pages
        /// </summary>
        /// <value>The configuration pages.</value>
        public IEnumerable<IPluginConfigurationPage> PluginConfigurationPages { get; private set; }

        /// <summary>
        /// Gets the intro providers.
        /// </summary>
        /// <value>The intro providers.</value>
        public IEnumerable<IIntroProvider> IntroProviders { get; private set; }

        /// <summary>
        /// Gets the list of currently registered weather prvoiders
        /// </summary>
        /// <value>The weather providers.</value>
        public IEnumerable<IWeatherProvider> WeatherProviders { get; private set; }

        /// <summary>
        /// Gets the list of currently registered metadata prvoiders
        /// </summary>
        /// <value>The metadata providers enumerable.</value>
        public BaseMetadataProvider[] MetadataProviders { get; private set; }

        /// <summary>
        /// Gets the list of currently registered image processors
        /// Image processors are specialized metadata providers that run after the normal ones
        /// </summary>
        /// <value>The image enhancers.</value>
        public IEnumerable<IImageEnhancer> ImageEnhancers { get; private set; }

        /// <summary>
        /// Gets the list of currently registered entity resolvers
        /// </summary>
        /// <value>The entity resolvers enumerable.</value>
        internal IEnumerable<IBaseItemResolver> EntityResolvers { get; private set; }

        /// <summary>
        /// Gets the list of BasePluginFolders added by plugins
        /// </summary>
        /// <value>The plugin folders.</value>
        internal IEnumerable<IVirtualFolderCreator> PluginFolderCreators { get; private set; }

        /// <summary>
        /// Gets the list of available user repositories
        /// </summary>
        /// <value>The user repositories.</value>
        private IEnumerable<IUserRepository> UserRepositories { get; set; }

        /// <summary>
        /// Gets the active user repository
        /// </summary>
        /// <value>The user repository.</value>
        public IUserRepository UserRepository { get; private set; }

        /// <summary>
        /// Gets the active user repository
        /// </summary>
        /// <value>The display preferences repository.</value>
        public IDisplayPreferencesRepository DisplayPreferencesRepository { get; private set; }

        /// <summary>
        /// Gets the list of available item repositories
        /// </summary>
        /// <value>The item repositories.</value>
        private IEnumerable<IItemRepository> ItemRepositories { get; set; }

        /// <summary>
        /// Gets the active item repository
        /// </summary>
        /// <value>The item repository.</value>
        public IItemRepository ItemRepository { get; private set; }

        /// <summary>
        /// Gets the list of available item repositories
        /// </summary>
        /// <value>The user data repositories.</value>
        private IEnumerable<IUserDataRepository> UserDataRepositories { get; set; }

        /// <summary>
        /// Gets the list of available DisplayPreferencesRepositories
        /// </summary>
        /// <value>The display preferences repositories.</value>
        private IEnumerable<IDisplayPreferencesRepository> DisplayPreferencesRepositories { get; set; }

        /// <summary>
        /// Gets the list of entity resolution ignore rules
        /// </summary>
        /// <value>The entity resolution ignore rules.</value>
        internal IEnumerable<IResolutionIgnoreRule> EntityResolutionIgnoreRules { get; private set; }

        /// <summary>
        /// Gets the active user data repository
        /// </summary>
        /// <value>The user data repository.</value>
        public IUserDataRepository UserDataRepository { get; private set; }

        /// <summary>
        /// Gets the UDP server port number.
        /// </summary>
        /// <value>The UDP server port number.</value>
        public override int UdpServerPortNumber
        {
            get { return 7359; }
        }

        /// <summary>
        /// Creates a kernel based on a Data path, which is akin to our current programdata path
        /// </summary>
        /// <param name="appHost">The app host.</param>
        /// <param name="appPaths">The app paths.</param>
        /// <param name="xmlSerializer">The XML serializer.</param>
        /// <param name="taskManager">The task manager.</param>
        /// <param name="logger">The logger.</param>
        /// <exception cref="System.ArgumentNullException">isoManager</exception>
        public Kernel(IApplicationHost appHost, IServerApplicationPaths appPaths, IXmlSerializer xmlSerializer, ILogger logger)
            : base(appHost, appPaths, xmlSerializer, logger)
        {
            Instance = this;

            // For now there's no real way to inject this properly
            BaseItem.Logger = logger;
            Ratings.Logger = logger;
            LocalizedStrings.Logger = logger;
            // For now, until this can become an interface
            BaseMetadataProvider.Logger = logger;
        }

        /// <summary>
        /// Composes the parts with ioc container.
        /// </summary>
        protected override void FindParts()
        {
            InstallationManager = (InstallationManager)ApplicationHost.CreateInstance(typeof(InstallationManager));
            FFMpegManager = (FFMpegManager)ApplicationHost.CreateInstance(typeof(FFMpegManager));
            LibraryManager = (LibraryManager)ApplicationHost.CreateInstance(typeof(LibraryManager));
            UserManager = (UserManager)ApplicationHost.CreateInstance(typeof(UserManager));
            ImageManager = (ImageManager)ApplicationHost.CreateInstance(typeof(ImageManager));
            ProviderManager = (ProviderManager)ApplicationHost.CreateInstance(typeof(ProviderManager));
            UserDataManager = (UserDataManager)ApplicationHost.CreateInstance(typeof(UserDataManager));
            SecurityManager = (PluginSecurityManager)ApplicationHost.CreateInstance(typeof(PluginSecurityManager));
            
            base.FindParts();

            EntityResolutionIgnoreRules = ApplicationHost.GetExports<IResolutionIgnoreRule>();
            UserDataRepositories = ApplicationHost.GetExports<IUserDataRepository>();
            UserRepositories = ApplicationHost.GetExports<IUserRepository>();
            DisplayPreferencesRepositories = ApplicationHost.GetExports<IDisplayPreferencesRepository>();
            ItemRepositories = ApplicationHost.GetExports<IItemRepository>();
            WeatherProviders = ApplicationHost.GetExports<IWeatherProvider>();
            IntroProviders = ApplicationHost.GetExports<IIntroProvider>();
            PluginConfigurationPages = ApplicationHost.GetExports<IPluginConfigurationPage>();
            ImageEnhancers = ApplicationHost.GetExports<IImageEnhancer>().OrderBy(e => e.Priority).ToArray();
            PluginFolderCreators = ApplicationHost.GetExports<IVirtualFolderCreator>();
            StringFiles = ApplicationHost.GetExports<LocalizedStringData>();
            EntityResolvers = ApplicationHost.GetExports<IBaseItemResolver>().OrderBy(e => e.Priority).ToArray();
            MetadataProviders = ApplicationHost.GetExports<BaseMetadataProvider>().OrderBy(e => e.Priority).ToArray();
        }

        /// <summary>
        /// Performs initializations that can be reloaded at anytime
        /// </summary>
        /// <returns>Task.</returns>
        protected override async Task ReloadInternal()
        {
            // Reset these so that they can be lazy loaded again
            Users = null;
            RootFolder = null;

            await base.ReloadInternal().ConfigureAwait(false);

            ReloadResourcePools();

            ReloadFileSystemManager();

            await UserManager.RefreshUsersMetadata(CancellationToken.None).ConfigureAwait(false);
        }

        /// <summary>
        /// Releases unmanaged and - optionally - managed resources.
        /// </summary>
        /// <param name="dispose"><c>true</c> to release both managed and unmanaged resources; <c>false</c> to release only unmanaged resources.</param>
        protected override void Dispose(bool dispose)
        {
            if (dispose)
            {
                DisposeResourcePools();

                DisposeFileSystemManager();
            }

            base.Dispose(dispose);
        }

        /// <summary>
        /// Disposes the resource pools.
        /// </summary>
        private void DisposeResourcePools()
        {
            if (ResourcePools != null)
            {
                ResourcePools.Dispose();
                ResourcePools = null;
            }
        }

        /// <summary>
        /// Reloads the resource pools.
        /// </summary>
        private void ReloadResourcePools()
        {
            DisposeResourcePools();
            ResourcePools = new ResourcePool();
        }

        /// <summary>
        /// Called when [composable parts loaded].
        /// </summary>
        /// <returns>Task.</returns>
        protected override async Task OnComposablePartsLoaded()
        {
            // The base class will start up all the plugins
            await base.OnComposablePartsLoaded().ConfigureAwait(false);

            // Get the current item repository
            ItemRepository = GetRepository(ItemRepositories, Configuration.ItemRepository);
            var itemRepoTask = ItemRepository.Initialize();

            // Get the current user repository
            UserRepository = GetRepository(UserRepositories, Configuration.UserRepository);
            var userRepoTask = UserRepository.Initialize();

            // Get the current item repository
            UserDataRepository = GetRepository(UserDataRepositories, Configuration.UserDataRepository);
            var userDataRepoTask = UserDataRepository.Initialize();

            // Get the current display preferences repository
            DisplayPreferencesRepository = GetRepository(DisplayPreferencesRepositories, Configuration.DisplayPreferencesRepository);
            var displayPreferencesRepoTask = DisplayPreferencesRepository.Initialize();

            await Task.WhenAll(itemRepoTask, userRepoTask, userDataRepoTask, displayPreferencesRepoTask).ConfigureAwait(false);
        }

        /// <summary>
        /// Gets a repository by name from a list, and returns the default if not found
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="repositories">The repositories.</param>
        /// <param name="name">The name.</param>
        /// <returns>``0.</returns>
        private T GetRepository<T>(IEnumerable<T> repositories, string name)
            where T : class, IRepository
        {
            var enumerable = repositories as T[] ?? repositories.ToArray();

            return enumerable.FirstOrDefault(r => string.Equals(r.Name, name, StringComparison.OrdinalIgnoreCase)) ??
                   enumerable.FirstOrDefault();
        }

        /// <summary>
        /// Disposes the file system manager.
        /// </summary>
        private void DisposeFileSystemManager()
        {
            if (FileSystemManager != null)
            {
                FileSystemManager.Dispose();
                FileSystemManager = null;
            }
        }

        /// <summary>
        /// Reloads the file system manager.
        /// </summary>
        private void ReloadFileSystemManager()
        {
            DisposeFileSystemManager();

            FileSystemManager = new FileSystemManager(this, Logger, ApplicationHost.Resolve<ITaskManager>());
            FileSystemManager.StartWatchers();
        }

        /// <summary>
        /// Gets a User by Id
        /// </summary>
        /// <param name="id">The id.</param>
        /// <returns>User.</returns>
        /// <exception cref="System.ArgumentNullException"></exception>
        public User GetUserById(Guid id)
        {
            if (id == Guid.Empty)
            {
                throw new ArgumentNullException();
            }

            return Users.FirstOrDefault(u => u.Id == id);
        }

        /// <summary>
        /// Finds a library item by Id and UserId.
        /// </summary>
        /// <param name="id">The id.</param>
        /// <param name="userId">The user id.</param>
        /// <returns>BaseItem.</returns>
        /// <exception cref="System.ArgumentNullException">id</exception>
        public BaseItem GetItemById(Guid id, Guid userId)
        {
            if (id == Guid.Empty)
            {
                throw new ArgumentNullException("id");
            }

            if (userId == Guid.Empty)
            {
                throw new ArgumentNullException("userId");
            }

            var user = GetUserById(userId);
            var userRoot = user.RootFolder;

            return userRoot.FindItemById(id, user);
        }

        /// <summary>
        /// Gets the item by id.
        /// </summary>
        /// <param name="id">The id.</param>
        /// <returns>BaseItem.</returns>
        /// <exception cref="System.ArgumentNullException">id</exception>
        public BaseItem GetItemById(Guid id)
        {
            if (id == Guid.Empty)
            {
                throw new ArgumentNullException("id");
            }

            return RootFolder.FindItemById(id, null);
        }

        /// <summary>
        /// Completely overwrites the current configuration with a new copy
        /// </summary>
        /// <param name="config">The config.</param>
        public void UpdateConfiguration(ServerConfiguration config)
        {
            Configuration = config;
            SaveConfiguration();

            // Validate currently executing providers, in the background
            Task.Run(() =>
            {
                ProviderManager.ValidateCurrentlyRunningProviders();
            });
        }

        /// <summary>
        /// Gets the system info.
        /// </summary>
        /// <returns>SystemInfo.</returns>
        public override SystemInfo GetSystemInfo()
        {
            var info = base.GetSystemInfo();

            if (InstallationManager != null)
            {
                info.InProgressInstallations = InstallationManager.CurrentInstallations.Select(i => i.Item1).ToArray();
                info.CompletedInstallations = InstallationManager.CompletedInstallations.ToArray();
            }

            return info;
        }
    }
}