using System;
using Xamarin.Forms.Xaml;
using TINK.Model;
using TINK.Model.Connector;
using TINK.Model.User.Account;
using Xamarin.Forms;
using Serilog;
using Serilog.Core;
using System.Collections.Generic;
using Serilog.Events;
using TINK.Model.Logging;
using TINK.Model.Device;
using System.Linq;
using MonkeyCache.FileStore;
using Plugin.Connectivity;
using System.Threading;
using TINK.Model.Settings;
using Plugin.Permissions;
using TINK.Services.BluetoothLock.Crypto;
using TINK.Model.Services.Geolocation;
using TINK.Services;
using System.Threading.Tasks;
using TINK.Services.Permissions;
#if ARENDI
using Arendi.BleLibrary.Local;
#endif

// Required for support of binding package, see  https://github.com/nuitsjp/Xamarin.Forms.GoogleMaps.Bindings.
[assembly: XamlCompilation(XamlCompilationOptions.Compile)]
namespace TINK
{
    public partial class App : Application
    {
        /// <summary>Title of the attachment file.</summary>
        private const string ATTACHMENTTITLE = "Diagnostics.txt";

        /// <summary> Model root. </summary>
        private static TinkApp m_oModelRoot;

        /// <summary>
        /// Gets the model root.
        /// </summary>
        public static TinkApp ModelRoot
        {
            get
            {
                if (m_oModelRoot != null)
                {
                    // Root model already exists, nothing to do.
                    return m_oModelRoot;
                }
  
                // Get folder where to read settings from
                var specialFolders = DependencyService.Get<ISpecialFolder>();
                var internalPersonalDir = specialFolders.GetInternalPersonalDir();
                
                // Delete attachtment from previous session.
                DeleteAttachment(internalPersonalDir);

                // Setup logger using default settings. 
                Log.Logger = new LoggerConfiguration()
                    .MinimumLevel.ControlledBy(new LoggingLevelSwitch { MinimumLevel = Model.Settings.Settings.DEFAULTLOGGINLEVEL })
                    .WriteTo.Debug()
                    .WriteTo.File(internalPersonalDir, Model.Logging.RollingInterval.Session)
                    .CreateLogger();

                // Subscribe to any unhandled/ unobserved exceptions.
                AppDomain.CurrentDomain.UnhandledException += (sender, unobservedTaskExceptionEventArgs) => { Log.Fatal("Unobserved task exception: {Exception}", unobservedTaskExceptionEventArgs.ExceptionObject); };
                TaskScheduler.UnobservedTaskException += (sender, unhandledExceptionEventArgs) => { Log.Fatal("Unhandled exception: {Exception}", unhandledExceptionEventArgs.Exception); };

                // Restore last model state from json- file.
                Dictionary<string, string> settingsJSON = new Dictionary<string, string>();
                try
                {
                    settingsJSON = JsonSettingsDictionary.Deserialize(internalPersonalDir);
                }
                catch (Exception exception)
                {
                    Log.Error("Reading application settings from file failed.", exception);
                }

                Model.Settings.Settings settings;
                try
                {
                    settings = new Model.Settings.Settings(
                        JsonSettingsDictionary.GetGroupFilterMapPage(settingsJSON),
                        JsonSettingsDictionary.GetGoupFilterSettings(settingsJSON),
                        JsonSettingsDictionary.GetCopriHostUri(settingsJSON),
                        JsonSettingsDictionary.GetPollingParameters(settingsJSON),
                        JsonSettingsDictionary.GetMinimumLoggingLevel(settingsJSON),
                        JsonSettingsDictionary.GetIsReportLevelVerbose(settingsJSON),
                        JsonSettingsDictionary.GetExpiresAfter(settingsJSON),
                        JsonSettingsDictionary.GetActiveLockService(settingsJSON),
                        JsonSettingsDictionary.GetConnectTimeout(settingsJSON),
                        JsonSettingsDictionary.GetActiveGeolocationService(settingsJSON),
                        JsonSettingsDictionary.GetCenterMapToCurrentLocation(settingsJSON),
                        JsonSettingsDictionary.GetLogToExternalFolder(settingsJSON),
                        JsonSettingsDictionary.GetIsSiteCachingOn(settingsJSON),
                        JsonSettingsDictionary.GetActiveTheme(settingsJSON) ?? typeof(Themes.LastenradBayern).FullName);
                }
                catch (Exception exception)
                {
                    Log.Error("Deserializing application settings from dictionary failed.", exception);
                    settings = new Model.Settings.Settings();
                }

                if (settings.MinimumLogEventLevel != Model.Settings.Settings.DEFAULTLOGGINLEVEL 
                    || settings.LogToExternalFolder)
                {
                    // Eigher
                    // - logging is not set to default value or
                    // - logging is performed to external folder.
                    // Need to reconfigure.
                    Log.CloseAndFlush(); // Close before modifying logger configuration. Otherwise a sharing vialation occurs.

                    Log.Logger = new LoggerConfiguration()
                        .MinimumLevel.ControlledBy(new LoggingLevelSwitch(settings.MinimumLogEventLevel))
                        .WriteTo.Debug()
                        .WriteTo.File(!settings.LogToExternalFolder ? internalPersonalDir : specialFolders.GetExternalFilesDir(), Model.Logging.RollingInterval.Session)
                        .CreateLogger();
                }

                // Get auth cookie
                Log.Debug("Get auth cookie.");
                IStore store = null;

                var lastVersion = JsonSettingsDictionary.GetAppVersion(settingsJSON);
                if (lastVersion > new Version(3, 0, 250))
                {
                    // App versions newer than 3.0.173 stored geolocation service in configuration.
                    // Force a switch to typeof(GeolocationService) for versions < 3.0.251
                    GeolocationServicesContainer.SetActive(settings.ActiveGeolocationService);
                }

                store = new Store();

                Barrel.ApplicationId = "TINKApp";

                var context = SynchronizationContext.Current;

                var appInfoService = DependencyService.Get<IAppInfo>();

                // Create new app instnace.
                Log.Debug("Constructing main model...");
                m_oModelRoot = new TinkApp(
                    settings,
                    store, // Manages user account
                    (isConnected, activeUri, sessionCookie, mail, expiresAfter) => ConnectorFactory.Create(isConnected, activeUri, $"sharee.bike/{appInfoService.Version}", sessionCookie, mail, expiresAfter),
                    GeolocationServicesContainer,
                    null, /* locksService */
                    DependencyService.Get<ISmartDevice>(),
                    specialFolders,
                    new Cipher(),
                    null, // Permissions, no more used.
#if ARENDI
                    DependencyService.Get<ICentral>(),
#else
                    null,
#endif
                    isConnectedFunc: () => CrossConnectivity.Current.IsConnected,
                    postAction: (d, obj) => context.Post(d, obj),
                    currentVersion: appInfoService.Version,
                    lastVersion: JsonSettingsDictionary.GetAppVersion(settingsJSON),
                    whatsNewShownInVersion: JsonSettingsDictionary.GetWhatsNew(settingsJSON) ?? settingsJSON.GetAppVersion());

                Log.Debug("Main model successfully constructed.");
                return m_oModelRoot;
            }
        }

        /// <summary>
        /// Entry point of application.
        /// </summary>
        public App()
        {
            InitializeComponent();

#if USEFLYOUT
            // Use flyout page.
            MainPage = ModelRoot.WhatsNew.IsShowRequired
                ? new View.WhatsNew.WhatsNewPage(() => MainPage = new View.Root.RootPage()) // Show whats new info.
                : (Page)new View.Root.RootPage(); // Just start sharee- app            
#else
            // Use shell.
            MainPage = ModelRoot.WhatsNew.IsShowRequired
            ? new View.WhatsNew.WhatsNewPage(() => MainPage = new View.RootShell.AppShell()) // Show whats new info.
                : (Page)new View.RootShell.AppShell(); // Just start sharee- app

#endif
        }

        /// <summary> Concatenates all log files to a single one. </summary>
        /// <returns>Full file name of attachment.</returns>
        public static string CreateAttachment()
        {
            var sessionLogFiles = Log.Logger.GetLogFiles().ToArray();

            if (sessionLogFiles.Length < 1)
            {
                // Either
                // - there is no logging file 
                // - an error occurred getting list of log files.
                return string.Empty;
            }

            var fullLogFileName = System.IO.Path.Combine(ModelRoot.LogFileParentFolder, ATTACHMENTTITLE);

            // Stop logging to avoid file access exception.
            Log.CloseAndFlush();

            System.IO.File.WriteAllLines(
                fullLogFileName,
                sessionLogFiles.SelectMany(name =>
                     (new List<string> { $"{{\"SessionFileName\":\"{name}\"}}" })
                        .Concat(System.IO.File.ReadLines(name).ToArray())));

            // Resume logging
            Log.Logger = new LoggerConfiguration()
                .MinimumLevel.ControlledBy(new LoggingLevelSwitch { MinimumLevel = ModelRoot.Level.MinimumLevel })
                .WriteTo.Debug()
                .WriteTo.File(ModelRoot.LogFileParentFolder, Model.Logging.RollingInterval.Session)
                .CreateLogger();

            return fullLogFileName;
        }

        /// <summary>Deletes an attachment if there is one.</summary>
        /// <param name="folder">Folder to delete, is null folder is queried from model.</param>
        private static void DeleteAttachment(string folder = null)
        {
            var attachment = System.IO.Path.Combine(folder ?? ModelRoot.LogFileParentFolder, ATTACHMENTTITLE);
            if (!System.IO.File.Exists(attachment))
            {
                // No attachment found.
                return;
            }

            System.IO.File.Delete(attachment);
        }

        protected override void OnSleep()
        {
            // Handle when your app sleeps
            Log.CloseAndFlush();
        }

        protected override void OnResume()
        {
            DeleteAttachment();

            Log.Logger = new LoggerConfiguration()
                .MinimumLevel.ControlledBy(new LoggingLevelSwitch { MinimumLevel = ModelRoot.Level.MinimumLevel })
                .WriteTo.Debug()
                .WriteTo.File(ModelRoot.LogFileParentFolder, Model.Logging.RollingInterval.Session)
                .CreateLogger();
        }

        /// <summary> Gets the current logging level.</summary>
        /// <returns></returns>
        private static LogEventLevel GetCurrentLogEventLevel()
        {
            foreach (LogEventLevel level in Enum.GetValues(typeof(LogEventLevel)))
            {
                if (Log.IsEnabled(level))
                    return level;
            }

            return LogEventLevel.Error;
        }

        /// <summary>
        /// Holds the permission service instance.
        /// </summary>
        private static ILocationPermission _PermissionsService = null;

        /// <summary>
        /// Service to manage permissions (location) of the app.
        /// </summary>
        public static ILocationPermission PermissionsService
        {
            get
            {
                if (_PermissionsService != null)
                    return _PermissionsService;

                _PermissionsService = new Services.Permissions.Plugin.Permissions();
                return _PermissionsService;
            }
        }

        /// <summary>
        /// Service to manage bluetooth stack.
        /// </summary>
        public static Plugin.BLE.Abstractions.Contracts.IBluetoothLE BluetoothService => Plugin.BLE.CrossBluetoothLE.Current;

        /// <summary>
        /// Service container to manage geolocation services.
        /// </summary>
        public static IServicesContainer<IGeolocation> GeolocationServicesContainer { get; } 
            = new ServicesContainerMutable<IGeolocation>(
                    new HashSet<IGeolocation> { 
                        new LastKnownGeolocationService(DependencyService.Get<IGeolodationDependent>()), 
                        new SimulatedGeolocationService(DependencyService.Get<IGeolodationDependent>()), 
                        new GeolocationService(DependencyService.Get<IGeolodationDependent>()) },
                    Model.Settings.Settings.DefaultLocationService.FullName);
    }
}