using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Linq;
using System.Threading.Tasks;
using Serilog;
using Serilog.Events;
using ShareeBike.Model;
using ShareeBike.Model.Connector;
using ShareeBike.Model.User.Account;
using ShareeBike.MultilingualResources;
using ShareeBike.Repository.Exception;
using ShareeBike.Services;
using ShareeBike.Services.BluetoothLock;
using ShareeBike.Services.Geolocation;
using ShareeBike.Settings;
using ShareeBike.View;
using ShareeBike.ViewModel.Map;
using ShareeBike.ViewModel.Settings;
using Xamarin.Forms;

namespace ShareeBike.ViewModel
{
	/// <summary>
	/// View model for settings.
	/// </summary>
	public class SettingsPageViewModel : INotifyPropertyChanged
	{
		/// <summary>
		/// Reference on view service to show modal notifications and to perform navigation.
		/// </summary>
		private IViewService m_oViewService;

		/// <summary>
		/// Fired if a property changes.
		/// </summary>
		public event PropertyChangedEventHandler PropertyChanged;

		/// <summary> Object to manage update of view model objects from Copri.</summary>
		private IPollingUpdateTaskManager m_oViewUpdateManager;

		/// <summary> List of copri server uris.</summary>
		public CopriServerUriListViewModel CopriServerUriList { get; }

		/// <summary> Manages selection of locks services.</summary>
		public LocksServicesViewModel LocksServices { get; }

		/// <summary>Settings determining the startup behavior of the app.</summary>
		public ServicesViewModel StartupSettings { get; } 

		/// <summary> Manages selection of geolocation services.</summary>
		public ServicesViewModel GeolocationServices { get; }

		/// <summary>
		/// Object to switch logging level.
		/// </summary>
		private LogEventLevel m_oMinimumLogEventLevel;

		/// <summary> Gets a value indicating whether reporting level is verbose or not.</summary>
		public bool IsReportLevelVerbose { get; set; }

		/// <summary> List of copri server uris.</summary>
		public ServicesViewModel Themes { get; }

		/// <summary> Reference on the shareeBike app instance. </summary>
		private IShareeBikeApp ShareeBikeApp { get; }

		IServicesContainer<IGeolocationService> GeolocationServicesContainer { get; }

		/// <summary> Constructs a settings page view model object.</summary>
		/// <param name="shareeBikeApp"> Reference to shareeBike app model.</param>
		/// <param name="geolocationServicesContainer"></param>
		/// <param name="viewService">Interface to view</param>
		public SettingsPageViewModel(
			IShareeBikeApp shareeBikeApp,
			IServicesContainer<IGeolocationService> geolocationServicesContainer,
			IViewService viewService)
		{
			ShareeBikeApp = shareeBikeApp
				?? throw new ArgumentException("Can not instantiate settings page view model- object. No shareeBike app object available.");

			GeolocationServicesContainer = geolocationServicesContainer
				?? throw new ArgumentException($"Can not instantiate {nameof(SettingsPageViewModel)}- object. Geolocation services container object must not be null.");

			m_oViewService = viewService
				?? throw new ArgumentException("Can not instantiate settings page view model- object. No user view service available.");

			m_oMinimumLogEventLevel = ShareeBikeApp.MinimumLogEventLevel;

			IsReportLevelVerbose = ShareeBikeApp.IsReportLevelVerbose;

			CenterMapToCurrentLocation = ShareeBikeApp.CenterMapToCurrentLocation;

			ExternalFolder = ShareeBikeApp.ExternalFolder;

			IsLogToExternalFolderVisible = !string.IsNullOrEmpty(ExternalFolder);

			LogToExternalFolderDisplayValue = IsLogToExternalFolderVisible ? ShareeBikeApp.LogToExternalFolder : false;

			IsSiteCachingOnDisplayValue = ShareeBikeApp.IsSiteCachingOn;

			if (ShareeBikeApp.Uris == null
				|| ShareeBikeApp.Uris.Uris.Count <= 0)
			{
				throw new ArgumentException("Can not instantiate settings page view model- object. No uri- list available.");
			}

			if (string.IsNullOrEmpty(ShareeBikeApp.NextActiveUri.AbsoluteUri))
			{
				throw new ArgumentException("Can not instantiate settings page view model- object. Next active uri must not be null or empty.");
			}

			GroupFilter = new SettingsBikeFilterViewModel(
				ShareeBikeApp.FilterGroupSetting,
				ShareeBikeApp.ActiveUser.IsLoggedIn ? ShareeBikeApp.ActiveUser.Group : null);

			GroupFilter.PropertyChanged += (s, e) =>
			{
				// Serialize on value changed. On iOS OnDisappearing might not be invoked (when app is directly closed before leaving settings page).
				try
				{
					var filterGroup = GroupFilter.ToDictionary(x => x.Key, x => x.State);
					ShareeBikeApp.FilterGroupSetting = new GroupFilterSettings(filterGroup.Count > 0 ? filterGroup : null);

					// Update map page filter. 
					// Reasons for which map page filter has to be updated:
					// - user activated/ deactivated a group (cargo/ city bikes)
					ShareeBikeApp.GroupFilterMapPage =
						GroupFilterMapPageHelper.CreateUpdated(
							ShareeBikeApp.GroupFilterMapPage,
							ShareeBikeApp.ActiveUser.DoFilter(ShareeBikeApp.FilterGroupSetting.DoFilter()));

					ShareeBikeApp.Save();
				}
				catch (Exception ex)
				{
					Log.ForContext<SettingsPageViewModel>().Error(ex, "Serializing startup page failed.");
				}
			};

			m_oViewUpdateManager = new IdlePollingUpdateTaskManager();

			Polling = new PollingViewModel(ShareeBikeApp.Polling);

			ExpiresAfterTotalSeconds = Convert.ToInt32(ShareeBikeApp.ExpiresAfter.TotalSeconds);

			CopriServerUriList = new CopriServerUriListViewModel(ShareeBikeApp.Uris);

			Themes = new ServicesViewModel(
				ShareeBikeApp.Themes.Select(x => x.GetType().FullName),
					new Dictionary<string, string> {
						{ typeof(Themes.ShareeBike).FullName, "sharee.bike" /* display name in picker */},
						{ typeof(Themes.LastenradBayern).FullName, "LastenradBayern" /* display name in picker */}
					},
					ShareeBikeApp.Themes.Active.GetType().FullName);

			Themes.PropertyChanged += OnThemesChanged;


			LocksServices = new LocksServicesViewModel(
				ShareeBikeApp.LocksServices.Active.TimeOut.MultiConnect,
				new ServicesViewModel(
					ShareeBikeApp.LocksServices,
					new Dictionary<string, string> {
						{ typeof(LocksServiceInReach).FullName, "Simulation - AllLocksInReach" },
						{ typeof(LocksServiceOutOfReach).FullName, "Simulation - AllLocksOutOfReach" },
						{ typeof(Services.BluetoothLock.BLE.LockItByScanServiceEventBased).FullName, "Live - Scan" },
						{ typeof(Services.BluetoothLock.BLE.LockItByScanServicePolling).FullName, "Live - Scan (Polling)" },
						{ typeof(Services.BluetoothLock.BLE.LockItByGuidService).FullName, "Live - Guid" },
					},
					ShareeBikeApp.LocksServices.Active.GetType().FullName));

			GeolocationServices = new ServicesViewModel(
				GeolocationServicesContainer.Select(x => x.GetType().FullName),
				new Dictionary<string, string> {
					{ typeof(LastKnownGeolocationService).FullName, "LastKnowGeolocation" },
					{ typeof(GeolocationAccuracyMediumService).FullName, "Medium Accuracy" },
					{ typeof(GeolocationAccuracyHighService).FullName, "High Accuracy" },
					{ typeof(GeolocationAccuracyBestService).FullName, "Best Accuracy" },
					{ typeof(SimulatedGeolocationService).FullName, "Simulation-AlwaysSamePosition" } },
				GeolocationServicesContainer.Active.GetType().FullName);

			StartupSettings = new PickerViewModel(
				new Dictionary<string, string> {
					{ ViewTypes.MapPage.ToString(), AppResources.MarkingBikeLocations },
					{ ViewTypes.SelectBikePage.ToString(), AppResources.MarkingSelectBike },
				},
				shareeBikeApp.StartupSettings.StartupPage.ToString());

			StartupSettings.PropertyChanged += (s, e) =>
			{
				// Serialize on value changed. On iOS OnDisappearing might not be invoked (when app is directly closed before leaving settings page).
				try
				{
					ShareeBikeApp.StartupSettings.StartupPage = Enum.TryParse(StartupSettings.Active, out ViewTypes startupPage)
							? startupPage
							: Model.Settings.StartupSettings.DefaultStartupPage;

					ShareeBikeApp.Save();
				} catch (Exception ex)
				{
					Log.ForContext<SettingsPageViewModel>().Error(ex, "Serializing startup page failed.");
				}
			};
		}

		/// <summary>
		/// User switches scheme.
		/// </summary>
		private void OnThemesChanged(object sender, PropertyChangedEventArgs e)
		{
			// Set active theme (leads to switch of title)
			ShareeBikeApp.Themes.SetActive(Themes.Active);

			// Switch theme.
			ICollection<ResourceDictionary> mergedDictionaries = Application.Current.Resources.MergedDictionaries;
			if (mergedDictionaries == null)
			{
				Log.ForContext<SettingsPageViewModel>().Error("No merged dictionary available.");
				return;
			}

			mergedDictionaries.Clear();

			if (Themes.Active == typeof(Themes.ShareeBike).FullName)
			{
				mergedDictionaries.Add(new Themes.ShareeBike());
			}
			else if (Themes.Active == typeof(Themes.LastenradBayern).FullName)
			{
				mergedDictionaries.Add(new Themes.LastenradBayern());
			}
			else
			{
				Log.ForContext<SettingsPageViewModel>().Debug($"No theme {Themes.Active} found.");
			}
		}

		/// <summary> Holds information whether app is connected to web or not. </summary>
		private bool? isConnected = null;

		/// <summary>Exposes the is connected state. </summary>
		private bool IsConnected
		{
			get => isConnected ?? false;
			set
			{
				isConnected = value;
			}
		}

		/// <summary> Holds a value indicating whether group filters GUI are visible or not</summary>
		public bool IsGroupFilterVisible => GroupFilter.Count > 0;

		/// <summary> Holds the bike types to fade out or show</summary>
		public SettingsBikeFilterViewModel GroupFilter { get; }

		/// <summary> Gets the value to path were copri mock files are located (for debugging purposes).</summary>
		public string ExternalFolder { get; }

		/// <summary>
		/// Gets the value to path were copri mock files are located (for debugging purposes).
		/// </summary>
		public string InternalPath => ShareeBikeApp.SettingsFileFolder;

		/// <summary>
		/// Gets the value of device identifier (for debugging purposes).
		/// </summary>
		public string DeviceIdentifier => ShareeBikeApp.SmartDevice.Identifier;

		/// <summary> 
		/// Invoked when page is shutdown. 
		/// Currently invoked by code behind, would be nice if called by XAML in future versions.
		/// </summary>
		public async Task OnDisappearing()
		{
			try
			{
				Log.ForContext<SettingsPageViewModel>().Information($"Entering {nameof(OnDisappearing)}...");

				// Update model values.
				ShareeBikeApp.NextActiveUri = CopriServerUriList.NextActiveUri;

				ShareeBikeApp.Polling = new PollingParameters(
					new TimeSpan(0, 0, Polling.PeriodeTotalSeconds),
					Polling.IsActivated);

				ShareeBikeApp.ExpiresAfter = TimeSpan.FromSeconds(ExpiresAfterTotalSeconds);

				if (IsLogToExternalFolderVisible)
				{
					// If no external folder is available do not update model value.
					ShareeBikeApp.LogToExternalFolder = LogToExternalFolderDisplayValue;
				}

				ShareeBikeApp.IsSiteCachingOn = IsSiteCachingOnDisplayValue;

				ShareeBikeApp.MinimumLogEventLevel = m_oMinimumLogEventLevel; // Update value to be serialized.
				ShareeBikeApp.UpdateLoggingLevel(m_oMinimumLogEventLevel); // Update logging server.

				ShareeBikeApp.IsReportLevelVerbose = IsReportLevelVerbose;

				ShareeBikeApp.LocksServices.SetActive(LocksServices.Services.Active);

				GeolocationServicesContainer.SetActive(GeolocationServices.Active);

				ShareeBikeApp.LocksServices.SetTimeOut(TimeSpan.FromSeconds(LocksServices.ConnectTimeoutSec));

				// Persist settings in case app is closed directly.
				ShareeBikeApp.Save();

				ShareeBikeApp.UpdateConnector();

				await m_oViewUpdateManager.StopAsync();

				Log.ForContext<SettingsPageViewModel>().Information($"{nameof(OnDisappearing)} done.");
			}
			catch (Exception l_oException)
			{
				await m_oViewService.DisplayAlert(
					AppResources.ErrorPageNotLoadedTitle,
					$"{AppResources.ErrorPageNotLoaded}\r\n{l_oException.Message}",
					AppResources.MessageAnswerOk);
			}
		}

		/// <summary> True if there is an error message to display.</summary>


		/// <summary>
		/// Exception which occurred getting bike information.
		/// </summary>
		protected Exception Exception { get; set; }

		/// <summary>
		/// If true debug controls are visible, false if not.
		/// </summary>
		public Permissions DebugLevel
		{
			get
			{
				return (Exception == null || Exception is WebConnectFailureException)
					? ShareeBikeApp.ActiveUser.DebugLevel
					: Permissions.None;
			}
		}

		/// <summary> Empty if no user is logged in session cookie otherwise. </summary>
		public string SessionCookie => ShareeBikeApp.ActiveUser.IsLoggedIn ? ShareeBikeApp.ActiveUser.SessionCookie : "";

		/// <summary>Polling period.</summary>
		public PollingViewModel Polling { get; }

		/// <summary> Active logging level</summary>
		public string SelectedLoggingLevel
		{
			get
			{
				return m_oMinimumLogEventLevel.ToString();
			}
			set
			{
				if (!Enum.TryParse(value, out LogEventLevel l_oNewLevel))
				{
					return;
				}

				m_oMinimumLogEventLevel = l_oNewLevel;
			}
		}

		bool _CenterMapToCurrentLocation = true;
		public bool CenterMapToCurrentLocation
		{
			get => _CenterMapToCurrentLocation;
			set
			{
				if (value == _CenterMapToCurrentLocation)
				{
					// Nothing to do.
					return;
				}

				_CenterMapToCurrentLocation = value;

				// Serialize on value changed. On iOS OnDisappearing might not be invoked (when app is directly closed before leaving settings page).
				ShareeBikeApp.CenterMapToCurrentLocation = CenterMapToCurrentLocation;
				ShareeBikeApp.Save();
			}
		}

		/// <summary> Holds either
		/// - a value indicating whether to use external folder (e.g. SD card)/ or internal folder for storing log-files or
		/// - is false if external folder is not available
		/// </summary>
		public bool LogToExternalFolderDisplayValue { get; set; }

		public bool IsSiteCachingOnDisplayValue { get; set; }

		/// <summary> Holds a value indicating whether user can use external folder (e.g. SD card) for storing log-files.</summary>
		public bool IsLogToExternalFolderVisible { get; }

		/// <summary>
		///  Holds the logging level serilog provides.
		/// </summary>
		public List<string> LoggingLevels
		{
			get
			{
				return new List<string>
				{
					LogEventLevel.Verbose.ToString(),
					LogEventLevel.Debug.ToString(),
					LogEventLevel.Information.ToString(),
					LogEventLevel.Warning.ToString(),
					LogEventLevel.Error.ToString(),
					LogEventLevel.Fatal.ToString(),
				};
			}
		}

		double expiresAfterTotalSeconds;

		public double ExpiresAfterTotalSeconds
		{
			get => expiresAfterTotalSeconds;
			set
			{
				if (value == expiresAfterTotalSeconds)
				{
					return;
				}

				expiresAfterTotalSeconds = value;
				PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(ExpiresAfterTotalSecondsText)));
			}
		}

		public string ExpiresAfterTotalSecondsText
		{
			get => expiresAfterTotalSeconds.ToString("0");
		}		
	}
}