using Xamarin.Forms;
using ShareeBike.View;
using ShareeBike.Model.Stations;
using System;
using System.Linq;
using ShareeBike.Model.Bikes;
using ShareeBike.Repository.Exception;
using ShareeBike.Model;
using Serilog;
using System.Collections.Generic;
using System.Threading.Tasks;
using System.ComponentModel;
using Xamarin.Forms.GoogleMaps;
using System.Collections.ObjectModel;
using ShareeBike.Services.Permissions;
using Xamarin.Essentials;
using System.Threading;
using ShareeBike.MultilingualResources;
using ShareeBike.Repository;
using ShareeBike.Services.Geolocation;
using ShareeBike.Model.State;
using ShareeBike.ViewModel.Map;
using ShareeBike.Model.Stations.StationNS;
using ShareeBike.Model.Bikes.BikeInfoNS.BC;

namespace ShareeBike.ViewModel.Contact
{
	public class SelectStationPageViewModel : INotifyPropertyChanged
	{
		/// <summary> Holds the count of custom icons centered.</summary>
		private const int CUSTOM_ICONS_COUNT = 30;

		/// <summary> Reference on view service to show modal notifications and to perform navigation. </summary>
		private IViewService ViewService { get; }

		/// <summary>
		/// Holds the exception which occurred getting bikes occupied information.
		/// </summary>
		private Exception m_oException;


		/// <summary>
		/// Service to query/ manage permissions (location) of the app.
		/// </summary>
		private ILocationPermission PermissionsService { get; }

		/// <summary>
		/// Service to manage bluetooth stack.
		/// </summary>
		private Plugin.BLE.Abstractions.Contracts.IBluetoothLE BluetoothService { get; set; }


		/// <summary> Notifies view about changes. </summary>
		public event PropertyChangedEventHandler PropertyChanged;


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

		/// <summary>Delegate to perform navigation.</summary>
		private INavigation m_oNavigation;

		private ObservableCollection<Pin> pins;

		public ObservableCollection<Pin> Pins
		{
			get
			{
				if (pins == null)
					pins = new ObservableCollection<Pin>(); // If view model is not binding context pins collection must be set programmatically.

				return pins;
			}

			set => pins = value;
		}

		/// <summary>Delegate to move map to region.</summary>
		private Action<MapSpan> m_oMoveToRegionDelegate;

		/// <summary> False if user tabed on station marker to show bikes at a given station.</summary>
		private bool isMapPageEnabled = false;

		IGeolocationService GeolocationService { get; }

		/// <summary> False if user tabed on station marker to show bikes at a given station.</summary>
		public bool IsMapPageEnabled
		{
			get => isMapPageEnabled;
			private set
			{
				if (isMapPageEnabled == value)
					return;

				isMapPageEnabled = value;
				PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(IsMapPageEnabled)));
			}
		}

		/// <summary> Prevents an invalid instane to be created. </summary>
		/// <param name="shareeBikeApp"> Reference to shareeBike app model.</param>
		/// <param name="moveToRegionDelegate">Delegate to center map and set zoom level.</param>
		/// <param name="viewService">View service to notify user.</param>
		/// <param name="navigation">Interface to navigate.</param>
		public SelectStationPageViewModel(
			IShareeBikeApp shareeBikeApp,
			ILocationPermission permissionsService,
			Plugin.BLE.Abstractions.Contracts.IBluetoothLE bluetoothService,
			IGeolocationService geolocationService,
			Action<MapSpan> moveToRegionDelegate,
			IViewService viewService,
			INavigation navigation)
		{
			ShareeBikeApp = shareeBikeApp
				?? throw new ArgumentException("Can not instantiate map page view model- object. No shareeBike app object available.");

			PermissionsService = permissionsService ??
				throw new ArgumentException($"Can not instantiate {nameof(SelectStationPageViewModel)}. Permissions service object must never be null.");

			BluetoothService = bluetoothService ??
				throw new ArgumentException($"Can not instantiate {nameof(SelectStationPageViewModel)}. Bluetooth service object must never be null.");

			GeolocationService = geolocationService ??
				throw new ArgumentException($"Can not instantiate {nameof(SelectStationPageViewModel)}. Geolocation service object must never be null.");

			m_oMoveToRegionDelegate = moveToRegionDelegate
				?? throw new ArgumentException("Can not instantiate map page view model- object. No move delegate available.");

			ViewService = viewService
				?? throw new ArgumentException("Can not instantiate map page view model- object. No view available.");

			m_oNavigation = navigation
				?? throw new ArgumentException("Can not instantiate map page view model- object. No navigation service available.");


			IsConnected = ShareeBikeApp.GetIsConnected();
		}

		public Command<PinClickedEventArgs> PinClickedCommand => new Command<PinClickedEventArgs>(
			args =>
			{
				OnStationClicked(args.Pin.Tag.ToString());
				args.Handled = true; // Prevents map to be centered to selected pin.
			});

		/// <summary>
		/// One time setup: Sets pins into map and connects to events.
		/// </summary>
		private void InitializePins(StationDictionary stations)
		{
			// Add pins to stations.
			Log.ForContext<SelectStationPageViewModel>().Debug($"Request to draw {stations.Count} pins.");
			foreach (var station in stations)
			{
				if (station.Position == null)
				{
					// There should be no reason for a position object to be null but this already occurred in past.
					Log.ForContext<SelectStationPageViewModel>().Error("Position object of station {@l_oStation} is null.", station);
					continue;
				}

				var l_oPin = new Pin
				{

					Position = new Xamarin.Forms.GoogleMaps.Position(station.Position.Latitude, station.Position.Longitude),
					Label = long.TryParse(station.Id, out long stationId) && stationId > CUSTOM_ICONS_COUNT
						? station.GetStationName()
						: string.Empty, // Stations with custom icons have already a id marker. No need for a label.

					Tag = station.Id,
					IsVisible = false, // Set to false to prevent showing default icons (flickering).
				};

				Pins.Add(l_oPin);
			}
		}

		/// <summary> Update all stations from ShareeBike. </summary>
		/// <param name="stationsColorList">List of colors to apply.</param>
		private void UpdatePinsColor(IList<Color> stationsColorList)
		{
			Log.ForContext<SelectStationPageViewModel>().Debug($"Starting update of stations pins color for {stationsColorList.Count} stations...");

			// Update colors of pins.
			for (int pinIndex = 0; pinIndex < stationsColorList.Count; pinIndex++)
			{
					var indexPartPrefix = int.TryParse(Pins[pinIndex].Tag.ToString(), out int stationId)
						&& stationId <= CUSTOM_ICONS_COUNT
						? $"{stationId}" // there is a station marker with index letter for given station id
						: "Open"; // there is no station marker. Use open marker.

					var colorPartPrefix = GetResourceNameColorPart(stationsColorList[pinIndex]);

					var l_iName = $"{indexPartPrefix.ToString().PadLeft(2, '0')}_{colorPartPrefix}{(DeviceInfo.Platform == DevicePlatform.Android ? ".png" : string.Empty)}";
					try
					{
						Pins[pinIndex].Icon = BitmapDescriptorFactory.FromBundle(l_iName);
					}
					catch (Exception l_oException)
					{
						Log.ForContext<SelectStationPageViewModel>().Error("Station icon {l_strName} can not be loaded. {@l_oException}.", l_oException);
						Pins[pinIndex].Label = stationId.ToString();
						Pins[pinIndex].Icon = BitmapDescriptorFactory.DefaultMarker(stationsColorList[pinIndex]);
					}

				Pins[pinIndex].IsVisible = true;
			}

			var pinsCount = Pins.Count;
			for (int pinIndex = stationsColorList.Count; pinIndex < pinsCount; pinIndex++)
			{
				Log.ForContext<SelectStationPageViewModel>().Error($"Unexpected count of pins detected. Expected {stationsColorList.Count} but is {pinsCount}.");
				Pins[pinIndex].IsVisible = false;
			}

			Log.ForContext<SelectStationPageViewModel>().Debug("Update of stations pins color done.");
		}

		/// <summary> Gets the color related part of the ressrouce name.</summary>
		/// <param name="color">Color to get name for.</param>
		/// <returns>Resource name.</returns>
		private static string GetResourceNameColorPart(Color color)
		{
			if (color == Color.Blue)
			{
				return "Blue";
			}

			if (color == Color.Green)
			{
				return "Green";
			}

			if (color == Color.LightBlue)
			{
				return "LightBlue";
			}

			if (color == Color.Red)
			{
				return "Red";
			}

			return color.ToString();
		}

		/// <summary>
		/// Invoked when page is shown. 
		/// Starts update process.
		/// </summary>
		/// <param name="p_oFilterDictionaryMapPage">Holds map page filter settings.</param>
		/// <param name="p_oPolling">Holds polling management object.</param>
		/// <param name="p_bIsShowWhatsNewRequired">If true whats new page will be shown.</param>
		public async Task OnAppearing()
		{
			try
			{
				IsProcessWithRunningProcessView = true;
				// Process map page.

				Log.ForContext<SelectStationPageViewModel>().Information(
					$"Current UI language is {Thread.CurrentThread.CurrentUICulture.Name}.");

				if (Pins.Count <= 0)
				{
					// Move and scale before getting stations and bikes which takes some time.
					if (ShareeBikeApp.CenterMapToCurrentLocation)
					{
						ActionText = AppResources.ActivityTextRequestingLocationPermissions;

						// Check location permission
						var status = await PermissionsService.CheckStatusAsync();
						if (!GeolocationService.IsSimulation
							&& status != Status.Granted)
						{
							var dialogResult = await ViewService.DisplayAlert(
								AppResources.MessageHintTitle,
								AppResources.ErrorMapCenterNoLocationPermissionOpenDialog,
								AppResources.MessageAnswerYes,
								AppResources.MessageAnswerNo);

							if (dialogResult)
							{
								// User decided to give access to locations permissions.
								PermissionsService.OpenAppSettings();
								ActionText = string.Empty;
								IsProcessWithRunningProcessView = false;
								IsMapPageEnabled = true;
								return;
							}
						}
						if (status == Status.Granted)
						{
							ActionText = AppResources.ActivityTextCenterMap;

							IGeolocation currentLocation = null;
							try
							{
								currentLocation = ShareeBikeApp.CenterMapToCurrentLocation
									? await GeolocationService.GetAsync()
									: null;
							}
							catch (Exception ex)
							{
								Log.ForContext<SelectStationPageViewModel>().Error("Getting location failed. {Exception}", ex);
							}

							MoveAndScale(m_oMoveToRegionDelegate, ShareeBikeApp.Uris.ActiveUri, currentLocation);
						}
					}
				}

				ActionText = AppResources.ActivityTextMapLoadingStationsAndBikes;
				IsConnected = ShareeBikeApp.GetIsConnected();
				var resultStationsAndBikes = await ShareeBikeApp.GetConnector(IsConnected).Query.GetBikesAndStationsAsync();

				ShareeBikeApp.Stations = resultStationsAndBikes.Response.StationsAll;
				ShareeBikeApp.ResourceUrls = resultStationsAndBikes.GeneralData.ResourceUrls;

				if (Pins.Count > 0 && Pins.Count != resultStationsAndBikes.Response.StationsAll.Count)
				{
					// Either
					// - user logged in/ logged out which might lead to more/ less stations beeing available
					// - new stations were added/ existing ones remove
					Pins.Clear();
				}

				// Check if there are already any pins to the map 
				// i.e detects first call of member OnAppearing after construction
				if (Pins.Count <= 0)
				{
					// Map was not yet initialized.
					// Get stations from Copri
					Log.ForContext<SelectStationPageViewModel>().Verbose("No pins detected on page.");
					if (resultStationsAndBikes.Response.StationsAll.CopriVersion < CopriCallsStatic.UnsupportedVersionLower)
					{
						await ViewService.DisplayAlert(
							AppResources.MessageWaring,
							string.Format(AppResources.MessageCopriVersionIsOutdated, ShareeBikeApp.Flavor.GetDisplayName()),
							AppResources.MessageAnswerOk);

						Log.ForContext<SelectStationPageViewModel>().Error($"Outdated version of app detected. Version expected is {resultStationsAndBikes.Response.StationsAll.CopriVersion}.");
					}

					if (resultStationsAndBikes.Response.StationsAll.CopriVersion >= CopriCallsStatic.UnsupportedVersionUpper)
					{
						await ViewService.DisplayAlert(
							AppResources.MessageWaring,
							string.Format(AppResources.MessageAppVersionIsOutdated, ShareeBikeApp.Flavor.GetDisplayName()),
							AppResources.MessageAnswerOk);

						Log.ForContext<SelectStationPageViewModel>().Error($"Outdated version of app detected. Version expected is {resultStationsAndBikes.Response.StationsAll.CopriVersion}.");
					}

					// Set pins to their positions on map.
					InitializePins(resultStationsAndBikes.Response.StationsAll);

					Log.ForContext<SelectStationPageViewModel>().Verbose("Update of pins done.");
				}


				if (resultStationsAndBikes.Exception?.GetType() == typeof(AuthcookieNotDefinedException))
				{
					Log.ForContext<SelectStationPageViewModel>().Error("Map page is shown (probable for the first time after startup of app) and COPRI auth cookie is not defined. {@l_oException}", resultStationsAndBikes.Exception);

					// COPRI reports an auth cookie error.
					await ViewService.DisplayAlert(
						AppResources.MessageWaring,
						AppResources.ErrorMapPageAuthcookieUndefined,
						AppResources.MessageAnswerOk);

					IsConnected = ShareeBikeApp.GetIsConnected();

					await ShareeBikeApp.GetConnector(IsConnected).Command.DoLogout();
					ShareeBikeApp.ActiveUser.Logout();
				}

				// Update pin colors.
				Log.ForContext<SelectStationPageViewModel>().Verbose("Starting update pins color...");

				var colors = GetStationColors(
					 Pins.Select(x => x.Tag.ToString()).ToList(),
					 resultStationsAndBikes.Response.StationsAll,
					 resultStationsAndBikes.Response.BikesOccupied);

				// Update pins color form count of bikes located at station.
				UpdatePinsColor(colors);


				Log.ForContext<SelectStationPageViewModel>().Verbose("Update pins color done.");

				Exception = resultStationsAndBikes.Exception;
				ActionText = string.Empty;
				IsProcessWithRunningProcessView = false;
				IsMapPageEnabled = true;
			}
			catch (Exception l_oException)
			{
				Log.ForContext<SelectStationPageViewModel>().Error($"An error occurred opening select station page.\r\n{l_oException.Message}");

				IsProcessWithRunningProcessView = false;

				await ViewService.DisplayAlert(
					AppResources.ErrorPageNotLoadedTitle,
					$"{AppResources.ErrorPageNotLoaded}\r\n{l_oException.Message}",
					AppResources.MessageAnswerOk);

				IsMapPageEnabled = true;
			}
		}

		/// <summary> Moves map and scales visible region depending on active filter. </summary>
		public static void MoveAndScale(
			Action<MapSpan> moveToRegionDelegate,
			Uri activeUri,
			IGeolocation currentLocation = null)
		{
			if (currentLocation != null)
			{
				// Move to current location.
				moveToRegionDelegate(MapSpan.FromCenterAndRadius(
					new Xamarin.Forms.GoogleMaps.Position(currentLocation.Latitude, currentLocation.Longitude),
					Distance.FromKilometers(1.0)));
				return;
			}

			// Center map to Freiburg
			moveToRegionDelegate(MapSpan.FromCenterAndRadius(
				new Xamarin.Forms.GoogleMaps.Position(47.995865, 7.815086),
				Distance.FromKilometers(2.9)));
		}

		/// <summary> User clicked on a bike. </summary>
		/// <param name="selectedStationId">Id of station user clicked on.</param>
		public async void OnStationClicked(string selectedStationId)
		{
				try
				{
					Log.ForContext<SelectStationPageViewModel>().Information($"User taped station {selectedStationId}.");

				
					// Lock action to prevent multiple instances of "BikeAtStation" being opened.
					IsMapPageEnabled = false;
				
					ShareeBikeApp.SelectedStation = ShareeBikeApp.Stations.FirstOrDefault(x => x.Id == selectedStationId)
					?? new Station(selectedStationId, new List<string>(), null); // Station might not be in list StationDictinaly because this list is not updated in background task.

					await ViewService.ShowPage("//ContactPage");
					IsMapPageEnabled = true;
					ActionText = string.Empty;
				}
				catch (Exception exception)
				{
					IsMapPageEnabled = true;
					ActionText = string.Empty;

					Log.ForContext<SelectStationPageViewModel>().Error("Fehler beim Öffnen der Ansicht \"Fahrräder an Station\" aufgetreten. {Exception}", exception);

				await ViewService.DisplayAlert(
					AppResources.ErrorPageNotLoadedTitle,
					$"{AppResources.ErrorPageNotLoaded}\r\n{exception.Message}",
					AppResources.MessageAnswerOk);
				}
		}

		/// <summary>
		/// Gets the list of station color for all stations.
		/// </summary>
		/// <param name="stationsId">Station id list to get color for.</param>
		/// <param name="stations">Station object dictionary to get count of available bike from for each station.</param>
		/// <param name="bikesReserved">Bike collection to get count of reserved/ rented bikes from for each station.</param>
		/// <returns></returns>
		internal static IList<Color> GetStationColors(
			IEnumerable<string> stationsId,
			IEnumerable<IStation> stations,
			IEnumerable<BikeInfo> bikesReserved)
		{
			if (stationsId == null)
			{
				Log.ForContext<SelectStationPageViewModel>().Debug("No stations available to update color for.");
				return new List<Color>();
			}

			if (stations == null)
			{
				Log.ForContext<SelectStationPageViewModel>().Error("No stations info available to get count of bikes available to determine whether a pin is green or not.");
			}

			if (bikesReserved == null)
			{
				Log.ForContext<SelectStationPageViewModel>().Error("No bikes info available to determine whether a pins is light blue or not.");
			}

			// Get state for each station.
			var colors = new List<Color>();
			foreach (var stationId in stationsId)
			{
				// Get color of given station.
				if (bikesReserved?.Where(x => x.StationId == stationId).Count() > 0)
				{
					// There is at least one requested or booked bike
					colors.Add(Color.LightBlue);
					continue;
				}

				if (stations?.FirstOrDefault(x => x.Id == stationId)?.AvailableBikesCount > 0)
				{
					// There is at least one bike available
					colors.Add(Color.Green);
					continue;
				}

				colors.Add(Color.Red);
			}

			return colors;
		}

		/// <summary>
		/// Exception which occurred getting bike information.
		/// </summary>
		public Exception Exception
		{
			get
			{
				return m_oException;
			}

			private set
			{
				var statusInfoText = StatusInfoText;
				m_oException = value;
				if (statusInfoText == StatusInfoText)
				{
					// Nothing to do because value did not change.
					return;
				}

				PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(StatusInfoText)));
			}
		}

		/// <summary> Holds info about current action. </summary>
		private string actionText;

		/// <summary> Holds info about current action. </summary>
		private string ActionText
		{
			get => actionText;
			set
			{
				var statusInfoText = StatusInfoText;
				actionText = value;
				if (statusInfoText == StatusInfoText)
				{
					// Nothing to do because value did not change.
					return;
				}

				PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(StatusInfoText)));
			}
		}

		/// <summary> Used to block more than on copri requests at a given time.</summary>
		private bool isProcessWithRunningProcessView = false;

		/// <summary>
		/// True if any action can be performed (request and cancel request)
		/// </summary>
		public bool IsProcessWithRunningProcessView
		{
			get => isProcessWithRunningProcessView;
			set
			{
				if (value == isProcessWithRunningProcessView)
					return;

				Log.ForContext<SelectStationPageViewModel>().Debug($"Switch value of {nameof(isProcessWithRunningProcessView)} to {value}.");
				isProcessWithRunningProcessView = value;
				PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(IsProcessWithRunningProcessView)));
			}
		}


		/// <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
			{
				var statusInfoText = StatusInfoText;
				isConnected = value;
				if (statusInfoText == StatusInfoText)
				{
					// Nothing to do.
					return;
				}

				PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(StatusInfoText)));
			}
		}

		/// <summary> Holds the status information text. </summary>
		public string StatusInfoText
		{
			get
			{
				//if (Exception != null)
				//{
				//	// An error occurred getting data from copri.
				//	return Exception.GetShortErrorInfoText(ShareeBikeApp.IsReportLevelVerbose);

				//}

				return ActionText ?? string.Empty;
			}
		}
	}
}