using System;
using System.ComponentModel;
using TINK.Model.Connector;
using TINK.Model.Device;
using TINK.Model.User;
using TINK.View;
using TINK.ViewModel.Bikes.Bike.BC.RequestHandler;
using BikeInfoMutable = TINK.Model.Bikes.BikeInfoNS.BC.BikeInfoMutable;

namespace TINK.ViewModel.Bikes.Bike.BC
{
	/// <summary>
	/// View model for a BC bike.
	/// Provides functionality for views
	/// - MyBikes
	/// - BikesAtStation
	/// </summary>
	public class BikeViewModel : BikeViewModelBase, INotifyPropertyChanged
	{
		/// <summary>
		/// Notifies GUI about changes.
		/// </summary>
		public override event PropertyChangedEventHandler PropertyChanged;

		/// <summary> Holds object which manages requests. </summary>
		private IRequestHandler RequestHandler { get; set; }

		/// <summary> Raises events in order to update GUI.</summary>
		public override void RaisePropertyChanged(object sender, PropertyChangedEventArgs eventArgs) => PropertyChanged?.Invoke(sender, eventArgs);

		/// <summary>
		/// Constructs a bike view model object.
		/// </summary>
		/// <param name="smartDevice">Provides info about the smart device (phone, tablet, ...).</param>
		/// <param name="selectedBike">Bike to be displayed.</param>
		/// <param name="activeUser">Object holding logged in user or an empty user object.</param>
		/// <param name="stateInfoProvider">Provides in use state information.</param>
		/// <param name="bikesViewModel">View model to be used for progress report and unlocking/ locking view.</param>
		/// <param name="openUrlInBrowser">Delegate to open browser.</param>
		public BikeViewModel(
			Func<bool> isConnectedDelegate,
			Func<bool, IConnector> connectorFactory,
			Action<string> bikeRemoveDelegate,
			Func<IPollingUpdateTaskManager> viewUpdateManager,
			ISmartDevice smartDevice,
			IViewService viewService,
			BikeInfoMutable selectedBike,
			IUser activeUser,
			IInUseStateInfoProvider stateInfoProvider,
			IBikesViewModel bikesViewModel,
			Action<string> openUrlInBrowser) : base(isConnectedDelegate, connectorFactory, bikeRemoveDelegate, viewUpdateManager, smartDevice, viewService, selectedBike, activeUser, new ViewContext(PageContext.BikesAtStation), stateInfoProvider, bikesViewModel, openUrlInBrowser)
		{
			RequestHandler = activeUser.IsLoggedIn
				? RequestHandlerFactory.Create(
					selectedBike,
					isConnectedDelegate,
					connectorFactory,
					viewUpdateManager,
					smartDevice,
					viewService,
					bikesViewModel,
					ActiveUser)
				: new NotLoggedIn(
					selectedBike.State.Value,
					viewService,
					bikesViewModel,
					ActiveUser);

			selectedBike.PropertyChanged += (sender, ev) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(IsButtonVisible)));
		}

		/// <summary>
		/// Handles BikeInfoMutable events. 
		/// Helper member to raise events. Maps model event change notification to view model events.
		/// Todo: Check which events are received here and filter, to avoid event storm.
		/// </summary>
		/// <param name="p_strNameOfProp"></param>
		public override void OnSelectedBikeStateChanged()
		{
			RequestHandler = RequestHandlerFactory.Create(
				Bike,
				IsConnectedDelegate,
				ConnectorFactory,
				ViewUpdateManager,
				SmartDevice,
				ViewService,
				BikesViewModel,
				ActiveUser);

			var handler = PropertyChanged;
			if (handler != null)
			{
				handler(this, new PropertyChangedEventArgs(nameof(ButtonText)));
				handler(this, new PropertyChangedEventArgs(nameof(IsButtonVisible)));
			}
		}

		/// <summary> Gets visibility of the copri command button. </summary>
		public bool IsButtonVisible
			=> RequestHandler.IsButtonVisible
				&& Bike.DataSource == Model.Bikes.BikeInfoNS.BC.DataSource.Copri /* do not show button if data is from cache */ ;  

		/// <summary> Gets the text of the copri command button. </summary>
		public string ButtonText => RequestHandler.ButtonText;

		/// <summary> Processes request to perform a copri action (reserve bike and cancel reservation). </summary>
		public System.Windows.Input.ICommand OnButtonClicked => new Xamarin.Forms.Command(async () =>
		{
			var lastHandler = RequestHandler;
			var lastState = Bike.State.Value;
			RequestHandler = await RequestHandler.HandleRequest();

			CheckRemoveBike(Id, lastState);

			if (lastHandler.GetType() == RequestHandler.GetType())
			{
				// No state change occurred.
				return;
			}

			// State changed and instance of request handler was switched. 
			if (lastHandler.ButtonText != ButtonText)
			{
				PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(ButtonText)));
			}

			if (lastHandler.IsButtonVisible != IsButtonVisible)
			{
				PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(nameof(IsButtonVisible)));
			}
		});
	}
}