using System;
using System.ComponentModel;
using TINK.Model.Connector;
using TINK.Model.User;
using TINK.View;
using TINK.ViewModel.Bikes.Bike.BC.RequestHandler;
using BikeInfoMutable = TINK.Model.Bike.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="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>
        public BikeViewModel(
            Func<bool> isConnectedDelegate,
            Func<bool, IConnector> connectorFactory,
            Action<int> bikeRemoveDelegate,
            Func<IPollingUpdateTaskManager> viewUpdateManager,
            IViewService viewService,
            BikeInfoMutable selectedBike,
            IUser activeUser,
            IInUseStateInfoProvider stateInfoProvider,
            IBikesViewModel bikesViewModel) : base(isConnectedDelegate, connectorFactory, bikeRemoveDelegate, viewUpdateManager, viewService, selectedBike, activeUser, stateInfoProvider, bikesViewModel)
        {
            RequestHandler = activeUser.IsLoggedIn
                ? RequestHandlerFactory.Create(
                    selectedBike,
                    isConnectedDelegate,
                    connectorFactory,
                    viewUpdateManager,
                    viewService,
                    bikesViewModel,
                    ActiveUser)
                : new NotLoggedIn(
                    selectedBike.State.Value,
                    viewService,
                    bikesViewModel,
                    ActiveUser);
        }

        /// <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,
                ViewService,
                BikesViewModel,
                ActiveUser);

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

        /// <summary> Gets visiblity of the copri command button. </summary>
        public bool IsButtonVisible => RequestHandler.IsButtonVisible;

        /// <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;
            RequestHandler = await RequestHandler.HandleRequest();

            if (lastHandler.IsRemoveBikeRequired)
            {
                BikeRemoveDelegate(Id);
            }

            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)));
            }
        });
    }
}