sharee.bike-App/Meinkonrad/TINK/ViewModel/RootFlyout/RootPageViewModel.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Runtime.CompilerServices;
using TINK.Services.CopriApi.ServerUris;
using TINK.View;
using TINK.View.Account;
using TINK.View.Contact;
using TINK.View.Info;
using TINK.View.Login;
using TINK.View.Map;
using TINK.View.FindBike;
using TINK.View.MyBikes;
using TINK.View.Root;
using TINK.View.Settings;
using Xamarin.Forms;
using TINK.ViewModel.MasterDetail;
#if USEFLYOUT
using TINK.View.MasterDetail;
#endif
using TINK.Services;
using TINK.View.Themes;

namespace TINK.ViewModel.Root
{
	/// <summary>
	/// View model for flyout menu entries. Respositility
	/// - populates entries depending on app state on showing menu
	/// - updates menu denpending on app state change, i.e. user logs in/ out. 
	/// </summary>
	public class RootPageFlyoutViewModel : INotifyPropertyChanged
	{
		/// <summary>
		/// Dictionary to manage collection of menu items.
		/// </summary>
		private Dictionary<Type, int> m_oEntryDictionary;

		public event PropertyChangedEventHandler PropertyChanged;

		/// <summary> Updates menu entries depending on state. </summary>
		private void UpdateMenuEntries()
		{
			for (int l_iIndex = MenuItems.Count - 1; l_iIndex >= 0; l_iIndex--)
			{
				MenuItems.Clear();
				m_oEntryDictionary.Clear();
			}

			CheckAddItem(typeof(MapPage));

			if (App.ModelRoot.ActiveUser.IsLoggedIn)
			{
				CheckAddItem(typeof(MyBikesPage));
				CheckAddItem(typeof(FindBikePage));
				CheckAddItem(typeof(AccountPage));
			}
			else
			{
				CheckAddItem(typeof(LoginPage));
			}

			if (App.ModelRoot.Uris.ActiveUri.Host.GetIsCopri()
				|| App.ModelRoot.ActiveUser.IsLoggedIn)
			{
				CheckAddItem(typeof(SettingsPage));
			}

			CheckAddItem(typeof(FeesAndBikesPage)); // Fees and bikes

			CheckAddItem(typeof(ContactPage)); // Feedback and contact

			CheckAddItem(typeof(InfoPage)); // About sharee.bike
		}

		/// <summary>Adds a menu item to master detail menu.</summary>
		/// <param name="p_oType">Type decribing entry to be added.</param>
		private void CheckAddItem(Type p_oType)
		{
			if (m_oEntryDictionary.ContainsKey(p_oType))
			{
				// Nothing to do because has already been added.
				return;
			}

			m_oEntryDictionary.Add(
				p_oType,
				m_oEntryDictionary.Count);

			MenuItems.Add(new RootPageFlyoutMenuItem
			{
				TargetType = p_oType,
				GlyphCode = Helper.GetGlyphCode(p_oType),
				Title = Helper.GetCaption(p_oType),
				Id = m_oEntryDictionary[p_oType]
			});
		}

		/// <summary> Removes a page from menu.</summary>
		/// <param name="p_oType"></param>
		private void RemoveItem(Type p_oType)
		{
			if (!m_oEntryDictionary.ContainsKey(p_oType))
			{
				// Nothing to do because item was never added/ already removed.
				return;
			}

			MenuItems.Remove(MenuItems[m_oEntryDictionary[p_oType]]);
			m_oEntryDictionary.Remove(p_oType);
		}

		public RootPageFlyoutViewModel()
		{
			MenuItems = new ObservableCollection<RootPageFlyoutMenuItem>();
			m_oEntryDictionary = new Dictionary<Type, int>();

			// Update menu entries on login/ logout actions.
			App.ModelRoot.ActiveUser.StateChanged += (sender, eventargs) => OnUpdateRequired();

			// Update flyout view model whenever theme is switched.
			App.ModelRoot.Themes.PropertyChanged += (sender, eventargs) =>
			{
				if (!(sender is ServicesContainerMutableT<object> themes))
					return;

				MasterDetailMenuTitlte = GetMasterDetailMenuTitle(themes.Active);

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

			MasterDetailMenuTitlte = GetMasterDetailMenuTitle(App.ModelRoot.Themes.Active);

			UpdateMenuEntries();
		}

		/// <summary>
		/// Gets the flyout title from theme name
		/// </summary>
		/// <param name="theme">Name of theme.</param>
		/// <returns>Flyout title.</returns>
		private string GetMasterDetailMenuTitle(object theme)
		{
			if (!(theme is ITheme active))
				return Themes.Konrad.OPERATORINFO;

			return $"{(!string.IsNullOrEmpty(active.OperatorInfo) ? ($"{active.OperatorInfo}") : "sharee.bike")}";
		}

		/// <summary>
		/// Holds the title of the fylout page.
		/// </summary>
		public string MasterDetailMenuTitlte { get; private set; }


		/// <summary>
		/// Provides collection of menu items for master page.
		/// </summary>
		public ObservableCollection<RootPageFlyoutMenuItem> MenuItems
		{
			get; private set;
		}

		/// <summary>
		/// Gets or sets the selected item.
		/// </summary>
		public MainPageMenuItem SelectedMenuItem
		{
			get;
			set;
		}

		/// <summary>
		/// Command object which is invoked from view when an item is selected.
		/// </summary>
		public Command MenuItemSelected
		{
			get
			{
				return new Command(OnUpdateRequired);
			}

		}

		/// <summary> Manges updates required due to selection of a menu or login events.</summary>
		public void OnUpdateRequired()
		{

			UpdateMenuEntries();

			if (SelectedMenuItem == null)
			{
				// Nothing to do if no menu entry is selected.
				return;
			}
		}
	}
}