[Core/Windows] Pass around resource provider

4 files changed, 113 insertions, 66 deletions

diff --git a/Xamarin.PropertyEditing.Windows.Standalone/MainWindow.xaml.cs b/Xamarin.PropertyEditing.Windows.Standalone/MainWindow.xaml.cs
index 0089d31..7fedb09 100644
--- a/Xamarin.PropertyEditing.Windows.Standalone/MainWindow.xaml.cs
+++ b/Xamarin.PropertyEditing.Windows.Standalone/MainWindow.xaml.cs
@@ -22,6 +22,7 @@ namespace Xamarin.PropertyEditing.Windows.Standalone
 				}
 			};
 			this.panel.EditorProvider = new MockEditorProvider ();
+			this.panel.ResourceProvider = new MockResourceProvider ();
 		}
 
 		private async void Button_Click (object sender, RoutedEventArgs e)
diff --git a/Xamarin.PropertyEditing.Windows/PropertyEditorPanel.cs b/Xamarin.PropertyEditing.Windows/PropertyEditorPanel.cs
index 1701c4a..e6202e4 100644
--- a/Xamarin.PropertyEditing.Windows/PropertyEditorPanel.cs
+++ b/Xamarin.PropertyEditing.Windows/PropertyEditorPanel.cs
@@ -27,7 +27,7 @@ namespace Xamarin.PropertyEditing.Windows
 		}
 
 		public static readonly DependencyProperty EditorProviderProperty = DependencyProperty.Register (
-			nameof(EditorProvider), typeof(IEditorProvider), typeof(PropertyEditorPanel), new PropertyMetadata (default(IEditorProvider), (o, args) => ((PropertyEditorPanel)o).OnEditorProviderChanged()));
+			nameof(EditorProvider), typeof(IEditorProvider), typeof(PropertyEditorPanel), new PropertyMetadata (default(IEditorProvider), (o, args) => ((PropertyEditorPanel)o).OnProviderChanged()));
 
 		public IEditorProvider EditorProvider
 		{
@@ -35,6 +35,15 @@ namespace Xamarin.PropertyEditing.Windows
 			set { SetValue (EditorProviderProperty, value); }
 		}
 
+		public static readonly DependencyProperty ResourceProviderProperty = DependencyProperty.Register (
+			nameof(ResourceProvider), typeof(IResourceProvider), typeof(PropertyEditorPanel), new PropertyMetadata (default(IResourceProvider), (o, args) => ((PropertyEditorPanel)o).OnProviderChanged()));
+
+		public IResourceProvider ResourceProvider
+		{
+			get { return (IResourceProvider) GetValue (ResourceProviderProperty); }
+			set { SetValue (ResourceProviderProperty, value); }
+		}
+
 		public static readonly DependencyProperty TargetPlatformProperty = DependencyProperty.Register (
 			"TargetPlatform", typeof(TargetPlatform), typeof(PropertyEditorPanel), new PropertyMetadata (TargetPlatform.Default));
 
@@ -86,7 +95,7 @@ namespace Xamarin.PropertyEditing.Windows
 			this.paneSelector = (ChoiceControl) GetTemplateChild ("paneSelector");
 			this.paneSelector.SelectedValue = EditingPane.Properties;
 			this.paneSelector.SelectedItemChanged += OnPaneChanged;
-			OnEditorProviderChanged();
+			OnProviderChanged();
 
 			if (this.vm.SelectedObjects.Count > 0)
 				OnArrangeModeChanged (ArrangeMode);
@@ -142,7 +151,7 @@ namespace Xamarin.PropertyEditing.Windows
 				OnArrangeModeChanged (ArrangeMode);
 		}
 
-		private void OnEditorProviderChanged ()
+		private void OnProviderChanged ()
 		{
 			if (this.root == null)
 				return;
@@ -150,7 +159,14 @@ namespace Xamarin.PropertyEditing.Windows
 			if (this.vm != null)
 				this.vm.PropertyChanged -= OnVmPropertyChanged;
 
-			this.root.DataContext = this.vm = (EditorProvider != null) ? new PanelViewModel (EditorProvider, TargetPlatform) : null;
+			PanelViewModel newVm = null;
+			if (EditorProvider != null) {
+				newVm = new PanelViewModel (EditorProvider, TargetPlatform) {
+					ResourceProvider = ResourceProvider
+				};
+			}
+
+			this.root.DataContext = this.vm = newVm;
 			
 			if (this.vm != null)
 				this.vm.PropertyChanged += OnVmPropertyChanged;
diff --git a/Xamarin.PropertyEditing/ViewModels/PropertiesViewModel.cs b/Xamarin.PropertyEditing/ViewModels/PropertiesViewModel.cs
index 52cd1f8..7526ece 100644
--- a/Xamarin.PropertyEditing/ViewModels/PropertiesViewModel.cs
+++ b/Xamarin.PropertyEditing/ViewModels/PropertiesViewModel.cs
@@ -28,6 +28,20 @@ namespace Xamarin.PropertyEditing.ViewModels
 
 		public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;
 
+		public IResourceProvider ResourceProvider
+		{
+			get { return this.resourceProvider; }
+			set
+			{
+				if (this.resourceProvider == value)
+					return;
+
+				this.resourceProvider = value;
+				UpdateResourceProvider();
+				OnPropertyChanged();
+			}
+		}
+
 		/// <remarks>Consumers should check for <see cref="INotifyCollectionChanged"/> and hook appropriately.</remarks>
 		public IReadOnlyList<EditorViewModel> Properties => this.editors;
 
@@ -200,6 +214,7 @@ namespace Xamarin.PropertyEditing.ViewModels
 		{
 		}
 
+		private IResourceProvider resourceProvider;
 		private INameableObject nameable;
 		private bool nameReadOnly;
 		private bool eventsEnabled;
@@ -404,6 +419,13 @@ namespace Xamarin.PropertyEditing.ViewModels
 			return newEditors;
 		}
 
+		private void UpdateResourceProvider()
+		{
+			foreach (PropertyViewModel vm in this.editors) {
+				vm.ResourceProvider = this.resourceProvider;
+			}
+		}
+
 		private void OnObjectEditorPropertiesChanged (object sender, NotifyCollectionChangedEventArgs e)
 		{
 			UpdateMembers();
@@ -411,6 +433,13 @@ namespace Xamarin.PropertyEditing.ViewModels
 
 		private PropertyViewModel GetViewModel (IPropertyInfo property)
 		{
+			var vm = GetViewModelCore (property);
+			vm.ResourceProvider = ResourceProvider;
+			return vm;
+		}
+
+		private PropertyViewModel GetViewModelCore (IPropertyInfo property)
+		{
 			Type[] interfaces = property.GetType ().GetInterfaces ();
 
 			Type hasPredefinedValues = interfaces.FirstOrDefault (t => t.IsGenericType && t.GetGenericTypeDefinition () == typeof(IHavePredefinedValues<>));
diff --git a/Xamarin.PropertyEditing/ViewModels/PropertyViewModel.cs b/Xamarin.PropertyEditing/ViewModels/PropertyViewModel.cs
index a727e7d..fcd8ae5 100644
--- a/Xamarin.PropertyEditing/ViewModels/PropertyViewModel.cs
+++ b/Xamarin.PropertyEditing/ViewModels/PropertyViewModel.cs
@@ -47,22 +47,6 @@ namespace Xamarin.PropertyEditing.ViewModels
 			}
 		}
 
-		public IReadOnlyList<Resource> Resources => this.resources;
-
-		public IResourceProvider ResourceProvider
-		{
-			get { return this.resourceProvider; }
-			set
-			{
-				if (this.resourceProvider == value)
-					return;
-
-				this.resourceProvider = value;
-				OnPropertyChanged ();
-				UpdateResources ();
-			}
-		}
-
 		protected virtual TValue ValidateValue (TValue validationValue)
 		{
 			return validationValue;
@@ -107,11 +91,7 @@ namespace Xamarin.PropertyEditing.ViewModels
 			}
 		}
 
-		private readonly ObservableCollection<Resource> resources = new ObservableCollection<Resource> ();
 		private ValueInfo<TValue> value;
-		private IResourceProvider resourceProvider;
-		private CancellationTokenSource cancelTokenSource;
-		private Task updateResourcesTask;
 
 		private bool SetCurrentValue (ValueInfo<TValue> newValue)
 		{
@@ -160,14 +140,7 @@ namespace Xamarin.PropertyEditing.ViewModels
 
 		private bool CanSetValueToResource (Resource resource)
 		{
-			if (resource == null || !Property.CanWrite)
-				return false;
-
-			// We're just going to block wait on this. There shouldn't be a scenario in which it would deadlock
-			// and we simply can't work async into the ICommand system. Looks bad, but practically shouldn't be an issue.
-			// Famous last words.
-			this.updateResourcesTask?.Wait ();
-			return this.resources.Contains (resource);
+			return (resource != null && SupportsResources);
 		}
 
 		private void OnSetValueToResource (Resource resource)
@@ -181,38 +154,6 @@ namespace Xamarin.PropertyEditing.ViewModels
 			});
 		}
 
-		private void UpdateResources ()
-		{
-			var source = new CancellationTokenSource ();
-			var cancelSource = Interlocked.Exchange (ref this.cancelTokenSource, source);
-			cancelSource?.Cancel ();
-
-			this.updateResourcesTask = UpdateResourcesAsync (source.Token);
-		}
-
-		private async Task UpdateResourcesAsync (CancellationToken cancelToken)
-		{
-			this.resources.Clear();
-
-			var provider = this.resourceProvider;
-			if (provider != null) {
-				if (cancelToken.IsCancellationRequested)
-					return;
-
-				try {
-					IReadOnlyList<Resource> gottenResources = await provider.GetResourcesAsync (Property, cancelToken);
-					if (cancelToken.IsCancellationRequested)
-						return;
-
-					this.resources.AddItems (gottenResources);
-				} catch (OperationCanceledException) {
-					return;
-				}
-			}
-
-			((RelayCommand<Resource>)SetValueResourceCommand).ChangeCanExecute ();
-		}
-
 		private void OnClearValue ()
 		{
 			SetValue (new ValueInfo<TValue> {
@@ -238,8 +179,11 @@ namespace Xamarin.PropertyEditing.ViewModels
 
 			Property = property;
 			SetupConstraints ();
+
+			this.requestResourceCommand = new RelayCommand (OnRequestResource, CanRequestResource);
 		}
 
+		public event EventHandler<ResourceRequestedEventArgs> ResourceRequested;
 		public event EventHandler<DataErrorsChangedEventArgs> ErrorsChanged;
 
 		public IPropertyInfo Property
@@ -265,12 +209,45 @@ namespace Xamarin.PropertyEditing.ViewModels
 
 		public virtual bool CanDelve => false;
 
+		public bool SupportsResources
+		{
+			get { return Property.CanWrite; }
+		}
+
+		public IResourceProvider ResourceProvider
+		{
+			get { return this.resourceProvider; }
+			set
+			{
+				if (this.resourceProvider == value)
+					return;
+
+				this.resourceProvider = value;
+				OnPropertyChanged ();
+			}
+		}
+
 		public ICommand SetValueResourceCommand
 		{
-			get;
-			protected set;
+			get { return this.setValueResourceCommand; }
+			protected set
+			{
+				if (this.setValueResourceCommand == value)
+					return;
+
+				if (this.setValueResourceCommand != null)
+					this.setValueResourceCommand.CanExecuteChanged -= OnSetValueResourceCommandCanExecuteChanged;
+
+				this.setValueResourceCommand = value;
+				if (this.setValueResourceCommand != null)
+					this.setValueResourceCommand.CanExecuteChanged += OnSetValueResourceCommandCanExecuteChanged;
+
+				((RelayCommand)RequestResourceCommand).ChangeCanExecute();
+			}
 		}
 
+		public ICommand RequestResourceCommand => this.requestResourceCommand;
+
 		public ICommand ClearValueCommand
 		{
 			get;
@@ -347,6 +324,9 @@ namespace Xamarin.PropertyEditing.ViewModels
 			editor.PropertyChanged -= OnEditorPropertyChanged;
 		}
 
+		private IResourceProvider resourceProvider;
+		private ICommand setValueResourceCommand;
+		private RelayCommand requestResourceCommand;
 		private HashSet<IPropertyInfo> constraintProperties;
 		private PropertyVariation variation;
 		private string error;
@@ -403,5 +383,26 @@ namespace Xamarin.PropertyEditing.ViewModels
 				return true;
 			}
 		}
+
+		private bool CanRequestResource ()
+		{
+			return SupportsResources && SetValueResourceCommand != null;
+		}
+
+		private void OnRequestResource ()
+		{
+			var e = new ResourceRequestedEventArgs();
+			ResourceRequested?.Invoke (this, e);
+			if (e.Resource == null)
+				return;
+
+			if (SetValueResourceCommand.CanExecute (e.Resource))
+				SetValueResourceCommand.Execute (e.Resource);
+		}
+
+		private void OnSetValueResourceCommandCanExecuteChanged (object sender, EventArgs e)
+		{
+			this.requestResourceCommand.ChangeCanExecute();
+		}
 	}
 }