From aad14eb370857064701cee77305bf56e72e665e2 Mon Sep 17 00:00:00 2001
From: Yuriy Durov <u.a.durov@gmail.com>
Date: Sun, 5 May 2024 13:17:02 +0400
Subject: [PATCH] State improvements

---
 .../Pages/CounterPage.razor                       | 11 ++++-------
 .../ViewModels/CounterPageViewModel.cs            | 15 ++++++++++++++-
 .../AddRenderingEnvironmentExtension.cs           |  2 +-
 .../Interfaces/IStateComponent.cs                 |  6 ++++++
 .../Models/ComponentViewModel.cs                  |  8 +++++---
 src/BitzArt.Blazor.MVVM/Models/PageBase.cs        | 11 ++++++-----
 .../Models/RenderingEnvironment.cs                | 11 +++++++++++
 7 files changed, 47 insertions(+), 17 deletions(-)
 create mode 100644 src/BitzArt.Blazor.MVVM/Interfaces/IStateComponent.cs

diff --git a/sample/BitzArt.Blazor.MVVM.SampleApp/BitzArt.Blazor.MVVM.SampleApp.Client/Pages/CounterPage.razor b/sample/BitzArt.Blazor.MVVM.SampleApp/BitzArt.Blazor.MVVM.SampleApp.Client/Pages/CounterPage.razor
index eba1212..6080969 100644
--- a/sample/BitzArt.Blazor.MVVM.SampleApp/BitzArt.Blazor.MVVM.SampleApp.Client/Pages/CounterPage.razor
+++ b/sample/BitzArt.Blazor.MVVM.SampleApp/BitzArt.Blazor.MVVM.SampleApp.Client/Pages/CounterPage.razor
@@ -6,16 +6,13 @@
 
 <h1>Counter</h1>
 
-<p>This page is currently being rendered using: @(OperatingSystem.IsBrowser() ? "WASM" : "Server")</p>
+<p>Current render mode: @RenderingEnvironment</p>
 
-@if (ViewModel.State is not null)
-{
-    <p>@ViewModel.State.Text</p>
+<p>@ViewModel.State?.Text</p>
 
-    <p role="status">Current count: @ViewModel.State.Count</p>
+<p role="status">Current count: @ViewModel.State?.Count</p>
 
-    <button class="btn btn-primary" @onclick="ViewModel.IncrementCount">Click me</button>
-}
+<button class="btn btn-primary" @onclick="ViewModel.IncrementCount">Click me</button>
 
 @{
     base.BuildRenderTree(__builder);
diff --git a/sample/BitzArt.Blazor.MVVM.SampleApp/BitzArt.Blazor.MVVM.SampleApp.Client/ViewModels/CounterPageViewModel.cs b/sample/BitzArt.Blazor.MVVM.SampleApp/BitzArt.Blazor.MVVM.SampleApp.Client/ViewModels/CounterPageViewModel.cs
index 670f808..1fcc566 100644
--- a/sample/BitzArt.Blazor.MVVM.SampleApp/BitzArt.Blazor.MVVM.SampleApp.Client/ViewModels/CounterPageViewModel.cs
+++ b/sample/BitzArt.Blazor.MVVM.SampleApp/BitzArt.Blazor.MVVM.SampleApp.Client/ViewModels/CounterPageViewModel.cs
@@ -2,10 +2,23 @@
 
 public class CounterPageViewModel : ComponentViewModel<CounterPageViewModelState>
 {
+    private readonly Timer _timer;
+
+    public CounterPageViewModel()
+    {
+        _timer = new Timer(TimerIncrementCount, null, 1000, 1000);
+    }
+
+    private void TimerIncrementCount(object? state)
+    {
+        State.Count++;
+        StateHasChanged();
+    }
+
     public override void InitializeState()
     {
         State.Count = 0;
-        State.Text = "ViewModel State initialized on: " + (OperatingSystem.IsBrowser() ? "Client" : "Server");
+        State.Text = $"ViewModel State initialized on: {RenderingEnvironment}";
     }
 
     public void IncrementCount()
diff --git a/src/BitzArt.Blazor.MVVM/Extensions/AddRenderingEnvironmentExtension.cs b/src/BitzArt.Blazor.MVVM/Extensions/AddRenderingEnvironmentExtension.cs
index 4c818bb..992bc19 100644
--- a/src/BitzArt.Blazor.MVVM/Extensions/AddRenderingEnvironmentExtension.cs
+++ b/src/BitzArt.Blazor.MVVM/Extensions/AddRenderingEnvironmentExtension.cs
@@ -7,7 +7,7 @@ public static class AddRenderingEnvironmentExtension
 {
     public static IServiceCollection AddRenderingEnvironment(this IServiceCollection services)
     {
-        services.AddTransient(x => x.GetRenderingEnvironment());
+        services.AddScoped(x => x.GetRenderingEnvironment());
 
         return services;
     }
diff --git a/src/BitzArt.Blazor.MVVM/Interfaces/IStateComponent.cs b/src/BitzArt.Blazor.MVVM/Interfaces/IStateComponent.cs
new file mode 100644
index 0000000..e436d12
--- /dev/null
+++ b/src/BitzArt.Blazor.MVVM/Interfaces/IStateComponent.cs
@@ -0,0 +1,6 @@
+namespace BitzArt.Blazor.MVVM;
+
+internal interface IStateComponent
+{
+    public void StateHasChanged();
+}
\ No newline at end of file
diff --git a/src/BitzArt.Blazor.MVVM/Models/ComponentViewModel.cs b/src/BitzArt.Blazor.MVVM/Models/ComponentViewModel.cs
index 8dda8d0..465d021 100644
--- a/src/BitzArt.Blazor.MVVM/Models/ComponentViewModel.cs
+++ b/src/BitzArt.Blazor.MVVM/Models/ComponentViewModel.cs
@@ -5,15 +5,16 @@
 /// </summary>
 public abstract class ComponentViewModel
 {
-    public delegate void StateChangedEventHandler();
-    public event StateChangedEventHandler? StateChanged;
+    internal IStateComponent Component { get; set; } = null!;
+
+    protected internal RenderingEnvironment RenderingEnvironment { get; internal set; } = null!;
 
     /// <summary>
     /// Notifies the component that the state has changed.
     /// </summary>
     protected void StateHasChanged()
     {
-        StateChanged?.Invoke();
+        Component.StateHasChanged();
     }
 }
 
@@ -24,6 +25,7 @@ protected void StateHasChanged()
 public abstract class ComponentViewModel<TState> : ComponentViewModel, IStatefulViewModel
     where TState : class, new()
 {
+
     /// <summary>
     /// Persistent state of this view model.
     /// </summary>
diff --git a/src/BitzArt.Blazor.MVVM/Models/PageBase.cs b/src/BitzArt.Blazor.MVVM/Models/PageBase.cs
index 8df5dd9..1542fd2 100644
--- a/src/BitzArt.Blazor.MVVM/Models/PageBase.cs
+++ b/src/BitzArt.Blazor.MVVM/Models/PageBase.cs
@@ -10,7 +10,7 @@ namespace BitzArt.Blazor.MVVM;
 /// Blazor page base class with view model support.
 /// </summary>
 /// <typeparam name="TViewModel">Type of this component's ViewModel</typeparam>
-public abstract partial class PageBase<TViewModel> : ComponentBase
+public abstract partial class PageBase<TViewModel> : ComponentBase, IStateComponent
     where TViewModel : ComponentViewModel
 {
     private const string StateKey = "state";
@@ -25,7 +25,7 @@ public abstract partial class PageBase<TViewModel> : ComponentBase
     private IJSRuntime Js { get; set; } = default!;
 
     [Inject]
-    private RenderingEnvironment RenderingEnvironment { get; set; } = null!;
+    protected RenderingEnvironment RenderingEnvironment { get; set; } = null!;
 
     /// <summary>
     /// Navigation manager.
@@ -48,10 +48,9 @@ protected override void BuildRenderTree(RenderTreeBuilder builder)
     /// <returns>A <see cref="Task"/> representing any asynchronous operation.</returns>
     protected override async Task OnInitializedAsync()
     {
-        ViewModel.StateChanged += StateHasChanged;
-
         await base.OnInitializedAsync();
-
+        ViewModel.Component = this;
+        ViewModel.RenderingEnvironment = RenderingEnvironment;
         await RestoreStateAsync();
     }
 
@@ -119,6 +118,8 @@ public override Task SetParametersAsync(ParameterView parameters)
 
         return base.SetParametersAsync(parameters);
     }
+
+    void IStateComponent.StateHasChanged() => InvokeAsync(StateHasChanged);
 }
 
 internal static class StateJsonOptionsProvider
diff --git a/src/BitzArt.Blazor.MVVM/Models/RenderingEnvironment.cs b/src/BitzArt.Blazor.MVVM/Models/RenderingEnvironment.cs
index 17a8d6b..1ae1973 100644
--- a/src/BitzArt.Blazor.MVVM/Models/RenderingEnvironment.cs
+++ b/src/BitzArt.Blazor.MVVM/Models/RenderingEnvironment.cs
@@ -5,4 +5,15 @@ public class RenderingEnvironment
     public required bool IsPrerender { get; init; }
     public required bool IsServer { get; init; }
     public required bool IsClient { get; init; }
+
+    public override string ToString()
+    {
+        if (IsClient) return "Client";
+        if (IsServer)
+        {
+            if (IsPrerender) return "Server (prerender)";
+            return "Server";
+        }
+        return "Unknown";
+    }
 }