Initialize the authentication state provider during static prerendering

Author: SteveSandersonMS

src/Components/Components/src/Auth/IHostEnvironmentAuthenticationStateProvider.cs

@@ -0,0 +1,20 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Components
+{
+    /// <summary>
+    /// An interface implemented by <see cref="AuthenticationStateProvider"/> classes that can receive authentication
+    /// state information from the host environment.
+    /// </summary>
+    public interface IHostEnvironmentAuthenticationStateProvider
+    {
+        /// <summary>
+        /// Supplies updated authentication state data to the <see cref="AuthenticationStateProvider"/>.
+        /// </summary>
+        /// <param name="authenticationStateTask">A task that resolves with the updated <see cref="AuthenticationState"/>.</param>
+        void SetAuthenticationState(Task<AuthenticationState> authenticationStateTask);
+    }
+}

src/Components/Server/src/Circuits/DefaultCircuitFactory.cs

@@ -14,6 +14,7 @@
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.JSInterop;
+using System.Threading.Tasks;
 
 namespace Microsoft.AspNetCore.Components.Server.Circuits
 {
@@ -50,9 +51,12 @@ public override CircuitHost CreateCircuitHost(
             jsRuntime.Initialize(client);
             componentContext.Initialize(client);
 
-            // You can replace the AuthenticationStateProvider with a custom one, but in that case initialization is up to you
-            var authenticationStateProvider = scope.ServiceProvider.GetService<AuthenticationStateProvider>();
-            (authenticationStateProvider as FixedAuthenticationStateProvider)?.Initialize(httpContext.User);
+            var authenticationStateProvider = scope.ServiceProvider.GetService<AuthenticationStateProvider>() as IHostEnvironmentAuthenticationStateProvider;
+            if (authenticationStateProvider != null)
+            {
+                var authenticationState = new AuthenticationState(httpContext.User); // TODO: Get this from the hub connection context instead
+                authenticationStateProvider.SetAuthenticationState(Task.FromResult(authenticationState));
+            }
 
             var uriHelper = (RemoteUriHelper)scope.ServiceProvider.GetRequiredService<IUriHelper>();
             var navigationInterception = (RemoteNavigationInterception)scope.ServiceProvider.GetRequiredService<INavigationInterception>();

src/Components/Server/src/Circuits/FixedAuthenticationStateProvider.cs

@@ -0,0 +1,26 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Threading.Tasks;
+
+namespace Microsoft.AspNetCore.Components.Server.Circuits
+{
+    /// <summary>
+    /// An <see cref="AuthenticationStateProvider"/> intended for use in server-side Blazor.
+    /// </summary>
+    internal class ServerAuthenticationStateProvider : AuthenticationStateProvider, IHostEnvironmentAuthenticationStateProvider
+    {
+        private Task<AuthenticationState> _authenticationStateTask;
+
+        public override Task<AuthenticationState> GetAuthenticationStateAsync()
+            => _authenticationStateTask
+            ?? throw new InvalidOperationException($"{nameof(GetAuthenticationStateAsync)} was called before {nameof(SetAuthenticationState)}.");
+
+        public void SetAuthenticationState(Task<AuthenticationState> authenticationStateTask)
+        {
+            _authenticationStateTask = authenticationStateTask ?? throw new ArgumentNullException(nameof(authenticationStateTask));
+            NotifyAuthenticationStateChanged(_authenticationStateTask);
+        }
+    }
+}

src/Components/Server/src/Circuits/ServerAuthenticationStateProvider.cs

@@ -76,7 +76,7 @@ public static IServerSideBlazorBuilder AddServerSideBlazor(this IServiceCollecti
             services.AddScoped<IJSRuntime, RemoteJSRuntime>();
             services.AddScoped<INavigationInterception, RemoteNavigationInterception>();
             services.AddScoped<IComponentContext, RemoteComponentContext>();
-            services.AddScoped<AuthenticationStateProvider, FixedAuthenticationStateProvider>();
+            services.AddScoped<AuthenticationStateProvider, ServerAuthenticationStateProvider>();
 
             services.TryAddEnumerable(ServiceDescriptor.Singleton<IConfigureOptions<CircuitOptions>, CircuitOptionsJSInteropDetailedErrorsConfiguration>());
 

src/Components/Server/src/DependencyInjection/ComponentServiceCollectionExtensions.cs

@@ -30,7 +30,7 @@ public async Task<IEnumerable<string>> PrerenderComponentAsync(
             HttpContext httpContext,
             Type componentType)
         {
-            InitializeUriHelper(httpContext);
+            InitializeStandardComponentServices(httpContext);
             var loggerFactory = (ILoggerFactory)httpContext.RequestServices.GetService(typeof (ILoggerFactory));
             using (var htmlRenderer = new HtmlRenderer(httpContext.RequestServices, loggerFactory, _encoder.Encode))
             {
@@ -62,15 +62,21 @@ public async Task<IEnumerable<string>> PrerenderComponentAsync(
             }
         }
 
-        private void InitializeUriHelper(HttpContext httpContext)
+        private void InitializeStandardComponentServices(HttpContext httpContext)
         {
-            // We don't know here if we are dealing with the default HttpUriHelper registered
-            // by MVC or with the RemoteUriHelper registered by AddComponents.
             // This might not be the first component in the request we are rendering, so
-            // we need to check if we already initialized the uri helper in this request.
+            // we need to check if we already initialized the services in this request.
             if (!_initialized)
             {
                 _initialized = true;
+
+                var authenticationStateProvider = httpContext.RequestServices.GetService<AuthenticationStateProvider>() as IHostEnvironmentAuthenticationStateProvider;
+                if (authenticationStateProvider != null)
+                {
+                    var authenticationState = new AuthenticationState(httpContext.User);
+                    authenticationStateProvider.SetAuthenticationState(Task.FromResult(authenticationState));
+                }
+
                 var helper = (UriHelperBase)httpContext.RequestServices.GetRequiredService<IUriHelper>();
                 helper.InitializeState(GetFullUri(httpContext.Request), GetContextBaseUri(httpContext.Request));
             }