From 9ec79ae9f76aada6014f1ee43fbd103175058d41 Mon Sep 17 00:00:00 2001
From: Steve Sanderson <SteveSandersonMS@users.noreply.github.com>
Date: Mon, 11 Dec 2017 19:45:02 +0000
Subject: [PATCH] Start making standalone hosting work again by automatically
 locating the client app assembly

---
 samples/HostedInAspNet.Server/Startup.cs      |  2 +-
 samples/MonoSanity/Startup.cs                 |  2 +-
 samples/MonoSanityClient/Examples.cs          |  2 +-
 .../Server/Startup.cs                         | 34 ++++++++++++++++++-
 .../BlazorAppBuilderExtensions.cs             |  9 ++---
 5 files changed, 41 insertions(+), 8 deletions(-)

diff --git a/samples/HostedInAspNet.Server/Startup.cs b/samples/HostedInAspNet.Server/Startup.cs
index 576c37f634..92ceba8905 100644
--- a/samples/HostedInAspNet.Server/Startup.cs
+++ b/samples/HostedInAspNet.Server/Startup.cs
@@ -25,7 +25,7 @@ namespace HostedInAspNet.Server
                 app.UseBlazorDevelopmentServer("../HostedInAspNet.Client");
             }
 
-            app.UseBlazor<Client.Program>();
+            app.UseBlazor(clientAssembly: typeof(Client.Program).Assembly);
         }
     }
 }
diff --git a/samples/MonoSanity/Startup.cs b/samples/MonoSanity/Startup.cs
index 144ea796f3..d40144e6fe 100644
--- a/samples/MonoSanity/Startup.cs
+++ b/samples/MonoSanity/Startup.cs
@@ -15,7 +15,7 @@ namespace MonoSanity
         {
             app.UseDeveloperExceptionPage();
             app.UseFileServer();
-            app.UseBlazor<MonoSanityClient.Examples>();         
+            app.UseBlazor(clientAssembly: typeof(MonoSanityClient.Examples).Assembly);
         }
     }
 }
diff --git a/samples/MonoSanityClient/Examples.cs b/samples/MonoSanityClient/Examples.cs
index 9983c89cd0..24be61d54e 100644
--- a/samples/MonoSanityClient/Examples.cs
+++ b/samples/MonoSanityClient/Examples.cs
@@ -6,7 +6,7 @@ using System.Text;
 
 namespace MonoSanityClient
 {
-    public class Examples
+    public static class Examples
     {
         public static string AddNumbers(int a, int b)
             => (a + b).ToString();
diff --git a/src/Microsoft.Blazor.DevHost/Server/Startup.cs b/src/Microsoft.Blazor.DevHost/Server/Startup.cs
index 148aa8c7f6..94af9dca25 100644
--- a/src/Microsoft.Blazor.DevHost/Server/Startup.cs
+++ b/src/Microsoft.Blazor.DevHost/Server/Startup.cs
@@ -1,8 +1,12 @@
 // 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.Reflection;
 using Microsoft.AspNetCore.Builder;
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.Extensions.DependencyInjection;
+using System.IO;
 
 namespace Microsoft.Blazor.DevHost.Server
 {
@@ -17,7 +21,35 @@ namespace Microsoft.Blazor.DevHost.Server
         {
             app.UseDeveloperExceptionPage();
             app.UseBlazorDevelopmentServer(".");
-            app.UseBlazor<object>(); // TODO
+            app.UseBlazor(clientAssembly: FindClientAssembly(app));
+        }
+
+        private static Assembly FindClientAssembly(IApplicationBuilder app)
+        {
+            var env = app.ApplicationServices.GetRequiredService<IHostingEnvironment>();
+            var contentRoot = env.ContentRootPath;
+            var binDir = FindClientBinDir(contentRoot);
+            var appName = Path.GetFileName(contentRoot); // TODO: Allow for the possibility that the assembly name has been overridden
+            var assemblyPath = Path.Combine(binDir, $"{appName}.dll");
+            if (!File.Exists(assemblyPath))
+            {
+                throw new FileNotFoundException($"Could not locate application assembly at expected location {assemblyPath}");
+            }
+
+            return Assembly.LoadFile(assemblyPath);
+        }
+
+        private static string FindClientBinDir(string clientAppSourceRoot)
+        {
+            var binDebugDir = Path.Combine(clientAppSourceRoot, "bin", "Debug");
+            var subdirectories = Directory.GetDirectories(binDebugDir);
+            if (subdirectories.Length != 1)
+            {
+                throw new InvalidOperationException($"Could not locate bin directory for Blazor app. " +
+                    $"Expected to find exactly 1 subdirectory in '{binDebugDir}', but found {subdirectories.Length}.");
+            }
+
+            return Path.Combine(binDebugDir, subdirectories[0]);
         }
     }
 }
diff --git a/src/Microsoft.Blazor.Server/BlazorAppBuilderExtensions.cs b/src/Microsoft.Blazor.Server/BlazorAppBuilderExtensions.cs
index 96dc2e743f..0d5c9af277 100644
--- a/src/Microsoft.Blazor.Server/BlazorAppBuilderExtensions.cs
+++ b/src/Microsoft.Blazor.Server/BlazorAppBuilderExtensions.cs
@@ -5,19 +5,20 @@ using Microsoft.AspNetCore.StaticFiles;
 using Microsoft.Blazor.Server.ClientFilesystem;
 using System.Collections.Generic;
 using System.Net.Mime;
+using System.Reflection;
 
 namespace Microsoft.AspNetCore.Builder
 {
     public static class BlazorAppBuilderExtensions
     {
-        public static void UseBlazor<TProgram>(this IApplicationBuilder applicationBuilder)
+        public static void UseBlazor(
+            this IApplicationBuilder applicationBuilder,
+            Assembly clientAssembly)
         {
-            var clientAppAssembly = typeof(TProgram).Assembly;
-
             applicationBuilder.UseStaticFiles(new StaticFileOptions
             {
                 RequestPath = "/_framework",
-                FileProvider = ClientFileProvider.Instantiate(clientAppAssembly),
+                FileProvider = ClientFileProvider.Instantiate(clientAssembly),
                 ContentTypeProvider = CreateContentTypeProvider(),
             });
         }