From 069fd0f35008e00a2bf77c65013cc3973d0c8d65 Mon Sep 17 00:00:00 2001
From: James Restall <6826786+jrestall@users.noreply.github.com>
Date: Sat, 14 Apr 2018 16:37:11 +1200
Subject: [PATCH] Adding IStartupFilter support

The middleware pipeline for a tenant can now be configured using IStartupFilter, this allows libraries that use this interface as part of their initialisation to work e.g. Microsoft.AspNetCore.Mvc.Versioning.
---
 .../ModularTenantRouterMiddleware.cs          | 35 +++++++++++++------
 1 file changed, 24 insertions(+), 11 deletions(-)

diff --git a/src/OrchardCore/OrchardCore.Modules/ModularTenantRouterMiddleware.cs b/src/OrchardCore/OrchardCore.Modules/ModularTenantRouterMiddleware.cs
index 534a4aaa691..936acf6ab13 100644
--- a/src/OrchardCore/OrchardCore.Modules/ModularTenantRouterMiddleware.cs
+++ b/src/OrchardCore/OrchardCore.Modules/ModularTenantRouterMiddleware.cs
@@ -3,6 +3,7 @@
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Builder;
 using Microsoft.AspNetCore.Builder.Internal;
+using Microsoft.AspNetCore.Hosting;
 using Microsoft.AspNetCore.Http;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
@@ -37,7 +38,6 @@ public async Task Invoke(HttpContext httpContext)
                 _logger.LogInformation("Begin Routing Request");
             }
 
-
             var shellSettings = httpContext.Features.Get<ShellSettings>();
 
             // Define a PathBase for the current request that is the RequestUrlPrefix.
@@ -85,15 +85,32 @@ public async Task Invoke(HttpContext httpContext)
         // Build the middleware pipeline for the current tenant
         public RequestDelegate BuildTenantPipeline(ShellSettings shellSettings, IServiceProvider serviceProvider)
         {
-            var startups = serviceProvider.GetServices<IStartup>();
+            var appBuilder = new ApplicationBuilder(serviceProvider);
+              
+            // Create a nested pipeline to configure the tenant middleware pipeline
+            var startupFilters = serviceProvider.GetService<IEnumerable<IStartupFilter>>(); 
+            Action<IApplicationBuilder> configure = ConfigureTenantPipeline;
+            foreach (var filter in startupFilters.Reverse())
+            {
+                configure = filter.Configure(configure);
+            }
+
+            configure(appBuilder);
+
+            var pipeline = appBuilder.Build();
+
+            return pipeline;
+        }
+
+        private void ConfigureTenantPipeline(IApplicationBuilder builder)
+        {
+            var startups = builder.ApplicationServices.GetServices<IStartup>();
 
             // IStartup instances are ordered by module dependency with an Order of 0 by default.
             // OrderBy performs a stable sort so order is preserved among equal Order values.
             startups = startups.OrderBy(s => s.Order);
 
-            var tenantRouteBuilder = serviceProvider.GetService<IModularTenantRouteBuilder>();
-            
-            var appBuilder = new ApplicationBuilder(serviceProvider);
+            var tenantRouteBuilder = builder.ApplicationServices.GetService<IModularTenantRouteBuilder>();
             var routeBuilder = tenantRouteBuilder.Build();
 
             // In the case of several tenants, they will all be checked by ShellSettings. To optimize
@@ -102,18 +119,14 @@ public RequestDelegate BuildTenantPipeline(ShellSettings shellSettings, IService
             // And the ShellSettings test in TenantRoute would also be useless.
             foreach (var startup in startups)
             {
-                startup.Configure(appBuilder, routeBuilder, serviceProvider);
+                startup.Configure(builder, routeBuilder, builder.ApplicationServices);
             }
 
             tenantRouteBuilder.Configure(routeBuilder);
 
             var router = routeBuilder.Build();
 
-            appBuilder.UseRouter(router);
-
-            var pipeline = appBuilder.Build();
-
-            return pipeline;
+            builder.UseRouter(router);
         }
     }
 }