[release/6.0] Initial Bootstrap v4 SxS support

src/Identity/UI/src/Areas/Identity/Pages/V4/Account/Login.cshtml

@@ -67,7 +67,7 @@
                     <form id="external-account" asp-page="./ExternalLogin" asp-route-returnUrl="@Model.ReturnUrl" method="post" class="form-horizontal">
                         <div>
                             <p>
-                                @foreach (var provider in Model.ExternalLogins)
+                                @foreach (var provider in Model.ExternalLogins!)
                                 {
                                     <button type="submit" class="btn btn-primary" name="provider" value="@provider.Name" title="Log in using your @provider.DisplayName account">@provider.DisplayName</button>
                                 }

src/Identity/UI/src/Areas/Identity/Pages/V4/Account/Logout.cshtml

@@ -7,7 +7,7 @@
 <header>
     <h1>@ViewData["Title"]</h1>
     @{
-        if (User.Identity.IsAuthenticated)
+        if (User.Identity!.IsAuthenticated)
         {
             <form class="form-inline" asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="@Url.Page("/", new { area = "" })" method="post">
                 <button type="submit" class="nav-link btn btn-link text-dark">Click here to Logout</button>

src/Identity/UI/src/Areas/Identity/Pages/V4/Account/Manage/_Layout.cshtml

@@ -1,7 +1,7 @@
 @{
     if (ViewData.TryGetValue("ParentLayout", out var parentLayout))
     {
-        Layout = (string)parentLayout;
+        Layout = (string)parentLayout!;
     }
     else
     {

src/Identity/UI/src/Areas/Identity/Pages/V4/Account/Manage/_ManageNav.cshtml

@@ -2,7 +2,7 @@
     <li class="nav-item"><a class="nav-link @ManageNavPages.IndexNavClass(ViewContext)" id="profile" asp-page="./Index">Profile</a></li>
     <li class="nav-item"><a class="nav-link @ManageNavPages.EmailNavClass(ViewContext)" id="email" asp-page="./Email">Email</a></li>
     <li class="nav-item"><a class="nav-link @ManageNavPages.ChangePasswordNavClass(ViewContext)" id="change-password" asp-page="./ChangePassword">Password</a></li>
-    @if ((bool)ViewData["ManageNav.HasExternalLogins"])
+    @if ((bool)(ViewData["ManageNav.HasExternalLogins"] ?? false))
     {
         <li id="external-logins" class="nav-item"><a id="external-login" class="nav-link @ManageNavPages.ExternalLoginsNavClass(ViewContext)" asp-page="./ExternalLogins">External logins</a></li>
     }

src/Identity/UI/src/Areas/Identity/Pages/V4/Account/Register.cshtml

@@ -49,7 +49,7 @@
                     <form id="external-account" asp-page="./ExternalLogin" asp-route-returnUrl="@Model.ReturnUrl" method="post" class="form-horizontal">
                         <div>
                             <p>
-                                @foreach (var provider in Model.ExternalLogins)
+                                @foreach (var provider in Model.ExternalLogins!)
                                 {
                                     <button type="submit" class="btn btn-primary" name="provider" value="@provider.Name" title="Log in using your @provider.DisplayName account">@provider.DisplayName</button>
                                 }

src/Identity/UI/src/Areas/Identity/Pages/V5/Account/Login.cshtml

@@ -67,7 +67,7 @@
                     <form id="external-account" asp-page="./ExternalLogin" asp-route-returnUrl="@Model.ReturnUrl" method="post" class="form-horizontal">
                         <div>
                             <p>
-                                @foreach (var provider in Model.ExternalLogins)
+                                @foreach (var provider in Model.ExternalLogins!)
                                 {
                                     <button type="submit" class="btn btn-primary" name="provider" value="@provider.Name" title="Log in using your @provider.DisplayName account">@provider.DisplayName</button>
                                 }

src/Identity/UI/src/Areas/Identity/Pages/V5/Account/Logout.cshtml

@@ -7,7 +7,7 @@
 <header>
     <h1>@ViewData["Title"]</h1>
     @{
-        if (User.Identity.IsAuthenticated)
+        if (User.Identity!.IsAuthenticated)
         {
             <form class="form-inline" asp-area="Identity" asp-page="/Account/Logout" asp-route-returnUrl="@Url.Page("/", new { area = "" })" method="post">
                 <button type="submit" class="nav-link btn btn-link text-dark">Click here to Logout</button>

src/Identity/UI/src/Areas/Identity/Pages/V5/Account/Manage/_Layout.cshtml

@@ -1,7 +1,7 @@
 @{
     if (ViewData.TryGetValue("ParentLayout", out var parentLayout))
     {
-        Layout = (string)parentLayout;
+        Layout = (string)parentLayout!;
     }
     else
     {

src/Identity/UI/src/Areas/Identity/Pages/V5/Account/Manage/_ManageNav.cshtml

@@ -2,7 +2,7 @@
     <li class="nav-item"><a class="nav-link @ManageNavPages.IndexNavClass(ViewContext)" id="profile" asp-page="./Index">Profile</a></li>
     <li class="nav-item"><a class="nav-link @ManageNavPages.EmailNavClass(ViewContext)" id="email" asp-page="./Email">Email</a></li>
     <li class="nav-item"><a class="nav-link @ManageNavPages.ChangePasswordNavClass(ViewContext)" id="change-password" asp-page="./ChangePassword">Password</a></li>
-    @if ((bool)ViewData["ManageNav.HasExternalLogins"])
+    @if ((bool)(ViewData["ManageNav.HasExternalLogins"] ?? false))
     {
         <li id="external-logins" class="nav-item"><a id="external-login" class="nav-link @ManageNavPages.ExternalLoginsNavClass(ViewContext)" asp-page="./ExternalLogins">External logins</a></li>
     }

src/Identity/UI/src/Areas/Identity/Pages/V5/Account/Register.cshtml

@@ -49,7 +49,7 @@
                     <form id="external-account" asp-page="./ExternalLogin" asp-route-returnUrl="@Model.ReturnUrl" method="post" class="form-horizontal">
                         <div>
                             <p>
-                                @foreach (var provider in Model.ExternalLogins)
+                                @foreach (var provider in Model.ExternalLogins!)
                                 {
                                     <button type="submit" class="btn btn-primary" name="provider" value="@provider.Name" title="Log in using your @provider.DisplayName account">@provider.DisplayName</button>
                                 }

src/Identity/UI/src/IdentityBuilderUIExtensions.cs

@@ -1,10 +1,15 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Reflection;
+using System.Linq;
 using Microsoft.AspNetCore.Identity.UI;
 using Microsoft.AspNetCore.Identity.UI.Services;
+using Microsoft.AspNetCore.Mvc.ApplicationParts;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.DependencyInjection.Extensions;
+using Microsoft.AspNetCore.Mvc.Razor.Compilation;
+using Microsoft.AspNetCore.Hosting;
 
 namespace Microsoft.AspNetCore.Identity
 {
@@ -27,7 +32,29 @@ public static class IdentityBuilderUIExtensions
         public static IdentityBuilder AddDefaultUI(this IdentityBuilder builder)
         {
             builder.AddSignInManager();
-            builder.Services.AddMvc();
+            builder.Services
+                .AddMvc()
+                .ConfigureApplicationPartManager(apm =>
+                {
+                    // We try to resolve the UI framework that was used by looking at the entry assembly.
+                    // When an app runs, the entry assembly will point to the built app. In some rare cases
+                    // (functional testing) the app assembly will be different, and we'll try to locate it through
+                    // the same mechanism that MVC uses today.
+                    // Finally, if for some reason we aren't able to find the assembly, we'll use our default value
+                    // (Bootstrap5)
+                    if (!TryResolveUIFramework(Assembly.GetEntryAssembly(), out var framework) &&
+                        !TryResolveUIFramework(GetApplicationAssembly(builder), out framework))
+                    {
+                        framework = default;
+                    }
+
+                    var parts = new ConsolidatedAssemblyApplicationPartFactory().GetApplicationParts(typeof(IdentityBuilderUIExtensions).Assembly);
+                    foreach (var part in parts)
+                    {
+                        apm.ApplicationParts.Add(part);
+                    }
+                    apm.FeatureProviders.Add(new ViewVersionFeatureProvider(framework));
+                });
 
             builder.Services.ConfigureOptions(
                 typeof(IdentityDefaultUIConfigureOptions<>)
@@ -36,5 +63,96 @@ public static IdentityBuilder AddDefaultUI(this IdentityBuilder builder)
 
             return builder;
         }
+
+        private static Assembly GetApplicationAssembly(IdentityBuilder builder)
+        {
+            // This is the same logic that MVC follows to find the application assembly.
+            var environment = builder.Services.Where(d => d.ServiceType == typeof(IWebHostEnvironment)).ToArray();
+            var applicationName = ((IWebHostEnvironment)environment.LastOrDefault()?.ImplementationInstance)
+                .ApplicationName;
+
+            if (applicationName == null)
+            {
+                return null;
+            }
+            var appAssembly = Assembly.Load(applicationName);
+            return appAssembly;
+        }
+
+        private static bool TryResolveUIFramework(Assembly assembly, out UIFramework uiFramework)
+        {
+            uiFramework = default;
+
+            var metadata = assembly?.GetCustomAttributes<UIFrameworkAttribute>()
+                .SingleOrDefault()?.UIFramework; // Bootstrap5 is the default
+            if (metadata == null)
+            {
+                return false;
+            }
+
+            // If we find the metadata there must be a valid framework here.
+            if (!Enum.TryParse(metadata, ignoreCase: true, out uiFramework))
+            {
+                var enumValues = string.Join(", ", Enum.GetNames(typeof(UIFramework)).Select(v => $"'{v}'"));
+                throw new InvalidOperationException(
+                    $"Found an invalid value for the 'IdentityUIFrameworkVersion'. Valid values are {enumValues}");
+            }
+
+            return true;
+        }
+
+        internal class ViewVersionFeatureProvider : IApplicationFeatureProvider<ViewsFeature>
+        {
+            private readonly UIFramework _framework;
+
+            public ViewVersionFeatureProvider(UIFramework framework) => _framework = framework;
+
+            public void PopulateFeature(IEnumerable<ApplicationPart> parts, ViewsFeature feature)
+            {
+                var viewsToRemove = new List<CompiledViewDescriptor>();
+                foreach (var descriptor in feature.ViewDescriptors)
+                {
+                    if (IsIdentityUIView(descriptor))
+                    {
+                        switch (_framework)
+                        {
+                            case UIFramework.Bootstrap4:
+                                if (descriptor.Type.FullName.Contains("V5"))
+                                {
+                                    // Remove V5 views
+                                    viewsToRemove.Add(descriptor);
+                                }
+                                else
+                                {
+                                    // Fix up paths to eliminate version subdir
+                                    descriptor.RelativePath = descriptor.RelativePath.Replace("V4/", "");
+                                }
+                                break;
+                            case UIFramework.Bootstrap5:
+                                if (descriptor.Type.FullName.Contains("V4"))
+                                {
+                                    // Remove V4 views
+                                    viewsToRemove.Add(descriptor);
+                                }
+                                else
+                                {
+                                    // Fix up paths to eliminate version subdir
+                                    descriptor.RelativePath = descriptor.RelativePath.Replace("V5/", "");
+                                }
+                                break;
+                            default:
+                                throw new InvalidOperationException($"Unknown framework: {_framework}");
+                        }
+                    }
+                }
+
+                foreach (var descriptorToRemove in viewsToRemove)
+                {
+                    feature.ViewDescriptors.Remove(descriptorToRemove);
+                }
+            }
+
+            private static bool IsIdentityUIView(CompiledViewDescriptor desc) => desc.RelativePath.StartsWith("/Areas/Identity", StringComparison.OrdinalIgnoreCase) && desc.Type.Assembly == typeof(IdentityBuilderUIExtensions).Assembly;
+        }
     }
 }

src/Identity/UI/src/Microsoft.AspNetCore.Identity.UI.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk.Razor">
+<Project Sdk="Microsoft.NET.Sdk.Razor">
 
   <PropertyGroup>
     <Description>ASP.NET Core Identity UI is the default Razor Pages built-in UI for the ASP.NET Core Identity framework.</Description>
@@ -8,14 +8,24 @@
     <PackageTags>aspnetcore;identity;membership;razorpages</PackageTags>
     <EnableDefaultRazorGenerateItems>false</EnableDefaultRazorGenerateItems>
     <AddRazorSupportForMvc>true</AddRazorSupportForMvc>
-    <StaticWebAssetBasePath>Identity</StaticWebAssetBasePath>
+
     <PackageThirdPartyNoticesFile>$(MSBuildThisFileDirectory)THIRD-PARTY-NOTICES.TXT</PackageThirdPartyNoticesFile>
     <Nullable>disable</Nullable>
+
+    <StaticWebAssetBasePath>Identity</StaticWebAssetBasePath>
+    <ProvideApplicationPartFactoryAttributeTypeName>Microsoft.AspNetCore.Mvc.ApplicationParts.NullApplicationPartFactory, Microsoft.AspNetCore.Mvc.Core</ProvideApplicationPartFactoryAttributeTypeName>
+    <GenerateStaticWebAssetsPackTargetsDependsOn>_GenerateIdentityUIPackItems;$(GenerateStaticWebAssetsPackTargetsDependsOn)</GenerateStaticWebAssetsPackTargetsDependsOn>
+    <DisableStaticWebAssetsBuildPropsFileGeneration>true</DisableStaticWebAssetsBuildPropsFileGeneration>
+    <StaticWebAssetsDisableProjectBuildPropsFileGeneration>true</StaticWebAssetsDisableProjectBuildPropsFileGeneration>
+    <StaticWebAssetsDisableProjectBuildMultiTargetingPropsFileGeneration>true</StaticWebAssetsDisableProjectBuildMultiTargetingPropsFileGeneration>
+    <StaticWebAssetsDisableProjectBuildTransitivePropsFileGeneration>true</StaticWebAssetsDisableProjectBuildTransitivePropsFileGeneration>
+    <StaticWebAssetsGetBuildAssetsTargets>GetIdentityUIAssets</StaticWebAssetsGetBuildAssetsTargets>
   </PropertyGroup>
 
   <ItemGroup>
-    <Content Remove="@(Content)" />
-    <Content Include="wwwroot\**\*" Pack="true" />
+    <None Include="build\*" Pack="true" PackagePath="build\" />
+    <None Include="buildMultiTargeting\*" Pack="true" PackagePath="buildMultiTargeting\" />
+    <None Include="buildTransitive\*" Pack="true" PackagePath="buildTransitive\" />
   </ItemGroup>
 
   <ItemGroup>
@@ -28,10 +38,83 @@
 
   <Target Name="SetupRazorInputs" BeforeTargets="ResolveRazorGenerateInputs">
     <ItemGroup>
-      <_RazorGenerate Include="Areas\Identity\Pages\V5\**\*.cshtml" />
+      <_RazorGenerate Include="Areas\Identity\Pages\**\*.cshtml" />
 
       <RazorGenerate Include="@(_RazorGenerate)" Link="Areas\Identity\Pages\%(RecursiveDir)%(Filename)%(Extension)" />
     </ItemGroup>
   </Target>
 
+  <Target Name="GetIdentityUIAssets" Returns="@(ReferenceAsset)">
+    <PropertyGroup>
+      <_ReferenceAssetContentRoot Condition="'$(IdentityDefaultUIFramework)' == 'Bootstrap5'">assets/V5</_ReferenceAssetContentRoot>
+      <_ReferenceAssetContentRoot Condition="'$(IdentityDefaultUIFramework)' == 'Bootstrap4'">assets/V4</_ReferenceAssetContentRoot>
+    </PropertyGroup>
+    <ItemGroup>
+      <ReferenceAssetCandidates Condition="'$(IdentityDefaultUIFramework)' == 'Bootstrap5'" Include="assets\V5\**" />
+      <ReferenceAssetCandidates Condition="'$(IdentityDefaultUIFramework)' == 'Bootstrap4'" Include="assets\V4\**" />
+      <ReferenceAssetCandidates>
+        <RelativePath>%(RecursiveDir)%(FileName)%(Extension)</RelativePath>
+        <ContentRoot>$([System.IO.Path]::GetFullPath($(_ReferenceAssetContentRoot)))</ContentRoot>
+      </ReferenceAssetCandidates>
+    </ItemGroup>
+    <DefineStaticWebAssets
+      Condition="'@(ReferenceAssetCandidates->Count())' != '0'"
+      CandidateAssets="@(ReferenceAssetCandidates)"
+      SourceId="$(PackageId)"
+      SourceType="Project"
+      AssetKind="All"
+      BasePath="$(StaticWebAssetBasePath)"
+    >
+      <Output TaskParameter="Assets" ItemName="ReferenceAsset" />
+    </DefineStaticWebAssets>
+    <ItemGroup>
+      <ReferenceAsset>
+        <ResultType>StaticWebAsset</ResultType>
+      </ReferenceAsset>
+    </ItemGroup>
+  </Target>
+
+  <Target Name="_GenerateIdentityUIPackItems">
+    <ItemGroup>
+      <V4AssetsCandidates Include="assets\V4\**" />
+      <V4AssetsCandidates>
+        <RelativePath>%(RecursiveDir)%(FileName)%(Extension)</RelativePath>
+      </V4AssetsCandidates>
+      <V5AssetsCandidates Include="assets\V5\**" />
+      <V5AssetsCandidates>
+        <RelativePath>%(RecursiveDir)%(FileName)%(Extension)</RelativePath>
+      </V5AssetsCandidates>
+    </ItemGroup>
+    <DefineStaticWebAssets Condition="'@(V4AssetsCandidates-&gt;Count())' != '0'" CandidateAssets="@(V4AssetsCandidates)" SourceId="$(PackageId)" SourceType="Discovered" AssetKind="All" ContentRoot="assets/V4" BasePath="$(StaticWebAssetBasePath)">
+      <Output TaskParameter="Assets" ItemName="V4Assets" />
+    </DefineStaticWebAssets>
+    <DefineStaticWebAssets Condition="'@(V5AssetsCandidates-&gt;Count())' != '0'" CandidateAssets="@(V5AssetsCandidates)" SourceId="$(PackageId)" SourceType="Discovered" AssetKind="All" ContentRoot="assets/V5" BasePath="$(StaticWebAssetBasePath)">
+      <Output TaskParameter="Assets" ItemName="V5Assets" />
+    </DefineStaticWebAssets>
+
+    <GenerateStaticWebAsssetsPropsFile StaticWebAssets="@(V4Assets)" PackagePathPrefix="staticwebassets/V4" TargetPropsFilePath="$(IntermediateOutputPath)IdentityUI.V4.targets" />
+    <GenerateStaticWebAsssetsPropsFile StaticWebAssets="@(V5Assets)" PackagePathPrefix="staticwebassets/V5" TargetPropsFilePath="$(IntermediateOutputPath)IdentityUI.V5.targets" />
+
+    <ComputeStaticWebAssetsTargetPaths Assets="@(V4Assets)" PathPrefix="staticwebassets/V4" AdjustPathsForPack="true">
+      <Output TaskParameter="AssetsWithTargetPath" ItemName="_PackV4Asset" />
+    </ComputeStaticWebAssetsTargetPaths>
+    <ComputeStaticWebAssetsTargetPaths Assets="@(V5Assets)" PathPrefix="staticwebassets/V5" AdjustPathsForPack="true">
+      <Output TaskParameter="AssetsWithTargetPath" ItemName="_PackV5Asset" />
+    </ComputeStaticWebAssetsTargetPaths>
+
+    <ItemGroup>
+      <TfmSpecificPackageFile Include="$(IntermediateOutputPath)IdentityUI.V4.targets">
+        <PackagePath>build\Microsoft.AspNetCore.StaticWebAssets.V4.targets</PackagePath>
+      </TfmSpecificPackageFile>
+      <TfmSpecificPackageFile Include="%(_PackV4Asset.Identity)">
+        <PackagePath>%(_PackV4Asset.TargetPath)</PackagePath>
+      </TfmSpecificPackageFile>
+      <TfmSpecificPackageFile Include="$(IntermediateOutputPath)IdentityUI.V5.targets">
+        <PackagePath>build\Microsoft.AspNetCore.StaticWebAssets.V5.targets</PackagePath>
+      </TfmSpecificPackageFile>
+      <TfmSpecificPackageFile Include="%(_PackV5Asset.Identity)">
+        <PackagePath>%(_PackV5Asset.TargetPath)</PackagePath>
+      </TfmSpecificPackageFile>
+    </ItemGroup>
+  </Target>
 </Project>