[PM-6165] Add x-enum-varnames to improve swagger generation (#3767)

Improves code generation of enums for the server bindings in the sdk. Bindings will now use the appropiate variable name from the server.

Works by adding a filter which appends x-enum-varnames to enums with the name from c#.

src/Api/Utilities/ServiceCollectionExtensions.cs

@@ -5,6 +5,7 @@ using Bit.Core.IdentityServer;
 using Bit.Core.Settings;
 using Bit.Core.Utilities;
 using Bit.SharedWeb.Health;
+using Bit.SharedWeb.Swagger;
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.OpenApi.Models;
 
@@ -69,6 +70,8 @@ public static class ServiceCollectionExtensions
             config.DescribeAllParametersInCamelCase();
             // config.UseReferencedDefinitionsForEnums();
 
+            config.SchemaFilter<EnumSchemaFilter>();
+
             var apiFilePath = Path.Combine(AppContext.BaseDirectory, "Api.xml");
             config.IncludeXmlComments(apiFilePath, true);
             var coreFilePath = Path.Combine(AppContext.BaseDirectory, "Core.xml");

src/Identity/Identity.csproj

@@ -14,7 +14,6 @@
 
   <ItemGroup>
     <PackageReference Include="MessagePack" Version="2.5.140" />
-    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerGen" Version="6.5.0" />
   </ItemGroup>
 
 </Project>

src/Identity/Startup.cs

@@ -9,6 +9,7 @@ using Bit.Core.SecretsManager.Repositories.Noop;
 using Bit.Core.Settings;
 using Bit.Core.Utilities;
 using Bit.Identity.Utilities;
+using Bit.SharedWeb.Swagger;
 using Bit.SharedWeb.Utilities;
 using Duende.IdentityServer.Extensions;
 using Microsoft.Extensions.DependencyInjection.Extensions;
@@ -64,6 +65,7 @@ public class Startup
 
         services.AddSwaggerGen(c =>
         {
+            c.SchemaFilter<EnumSchemaFilter>();
             c.SwaggerDoc("v1", new OpenApiInfo { Title = "Bitwarden Identity", Version = "v1" });
         });
 

src/SharedWeb/SharedWeb.csproj

@@ -6,4 +6,8 @@
     <ProjectReference Include="..\Infrastructure.EntityFramework\Infrastructure.EntityFramework.csproj" />
   </ItemGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Swashbuckle.AspNetCore.SwaggerGen" Version="6.5.0" />
+  </ItemGroup>
+
 </Project>

src/SharedWeb/Swagger/EnumSchemaFilter.cs

@@ -0,0 +1,26 @@
+using Microsoft.OpenApi.Any;
+using Microsoft.OpenApi.Models;
+using Swashbuckle.AspNetCore.SwaggerGen;
+
+namespace Bit.SharedWeb.Swagger;
+
+/// <summary>
+/// Adds x-enum-varnames containing the name of enums. Useful for code generation.
+///</summary>
+/// <remarks>
+/// Ideally we would use `oneOf` instead but it's not currently handled well by our swagger generator.
+///
+/// Credits: https://github.com/domaindrivendev/Swashbuckle.WebApi/issues/1287#issuecomment-655164215
+/// </remarks>
+public class EnumSchemaFilter : ISchemaFilter
+{
+    public void Apply(OpenApiSchema schema, SchemaFilterContext context)
+    {
+        if (context.Type.IsEnum)
+        {
+            var array = new OpenApiArray();
+            array.AddRange(Enum.GetNames(context.Type).Select(n => new OpenApiString(n)));
+            schema.Extensions.Add("x-enum-varnames", array);
+        }
+    }
+}