From e4db75cf107878f391978da69ff2f8328972a36a Mon Sep 17 00:00:00 2001
From: SonicGD <sonicgd@gmail.com>
Date: Tue, 26 Mar 2024 11:12:39 +0500
Subject: [PATCH] feat: add metadata provider

---
 .../GrpcClientModuleOptions.cs                | 28 +++++++++++++++++++
 .../IGrpcMetadataProvider.cs                  |  6 ++++
 2 files changed, 34 insertions(+)
 create mode 100644 src/Sitko.Core.Grpc.Client/IGrpcMetadataProvider.cs

diff --git a/src/Sitko.Core.Grpc.Client/GrpcClientModuleOptions.cs b/src/Sitko.Core.Grpc.Client/GrpcClientModuleOptions.cs
index a40b9589b..5e8bc7025 100644
--- a/src/Sitko.Core.Grpc.Client/GrpcClientModuleOptions.cs
+++ b/src/Sitko.Core.Grpc.Client/GrpcClientModuleOptions.cs
@@ -29,6 +29,34 @@ internal void ConfigureClient(IServiceCollection services, IHttpClientBuilder bu
         configureAuthAction?.Invoke(services, builder);
     }
 
+    public GrpcClientModuleOptions<TClient> AddMetadataProvider<TMetadataProvider>()
+        where TMetadataProvider : class, IGrpcMetadataProvider
+    {
+        configureAuthAction = (services, builder) =>
+        {
+            services.TryAddTransient<IGrpcMetadataProvider, TMetadataProvider>();
+            builder.AddCallCredentials(async (_, metadata, serviceProvider) =>
+            {
+                var provider = serviceProvider.GetRequiredService<TMetadataProvider>();
+                var newMetadata = await provider.GetMetadataAsync();
+                if (newMetadata.Count != 0)
+                {
+                    foreach (var (key, value) in newMetadata)
+                    {
+                        var oldEntries = metadata.GetAll(key);
+                        foreach (var entry in oldEntries)
+                        {
+                            metadata.Remove(entry);
+                        }
+
+                        metadata.Add(key, value);
+                    }
+                }
+            });
+        };
+        return this;
+    }
+
     public GrpcClientModuleOptions<TClient> AddTokenAuth<TTokenProvider>()
         where TTokenProvider : class, IGrpcTokenProvider
     {
diff --git a/src/Sitko.Core.Grpc.Client/IGrpcMetadataProvider.cs b/src/Sitko.Core.Grpc.Client/IGrpcMetadataProvider.cs
new file mode 100644
index 000000000..eb8db29e3
--- /dev/null
+++ b/src/Sitko.Core.Grpc.Client/IGrpcMetadataProvider.cs
@@ -0,0 +1,6 @@
+namespace Sitko.Core.Grpc.Client;
+
+public interface IGrpcMetadataProvider
+{
+    Task<Dictionary<string, string>> GetMetadataAsync();
+}