Implement nextLink paging (#6353)

Fixes #6290

Author: JoshLove-msft

packages/http-client-csharp/emitter/test/Unit/operation-paging.test.ts

@@ -48,6 +48,37 @@ describe("Next link operations", () => {
     strictEqual(paging.NextLink?.ResponseSegments[0], "next");
   });
 
+  // skipped until https://github.com/Azure/typespec-azure/issues/2341 is fixed
+  it.skip("next link as response header", async () => {
+    const program = await typeSpecCompile(
+      `
+        @list
+        op link(): {
+          @pageItems
+          items: Foo[];
+
+          @header @nextLink
+          next?: url;
+        };
+        model Foo {
+          bar: string;
+          baz: int32;
+        };
+      `,
+      runner,
+    );
+    const context = createEmitterContext(program);
+    const sdkContext = await createCSharpSdkContext(context);
+    const root = createModel(sdkContext);
+    const paging = root.Clients[0].Operations[0].Paging;
+    ok(paging);
+    ok(paging.ItemPropertySegments);
+    strictEqual(paging.ItemPropertySegments[0], "items");
+    strictEqual(paging.NextLink?.ResponseLocation, ResponseLocation.Header);
+    strictEqual(paging.NextLink?.ResponseSegments.length, 1);
+    strictEqual(paging.NextLink?.ResponseSegments[0], "next");
+  });
+
   // skipped until https://github.com/Azure/typespec-azure/issues/2287 is fixed
   it.skip("next link with nested property", async () => {
     const program = await typeSpecCompile(

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/ClientModelExtensions.cs

@@ -58,5 +58,8 @@ public static ParameterProvider ClientOptions(CSharpType clientOptionsType)
         };
 
         public static readonly ParameterProvider ContentType = new("contentType", $"The contentType to use which has the multipart/form-data boundary.", typeof(string), wireInfo: new PropertyWireInformation(SerializationFormat.Default, true, false, false, false, "Content-Type"));
+
+        public static readonly ParameterProvider Endpoint =
+            new ParameterProvider("endpoint", FormattableStringHelpers.Empty, typeof(Uri));
     }
 }

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Primitives/ScmKnownParameters.cs

@@ -32,6 +32,12 @@ protected ClientResponseApi(Type type, ValueExpression original) : base(type, or
 
         public abstract CSharpType ClientResponseOfTType { get; }
 
+        public abstract CSharpType ClientCollectionResponseType { get; }
+        public abstract CSharpType ClientCollectionAsyncResponseType { get; }
+
+        public abstract CSharpType ClientCollectionResponseOfTType { get; }
+        public abstract CSharpType ClientCollectionAsyncResponseOfTType { get; }
+
         public abstract CSharpType ClientResponseExceptionType { get; }
     }
 }

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/Abstractions/ClientResponseApi.cs

@@ -21,6 +21,8 @@ protected HttpResponseApi(Type type, ValueExpression original) : base(type, orig
 
         public abstract ScopedApi<bool> IsError();
 
+        public abstract ScopedApi<bool> TryGetHeader(string name, out ScopedApi<string>? value);
+
         public abstract CSharpType HttpResponseType { get; }
 
         public abstract HttpResponseApi FromExpression(ValueExpression original);

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/Abstractions/HttpResponseApi.cs

@@ -12,5 +12,13 @@ public interface IClientResponseApi : IExpressionApi<ClientResponseApi>
         CSharpType ClientResponseType { get; }
 
         CSharpType ClientResponseOfTType { get; }
+
+        CSharpType ClientCollectionResponseType { get; }
+
+        CSharpType ClientCollectionAsyncResponseType { get; }
+
+        CSharpType ClientCollectionResponseOfTType { get; }
+
+        CSharpType ClientCollectionAsyncResponseOfTType { get; }
     }
 }

packages/http-client-csharp/generator/Microsoft.TypeSpec.Generator.ClientModel/src/Providers/Abstractions/IClientResponseApi.cs

@@ -22,6 +22,10 @@ public ClientResultProvider(ValueExpression clientResult) : base(typeof(ClientRe
         public override CSharpType ClientResponseType => typeof(ClientResult);
 
         public override CSharpType ClientResponseOfTType => typeof(ClientResult<>);
+        public override CSharpType ClientCollectionResponseType => typeof(CollectionResult);
+        public override CSharpType ClientCollectionAsyncResponseType => typeof(AsyncCollectionResult);
+        public override CSharpType ClientCollectionResponseOfTType => typeof(CollectionResult<>);
+        public override CSharpType ClientCollectionAsyncResponseOfTType => typeof(AsyncCollectionResult<>);
 
         public override CSharpType ClientResponseExceptionType => typeof(ClientResultException);