Generate an input shape with additionalInput member for operations with Unit input

Fixes #863

Author: rhernandez35

model-bundle/model-bundle-api/src/main/java/software/amazon/smithy/modelbundle/api/ModelBundles.java

@@ -25,7 +25,7 @@ private ModelBundles() {}
     private static final PluginProviders PLUGIN_PROVIDERS = PluginProviders.builder().build();
 
     public static Service getService(SmithyBundle smithyBundle) {
-        var model = getModel(smithyBundle);
+        var model = prepareModelForBundling(smithyBundle);
         var plugin = PLUGIN_PROVIDERS.getPlugin(smithyBundle.getConfigType(), smithyBundle.getConfig());
         return ProxyService.builder()
                 .model(model)
@@ -35,7 +35,8 @@ public static Service getService(SmithyBundle smithyBundle) {
                 .build();
     }
 
-    private static Model getModel(SmithyBundle bundle) {
+    // visible for testing
+    static Model prepareModelForBundling(SmithyBundle bundle) {
         // TODO: model the type in the returned bundle
         var suffix = bundle.getModel().startsWith("$version") ? "smithy" : "json";
         var modelAssemble = new ModelAssembler().putProperty(ModelAssembler.ALLOW_UNKNOWN_TRAITS, true)
@@ -49,7 +50,6 @@ private static Model getModel(SmithyBundle bundle) {
             model = modelAssemble.assemble().unwrap();
             additionalInputShape =
                     model.expectShape(ShapeId.from(additionalInput.getIdentifier())).asStructureShape().get();
-
         } else {
             model = modelAssemble.assemble().unwrap();
         }
@@ -116,16 +116,24 @@ private static void addProxyOperationWithAdditionalInput(
         var input = op.getInput();
         StructureShape finalInput;
         if (op.getInput().isEmpty()) {
-            finalInput = additionalInput;
+            var containerId = syntheticContainerForInput(additionalInput);
+            var container = builder.getCurrentShapes().get(containerId);
+            if (container == null) {
+                finalInput = createSyntheticInput(containerId, additionalInput);
+                builder.addShape(finalInput);
+            } else {
+                finalInput = (StructureShape) container;
+            }
         } else {
             var inputBuilder = model.expectShape(input.get(), StructureShape.class).toBuilder();
             inputBuilder.addMember(MemberShape.builder()
                     .id(ShapeId.from(inputBuilder.getId().toString() + "$additionalInput"))
                     .target(additionalInput.getId())
                     .build());
             finalInput = inputBuilder.id(ShapeId.from(inputBuilder.getId().toString()) + "Proxy").build();
+            builder.addShape(finalInput);
         }
-        builder.addShape(finalInput);
+
         var newOperation = op.toBuilder()
                 .id(ShapeId.from(op.getId().toString() + "Proxy"))
                 .input(finalInput)
@@ -135,4 +143,18 @@ private static void addProxyOperationWithAdditionalInput(
         builder.addShape(newOperation);
         serviceBuilder.addOperation(newOperation).build();
     }
+
+    private static ShapeId syntheticContainerForInput(StructureShape additionalInput) {
+        return ShapeId.from("smithy.mcp#AdditionalInputFor" + additionalInput.getId().getName());
+    }
+
+    private static StructureShape createSyntheticInput(ShapeId containerId, StructureShape additionalInput) {
+        return StructureShape.builder()
+                .id(containerId)
+                .addMember(MemberShape.builder()
+                        .id(containerId.toString() + "$additionalInput")
+                        .target(additionalInput.getId())
+                        .build())
+                .build();
+    }
 }

model-bundle/model-bundle-api/src/test/java/software/amazon/smithy/modelbundle/api/ModelBundlesTest.java

@@ -0,0 +1,83 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package software.amazon.smithy.modelbundle.api;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
+import software.amazon.smithy.java.core.serde.document.Document;
+import software.amazon.smithy.model.shapes.ShapeId;
+import software.amazon.smithy.model.shapes.StructureShape;
+import software.amazon.smithy.modelbundle.api.model.AdditionalInput;
+import software.amazon.smithy.modelbundle.api.model.SmithyBundle;
+
+class ModelBundlesTest {
+
+    @Test
+    void testOperationWithNoInputGetsSyntheticAdditionalInputShape() {
+        String smithyModel = """
+                $version: "2.0"
+
+                namespace com.example
+
+                service TestService {
+                    version: "1.0"
+                    operations: [TestOperation]
+                }
+
+                operation TestOperation {
+                    output: TestOutput
+                }
+
+                structure TestOutput {
+                    result: String
+                }
+                """;
+
+        String additionalInputModel = """
+                $version: "2.0"
+
+                namespace com.example.additional
+
+                structure AdditionalInputData {
+                    context: String
+                }
+                """;
+
+        AdditionalInput additionalInput = AdditionalInput.builder()
+                .identifier("com.example.additional#AdditionalInputData")
+                .model(additionalInputModel)
+                .build();
+
+        SmithyBundle bundle = SmithyBundle.builder()
+                .model(smithyModel)
+                .serviceName("com.example#TestService")
+                .additionalInput(additionalInput)
+                .configType("configType")
+                .config(Document.ofObject(null))
+                .build();
+
+        var model = ModelBundles.prepareModelForBundling(bundle);
+
+        ShapeId syntheticInputId = ShapeId.from("smithy.mcp#AdditionalInputForAdditionalInputData");
+        assertTrue(model.getShape(syntheticInputId).isPresent());
+        var syntheticInputShape = model.expectShape(syntheticInputId, StructureShape.class);
+        assertEquals(1, syntheticInputShape.members().size());
+        assertTrue(syntheticInputShape.getMember("additionalInput").isPresent());
+        var additionalInputMember = syntheticInputShape.getMember("additionalInput").get();
+        assertEquals(ShapeId.from("com.example.additional#AdditionalInputData"),
+                additionalInputMember.getTarget());
+
+        ShapeId proxyOperationId = ShapeId.from("com.example#TestOperationProxy");
+        assertTrue(model.getShape(proxyOperationId).isPresent());
+
+        var proxyOperation = model.expectShape(proxyOperationId).asOperationShape().get();
+        assertTrue(proxyOperation.getInput().isPresent());
+
+        assertEquals(syntheticInputId, proxyOperation.getInputShape());
+    }
+}