generate noop impl, tmp codegen integration

codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/GoStdlibTypes.java

@@ -30,6 +30,7 @@ public static final class Context {
 
     public static final class Fmt {
         public static final Symbol Errorf = SmithyGoDependency.FMT.valueSymbol("Errorf");
+        public static final Symbol Sprintf = SmithyGoDependency.FMT.valueSymbol("Sprintf");
     }
 
     public static final class Net {

codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/service/NoopServiceStruct.java

@@ -0,0 +1,91 @@
+/*
+ * Copyright 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.smithy.go.codegen.service;
+
+import static software.amazon.smithy.go.codegen.GoWriter.goTemplate;
+
+import software.amazon.smithy.codegen.core.SymbolProvider;
+import software.amazon.smithy.go.codegen.GoStdlibTypes;
+import software.amazon.smithy.go.codegen.GoWriter;
+import software.amazon.smithy.model.Model;
+import software.amazon.smithy.model.knowledge.TopDownIndex;
+import software.amazon.smithy.model.shapes.OperationShape;
+import software.amazon.smithy.model.shapes.ServiceShape;
+import software.amazon.smithy.utils.MapUtils;
+
+/**
+ * Generates a no-op implementation of the service that returns 501 Not Implemented for every operation.
+ */
+public final class NoopServiceStruct implements GoWriter.Writable {
+    public static final String NAME = "NoopService";
+
+    private final Model model;
+    private final ServiceShape service;
+    private final SymbolProvider symbolProvider;
+
+    public NoopServiceStruct(Model model, ServiceShape service, SymbolProvider symbolProvider) {
+        this.model = model;
+        this.service = service;
+        this.symbolProvider = symbolProvider;
+    }
+
+    @Override
+    public void accept(GoWriter writer) {
+        writer.write(generateStruct());
+    }
+
+    private GoWriter.Writable generateStruct() {
+        return goTemplate("""
+                type $struct:L struct{}
+
+                var _ $interface:L = (*$struct:L)(nil)
+
+                $operations:W
+                """,
+                MapUtils.of(
+                        "struct", NAME,
+                        "interface", ServiceInterface.NAME,
+                        "operations", generateOperations()
+                ));
+    }
+
+    private GoWriter.Writable generateOperations() {
+        return GoWriter.ChainWritable.of(
+                TopDownIndex.of(model).getContainedOperations(service).stream()
+                        .map(this::generateOperation)
+                        .toList()
+        ).compose();
+    }
+
+    private GoWriter.Writable generateOperation(OperationShape operation) {
+        final var operationSymbol = symbolProvider.toSymbol(operation);
+        return goTemplate("""
+                func (*$struct:L) $operation:T($context:T, $input:P) ($output:P, error) {
+                    return nil, &$notImplemented:L{$operationName:S}
+                }
+                """,
+                MapUtils.of(
+                        "struct", NAME,
+                        "operation", operationSymbol,
+                        "context", GoStdlibTypes.Context.Context,
+                        "input", symbolProvider.toSymbol(model.expectShape(operation.getInputShape())),
+                        "output", symbolProvider.toSymbol(model.expectShape(operation.getOutputShape())),
+                        "notImplemented", NotImplementedError.NAME,
+                        "operationName", operationSymbol.getName()
+                )
+        );
+    }
+}

codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/service/NotImplementedError.java

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.smithy.go.codegen.service;
+
+import static software.amazon.smithy.go.codegen.GoWriter.goTemplate;
+
+import software.amazon.smithy.go.codegen.GoStdlibTypes;
+import software.amazon.smithy.go.codegen.GoWriter;
+import software.amazon.smithy.utils.MapUtils;
+
+/**
+ * Generates the NotImplemented error sentinel to be returned when a service doesn't support a specific action.
+ */
+public final class NotImplementedError implements GoWriter.Writable {
+    public static final String NAME = "NotImplemented";
+
+    @Override
+    public void accept(GoWriter writer) {
+        writer.write(generateStruct());
+    }
+
+    private GoWriter.Writable generateStruct() {
+        return goTemplate("""
+                type $struct:L struct {
+                    Operation string
+                }
+
+                var _ error = (*$struct:L)(nil)
+
+                func (err *$struct:L) Error() string {
+                    return $sprintf:T("%s is not implemented", err.Operation)
+                }
+                """,
+                MapUtils.of(
+                        "struct", NAME,
+                        "sprintf", GoStdlibTypes.Fmt.Sprintf
+                ));
+    }
+}

codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/service/ProtocolGenerator.java

@@ -20,7 +20,11 @@
 public interface ProtocolGenerator {
     /**
      * Generate the operation routing logic for this protocol.
-     * @return The writable operation handler.
      */
     GoWriter.Writable generateHandler();
+
+    /**
+     * Generate the serializing logic for the builtin NotImplemented error.
+     */
+    GoWriter.Writable generateSerializeNotImplemented();
 }

codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/service/ServiceInterface.java

@@ -65,7 +65,7 @@ private GoWriter.Writable generateOperations() {
 
     private GoWriter.Writable generateOperation(OperationShape operation) {
         return goTemplate(
-                "$operation:T($context:L, $input:P) ($output:P, error)",
+                "$operation:T($context:T, $input:P) ($output:P, error)",
                 MapUtils.of(
                         "operation", symbolProvider.toSymbol(operation),
                         "context", GoStdlibTypes.Context.Context,

codegen/smithy-go-codegen/src/main/java/software/amazon/smithy/go/codegen/service/TmpCodegenIntegration.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file is distributed
+ * on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
+ * express or implied. See the License for the specific language governing
+ * permissions and limitations under the License.
+ */
+
+package software.amazon.smithy.go.codegen.service;
+
+import software.amazon.smithy.codegen.core.SymbolProvider;
+import software.amazon.smithy.go.codegen.GoDelegator;
+import software.amazon.smithy.go.codegen.GoSettings;
+import software.amazon.smithy.go.codegen.GoWriter;
+import software.amazon.smithy.go.codegen.integration.GoIntegration;
+import software.amazon.smithy.model.Model;
+
+// TODO: setup invocation of codegen via cli, remove this
+public class TmpCodegenIntegration implements GoIntegration {
+    @Override
+    public void writeAdditionalFiles(
+            GoSettings settings, Model model, SymbolProvider symbolProvider, GoDelegator goDelegator
+    ) {
+        final var service = settings.getService(model);
+        goDelegator.useFileWriter("feat_svcgen.go", settings.getModuleName(), GoWriter.ChainWritable.of(
+                new ServiceInterface(model, service, symbolProvider),
+                new NoopServiceStruct(model, service, symbolProvider),
+                new NotImplementedError()
+        ).compose());
+    }
+}

codegen/smithy-go-codegen/src/main/resources/META-INF/services/software.amazon.smithy.go.codegen.integration.GoIntegration

@@ -14,3 +14,6 @@ software.amazon.smithy.go.codegen.integration.auth.SigV4AuthScheme
 software.amazon.smithy.go.codegen.integration.auth.AnonymousAuthScheme
 
 software.amazon.smithy.go.codegen.requestcompression.RequestCompression
+
+# TODO: remove this when we can call into service codegen directly
+software.amazon.smithy.go.codegen.service.TmpCodegenIntegration