Add flattenNamespaces transformer

docs/source/1.0/guides/building-models/build-config.rst

@@ -862,6 +862,64 @@ key is not in the provided ``keys`` list.
             }
         }
 
+.. _flattenNamespaces:
+
+flattenNamespaces
+-----------------
+
+Flattens namespaces of any shapes connected to a service into a target
+namespace. Shapes not connected to a service will not be flattened.
+
+.. list-table::
+    :header-rows: 1
+    :widths: 10 20 70
+
+    * - Property
+      - Type
+      - Description
+    * - namespace
+      - ``string``
+      - **REQUIRED** The target namespace.
+    * - service
+      - ``shapeId``
+      - **REQUIRED** The service to be flattened.
+    * - includeTagged
+      - ``[string]``
+      - The set of tags that, if found on a shape not connected to the service,
+        forces the shape to have its namespace flattened into the target
+        namespace. When additional shapes are included, the shapes are replaced
+        entirely, along with any references to the shapes which may exist within
+        separate :ref:`service closure <service-closure>`.
+
+
+The following example will flatten the namespaces of the shapes connected to
+the ``ns.bar#MyService`` service into the target namespace, ``ns.foo``. Shapes
+tagged with ``baz`` or ``qux`` will also be flattened into the ``ns.foo``
+namespace, so long as they don't conflict with a shape within the :ref:`service closure <service-closure>`.
+
+.. tabs::
+
+    .. code-tab:: json
+
+        {
+            "version": "1.0",
+            "projections": {
+                "exampleProjection": {
+                    "transforms": [
+                        {
+                            "name": "flattenNamespaces",
+                            "args": {
+                                "namespace": "ns.foo",
+                                "service": "ns.bar#MyService",
+                                "includeTagged": ["baz", "qux"]
+                            }
+                        }
+                    ]
+                }
+            }
+        }
+
+
 .. _removeTraitDefinitions-transform:
 
 removeTraitDefinitions

smithy-build/src/main/java/software/amazon/smithy/build/transforms/FlattenNamespaces.java

@@ -0,0 +1,181 @@
+/*
+ * Copyright 2020 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.build.transforms;
+
+import java.util.Collections;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Collectors;
+import software.amazon.smithy.build.SmithyBuildException;
+import software.amazon.smithy.build.TransformContext;
+import software.amazon.smithy.model.Model;
+import software.amazon.smithy.model.knowledge.NeighborProviderIndex;
+import software.amazon.smithy.model.loader.Prelude;
+import software.amazon.smithy.model.neighbor.Walker;
+import software.amazon.smithy.model.shapes.ServiceShape;
+import software.amazon.smithy.model.shapes.Shape;
+import software.amazon.smithy.model.shapes.ShapeId;
+import software.amazon.smithy.model.transform.ModelTransformer;
+import software.amazon.smithy.utils.FunctionalUtils;
+import software.amazon.smithy.utils.Pair;
+
+/**
+ * {@code flattenNamespaces} updates a model by flattening the namespaces of
+ * shapes connected to a service into a single, target namespace. When
+ * configuring the transformer, a service and target namespace must be
+ * specified. Optionally, tags can be specified for including any additional
+ * shapes that should be flattened into the the target namespace. Any shape
+ * from outside the service closure that is included via the application of a
+ * tag will not be included if it conflicts with a shape in the service closure.
+ */
+public final class FlattenNamespaces extends ConfigurableProjectionTransformer<FlattenNamespaces.Config> {
+
+    /**
+     * {@code removeTraitShapes} configuration settings.
+     */
+    public static final class Config {
+
+        private String namespace;
+        private ShapeId service;
+        private Set<String> tags = Collections.emptySet();
+
+        /**
+         * Sets the target namespace that existing namespaces will be flattened
+         * into.
+         *
+         * @param namespace The target namespace to use in the model.
+         */
+        public void setNamespace(String namespace) {
+            this.namespace = namespace;
+        }
+
+        /**
+         * Gets the target namespace that existing namespaces will be flattened
+         * into.
+         *
+         * @return the target namespace to be used in the model.
+         */
+        public String getNamespace() {
+            return namespace;
+        }
+
+        /**
+         * Sets the service ShapeId that will be flattened into the target
+         * namespace.
+         *
+         * @param service The ID of the service.
+         */
+        public void setService(ShapeId service) {
+            this.service = service;
+        }
+
+        /**
+         * @return Gets the service shape ID of the service that will have
+         * its shape namespaces updated.
+         */
+        public ShapeId getService() {
+            return service;
+        }
+
+        /**
+         * Sets the set of tags that are retained in the model.
+         *
+         * @param tags The tags to retain in the model.
+         */
+        public void setIncludeTagged(Set<String> tags) {
+            this.tags = tags;
+        }
+
+        /**
+         * Gets the set of tags that are retained in the model.
+         *
+         * @return Returns the tags to retain.
+         */
+        public Set<String> getIncludeTagged() {
+            return tags;
+        }
+    }
+
+    @Override
+    public Class<Config> getConfigType() {
+        return Config.class;
+    }
+
+    @Override
+    protected Model transformWithConfig(TransformContext context, Config config) {
+        if (config.getService() == null || config.getNamespace() == null) {
+            throw new SmithyBuildException(
+                    "'namespace' and 'service'properties must be set on flattenNamespace transformer.");
+        }
+        Model model = context.getModel();
+        Map<ShapeId, ShapeId> shapesToRename = getRenamedShapes(config, model);
+        return ModelTransformer.create().renameShapes(model, shapesToRename);
+    }
+
+    @Override
+    public String getName() {
+        return "flattenNamespaces";
+    }
+
+    private Map<ShapeId, ShapeId> getRenamedShapes(Config config, Model model) {
+        if (!model.getShape(config.getService()).isPresent()) {
+            throw new SmithyBuildException("Service not found in model when performing flattenNamespaces transform.");
+        }
+
+        Map<ShapeId, ShapeId> shapesToRename = getRenamedShapesConnectedToService(config, model);
+        Set<ShapeId> taggedShapesToInclude = getTaggedShapesToInclude(config.getIncludeTagged(), model);
+
+        for (ShapeId id : taggedShapesToInclude) {
+            ShapeId updatedShapeId = updateNamespace(id, config.getNamespace());
+            // If new shape ID already exists in map of shapes to rename, skip
+            // including the additional shape to avoid a conflict.
+            if (!shapesToRename.containsValue(updatedShapeId)) {
+                shapesToRename.put(id, updatedShapeId);
+            }
+        }
+
+        return shapesToRename;
+    }
+
+    private ShapeId updateNamespace(ShapeId shapeId, String namespace) {
+        if (shapeId.getMember().isPresent()) {
+            return ShapeId.fromParts(namespace, shapeId.getName(), shapeId.getMember().get());
+        }
+        return ShapeId.fromParts(namespace, shapeId.getName());
+    }
+
+    private Map<ShapeId, ShapeId> getRenamedShapesConnectedToService(Config config, Model model) {
+        Walker shapeWalker = new Walker(model.getKnowledge(NeighborProviderIndex.class, NeighborProviderIndex::new)
+                .getProvider());
+        ServiceShape service = model.expectShape(config.getService(), ServiceShape.class);
+        return shapeWalker.walkShapes(service).stream()
+                .filter(FunctionalUtils.not(Prelude::isPreludeShape))
+                .map(shape -> Pair.of(shape.getId(), updateNamespace(shape.getId(), config.getNamespace())))
+                .collect(Collectors.toMap(Pair::getLeft, Pair::getRight));
+    }
+
+    private Set<ShapeId> getTaggedShapesToInclude(Set<String> tags, Model model) {
+        return model.shapes()
+                .filter(FunctionalUtils.not(Prelude::isPreludeShape))
+                .filter(shape -> isTagged(tags, shape))
+                .map(Shape::getId)
+                .collect(Collectors.toSet());
+    }
+
+    private boolean isTagged(Set<String> tags, Shape shape) {
+        return shape.getTags().stream().anyMatch(tags::contains);
+    }
+}