1 files changed, 250 insertions, 0 deletions
diff --git a/infra/translate-utils/src/main/java/io/fd/honeycomb/translate/util/read/registry/SubtreeReader.java b/infra/translate-utils/src/main/java/io/fd/honeycomb/translate/util/read/registry/SubtreeReader.java
new file mode 100644
index 000000000..720bd0b11
--- /dev/null
+++ b/infra/translate-utils/src/main/java/io/fd/honeycomb/translate/util/read/registry/SubtreeReader.java
@@ -0,0 +1,250 @@
+/*
+ * Copyright (c) 2016 Cisco and/or its affiliates.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at:
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License 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 io.fd.honeycomb.translate.util.read.registry;
+
+import static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.base.Optional;
+import com.google.common.base.Predicate;
+import com.google.common.collect.Iterables;
+import io.fd.honeycomb.translate.read.ListReader;
+import io.fd.honeycomb.translate.read.ReadContext;
+import io.fd.honeycomb.translate.read.ReadFailedException;
+import io.fd.honeycomb.translate.read.Reader;
+import io.fd.honeycomb.translate.util.RWUtils;
+import io.fd.honeycomb.translate.util.ReflectionUtils;
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import org.opendaylight.yangtools.concepts.Builder;
+import org.opendaylight.yangtools.yang.binding.DataObject;
+import org.opendaylight.yangtools.yang.binding.Identifiable;
+import org.opendaylight.yangtools.yang.binding.Identifier;
+import org.opendaylight.yangtools.yang.binding.InstanceIdentifier;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Simple Reader delegate for subtree Readers (Readers handling also children nodes) providing a list of all the
+ * children nodes being handled.
+ */
+class SubtreeReader<D extends DataObject, B extends Builder<D>> implements Reader<D, B> {
+
+    private static final Logger LOG = LoggerFactory.getLogger(SubtreeReader.class);
+
+    private final Reader<D, B> delegate;
+    private final Set<InstanceIdentifier<?>> handledChildTypes = new HashSet<>();
+
+    private SubtreeReader(final Reader<D, B> delegate, Set<InstanceIdentifier<?>> handledTypes) {
+        this.delegate = delegate;
+        for (InstanceIdentifier<?> handledType : handledTypes) {
+            // Iid has to start with Reader's handled root type
+            checkArgument(delegate.getManagedDataObjectType().getTargetType().equals(
+                    handledType.getPathArguments().iterator().next().getType()),
+                    "Handled node from subtree has to be identified by an instance identifier starting from: %s."
+                            + "Instance identifier was: %s", getManagedDataObjectType().getTargetType(), handledType);
+            checkArgument(Iterables.size(handledType.getPathArguments()) > 1,
+                    "Handled node from subtree identifier too short: %s", handledType);
+            handledChildTypes.add(InstanceIdentifier.create(Iterables.concat(
+                    getManagedDataObjectType().getPathArguments(), Iterables.skip(handledType.getPathArguments(), 1))));
+        }
+    }
+
+    /**
+     * Return set of types also handled by this Reader. All of the types are children of the type managed by this Reader
+     * excluding the type of this Reader.
+     */
+    Set<InstanceIdentifier<?>> getHandledChildTypes() {
+        return handledChildTypes;
+    }
+
+    @Override
+    @Nonnull
+    public Optional<? extends DataObject> read(
+            @Nonnull final InstanceIdentifier<? extends DataObject> id,
+            @Nonnull final ReadContext ctx) throws ReadFailedException {
+        final InstanceIdentifier<?> wildcarded = RWUtils.makeIidWildcarded(id);
+
+        // Reading entire subtree and filtering if is current reader responsible
+        if (getHandledChildTypes().contains(wildcarded)) {
+            LOG.debug("{}: Subtree node managed by this writer requested: {}. Reading current and filtering", this, id);
+            // If there's no dedicated reader, use read current
+            final InstanceIdentifier<D> currentId = RWUtils.cutId(id, getManagedDataObjectType());
+            final Optional<? extends DataObject> current = delegate.read(currentId, ctx);
+            // then perform post-reading filtering (return only requested sub-node)
+            final Optional<? extends DataObject> readSubtree = current.isPresent()
+                ? filterSubtree(current.get(), id, getManagedDataObjectType().getTargetType())
+                : current;
+
+            LOG.debug("{}: Subtree: {} read successfully. Result: {}", this, id, readSubtree);
+            return readSubtree;
+
+        // Fallback solution, try delegate, maybe it can read the ID
+        } else {
+            return delegate.read(id, ctx);
+        }
+    }
+
+    @Override
+    public void readCurrentAttributes(@Nonnull final InstanceIdentifier<D> id, @Nonnull final B builder,
+                                      @Nonnull final ReadContext ctx)
+            throws ReadFailedException {
+        delegate.readCurrentAttributes(id, builder, ctx);
+    }
+
+    @Nonnull
+    @Override
+    public B getBuilder(final InstanceIdentifier<D> id) {
+        return delegate.getBuilder(id);
+    }
+
+    @Override
+    public void merge(@Nonnull final Builder<? extends DataObject> parentBuilder, @Nonnull final D readValue) {
+        delegate.merge(parentBuilder, readValue);
+    }
+
+    @Nonnull
+    private static Optional<? extends DataObject> filterSubtree(@Nonnull final DataObject parent,
+                                                                @Nonnull final InstanceIdentifier<? extends DataObject> absolutPath,
+                                                                @Nonnull final Class<?> managedType) {
+        final InstanceIdentifier.PathArgument nextId =
+                RWUtils.getNextId(absolutPath, InstanceIdentifier.create(parent.getClass()));
+
+        final Optional<? extends DataObject> nextParent = findNextParent(parent, nextId, managedType);
+
+        if (Iterables.getLast(absolutPath.getPathArguments()).equals(nextId)) {
+            return nextParent; // we found the dataObject identified by absolutePath
+        } else if (nextParent.isPresent()) {
+            return filterSubtree(nextParent.get(), absolutPath, nextId.getType());
+        } else {
+            return nextParent; // we can't go further, return Optional.absent()
+        }
+    }
+
+    private static Optional<? extends DataObject> findNextParent(@Nonnull final DataObject parent,
+                                                                 @Nonnull final InstanceIdentifier.PathArgument nextId,
+                                                                 @Nonnull final Class<?> managedType) {
+        // TODO is there a better way than reflection ? e.g. convert into NN and filter out with a utility
+        Optional<Method> method = ReflectionUtils.findMethodReflex(managedType, "get",
+                Collections.emptyList(), nextId.getType());
+
+        if (method.isPresent()) {
+            return Optional.fromNullable(filterSingle(parent, nextId, method.get()));
+        } else {
+            // List child nodes
+            method = ReflectionUtils.findMethodReflex(managedType,
+                    "get" + nextId.getType().getSimpleName(), Collections.emptyList(), List.class);
+
+            if (method.isPresent()) {
+                return filterList(parent, nextId, method.get());
+            } else {
+                throw new IllegalStateException(
+                        "Unable to filter " + nextId + " from " + parent + " getters not found using reflexion");
+            }
+        }
+    }
+
+    @SuppressWarnings("unchecked")
+    private static Optional<? extends DataObject> filterList(final DataObject parent,
+                                                             final InstanceIdentifier.PathArgument nextId,
+                                                             final Method method) {
+        final List<? extends DataObject> invoke = (List<? extends DataObject>) invoke(method, nextId, parent);
+
+        checkArgument(nextId instanceof InstanceIdentifier.IdentifiableItem<?, ?>,
+                "Unable to perform wildcarded read for %s", nextId);
+        final Identifier key = ((InstanceIdentifier.IdentifiableItem) nextId).getKey();
+        // TODO replace with stream().filter().findFirst() when we switch to using java's Optional instead of Guava's
+        // because now we would have to do awkward Optional transformation since findFirstReturns guava's optional
+        return Iterables.tryFind(invoke, new Predicate<DataObject>() {
+
+            @Override
+            public boolean apply(@Nullable final DataObject input) {
+                final Optional<Method> keyGetter = ReflectionUtils.findMethodReflex(nextId.getType(), "get",
+                                Collections.emptyList(), key.getClass());
+                final Object actualKey;
+                actualKey = invoke(keyGetter.get(), nextId, input);
+                return key.equals(actualKey);
+            }
+        });
+    }
+
+    private static DataObject filterSingle(final DataObject parent,
+                                           final InstanceIdentifier.PathArgument nextId, final Method method) {
+        return nextId.getType().cast(invoke(method, nextId, parent));
+    }
+
+    private static Object invoke(final Method method,
+                                 final InstanceIdentifier.PathArgument nextId, final DataObject parent) {
+        try {
+            return method.invoke(parent);
+        } catch (IllegalAccessException | InvocationTargetException e) {
+            throw new IllegalArgumentException("Unable to get " + nextId + " from " + parent, e);
+        }
+    }
+
+    @Override
+    @Nonnull
+    public InstanceIdentifier<D> getManagedDataObjectType() {
+        return delegate.getManagedDataObjectType();
+    }
+
+    /**
+     * Wrap a Reader as a subtree Reader.
+     */
+    static <D extends DataObject, B extends Builder<D>> Reader<D, B> createForReader(@Nonnull final Set<InstanceIdentifier<?>> handledChildren,
+                                                                                     @Nonnull final Reader<D, B> reader) {
+        return (reader instanceof ListReader)
+                ? new SubtreeListReader<>((ListReader) reader, handledChildren)
+                : new SubtreeReader<>(reader, handledChildren);
+    }
+
+    private static final class SubtreeListReader<D extends DataObject & Identifiable<K>, B extends Builder<D>, K extends Identifier<D>>
+            extends SubtreeReader<D, B> implements ListReader<D, K, B> {
+
+        private final ListReader<D, K, B> delegate;
+
+        private SubtreeListReader(final ListReader<D, K, B> delegate,
+                                  final Set<InstanceIdentifier<?>> handledTypes) {
+            super(delegate, handledTypes);
+            this.delegate = delegate;
+        }
+
+        @Nonnull
+        @Override
+        public List<D> readList(@Nonnull final InstanceIdentifier<D> id, @Nonnull final ReadContext ctx)
+                throws ReadFailedException {
+            return delegate.readList(id, ctx);
+        }
+
+        @Override
+        public void merge(@Nonnull final Builder<? extends DataObject> builder, @Nonnull final List<D> readData) {
+            delegate.merge(builder, readData);
+        }
+
+        @Override
+        public List<K> getAllIds(@Nonnull final InstanceIdentifier<D> id,
+                                 @Nonnull final ReadContext ctx) throws ReadFailedException {
+            return delegate.getAllIds(id, ctx);
+        }
+    }
+
+}