+/*
+ * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.controller.md.sal.dom.store.impl.tree;
+
+import static com.google.common.base.Preconditions.checkState;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+import org.opendaylight.yangtools.concepts.Identifiable;
+import org.opendaylight.yangtools.yang.data.api.InstanceIdentifier.PathArgument;
+import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
+
+import com.google.common.base.Optional;
+
+/**
+ * Node Modification Node and Tree
+ *
+ * Tree which structurally resembles data tree and captures client modifications
+ * to the data store tree.
+ *
+ * This tree is lazily created and populated via {@link #modifyChild(PathArgument)}
+ * and {@link StoreMetadataNode} which represents original state {@link #getOriginal()}.
+ *
+ */
+public class NodeModification implements StoreTreeNode<NodeModification>, Identifiable<PathArgument> {
+
+ private final PathArgument identifier;
+ private ModificationType modificationType = ModificationType.UNMODIFIED;
+
+
+ private final Optional<StoreMetadataNode> original;
+
+ private NormalizedNode<?, ?> value;
+
+ private StoreMetadataNode snapshotCache;
+
+ private final Map<PathArgument, NodeModification> childModification;
+
+ private boolean sealed = false;
+
+ protected NodeModification(final PathArgument identifier, final Optional<StoreMetadataNode> original) {
+ this.identifier = identifier;
+ this.original = original;
+ childModification = new LinkedHashMap<>();
+ }
+
+ /**
+ *
+ *
+ * @return
+ */
+ public NormalizedNode<?, ?> getWritenValue() {
+ return value;
+ }
+
+ @Override
+ public PathArgument getIdentifier() {
+ return identifier;
+ }
+
+ /**
+ *
+ * Returns original store metadata
+ * @return original store metadata
+ */
+ public final Optional<StoreMetadataNode> getOriginal() {
+ return original;
+ }
+
+ /**
+ * Returns modification type
+ *
+ * @return modification type
+ */
+ public final ModificationType getModificationType() {
+ return modificationType;
+ }
+
+ /**
+ *
+ * Returns child modification if child was modified
+ *
+ * @return Child modification if direct child or it's subtree
+ * was modified.
+ *
+ */
+ @Override
+ public Optional<NodeModification> getChild(final PathArgument child) {
+ return Optional.<NodeModification> fromNullable(childModification.get(child));
+ }
+
+ /**
+ *
+ * Returns child modification if child was modified, creates {@link NodeModification}
+ * for child otherwise.
+ *
+ * If this node's {@link ModificationType} is {@link ModificationType#UNMODIFIED}
+ * changes modification type to {@link ModificationType#SUBTREE_MODIFIED}
+ *
+ * @param child
+ * @return {@link NodeModification} for specified child, with {@link #getOriginal()}
+ * containing child metadata if child was present in original data.
+ */
+ public synchronized NodeModification modifyChild(final PathArgument child) {
+ checkSealed();
+ if(modificationType == ModificationType.UNMODIFIED) {
+ updateModificationType(ModificationType.SUBTREE_MODIFIED);
+ }
+ final NodeModification potential = childModification.get(child);
+ if (potential != null) {
+ return potential;
+ }
+ Optional<StoreMetadataNode> currentMetadata = Optional.absent();
+ if(original.isPresent()) {
+ currentMetadata = original.get().getChild(child);
+ }
+ NodeModification newlyCreated = new NodeModification(child,currentMetadata);
+ childModification.put(child, newlyCreated);
+ return newlyCreated;
+ }
+
+ /**
+ *
+ * Returns all recorded direct child modification
+ *
+ * @return all recorded direct child modifications
+ */
+ public Iterable<NodeModification> getModifications() {
+ return childModification.values();
+ }
+
+
+ /**
+ *
+ * Records a delete for associated node.
+ *
+ */
+ public synchronized void delete() {
+ checkSealed();
+ updateModificationType(ModificationType.DELETE);
+ childModification.clear();
+ this.value = null;
+ }
+
+ /**
+ *
+ * Records a write for associated node.
+ *
+ * @param value
+ */
+ public synchronized void write(final NormalizedNode<?, ?> value) {
+ checkSealed();
+ updateModificationType(ModificationType.WRITE);
+ childModification.clear();
+ this.value = value;
+ }
+
+ private void checkSealed() {
+ checkState(!sealed, "Node Modification is sealed. No further changes allowed.");
+ }
+
+ public synchronized void seal() {
+ sealed = true;
+ for(NodeModification child : childModification.values()) {
+ child.seal();
+ }
+ }
+
+ private void clearSnapshot() {
+ snapshotCache = null;
+ }
+
+ public boolean hasAdditionalModifications() {
+ return !childModification.isEmpty();
+ }
+
+ public void updateModificationType(final ModificationType type) {
+ modificationType = type;
+ clearSnapshot();
+ }
+
+ @Override
+ public String toString() {
+ return "NodeModification [identifier=" + identifier + ", modificationType="
+ + modificationType + ", value=" + value + ", childModification=" + childModification + "]";
+ }
+
+ public static NodeModification createUnmodified(final StoreMetadataNode metadataTree) {
+ return new NodeModification(metadataTree.getIdentifier(), Optional.of(metadataTree));
+ }
+
+}