Fetching data node by xpath - rest and service layers

IssueID: CPS-71
Change-Id: I54801fc12a8aa700d85e774780c9990b7f19c747
Signed-off-by: Ruslan Kashapov <ruslan.kashapov@pantheon.tech>

4 files changed, 149 insertions, 0 deletions

diff --git a/cps-service/src/main/java/org/onap/cps/api/CpsDataService.java b/cps-service/src/main/java/org/onap/cps/api/CpsDataService.java
index a8f49655a4..7960d12ef0 100644
--- a/cps-service/src/main/java/org/onap/cps/api/CpsDataService.java
+++ b/cps-service/src/main/java/org/onap/cps/api/CpsDataService.java
@@ -1,6 +1,7 @@
 /*
  * ============LICENSE_START=======================================================
  *  Copyright (C) 2020 Nordix Foundation
+ *  Modifications Copyright (C) 2021 Pantheon.tech
  *  ================================================================================
  *  Licensed under the Apache License, Version 2.0 (the "License");
  *  you may not use this file except in compliance with the License.
@@ -20,12 +21,15 @@
 package org.onap.cps.api;
 
 import org.checkerframework.checker.nullness.qual.NonNull;
+import org.onap.cps.spi.FetchDescendantsOption;
 import org.onap.cps.spi.exceptions.DataValidationException;
+import org.onap.cps.spi.model.DataNode;
 
 /*
  * Datastore interface for handling CPS data.
  */
 public interface CpsDataService {
+
     /**
      * Persists data for the given anchor and dataspace.
      *
@@ -35,4 +39,18 @@ public interface CpsDataService {
      * @throws DataValidationException when json data is invalid
      */
     void saveData(@NonNull String dataspaceName, @NonNull String anchorName, @NonNull String jsonData);
+
+    /**
+     * Retrieves datanode by XPath for given dataspace and anchor.
+     *
+     * @param dataspaceName          dataspace name
+     * @param anchorName             anchor name
+     * @param xpath                  xpath
+     * @param fetchDescendantsOption defines the scope of data to fetch: either single node or all the descendant nodes
+     *                               (recursively) as well
+     * @return data node object
+     */
+    DataNode getDataNode(@NonNull String dataspaceName, @NonNull String anchorName, @NonNull String xpath,
+        @NonNull FetchDescendantsOption fetchDescendantsOption);
+
 }
diff --git a/cps-service/src/main/java/org/onap/cps/api/impl/CpsDataServiceImpl.java b/cps-service/src/main/java/org/onap/cps/api/impl/CpsDataServiceImpl.java
index 2a1e18b6d5..26990de754 100644
--- a/cps-service/src/main/java/org/onap/cps/api/impl/CpsDataServiceImpl.java
+++ b/cps-service/src/main/java/org/onap/cps/api/impl/CpsDataServiceImpl.java
@@ -2,6 +2,7 @@
  * ============LICENSE_START=======================================================
  *  Copyright (C) 2021 Nordix Foundation
  *  Modifications Copyright (C) 2020 Bell Canada. All rights reserved.
+ *  Modifications Copyright (C) 2021 Pantheon.tech
  *  ================================================================================
  *  Licensed under the Apache License, Version 2.0 (the "License");
  *  you may not use this file except in compliance with the License.
@@ -24,6 +25,7 @@ import org.onap.cps.api.CpsAdminService;
 import org.onap.cps.api.CpsDataService;
 import org.onap.cps.api.CpsModuleService;
 import org.onap.cps.spi.CpsDataPersistenceService;
+import org.onap.cps.spi.FetchDescendantsOption;
 import org.onap.cps.spi.model.Anchor;
 import org.onap.cps.spi.model.DataNode;
 import org.onap.cps.spi.model.DataNodeBuilder;
@@ -60,4 +62,10 @@ public class CpsDataServiceImpl implements CpsDataService {
     private SchemaContext getSchemaContext(final String dataspaceName, final String schemaSetName) {
         return yangTextSchemaSourceSetCache.get(dataspaceName, schemaSetName).getSchemaContext();
     }
+
+    @Override
+    public DataNode getDataNode(final String dataspaceName, final String anchorName, final String xpath,
+        final FetchDescendantsOption fetchDescendantsOption) {
+        return cpsDataPersistenceService.getDataNode(dataspaceName, anchorName, xpath, fetchDescendantsOption);
+    }
 }
\ No newline at end of file
diff --git a/cps-service/src/main/java/org/onap/cps/spi/FetchChildrenOption.java b/cps-service/src/main/java/org/onap/cps/spi/FetchChildrenOption.java
new file mode 100644
index 0000000000..97712c128c
--- /dev/null
+++ b/cps-service/src/main/java/org/onap/cps/spi/FetchChildrenOption.java
@@ -0,0 +1,25 @@
+/*
+ *  ============LICENSE_START=======================================================
+ *  Copyright (C) 2021 Pantheon.tech
+ *  ================================================================================
+ *  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.
+ *
+ *  SPDX-License-Identifier: Apache-2.0
+ *  ============LICENSE_END=========================================================
+ */
+
+package org.onap.cps.spi;
+
+public enum FetchChildrenOption {
+    OMIT_CHILDREN,
+    INCLUDE_ALL_CHILDREN
+}
diff --git a/cps-service/src/main/java/org/onap/cps/utils/DataMapUtils.java b/cps-service/src/main/java/org/onap/cps/utils/DataMapUtils.java
new file mode 100644
index 0000000000..3ec4764bd6
--- /dev/null
+++ b/cps-service/src/main/java/org/onap/cps/utils/DataMapUtils.java
@@ -0,0 +1,98 @@
+/*
+ *  ============LICENSE_START=======================================================
+ *  Copyright (C) 2021 Pantheon.tech
+ *  ================================================================================
+ *  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.
+ *
+ *  SPDX-License-Identifier: Apache-2.0
+ *  ============LICENSE_END=========================================================
+ */
+
+package org.onap.cps.utils;
+
+import static java.util.stream.Collectors.groupingBy;
+import static java.util.stream.Collectors.mapping;
+import static java.util.stream.Collectors.toUnmodifiableList;
+import static java.util.stream.Collectors.toUnmodifiableMap;
+
+import com.google.common.collect.ImmutableMap;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Map;
+import lombok.AccessLevel;
+import lombok.NoArgsConstructor;
+import org.onap.cps.spi.model.DataNode;
+
+/*
+ TODO: this utility class belongs to REST, however it expected to be used by both CPS Core and xNF Proxy;
+  placed in cps-service until shared module is done for REST services, then to be moved there
+  */
+@NoArgsConstructor(access = AccessLevel.PRIVATE)
+public class DataMapUtils {
+
+    /**
+     * Converts DataNode structure into a map for a JSON response.
+     *
+     * @param dataNode data node object
+     * @return a map representing same data
+     */
+
+    public static Map<String, Object> toDataMap(final DataNode dataNode) {
+        return ImmutableMap.<String, Object>builder()
+            .putAll(dataNode.getLeaves())
+            .putAll(listElementsAsMap(dataNode.getChildDataNodes()))
+            .putAll(containerElementsAsMap(dataNode.getChildDataNodes()))
+            .build();
+    }
+
+    private static Map<String, Object> listElementsAsMap(final Collection<DataNode> dataNodes) {
+        if (dataNodes.isEmpty()) {
+            return Collections.emptyMap();
+        }
+        return ImmutableMap.<String, Object>builder()
+            .putAll(
+                dataNodes.stream()
+                    .filter(dataNode -> isListNode(dataNode.getXpath()))
+                    .collect(groupingBy(
+                        dataNode -> getNodeIdentifier(dataNode.getXpath()),
+                        mapping(DataMapUtils::toDataMap, toUnmodifiableList())
+                    ))
+            ).build();
+    }
+
+    private static Map<String, Object> containerElementsAsMap(final Collection<DataNode> dataNodes) {
+        if (dataNodes.isEmpty()) {
+            return Collections.emptyMap();
+        }
+        return dataNodes.stream()
+            .filter(dataNode -> isContainerNode(dataNode.getXpath()))
+            .collect(
+                toUnmodifiableMap(
+                    dataNode -> getNodeIdentifier(dataNode.getXpath()),
+                    DataMapUtils::toDataMap
+                ));
+    }
+
+    private static String getNodeIdentifier(final String xpath) {
+        final int fromIndex = xpath.lastIndexOf("/") + 1;
+        final int toIndex = xpath.indexOf("[", fromIndex);
+        return toIndex > 0 ? xpath.substring(fromIndex, toIndex) : xpath.substring(fromIndex);
+    }
+
+    private static boolean isContainerNode(final String xpath) {
+        return !isListNode(xpath);
+    }
+
+    private static boolean isListNode(final String xpath) {
+        return xpath.endsWith("]");
+    }
+}