1 files changed, 133 insertions, 0 deletions
diff --git a/cps-service/src/main/java/org/onap/cps/utils/PrefixResolver.java b/cps-service/src/main/java/org/onap/cps/utils/PrefixResolver.java
new file mode 100644
index 0000000000..58b239c34c
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+++ b/cps-service/src/main/java/org/onap/cps/utils/PrefixResolver.java
@@ -0,0 +1,133 @@
+/*
+ *  ============LICENSE_START=======================================================
+ *  Copyright (C) 2022 Nordix Foundation.
+ *  ================================================================================
+ *  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 com.hazelcast.map.IMap;
+import java.io.Serializable;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.concurrent.TimeUnit;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import lombok.RequiredArgsConstructor;
+import org.onap.cps.api.CpsAdminService;
+import org.onap.cps.api.impl.YangTextSchemaSourceSetCache;
+import org.onap.cps.cache.AnchorDataCacheEntry;
+import org.onap.cps.spi.model.Anchor;
+import org.onap.cps.yang.YangTextSchemaSourceSet;
+import org.opendaylight.yangtools.yang.common.QNameModule;
+import org.opendaylight.yangtools.yang.model.api.DataNodeContainer;
+import org.opendaylight.yangtools.yang.model.api.DataSchemaNode;
+import org.opendaylight.yangtools.yang.model.api.Module;
+import org.opendaylight.yangtools.yang.model.api.SchemaContext;
+import org.springframework.stereotype.Component;
+
+@Component
+@RequiredArgsConstructor
+public class PrefixResolver {
+    private static final long ANCHOR_DATA_CACHE_TTL_SECS = TimeUnit.HOURS.toSeconds(1);
+
+    private static final String CACHE_ENTRY_PROPERTY_NAME = "prefixPerContainerName";
+
+    private final CpsAdminService cpsAdminService;
+
+    private final YangTextSchemaSourceSetCache yangTextSchemaSourceSetCache;
+
+    private final IMap<String, AnchorDataCacheEntry> anchorDataCache;
+
+    private static final Pattern TOP_LEVEL_NODE_NAME_FINDER
+        = Pattern.compile("\\/([\\w-]*)(\\[@(?!.*\\[).*?])?(\\/.*)?");  //NOSONAR
+
+    /**
+     * Get the module prefix for the given xpath for a dataspace and anchor name.
+     *
+     * @param dataspaceName the name of the dataspace
+     * @param anchorName the name of the anchor the xpath belongs to
+     * @param xpath the xpath to prefix a prefix for
+     * @return the prefix of the module the top level element of given xpath
+     */
+    public String getPrefix(final String dataspaceName, final String anchorName, final String xpath) {
+        final Anchor anchor = cpsAdminService.getAnchor(dataspaceName, anchorName);
+        return getPrefix(anchor, xpath);
+    }
+
+    /**
+     * Get the module prefix for the given xpath under the given anchor.
+     *
+     * @param anchor the anchor the xpath belong to
+     * @param xpath the xpath to prefix a prefix for
+     * @return the prefix of the module the top level element of given xpath
+     */
+    public String getPrefix(final Anchor anchor, final String xpath) {
+        final Map<String, String> prefixPerContainerName = getPrefixPerContainerName(anchor);
+        return getPrefixForTopContainer(prefixPerContainerName, xpath);
+    }
+
+    private Map<String, String> getPrefixPerContainerName(final Anchor anchor) {
+        if (anchorDataCache.containsKey(anchor.getName())) {
+            final AnchorDataCacheEntry anchorDataCacheEntry = anchorDataCache.get(anchor.getName());
+            if (anchorDataCacheEntry.hasProperty(CACHE_ENTRY_PROPERTY_NAME)) {
+                return (Map) anchorDataCacheEntry.getProperty(CACHE_ENTRY_PROPERTY_NAME);
+            }
+        }
+        return createAndCachePrefixPerContainerNameMap(anchor);
+    }
+
+    private String getPrefixForTopContainer(final Map<String, String> prefixPerContainerName,
+                                            final String xpath) {
+        final Matcher matcher = TOP_LEVEL_NODE_NAME_FINDER.matcher(xpath);
+        if (matcher.matches()) {
+            final String topLevelContainerName = matcher.group(1);
+            if (prefixPerContainerName.containsKey(topLevelContainerName)) {
+                return prefixPerContainerName.get(topLevelContainerName);
+            }
+        }
+        return "";
+    }
+
+    private Map<String, String> createAndCachePrefixPerContainerNameMap(final Anchor anchor) {
+        final YangTextSchemaSourceSet yangTextSchemaSourceSet =
+            yangTextSchemaSourceSetCache.get(anchor.getDataspaceName(), anchor.getSchemaSetName());
+        final SchemaContext schemaContext = yangTextSchemaSourceSet.getSchemaContext();
+        final Map<QNameModule, String> prefixPerQNameModule = new HashMap<>(schemaContext.getModules().size());
+        for (final Module module : schemaContext.getModules()) {
+            prefixPerQNameModule.put(module.getQNameModule(), module.getPrefix());
+        }
+        final HashMap<String, String> prefixPerContainerName = new HashMap<>();
+        for (final DataSchemaNode dataSchemaNode : schemaContext.getChildNodes()) {
+            if (dataSchemaNode instanceof DataNodeContainer) {
+                final String containerName = dataSchemaNode.getQName().getLocalName();
+                final String prefix = prefixPerQNameModule.get(dataSchemaNode.getQName().getModule());
+                prefixPerContainerName.put(containerName, prefix);
+            }
+        }
+        cachePrefixPerContainerNameMap(anchor.getName(), prefixPerContainerName);
+        return prefixPerContainerName;
+    }
+
+    private void cachePrefixPerContainerNameMap(final String anchorName,
+                                                final Serializable prefixPerContainerName) {
+        final AnchorDataCacheEntry anchorDataCacheEntry = new AnchorDataCacheEntry();
+        anchorDataCacheEntry.setProperty(CACHE_ENTRY_PROPERTY_NAME, prefixPerContainerName);
+        anchorDataCache.put(anchorName, anchorDataCacheEntry, ANCHOR_DATA_CACHE_TTL_SECS, TimeUnit.SECONDS);
+    }
+
+}