ETags on resources

[aai/gizmo.git] / src / main / java / org / onap / crud / util / etag / EtagGenerator.java

diff --git a/src/main/java/org/onap/crud/util/etag/EtagGenerator.java b/src/main/java/org/onap/crud/util/etag/EtagGenerator.java
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+++ b/src/main/java/org/onap/crud/util/etag/EtagGenerator.java
@@ -0,0 +1,92 @@
+/**
+ * ============LICENSE_START=======================================================
+ * org.onap.aai
+ * ================================================================================
+ * Copyright © 2017-2018 AT&T Intellectual Property. All rights reserved.
+ * Copyright © 2017-2018 Amdocs
+ * ================================================================================
+ * 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.
+ * ============LICENSE_END=========================================================
+ */
+package org.onap.crud.util.etag;
+
+import java.io.IOException;
+import java.security.NoSuchAlgorithmException;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+import java.util.Map;
+import java.util.Map.Entry;
+import org.onap.crud.event.GraphEventEdge;
+import org.onap.crud.event.GraphEventVertex;
+import org.onap.crud.util.HashGenerator;
+import com.google.gson.JsonElement;
+import com.google.gson.JsonObject;
+
+/**
+ * Computes hash for GraphEventVertex and GraphEventEdge
+ */
+public class EtagGenerator {
+
+    private static final String AAI_LAST_MOD_TS = "aai-last-mod-ts";
+    private final HashGenerator hashGenerator;
+
+    public EtagGenerator() throws NoSuchAlgorithmException {
+        this.hashGenerator = new HashGenerator();
+    }
+
+    /**
+     * Takes in the GraphEventVertex for which the hash is to be computed.
+     * @param GraphEventVertex
+     * @return hash for the GraphEventVertex
+     * @throws IOException
+     */
+    public String computeHashForVertex(GraphEventVertex graphEventVertex) throws IOException {
+        return hashGenerator.generateSHA256AsHex(graphEventVertex.getId(), graphEventVertex.getType(), convertPropertiesToMap(graphEventVertex.getProperties()));
+    }
+
+    /**
+     * Takes in the GraphEventEdge for which the hash is to be computed.
+     * @param GraphEventEdge
+     * @return hash for the GraphEventEdge
+     * @throws IOException
+     */
+    public String computeHashForEdge(GraphEventEdge graphEventEdge) throws IOException {
+        return hashGenerator.generateSHA256AsHex(graphEventEdge.getId(), graphEventEdge.getType(),
+                convertPropertiesToMap(graphEventEdge.getProperties()),
+                computeHashForVertex(graphEventEdge.getSource()), computeHashForVertex(graphEventEdge.getTarget()));
+    }
+
+    private Map<String, Object> convertPropertiesToMap(JsonElement properties) {
+        Map<String, Object> propertiesMap = new HashMap<>();
+        if (null != properties) {
+            JsonObject propsObject = properties.getAsJsonObject();
+            for (Entry<String, JsonElement> props : propsObject.entrySet()) {
+                String key = props.getKey();
+                String value = props.getValue().getAsString();
+                propertiesMap.put(key, value);
+            }
+        }
+        return filterAndSortProperties(propertiesMap);
+    }
+
+    private Map<String, Object> filterAndSortProperties(Map<String, Object> properties) {
+        return properties
+                .entrySet()
+                .stream()
+                .filter(x -> !x.getKey().equals(AAI_LAST_MOD_TS))
+                .sorted((x, y) -> x.getKey().compareTo(y.getKey()))
+                .collect(LinkedHashMap::new,
+                        (m, e) -> m.put(e.getKey(), e.getValue()),
+                        Map::putAll);
+    }
+}
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