ETags on resources

An etag should be generated (by Champ) when creating
a resource (edge or vertex). The Champ microservice should return
this etag in the response header. Gizmo should also return the etag
in it's response header (Gizmo will receive the etag from Champ).

Issue-ID: AAI-1196

Change-Id: Ie16f871eccbceeccde037e73e0de0d96eeba18bd
Signed-off-by: Sotiropoulos, Ioannis (is948x) <Ioannis.Sotiropoulos@amdocs.com>

1 files changed, 92 insertions, 0 deletions

diff --git a/src/main/java/org/onap/crud/util/etag/EtagGenerator.java b/src/main/java/org/onap/crud/util/etag/EtagGenerator.java
new file mode 100644
index 0000000..b288b78
--- /dev/null
+++ 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);
+    }
+}
\ No newline at end of file