VOL-3818: Initial version of OLT Topology discovery app; used to find active links between OLT NNI and Leaf switch ports.

Change-Id: I058b603d028446e8176821d85a25af8963e28924
diff --git a/app/src/main/java/org/opencord/olttopology/impl/OltTopologyInformationCodec.java b/app/src/main/java/org/opencord/olttopology/impl/OltTopologyInformationCodec.java
new file mode 100644
index 0000000..bd45bed
--- /dev/null
+++ b/app/src/main/java/org/opencord/olttopology/impl/OltTopologyInformationCodec.java
@@ -0,0 +1,82 @@
+/*
+ * Copyright 2017-present Open Networking 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.
+ */
+package org.opencord.olttopology.impl;
+
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onlab.packet.LLDPTLV;
+import org.onosproject.codec.CodecContext;
+import org.onosproject.codec.JsonCodec;
+import org.opencord.olttopology.OltNeighborInfo;
+
+import java.util.Date;
+import java.util.List;
+
+/*
+Codec for JSON encoding of OLT topology information.
+ */
+public class OltTopologyInformationCodec extends JsonCodec<OltNeighborInfo> {
+    /**
+     * Encoder for the information in Json format.
+     *
+     * @param en      : The topology information to be encoded
+     * @param context : The context to which the Json data needs to be added
+     * @return Json Object Node
+     */
+    @Override
+    public ObjectNode encode(OltNeighborInfo en, CodecContext context) {
+        final ObjectNode result = context.mapper().createObjectNode()
+                .put("oltName", (en.oltName() == null) ? "" : en.oltName())
+                .put("oltPort", (en.oltPort().annotations().value("portName").isEmpty()) ? "" :
+                        en.oltPort().annotations().value("portName"))
+                .put("oltSerialNo", (en.oltSerialNo() == null) ? "" : en.oltSerialNo())
+                .put("neighborName", (en.neighborName() == null) ? "" : en.neighborName())
+                .put("neighborPort", (en.neighborPort() == null) ? "" : en.neighborPort())
+                .put("neighborManagementAddress", (en.mgmtAddr() == null) ? "" : en.mgmtAddr());
+
+        if (en.getOtherOptionalTlvs() != null) {
+            ArrayNode optionalTlvNodes = result.putArray("optionalTlvs");
+
+            List<LLDPTLV> optionalTlvsList = en.getOtherOptionalTlvs();
+            for (LLDPTLV tlv : optionalTlvsList) {
+                ObjectNode optionalTlvNode = context.mapper().createObjectNode();
+                optionalTlvNode.put("type", tlv.getType());
+                optionalTlvNode.put("value", "0x" + byteArrayInHex(tlv.getValue()));
+                optionalTlvNodes.add(optionalTlvNode);
+            }
+        }
+
+        Date currentTime = new Date();
+        long lastUpdatedValue = currentTime.getTime() - en.getLastUpdated().getTime();
+        long lastUpdatedSecondsValue = lastUpdatedValue / 1000;
+        result.put("last_updated", Long.toString(lastUpdatedSecondsValue));
+        return result;
+    }
+
+    /**
+     * Utility function to convert byte array to Hex String.
+     *
+     * @param bytes : The byte arrary to be converted
+     * @return Hex string representation of the byte array
+     */
+    private String byteArrayInHex(byte[] bytes) {
+        String s = "";
+        for (byte b : bytes) {
+            s += String.format("%02x", b);
+        }
+        return s;
+    }
+}