[ONOS-6170] Implement codec for MappingAction primitives

Change-Id: I8f92b05c814158285e97616bdaa8f24de7064833
diff --git a/apps/mappingmanagement/web/src/main/java/org/onosproject/mapping/web/codec/DecodeMappingActionCodecHelper.java b/apps/mappingmanagement/web/src/main/java/org/onosproject/mapping/web/codec/DecodeMappingActionCodecHelper.java
new file mode 100644
index 0000000..64c58fb
--- /dev/null
+++ b/apps/mappingmanagement/web/src/main/java/org/onosproject/mapping/web/codec/DecodeMappingActionCodecHelper.java
@@ -0,0 +1,97 @@
+/*
+ * Copyright 2017-present Open Networking Laboratory
+ *
+ * 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.onosproject.mapping.web.codec;
+
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onosproject.mapping.actions.MappingAction;
+import org.onosproject.mapping.actions.MappingActions;
+
+import static org.onlab.util.Tools.nullIsIllegal;
+
+/**
+ * Decode portion of the mapping action codec.
+ */
+public final class DecodeMappingActionCodecHelper {
+    private final ObjectNode json;
+
+    /**
+     * Creates a decode mapping action codec object.
+     *
+     * @param json    JSON object to decode
+     */
+    public DecodeMappingActionCodecHelper(ObjectNode json) {
+        this.json = json;
+    }
+
+    /**
+     * Decodes a no mapping action.
+     *
+     * @return mapping action object decoded from the JSON
+     */
+    private MappingAction decodeNoAction() {
+        return MappingActions.noAction();
+    }
+
+    /**
+     * Decodes a forward mapping action.
+     *
+     * @return mapping action object decoded from the JSON
+     */
+    private MappingAction decodeForwardAction() {
+        return MappingActions.forward();
+    }
+
+    /**
+     * Decodes a native forward mapping action.
+     *
+     * @return mapping action object decoded from the JSON
+     */
+    private MappingAction decodeNativeForwardAction() {
+        return MappingActions.nativeForward();
+    }
+
+    /**
+     * Decodes a drop mapping action.
+     *
+     * @return mapping action object decoded from the JSON
+     */
+    private MappingAction decodeDropAction() {
+        return MappingActions.drop();
+    }
+
+    /**
+     * Decodes the JSON into a mapping action object.
+     *
+     * @return MappingAction object
+     * @throws IllegalArgumentException if the JSON is invalid
+     */
+    public MappingAction decode() {
+       String type =  nullIsIllegal(json.get(MappingActionCodec.TYPE),
+               MappingActionCodec.TYPE + MappingActionCodec.ERROR_MESSAGE).asText();
+
+       if (type.equals(MappingAction.Type.DROP.name())) {
+           return decodeDropAction();
+       } else if (type.equals(MappingAction.Type.FORWARD.name())) {
+           return decodeForwardAction();
+       } else if (type.equals(MappingAction.Type.NATIVE_FORWARD.name())) {
+           return decodeNativeForwardAction();
+       } else if (type.equals(MappingAction.Type.NO_ACTION.name())) {
+           return decodeNoAction();
+       }
+       throw new IllegalArgumentException("MappingAction type "
+                + type + " is not supported");
+    }
+}