Add REST API for query/update/delete/enable/disable telemetry config

1. Add unit test for newly added REST APIs
2. Add codec and unit tests for TelemetryConfig
3. Split web package out from app package due to dep conflict

Change-Id: I85f52b2a7d059622e98832843bc9613cb8befa98
diff --git a/apps/openstacktelemetry/web/src/main/java/org/onosproject/openstacktelemetry/codec/rest/TelemetryConfigJsonCodec.java b/apps/openstacktelemetry/web/src/main/java/org/onosproject/openstacktelemetry/codec/rest/TelemetryConfigJsonCodec.java
new file mode 100644
index 0000000..8c0a6e3
--- /dev/null
+++ b/apps/openstacktelemetry/web/src/main/java/org/onosproject/openstacktelemetry/codec/rest/TelemetryConfigJsonCodec.java
@@ -0,0 +1,131 @@
+/*
+ * Copyright 2018-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.onosproject.openstacktelemetry.codec.rest;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import com.google.common.collect.ImmutableList;
+import com.google.common.collect.Maps;
+import org.onosproject.codec.CodecContext;
+import org.onosproject.codec.JsonCodec;
+import org.onosproject.openstacktelemetry.api.DefaultTelemetryConfig;
+import org.onosproject.openstacktelemetry.api.config.TelemetryConfig;
+
+import java.util.Map;
+import java.util.stream.IntStream;
+
+import static com.google.common.base.Preconditions.checkNotNull;
+import static org.onlab.util.Tools.nullIsIllegal;
+
+/**
+ * Openstack telemetry config codec used for serializing and de-serializing JSON string.
+ */
+public final class TelemetryConfigJsonCodec extends JsonCodec<TelemetryConfig> {
+
+    private static final String NAME = "name";
+    private static final String TYPE = "type";
+    private static final String MANUFACTURER = "manufacturer";
+    private static final String SW_VERSION = "swVersion";
+    private static final String ENABLED = "enabled";
+    private static final String PROPS = "props";
+    private static final String KEY = "key";
+    private static final String VALUE = "value";
+
+    private static final String MISSING_MESSAGE = " is required in TelemetryConfig";
+
+    @Override
+    public ObjectNode encode(TelemetryConfig config, CodecContext context) {
+        checkNotNull(config, "TelemetryConfig cannot be null");
+
+        ObjectNode node = context.mapper().createObjectNode()
+                .put(NAME, config.name())
+                .put(TYPE, config.type().name())
+                .put(MANUFACTURER, config.manufacturer())
+                .put(SW_VERSION, config.swVersion())
+                .put(ENABLED, config.enabled());
+
+        Map<String, String> props = config.properties();
+        ArrayNode propsJson = context.mapper().createArrayNode();
+        props.forEach((k, v) -> {
+            ObjectNode propNode = context.mapper().createObjectNode();
+            propNode.put(KEY, k);
+            propNode.put(VALUE, v);
+            propsJson.add(propNode);
+        });
+        node.set(PROPS, propsJson);
+        return node;
+    }
+
+    @Override
+    public TelemetryConfig decode(ObjectNode json, CodecContext context) {
+        if (json == null || !json.isObject()) {
+            return null;
+        }
+
+        // parse name
+        String name = nullIsIllegal(json.get(NAME),
+                NAME + MISSING_MESSAGE).asText();
+
+        // parse type
+        String type = nullIsIllegal(json.get(TYPE),
+                TYPE + MISSING_MESSAGE).asText();
+
+        TelemetryConfig.ConfigType configType = configType(type);
+
+        // parse manufacturer
+        String manufacturer = nullIsIllegal(json.get(MANUFACTURER).asText(),
+                MANUFACTURER + MISSING_MESSAGE);
+
+        // parse software version
+        String swVersion = nullIsIllegal(json.get(SW_VERSION),
+                SW_VERSION + MISSING_MESSAGE).asText();
+
+        // parse enabled flag
+        boolean enabled = nullIsIllegal(json.get(ENABLED),
+                ENABLED + MISSING_MESSAGE).asBoolean();
+
+        JsonNode propertiesJson = json.get(PROPS);
+        Map<String, String> properties = Maps.newConcurrentMap();
+        if (propertiesJson != null) {
+            IntStream.range(0, propertiesJson.size()).forEach(i -> {
+                ObjectNode propertyJson = get(propertiesJson, i);
+                properties.put(propertyJson.get(KEY).asText(),
+                        propertyJson.get(VALUE).asText());
+            });
+        }
+
+        return new DefaultTelemetryConfig(name, configType,
+                ImmutableList.of(), manufacturer, swVersion, enabled, properties);
+    }
+
+    private TelemetryConfig.ConfigType configType(String type) {
+        switch (type.toUpperCase()) {
+            case "KAFKA" :
+                return TelemetryConfig.ConfigType.KAFKA;
+            case "GRPC" :
+                return TelemetryConfig.ConfigType.GRPC;
+            case "INFLUXDB" :
+                return TelemetryConfig.ConfigType.INFLUXDB;
+            case "PROMETHEUS" :
+                return TelemetryConfig.ConfigType.PROMETHEUS;
+            case "REST" :
+                return TelemetryConfig.ConfigType.REST;
+            default:
+                return TelemetryConfig.ConfigType.UNKNOWN;
+        }
+    }
+}