[ONOS-3603] Implement REST API for Group query, insert, delete

* Implement decoding feature for GroupBucketCodec and GroupCodec
* Implement GroupsWebResource
* Add unit test for GroupBucketCodec and GroupCodec
* Add unit test for GroupsWebResource
* Add group insertion json example
* Add Swagger doc

Change-Id: Ie58cba2e1af996c7b8652a55d9ef0c27207beafc
diff --git a/web/api/src/main/java/org/onosproject/rest/resources/CoreWebApplication.java b/web/api/src/main/java/org/onosproject/rest/resources/CoreWebApplication.java
index cec1faa..afce7f7 100644
--- a/web/api/src/main/java/org/onosproject/rest/resources/CoreWebApplication.java
+++ b/web/api/src/main/java/org/onosproject/rest/resources/CoreWebApplication.java
@@ -37,6 +37,7 @@
                           HostsWebResource.class,
                           IntentsWebResource.class,
                           FlowsWebResource.class,
+                          GroupsWebResource.class,
                           TopologyWebResource.class,
                           ConfigWebResource.class,
                           PathsWebResource.class,
diff --git a/web/api/src/main/java/org/onosproject/rest/resources/GroupsWebResource.java b/web/api/src/main/java/org/onosproject/rest/resources/GroupsWebResource.java
new file mode 100644
index 0000000..733fc41
--- /dev/null
+++ b/web/api/src/main/java/org/onosproject/rest/resources/GroupsWebResource.java
@@ -0,0 +1,152 @@
+/*
+ * Copyright 2014-2015 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.rest.resources;
+
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.ArrayNode;
+import com.fasterxml.jackson.databind.node.ObjectNode;
+import org.onosproject.net.Device;
+import org.onosproject.net.DeviceId;
+import org.onosproject.net.device.DeviceService;
+import org.onosproject.net.group.DefaultGroupDescription;
+import org.onosproject.net.group.DefaultGroupKey;
+import org.onosproject.net.group.Group;
+import org.onosproject.net.group.GroupDescription;
+import org.onosproject.net.group.GroupKey;
+import org.onosproject.net.group.GroupService;
+import org.onosproject.rest.AbstractWebResource;
+
+import javax.ws.rs.Consumes;
+import javax.ws.rs.DELETE;
+import javax.ws.rs.GET;
+import javax.ws.rs.POST;
+import javax.ws.rs.Path;
+import javax.ws.rs.PathParam;
+import javax.ws.rs.Produces;
+import javax.ws.rs.core.MediaType;
+import javax.ws.rs.core.Response;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URI;
+import java.net.URISyntaxException;
+
+/**
+ * Query and program group rules.
+ */
+
+@Path("groups")
+public class GroupsWebResource extends AbstractWebResource {
+    public static final String DEVICE_INVALID = "Invalid deviceId in group creation request";
+
+    final GroupService groupService = get(GroupService.class);
+    final ObjectNode root = mapper().createObjectNode();
+    final ArrayNode groupsNode = root.putArray("groups");
+
+    /**
+     * Returns all groups of all devices.
+     * @onos.rsModel Groups
+     * @return array of all the groups in the system
+     */
+    @GET
+    @Produces(MediaType.APPLICATION_JSON)
+    public Response getGroups() {
+        final Iterable<Device> devices = get(DeviceService.class).getDevices();
+        devices.forEach(device -> {
+            final Iterable<Group> groups = groupService.getGroups(device.id());
+            if (groups != null) {
+                groups.forEach(group -> groupsNode.add(codec(Group.class).encode(group, this)));
+            }
+        });
+
+        return ok(root).build();
+    }
+
+    /**
+     * Returns all groups associated with the given device.
+     *
+     * @param deviceId device identifier
+     * @onos.rsModel Groups
+     * @return array of all the groups in the system
+     */
+    @GET
+    @Produces(MediaType.APPLICATION_JSON)
+    @Path("{deviceId}")
+    public Response getGroupsByDeviceId(@PathParam("deviceId") String deviceId) {
+        final Iterable<Group> groups = groupService.getGroups(DeviceId.deviceId(deviceId));
+
+        groups.forEach(group -> groupsNode.add(codec(Group.class).encode(group, this)));
+
+        return ok(root).build();
+    }
+
+    /**
+     * Create new group rule. Creates and installs a new group rule for the
+     * specified device.
+     *
+     * @param deviceId device identifier
+     * @param stream   group rule JSON
+     * @onos.rsModel GroupsPost
+     * @return status of the request - CREATED if the JSON is correct,
+     * BAD_REQUEST if the JSON is invalid
+     */
+    @POST
+    @Path("{deviceId}")
+    @Consumes(MediaType.APPLICATION_JSON)
+    @Produces(MediaType.APPLICATION_JSON)
+    public Response createGroup(@PathParam("deviceId") String deviceId,
+                                InputStream stream) {
+        URI location;
+        try {
+            ObjectNode jsonTree = (ObjectNode) mapper().readTree(stream);
+            JsonNode specifiedDeviceId = jsonTree.get("deviceId");
+
+            if (specifiedDeviceId != null &&
+                    !specifiedDeviceId.asText().equals(deviceId)) {
+                throw new IllegalArgumentException(DEVICE_INVALID);
+            }
+            jsonTree.put("deviceId", deviceId);
+            Group group = codec(Group.class).decode(jsonTree, this);
+            GroupDescription description = new DefaultGroupDescription(
+                    group.deviceId(), group.type(), group.buckets(),
+                    group.appCookie(), group.id().id(), group.appId());
+            groupService.addGroup(description);
+            location = new URI(Long.toString(group.id().id()));
+        } catch (IOException | URISyntaxException ex) {
+            throw new IllegalArgumentException(ex);
+        }
+
+        return Response
+                .created(location)
+                .build();
+    }
+
+    /**
+     * Removes the specified group.
+     *
+     * @param deviceId  device identifier
+     * @param appCookie application cookie to be used for lookup
+     */
+    @DELETE
+    @Produces(MediaType.APPLICATION_JSON)
+    @Path("{deviceId}/{appCookie}")
+    public void deleteGroupByDeviceIdAndAppCookie(@PathParam("deviceId") String deviceId,
+                                                  @PathParam("appCookie") String appCookie) {
+        DeviceId deviceIdInstance = DeviceId.deviceId(deviceId);
+        GroupKey appCookieInstance = new DefaultGroupKey(appCookie.getBytes());
+
+        groupService.removeGroup(deviceIdInstance, appCookieInstance, null);
+    }
+}
diff --git a/web/api/src/main/resources/definitions/Groups.json b/web/api/src/main/resources/definitions/Groups.json
new file mode 100644
index 0000000..517c564
--- /dev/null
+++ b/web/api/src/main/resources/definitions/Groups.json
@@ -0,0 +1,124 @@
+{
+  "type": "object",
+  "title": "groups",
+  "required": [
+    "groups"
+  ],
+  "properties": {
+    "groups": {
+      "type": "array",
+      "xml": {
+        "name": "groups",
+        "wrapped": true
+      },
+      "items": {
+        "type": "object",
+        "title": "group",
+        "required": [
+          "id",
+          "state",
+          "life",
+          "packets",
+          "bytes",
+          "referenceCount",
+          "type",
+          "deviceId",
+          "buckets"
+        ],
+        "properties": {
+          "id": {
+            "type": "string",
+            "example": "1"
+          },
+          "state": {
+            "type": "string",
+            "example": "PENDING_ADD"
+          },
+          "life": {
+            "type": "integer",
+            "format": "int64",
+            "example": 69889
+          },
+          "packets": {
+            "type": "integer",
+            "format": "int64",
+            "example": 22546
+          },
+          "bytes": {
+            "type": "integer",
+            "format": "int64",
+            "example": 1826226
+          },
+          "referenceCount": {
+            "type": "integer",
+            "format": "int64",
+            "example": 1826226
+          },
+          "type": {
+            "type": "string",
+            "example": "ALL"
+          },
+          "deviceId": {
+            "type": "string",
+            "example": "of:0000000000000003"
+          },
+          "buckets": {
+            "type": "array",
+            "xml": {
+              "name": "buckets",
+              "wrapped": true
+            },
+            "items": {
+              "type": "object",
+              "title": "buckets",
+              "required": [
+                "treatment",
+                "weight",
+                "watchPort",
+                "watchGroup"
+              ],
+              "properties": {
+                "treatment": {
+                  "type": "object",
+                  "title": "treatment",
+                  "required": [
+                    "instructions",
+                    "deferred"
+                  ],
+                  "properties": {
+                    "instructions": {
+                      "type": "array",
+                      "title": "treatment",
+                      "required": [
+                        "properties",
+                        "port"
+                      ],
+                      "items": {
+                        "type": "object",
+                        "title": "instructions",
+                        "required": [
+                          "type",
+                          "port"
+                        ],
+                        "properties": {
+                          "type": {
+                            "type": "string",
+                            "example": "OUTPUT"
+                          },
+                          "port": {
+                            "type": "string",
+                            "example": "2"
+                          }
+                        }
+                      }
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}
\ No newline at end of file
diff --git a/web/api/src/main/resources/definitions/GroupsPost.json b/web/api/src/main/resources/definitions/GroupsPost.json
new file mode 100644
index 0000000..f096201
--- /dev/null
+++ b/web/api/src/main/resources/definitions/GroupsPost.json
@@ -0,0 +1,84 @@
+{
+  "type": "object",
+  "title": "group",
+  "required": [
+    "type",
+    "deviceId",
+    "appCookie",
+    "groupId",
+    "buckets"
+  ],
+  "properties": {
+    "type": {
+      "type": "string",
+      "example": "ALL"
+    },
+    "deviceId": {
+      "type": "string",
+      "example": "of:0000000000000001"
+    },
+    "appCookie": {
+      "type": "string",
+      "example": "1"
+    },
+    "groupId": {
+      "type": "string",
+      "example": "1"
+    },
+    "buckets": {
+      "type": "array",
+      "xml": {
+        "name": "buckets",
+        "wrapped": true
+      },
+      "items": {
+        "type": "object",
+        "title": "buckets",
+        "required": [
+          "treatment",
+          "weight",
+          "watchPort",
+          "watchGroup"
+        ],
+        "properties": {
+          "treatment": {
+            "type": "object",
+            "title": "treatment",
+            "required": [
+              "instructions",
+              "deferred"
+            ],
+            "properties": {
+              "instructions": {
+                "type": "array",
+                "title": "treatment",
+                "required": [
+                  "properties",
+                  "port"
+                ],
+                "items": {
+                  "type": "object",
+                  "title": "instructions",
+                  "required": [
+                    "type",
+                    "port"
+                  ],
+                  "properties": {
+                    "type": {
+                      "type": "string",
+                      "example": "OUTPUT"
+                    },
+                    "port": {
+                      "type": "string",
+                      "example": "2"
+                    }
+                  }
+                }
+              }
+            }
+          }
+        }
+      }
+    }
+  }
+}
\ No newline at end of file