Basic BBSimCtl implementation

Change-Id: Ib5e6f7f462cdb10a3d976b99812658bf7e225dfb
diff --git a/internal/bbsimctl/commands/onu.go b/internal/bbsimctl/commands/onu.go
new file mode 100644
index 0000000..7d6da8e
--- /dev/null
+++ b/internal/bbsimctl/commands/onu.go
@@ -0,0 +1,73 @@
+/*
+ * Portions copyright 2019-present Open Networking Foundation
+ * Original copyright 2019-present Ciena Corporation
+ *
+ * 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 commands
+
+import (
+	"context"
+	"github.com/jessevdk/go-flags"
+	pb "github.com/opencord/bbsim/api/bbsim"
+	"github.com/opencord/bbsim/internal/bbsimctl/config"
+	"github.com/opencord/cordctl/pkg/format"
+	log "github.com/sirupsen/logrus"
+	"google.golang.org/grpc"
+	"os"
+)
+
+const (
+	DEFAULT_ONU_DEVICE_HEADER_FORMAT = "table{{ .PonPortID }}\t{{ .ID }}\t{{ .SerialNumber }}\t{{ .OperState }}\t{{ .InternalState }}"
+)
+
+type ONUOptions struct{}
+
+func RegisterONUCommands(parser *flags.Parser) {
+	parser.AddCommand("onus", "List ONU Devices", "Commands to list the ONU devices and their internal state", &ONUOptions{})
+}
+
+func getONUs() *pb.ONUs {
+	conn, err := grpc.Dial(config.GlobalConfig.Server, grpc.WithInsecure())
+
+	if err != nil {
+		log.Fatal("did not connect: %v", err)
+		return nil
+	}
+	defer conn.Close()
+	c := pb.NewBBSimClient(conn)
+
+	// Contact the server and print out its response.
+
+	ctx, cancel := context.WithTimeout(context.Background(), config.GlobalConfig.Grpc.Timeout)
+	defer cancel()
+	onus, err := c.GetONUs(ctx, &pb.Empty{})
+	if err != nil {
+		log.Fatal("could not get OLT: %v", err)
+		return nil
+	}
+	return onus
+}
+
+func (options *ONUOptions) Execute(args []string) error {
+	onus := getONUs()
+
+	// print out
+	tableFormat := format.Format(DEFAULT_ONU_DEVICE_HEADER_FORMAT)
+	if err := tableFormat.Execute(os.Stdout, true, onus.Items); err != nil {
+		log.Fatalf("Error while formatting ONUs table: %s", err)
+	}
+
+	return nil
+}