SEBA-580 Add backup commands;
Retrieve server version;
Show available models

Change-Id: I3dc37d6f155661a2635fb4c95cf42b2aa81035e8
diff --git a/commands/transfer_handler.go b/commands/transfer_handler.go
new file mode 100644
index 0000000..0fce0f6
--- /dev/null
+++ b/commands/transfer_handler.go
@@ -0,0 +1,144 @@
+/*
+ * 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"
+	"crypto/sha1"
+	"github.com/fullstorydev/grpcurl"
+	"github.com/golang/protobuf/proto"
+	"github.com/jhump/protoreflect/dynamic"
+	"google.golang.org/grpc"
+	"hash"
+	"io"
+	"os"
+)
+
+/* Handlers for streaming upload and download */
+
+type DownloadHandler struct {
+	RpcEventHandler
+	f      *os.File
+	chunks int
+	bytes  int
+	status string
+	hash   hash.Hash
+}
+
+type UploadHandler struct {
+	RpcEventHandler
+	chunksize int
+	f         *os.File
+	uri       string
+}
+
+func (h *DownloadHandler) OnReceiveResponse(m proto.Message) {
+	d, err := dynamic.AsDynamicMessage(m)
+	if err != nil {
+		h.status = "ERROR"
+		// TODO(smbaker): How to raise an exception?
+		return
+	}
+	chunk := d.GetFieldByName("chunk").(string)
+	io.WriteString(h.hash, chunk)
+	h.f.Write([]byte(chunk))
+	h.chunks += 1
+	h.bytes += len(chunk)
+}
+
+func (h *UploadHandler) GetParams(msg proto.Message) error {
+	dmsg, err := dynamic.AsDynamicMessage(msg)
+	if err != nil {
+		return err
+	}
+
+	//fmt.Printf("streamer, MessageName: %s\n", dmsg.XXX_MessageName())
+
+	block := make([]byte, h.chunksize)
+	bytes_read, err := h.f.Read(block)
+
+	if err == io.EOF {
+		h.f.Close()
+		//fmt.Print("EOF\n")
+		return err
+	}
+
+	if err != nil {
+		//fmt.Print("ERROR!\n")
+		return err
+	}
+
+	dmsg.TrySetFieldByName("uri", h.uri)
+	dmsg.TrySetFieldByName("chunk", string(block[:bytes_read]))
+
+	return nil
+}
+
+func UploadFile(conn *grpc.ClientConn, descriptor grpcurl.DescriptorSource, local_name string, uri string, chunkSize int) (*dynamic.Message, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), GlobalConfig.Grpc.Timeout)
+	defer cancel()
+
+	headers := GenerateHeaders()
+
+	f, err := os.Open(local_name)
+	if err != nil {
+		return nil, err
+	}
+
+	h := &UploadHandler{uri: uri, f: f, chunksize: chunkSize}
+
+	err = grpcurl.InvokeRPC(ctx, descriptor, conn, "xos.filetransfer/Upload", headers, h, h.GetParams)
+	if err != nil {
+		return nil, err
+	}
+	d, err := dynamic.AsDynamicMessage(h.Response)
+	if err != nil {
+		return nil, err
+	}
+
+	return d, err
+}
+
+func DownloadFile(conn *grpc.ClientConn, descriptor grpcurl.DescriptorSource, uri string, local_name string) (*DownloadHandler, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), GlobalConfig.Grpc.Timeout)
+	defer cancel()
+
+	headers := GenerateHeaders()
+
+	f, err := os.Create(local_name)
+	if err != nil {
+		return nil, err
+	}
+
+	dm := make(map[string]interface{})
+	dm["uri"] = uri
+
+	h := &DownloadHandler{
+		RpcEventHandler: RpcEventHandler{
+			Fields: map[string]map[string]interface{}{"xos.FileRequest": dm},
+		},
+		f:      f,
+		hash:   sha1.New(),
+		status: "SUCCESS"}
+
+	err = grpcurl.InvokeRPC(ctx, descriptor, conn, "xos.filetransfer/Download", headers, h, h.GetParams)
+	if err != nil {
+		return nil, err
+	}
+
+	return h, err
+}