refactor command service to use one method per file (#416)

Updated the command service to have the same structure as all the other services within platform/...

platform/command/new_command.go

@@ -0,0 +1,71 @@
+package command
+
+import (
+	"net/http"
+
+	"github.com/go-kit/kit/endpoint"
+	"github.com/pkg/errors"
+	"golang.org/x/net/context"
+
+	"github.com/micromdm/micromdm/mdm/mdm"
+	"github.com/micromdm/micromdm/pkg/httputil"
+)
+
+const (
+	// CommandTopic is a PubSub topic that events are published to.
+	CommandTopic = "mdm.Command"
+)
+
+func (svc *CommandService) NewCommand(ctx context.Context, request *mdm.CommandRequest) (*mdm.CommandPayload, error) {
+	if request == nil {
+		return nil, errors.New("empty CommandRequest")
+	}
+	payload, err := mdm.NewCommandPayload(request)
+	if err != nil {
+		return nil, errors.Wrap(err, "creating mdm payload")
+	}
+	event := NewEvent(payload, request.UDID)
+	msg, err := MarshalEvent(event)
+	if err != nil {
+		return nil, errors.Wrap(err, "marshalling mdm command event")
+	}
+	if err := svc.publisher.Publish(context.TODO(), CommandTopic, msg); err != nil {
+		return nil, errors.Wrapf(err, "publish mdm command on topic: %s", CommandTopic)
+	}
+	return payload, nil
+}
+
+type newCommandRequest struct {
+	mdm.CommandRequest
+}
+
+type newCommandResponse struct {
+	Payload *mdm.CommandPayload `json:"payload,omitempty"`
+	Err     error               `json:"error,omitempty"`
+}
+
+func (r newCommandResponse) Failed() error   { return r.Err }
+func (r newCommandResponse) StatusCode() int { return http.StatusCreated }
+
+func decodeNewCommandRequest(ctx context.Context, r *http.Request) (interface{}, error) {
+	var req newCommandRequest
+	err := httputil.DecodeJSONRequest(r, &req)
+	return req, err
+}
+
+var errEmptyRequest = errors.New("request must contain UDID of the device")
+
+// MakeNewCommandEndpoint creates an endpoint which creates new MDM Commands.
+func MakeNewCommandEndpoint(svc Service) endpoint.Endpoint {
+	return func(ctx context.Context, request interface{}) (interface{}, error) {
+		req := request.(newCommandRequest)
+		if req.UDID == "" || req.RequestType == "" {
+			return newCommandResponse{Err: errEmptyRequest}, nil
+		}
+		payload, err := svc.NewCommand(ctx, &req.CommandRequest)
+		if err != nil {
+			return newCommandResponse{Err: err}, nil
+		}
+		return newCommandResponse{Payload: payload}, nil
+	}
+}