Add MergeDirs optional interface and implement it for drive

drive/drive.go

@@ -723,6 +723,46 @@ func (f *Fs) PutUnchecked(in io.Reader, src fs.ObjectInfo, options ...fs.OpenOpt
 	return o, nil
 }
 
+// MergeDirs merges the contents of all the directories passed
+// in into the first one and rmdirs the other directories.
+func (f *Fs) MergeDirs(dirs []fs.Directory) error {
+	if len(dirs) < 2 {
+		return nil
+	}
+	dstDir := dirs[0]
+	for _, srcDir := range dirs[1:] {
+		// list the the objects
+		infos := []*drive.File{}
+		_, err := f.list(srcDir.ID(), "", false, false, true, func(info *drive.File) bool {
+			infos = append(infos, info)
+			return false
+		})
+		if err != nil {
+			return errors.Wrapf(err, "MergeDirs list failed on %v", srcDir)
+		}
+		// move them into place
+		for _, info := range infos {
+			fs.Infof(srcDir, "merging %q", info.Title)
+			// Move the file into the destination
+			err = f.pacer.Call(func() (bool, error) {
+				info.Parents = []*drive.ParentReference{{Id: dstDir.ID()}}
+				info, err = f.svc.Files.Patch(info.Id, info).SetModifiedDate(true).Fields(googleapi.Field(partialFields)).SupportsTeamDrives(f.isTeamDrive).Do()
+				return shouldRetry(err)
+			})
+			if err != nil {
+				return errors.Wrapf(err, "MergDirs move failed on %q in %v", info.Title, srcDir)
+			}
+		}
+		// rmdir (into trash) the now empty source directory
+		err = f.rmdir(srcDir.ID(), true)
+		if err != nil {
+			fs.Infof(srcDir, "removing empty directory")
+			return errors.Wrapf(err, "MergDirs move failed to rmdir %q", srcDir)
+		}
+	}
+	return nil
+}
+
 // Mkdir creates the container if it doesn't exist
 func (f *Fs) Mkdir(dir string) error {
 	err := f.dirCache.FindRoot(true)
@@ -735,6 +775,19 @@ func (f *Fs) Mkdir(dir string) error {
 	return err
 }
 
+// Rmdir deletes a directory unconditionally by ID
+func (f *Fs) rmdir(directoryID string, useTrash bool) error {
+	return f.pacer.Call(func() (bool, error) {
+		var err error
+		if useTrash {
+			_, err = f.svc.Files.Trash(directoryID).Fields(googleapi.Field(partialFields)).SupportsTeamDrives(f.isTeamDrive).Do()
+		} else {
+			err = f.svc.Files.Delete(directoryID).Fields(googleapi.Field(partialFields)).SupportsTeamDrives(f.isTeamDrive).Do()
+		}
+		return shouldRetry(err)
+	})
+}
+
 // Rmdir deletes a directory
 //
 // Returns an error if it isn't empty
@@ -761,19 +814,11 @@ func (f *Fs) Rmdir(dir string) error {
 	if found {
 		return errors.Errorf("directory not empty")
 	}
-	// Delete the directory if it isn't the root
 	if root != "" {
-		err = f.pacer.Call(func() (bool, error) {
-			// trash the directory if it had trashed files
-			// in or the user wants to trash, otherwise
-			// delete it.
-			if trashedFiles || *driveUseTrash {
-				_, err = f.svc.Files.Trash(directoryID).Fields(googleapi.Field(partialFields)).SupportsTeamDrives(f.isTeamDrive).Do()
-			} else {
-				err = f.svc.Files.Delete(directoryID).Fields(googleapi.Field(partialFields)).SupportsTeamDrives(f.isTeamDrive).Do()
-			}
-			return shouldRetry(err)
-		})
+		// trash the directory if it had trashed files
+		// in or the user wants to trash, otherwise
+		// delete it.
+		err = f.rmdir(directoryID, trashedFiles || *driveUseTrash)
 		if err != nil {
 			return err
 		}
@@ -1375,6 +1420,7 @@ var (
 	_ fs.DirCacheFlusher   = (*Fs)(nil)
 	_ fs.DirChangeNotifier = (*Fs)(nil)
 	_ fs.PutUncheckeder    = (*Fs)(nil)
+	_ fs.MergeDirser       = (*Fs)(nil)
 	_ fs.Object            = (*Object)(nil)
 	_ fs.MimeTyper         = &Object{}
 )