Add dry-run flag for syncing

2 files changed, 52 insertions, 8 deletions

diff --git a/drive/sync_download.go b/drive/sync_download.go
index 37c78cb..ba86aae 100644
--- a/drive/sync_download.go
+++ b/drive/sync_download.go
@@ -16,6 +16,7 @@ type DownloadSyncArgs struct {
     Progress io.Writer
     RootId string
     Path string
+    DryRun bool
     DeleteExtraneous bool
 }
 
@@ -104,6 +105,11 @@ func (self *Drive) createMissingLocalDirs(files *syncFiles, args DownloadSyncArg
             return nil, fmt.Errorf("Failed to determine local absolute path: %s", err)
         }
         fmt.Fprintf(args.Out, "[%04d/%04d] Creating directory: %s\n", i + 1, missingCount, path)
+
+        if args.DryRun {
+            continue
+        }
+
         mkdir(path)
     }
 
@@ -125,6 +131,11 @@ func (self *Drive) downloadMissingFiles(files *syncFiles, args DownloadSyncArgs)
             return fmt.Errorf("Failed to determine local absolute path: %s", err)
         }
         fmt.Fprintf(args.Out, "[%04d/%04d] Downloading %s -> %s\n", i + 1, missingCount, remotePath, localPath)
+
+        if args.DryRun {
+            continue
+        }
+
         err = self.downloadRemoteFile(rf.file.Id, localPath, args)
         if err != nil {
             return err
@@ -149,6 +160,11 @@ func (self *Drive) downloadChangedFiles(files *syncFiles, args DownloadSyncArgs)
             return fmt.Errorf("Failed to determine local absolute path: %s", err)
         }
         fmt.Fprintf(args.Out, "[%04d/%04d] Downloading %s -> %s\n", i + 1, changedCount, remotePath, localPath)
+
+        if args.DryRun {
+            continue
+        }
+
         err = self.downloadRemoteFile(cf.remote.file.Id, localPath, args)
         if err != nil {
             return err
@@ -206,6 +222,11 @@ func (self *Drive) deleteExtraneousLocalFiles(files *syncFiles, args DownloadSyn
 
     for i, lf := range extraneousFiles {
         fmt.Fprintf(args.Out, "[%04d/%04d] Deleting %s\n", i + 1, extraneousCount, lf.absPath)
+
+        if args.DryRun {
+            continue
+        }
+
         err := os.Remove(lf.absPath)
         if err != nil {
             return fmt.Errorf("Failed to delete local file: %s", err)
diff --git a/drive/sync_upload.go b/drive/sync_upload.go
index d1c155d..151a9f8 100644
--- a/drive/sync_upload.go
+++ b/drive/sync_upload.go
@@ -16,6 +16,7 @@ type UploadSyncArgs struct {
     Progress io.Writer
     Path string
     RootId string
+    DryRun bool
     DeleteExtraneous bool
     ChunkSize int64
 }
@@ -141,15 +142,22 @@ func (self *Drive) createMissingRemoteDirs(files *syncFiles, args UploadSyncArgs
 
         fmt.Fprintf(args.Out, "[%04d/%04d] Creating directory: %s\n", i + 1, missingCount, filepath.Join(files.root.file.Name, lf.relPath))
 
-        f, err := self.service.Files.Create(dstFile).Do()
-        if err != nil {
-            return nil, fmt.Errorf("Failed to create directory: %s", err)
+        if args.DryRun {
+            files.remote = append(files.remote, &remoteFile{
+                relPath: lf.relPath,
+                file: dstFile,
+            })
+        } else {
+            f, err := self.service.Files.Create(dstFile).Do()
+            if err != nil {
+                return nil, fmt.Errorf("Failed to create directory: %s", err)
+            }
+
+            files.remote = append(files.remote, &remoteFile{
+                relPath: lf.relPath,
+                file: f,
+            })
         }
-
-        files.remote = append(files.remote, &remoteFile{
-            relPath: lf.relPath,
-            file: f,
-        })
     }
 
     return files, nil
@@ -171,6 +179,11 @@ func (self *Drive) uploadMissingFiles(files *syncFiles, args UploadSyncArgs) err
         }
 
         fmt.Fprintf(args.Out, "[%04d/%04d] Uploading %s -> %s\n", i + 1, missingCount, lf.absPath, filepath.Join(files.root.file.Name, lf.relPath))
+
+        if args.DryRun {
+            continue
+        }
+
         err := self.uploadMissingFile(parent.file.Id, lf, args)
         if err != nil {
             return err
@@ -190,6 +203,11 @@ func (self *Drive) updateChangedFiles(files *syncFiles, args UploadSyncArgs) err
 
     for i, cf := range changedFiles {
         fmt.Fprintf(args.Out, "[%04d/%04d] Updating %s -> %s\n", i + 1, changedCount, cf.local.absPath, filepath.Join(files.root.file.Name, cf.local.relPath))
+
+        if args.DryRun {
+            continue
+        }
+
         err := self.updateChangedFile(cf, args)
         if err != nil {
             return err
@@ -212,6 +230,11 @@ func (self *Drive) deleteExtraneousRemoteFiles(files *syncFiles, args UploadSync
 
     for i, rf := range extraneousFiles {
         fmt.Fprintf(args.Out, "[%04d/%04d] Deleting %s\n", i + 1, extraneousCount, filepath.Join(files.root.file.Name, rf.relPath))
+
+        if args.DryRun {
+            continue
+        }
+
         err := self.deleteRemoteFile(rf, args)
         if err != nil {
             return err