Implement export

1 files changed, 111 insertions, 0 deletions

diff --git a/drive/export.go b/drive/export.go
new file mode 100644
index 0000000..2cbc265
--- /dev/null
+++ b/drive/export.go
@@ -0,0 +1,111 @@
+package drive
+
+import (
+    "io"
+    "os"
+    "fmt"
+    "mime"
+)
+
+var DefaultExportMime = map[string]string{
+    "application/vnd.google-apps.form": "application/zip",
+    "application/vnd.google-apps.document": "application/pdf",
+    "application/vnd.google-apps.drawing": "image/svg+xml",
+    "application/vnd.google-apps.spreadsheet": "text/csv",
+    "application/vnd.google-apps.script": "application/vnd.google-apps.script+json",
+    "application/vnd.google-apps.presentation": "application/pdf",
+}
+
+type ExportArgs struct {
+    Out io.Writer
+    Id string
+    PrintMimes bool
+    Mime string
+    Force bool
+}
+
+func (self *Drive) Export(args ExportArgs) (err error) {
+    f, err := self.service.Files.Get(args.Id).Fields("name", "mimeType").Do()
+    if err != nil {
+        return fmt.Errorf("Failed to get file: %s", err)
+    }
+
+    if args.PrintMimes {
+        return self.printMimes(args.Out, f.MimeType)
+    }
+
+    exportMime, err := getExportMime(args.Mime, f.MimeType)
+    if err != nil {
+        return err
+    }
+
+    filename := getExportFilename(f.Name, exportMime)
+
+    res, err := self.service.Files.Export(args.Id, exportMime).Download()
+    if err != nil {
+        return fmt.Errorf("Failed to download file: %s", err)
+    }
+
+    // Close body on function exit
+    defer res.Body.Close()
+
+    // Check if file exists
+    if !args.Force && fileExists(filename) {
+        return fmt.Errorf("File '%s' already exists, use --force to overwrite", filename)
+    }
+
+    // Create new file
+    outFile, err := os.Create(filename)
+    if err != nil {
+        return fmt.Errorf("Unable to create new file '%s': %s", filename, err)
+    }
+
+    // Close file on function exit
+    defer outFile.Close()
+
+    // Save file to disk
+    bytes, err := io.Copy(outFile, res.Body)
+    if err != nil {
+        return fmt.Errorf("Failed saving file: %s", err)
+    }
+
+    fmt.Fprintf(args.Out, "Exported '%s' at %s, total %d\n", filename, "x/s", bytes)
+    return
+}
+
+func (self *Drive) printMimes(out io.Writer, mimeType string) error {
+    about, err := self.service.About.Get().Fields("exportFormats").Do()
+    if err != nil {
+        return fmt.Errorf("Failed to get about: %s", err)
+    }
+
+    mimes, ok := about.ExportFormats[mimeType]
+    if !ok {
+        return fmt.Errorf("File with type '%s' cannot be exported", mimeType)
+    }
+
+    fmt.Fprintf(out, "Available mime types: %s\n", formatList(mimes))
+    return nil
+}
+
+func getExportMime(userMime, fileMime string) (string, error) {
+    if userMime != "" {
+        return userMime, nil
+    }
+
+    defaultMime, ok := DefaultExportMime[fileMime]
+    if !ok {
+        return "", fmt.Errorf("File with type '%s' does not have a default export mime, and can probably not be exported", fileMime)
+    }
+
+    return defaultMime, nil
+}
+
+func getExportFilename(name, mimeType string) string {
+    extensions, err := mime.ExtensionsByType(mimeType)
+    if err != nil {
+        return name
+    }
+
+    return name + extensions[0]
+}