jottacloud: fix issue with server-side copy when destination is in trash

A strange feature (probably bug) in the api used by the server-side copy implementation
in Jottacloud backend is that if the destination file is in trash, the copy request
succeeds but the destination will still be in trash! When this situation occurs in
rclone, the copy command will fail with "Failed to copy: object not found" because
rclone verifies that the file info in the response from the copy request is valid,
and since it is marked as deleted it is treated as invalid.

This commit works around this problem by looking for this situation in the response
from the copy operation, and send an additional request to a built-in deduplication
endpoint that will restore the file from trash.

Fixes #6112

backend/jottacloud/jottacloud.go

@@ -1210,6 +1210,45 @@ func (f *Fs) Purge(ctx context.Context, dir string) error {
 	return f.purgeCheck(ctx, dir, false)
 }
 
+// createOrUpdate tries to make remote file match without uploading.
+// If the remote file exists, and has matching size and md5, only
+// timestamps are updated. If the file does not exist or does does
+// not match size and md5, but matching content can be constructed
+// from deduplication, the file will be updated/created. If the file
+// is currently in trash, but can be made to match, it will be
+// restored. Returns ErrorObjectNotFound if upload will be necessary
+// to get a matching remote file.
+func (f *Fs) createOrUpdate(ctx context.Context, file string, modTime time.Time, size int64, md5 string) (info *api.JottaFile, err error) {
+	opts := rest.Opts{
+		Method:       "POST",
+		Path:         f.filePath(file),
+		Parameters:   url.Values{},
+		ExtraHeaders: make(map[string]string),
+	}
+
+	opts.Parameters.Set("cphash", "true")
+
+	fileDate := api.Time(modTime).String()
+	opts.ExtraHeaders["JSize"] = strconv.FormatInt(size, 10)
+	opts.ExtraHeaders["JMd5"] = md5
+	opts.ExtraHeaders["JCreated"] = fileDate
+	opts.ExtraHeaders["JModified"] = fileDate
+
+	var resp *http.Response
+	err = f.pacer.Call(func() (bool, error) {
+		resp, err = f.srv.CallXML(ctx, &opts, nil, &info)
+		return shouldRetry(ctx, resp, err)
+	})
+
+	if apiErr, ok := err.(*api.Error); ok {
+		// does not exist, i.e. not matching size and md5, and not possible to make it by deduplication
+		if apiErr.StatusCode == http.StatusNotFound {
+			return nil, fs.ErrorObjectNotFound
+		}
+	}
+	return info, nil
+}
+
 // copyOrMoves copies or moves directories or files depending on the method parameter
 func (f *Fs) copyOrMove(ctx context.Context, method, src, dest string) (info *api.JottaFile, err error) {
 	opts := rest.Opts{
@@ -1253,6 +1292,12 @@ func (f *Fs) Copy(ctx context.Context, src fs.Object, remote string) (fs.Object,
 	}
 	info, err := f.copyOrMove(ctx, "cp", srcObj.filePath(), remote)
 
+	// if destination was a trashed file then after a successfull copy the copied file is still in trash (bug in api?)
+	if err == nil && bool(info.Deleted) && !f.opt.TrashedOnly && info.State == "COMPLETED" {
+		fs.Debugf(src, "Server-side copied to trashed destination, restoring")
+		info, err = f.createOrUpdate(ctx, remote, srcObj.modTime, srcObj.size, srcObj.md5)
+	}
+
 	if err != nil {
 		return nil, fmt.Errorf("couldn't copy file: %w", err)
 	}