diff --git a/by_url.go b/by_url.go
deleted file mode 100644
index 9470c65..0000000
--- a/by_url.go
+++ /dev/null
@@ -1,37 +0,0 @@
-package download
-
-import (
-	"fmt"
-	"io"
-	"net/http"
-	"os"
-)
-
-func ByURL(url, location string) (err error) {
-	// Create the file
-	out, err := os.Create(location)
-	if err != nil {
-		return err
-	}
-	defer out.Close()
-
-	// Get the data
-	resp, err := http.Get(url)
-	if err != nil {
-		return err
-	}
-	defer resp.Body.Close()
-
-	// Check server response
-	if resp.StatusCode != http.StatusOK {
-		return fmt.Errorf("bad status: %s", resp.Status)
-	}
-
-	// Writer the body to file
-	_, err = io.Copy(out, resp.Body)
-	if err != nil {
-		return err
-	}
-
-	return nil
-}
diff --git a/google_drive.go b/google_drive.go
index bd6e677..5f597e0 100644
--- a/google_drive.go
+++ b/google_drive.go
@@ -4,8 +4,9 @@ import (
 	"context"
 	"errors"
 	"fmt"
-
-	"github.com/kr/pretty"
+	"io"
+	"net/http"
+	"os"
 
 	"github.com/tanaikech/go-getfilelist"
 
@@ -15,9 +16,8 @@ import (
 )
 
 type GoogleDrive struct {
-	APIKey string
-
-	svc *drive.Service
+	apiKey string
+	svc    *drive.Service
 }
 
 type GoogleDriveFile struct {
@@ -25,19 +25,21 @@ type GoogleDriveFile struct {
 	Name string
 }
 
-func (g GoogleDrive) Init() (err error) {
-	if g.APIKey == "" {
-		err = errors.New("missing google api key")
+var ggdrive GoogleDrive
+
+func Init(apiKey string) (*GoogleDrive, error) {
+	if apiKey == "" {
+		err := errors.New("missing google api key")
 		logger.Error("validation", logger.LogData{
 			Source:  "download.google_drive.Init",
 			Message: err.Error(),
 			Data:    nil,
 		})
-		return
+		return nil, err
 	}
 
 	// init google drive
-	svc, err := drive.NewService(context.Background(), option.WithAPIKey(g.APIKey))
+	svc, err := drive.NewService(context.Background(), option.WithAPIKey(apiKey))
 	if err != nil {
 		err = fmt.Errorf("unable to retrieve Drive: %v", err)
 		logger.Error("init google drive service", logger.LogData{
@@ -45,13 +47,14 @@ func (g GoogleDrive) Init() (err error) {
 			Message: err.Error(),
 			Data:    nil,
 		})
-		return
+		return nil, err
 	}
 
 	// assign
-	g.svc = svc
+	ggdrive.apiKey = apiKey
+	ggdrive.svc = svc
 
-	return
+	return &ggdrive, nil
 }
 
 func (g GoogleDrive) GetFilesByFolderID(folderID string) ([]GoogleDriveFile, error) {
@@ -70,12 +73,66 @@ func (g GoogleDrive) GetFilesByFolderID(folderID string) ([]GoogleDriveFile, err
 		return result, err
 	}
 
-	// if there is no files
-	//if len(res.FileList) == 0 {
-	//	return result, nil
-	//}
+	// if there is more than 1 subfolder
+	if len(res.FileList) != 1 {
+		err := fmt.Errorf("folder %s have more than 1 subfolder", folderID)
+		logger.Error("", logger.LogData{
+			Source:  "download.google_drive.GetFilesByFolderID",
+			Message: err.Error(),
+			Data:    logger.Map{"folder": folderID},
+		})
+		return result, err
+	}
 
-	pretty.Println("res", res)
+	// check list files
+	fol := res.FileList[0]
+	if len(fol.Files) == 0 {
+		return result, nil
+	}
+
+	// collect files
+	for _, f := range fol.Files {
+		result = append(result, GoogleDriveFile{
+			ID:   f.Id,
+			Name: f.Name,
+		})
+	}
+
+	//pretty.Println("res", res)
 
 	return result, nil
 }
+
+func (g GoogleDrive) DownloadByFileID(id, name, location string) (err error) {
+	fmt.Printf("[google drive] start download file %s \n", name)
+	defer fmt.Printf("[google drive] done download file %s \n", name)
+
+	url := fmt.Sprintf("https://drive.google.com/uc?export=download&id=%s", id)
+
+	// Create the file
+	out, err := os.Create(location)
+	if err != nil {
+		return err
+	}
+	defer out.Close()
+
+	// Get the data
+	resp, err := http.Get(url)
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	// Check server response
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("bad status: %s", resp.Status)
+	}
+
+	// Writer the body to file
+	_, err = io.Copy(out, resp.Body)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}