We must needs traverse everything file by file.

src/Guestbooky-backup/internal/compactor/compactor.go

@@ -1,12 +1,14 @@
 package compactor
 
 import (
+	"archive/tar"
 	"compress/gzip"
 	"errors"
 	"fmt"
 	"io"
 	"io/fs"
 	"os"
+	"path/filepath"
 )
 
 func Compact(source, destination string) error {
@@ -15,15 +17,9 @@ func Compact(source, destination string) error {
 	)
 
 	if _, err := os.Stat(source); errors.Is(err, fs.ErrNotExist) {
-		return errors.New("source file does not exist")
+		return errors.New("source does not exist")
 	}
 
-	originFileHandle, err := os.Open(source)
-	if err != nil {
-		return errors.New("failed to open source file")
-	}
-	defer originFileHandle.Close()
-
 	destinationFileHandle, err := os.Create(destination)
 	if err != nil {
 		return errors.New("failed to create destination file")
@@ -33,8 +29,43 @@ func Compact(source, destination string) error {
 	zipWriter := gzip.NewWriter(destinationFileHandle)
 	defer zipWriter.Close()
 
-	if _, err := io.Copy(zipWriter, originFileHandle); err != nil {
-		return errors.New("failed to copy zip to destination file: " + err.Error()) //nolint:wraperr
+	err = filepath.Walk(source, func(path string, info fs.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if info.IsDir() {
+			return nil
+		}
+
+		originFileHandle, err := os.Open(path)
+		if err != nil {
+			return errors.New("failed to open origin file: " + err.Error())
+		}
+		defer originFileHandle.Close()
+
+		header, err := tar.FileInfoHeader(info, "")
+		if err != nil {
+			return errors.New("failed to create gzip file info header: " + err.Error())
+		}
+		header.Name = path
+
+		tarWriter := tar.NewWriter(zipWriter)
+		defer tarWriter.Close()
+
+		if err := tarWriter.WriteHeader(header); err != nil {
+			return errors.New("failed to write gzip header: " + err.Error())
+		}
+
+		if _, err := io.Copy(tarWriter, originFileHandle); err != nil {
+			return errors.New("failed to copy zip to destination file: " + err.Error())
+		}
+
+		return nil
+	})
+
+	if err != nil {
+		return errors.New("failed to walk source directory: " + err.Error())
 	}
 
 	return nil