fix: Ensure bookmark files are correctly downloaded before deleting current ones

internal/core/ebook.go

@@ -16,7 +16,10 @@ import (
 	"github.com/pkg/errors"
 )
 
-func GenerateEbook(req ProcessRequest) (book model.Bookmark, err error) {
+// GenerateEbook receives a `ProcessRequest` and generates an ebook file in the destination path specified.
+// The destination path `dstPath` should include file name with ".epub" extension
+// The bookmark model will be used to update the UI based on whether this function is successful or not.
+func GenerateEbook(req ProcessRequest, dstPath string) (book model.Bookmark, err error) {
 	// variable for store generated html code
 	var html string
 
@@ -27,6 +30,7 @@ func GenerateEbook(req ProcessRequest) (book model.Bookmark, err error) {
 		return book, errors.New("bookmark ID is not valid")
 	}
 
+	// get current state of bookmark
 	// cheak archive and thumb
 	strID := strconv.Itoa(book.ID)
 
@@ -40,35 +44,23 @@ func GenerateEbook(req ProcessRequest) (book model.Bookmark, err error) {
 	if _, err := os.Stat(archivePath); err == nil {
 		book.HasArchive = true
 	}
-	ebookfile := fp.Join(req.DataDir, "ebook", fmt.Sprintf("%d.epub", book.ID))
-	// if epub exist finish prosess else continue
-	if _, err := os.Stat(ebookfile); err == nil {
-		book.HasEbook = true
-		return book, nil
-	}
+
+	// this function create ebook from reader mode of bookmark so
+	// we can't create ebook from PDF so we return error here if bookmark is a pdf
 	contentType := req.ContentType
 	if strings.Contains(contentType, "application/pdf") {
 		return book, errors.New("can't create ebook for pdf")
 	}
 
-	ebookDir := fp.Join(req.DataDir, "ebook")
-	// check if directory not exsist create that
-	if _, err := os.Stat(ebookDir); os.IsNotExist(err) {
-		err := os.MkdirAll(ebookDir, model.DataDirPerm)
-		if err != nil {
-			return book, errors.Wrap(err, "can't create ebook directory")
-		}
-	}
-	// create epub file
-	epubFile, err := os.Create(ebookfile)
+	// create temporary epub file
+	tmpFile, err := os.CreateTemp("", "ebook")
 	if err != nil {
-		return book, errors.Wrap(err, "can't create ebook")
+		return book, errors.Wrap(err, "can't create temporary EPUB file")
 	}
-	defer epubFile.Close()
+	defer os.Remove(tmpFile.Name())
 
 	// Create zip archive
-	epubWriter := zip.NewWriter(epubFile)
-	defer epubWriter.Close()
+	epubWriter := zip.NewWriter(tmpFile)
 
 	// Create the mimetype file
 	mimetypeWriter, err := epubWriter.Create("mimetype")
@@ -223,6 +215,27 @@ img {
 	if err != nil {
 		return book, errors.Wrap(err, "can't write into content.html")
 	}
+	// close epub and tmpFile
+	err = epubWriter.Close()
+	if err != nil {
+		return book, errors.Wrap(err, "failed to close EPUB writer")
+	}
+	err = tmpFile.Close()
+	if err != nil {
+		return book, errors.Wrap(err, "failed to close temporary EPUB file")
+	}
+	// open temporary file again
+	tmpFile, err = os.Open(tmpFile.Name())
+	if err != nil {
+		return book, errors.Wrap(err, "can't open temporary EPUB file")
+	}
+	defer tmpFile.Close()
+	// if everitings go well we start move ebook to dstPath
+	err = MoveFileToDestination(dstPath, tmpFile)
+	if err != nil {
+		return book, errors.Wrap(err, "failed move ebook to destination")
+	}
+
 	book.HasEbook = true
 	return book, nil
 }