From f7621b2c6c96a245112ed748637c95a5434357a3 Mon Sep 17 00:00:00 2001
From: l <luca.capra@gmail.com>
Date: Sun, 24 Dec 2023 19:39:33 +0100
Subject: [PATCH] feat: partial download (#1486)

* add .partial download

* fix Stat check

* review partial download
---
 pkg/utils/uri.go | 36 ++++++++++++++++++++++++++++++++----
 1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/pkg/utils/uri.go b/pkg/utils/uri.go
index 8046b89f..260e65a9 100644
--- a/pkg/utils/uri.go
+++ b/pkg/utils/uri.go
@@ -94,6 +94,20 @@ func ConvertURL(s string) string {
 	return s
 }
 
+func removePartialFile(tmpFilePath string) error {
+	_, err := os.Stat(tmpFilePath)
+	if err == nil {
+		log.Debug().Msgf("Removing temporary file %s", tmpFilePath)
+		err = os.Remove(tmpFilePath)
+		if err != nil {
+			err1 := fmt.Errorf("failed to remove temporary download file %s: %v", tmpFilePath, err)
+			log.Warn().Msg(err1.Error())
+			return err1
+		}
+	}
+	return nil
+}
+
 func DownloadFile(url string, filePath, sha string, downloadStatus func(string, string, string, float64)) error {
 	url = ConvertURL(url)
 	// Check if the file already exists
@@ -143,15 +157,24 @@ func DownloadFile(url string, filePath, sha string, downloadStatus func(string,
 		return fmt.Errorf("failed to create parent directory for file %q: %v", filePath, err)
 	}
 
-	// Create and write file content
-	outFile, err := os.Create(filePath)
+	// save partial download to dedicated file
+	tmpFilePath := filePath + ".partial"
+
+	// remove tmp file
+	err = removePartialFile(tmpFilePath)
 	if err != nil {
-		return fmt.Errorf("failed to create file %q: %v", filePath, err)
+		return err
+	}
+
+	// Create and write file content
+	outFile, err := os.Create(tmpFilePath)
+	if err != nil {
+		return fmt.Errorf("failed to create file %q: %v", tmpFilePath, err)
 	}
 	defer outFile.Close()
 
 	progress := &progressWriter{
-		fileName:       filePath,
+		fileName:       tmpFilePath,
 		total:          resp.ContentLength,
 		hash:           sha256.New(),
 		downloadStatus: downloadStatus,
@@ -161,6 +184,11 @@ func DownloadFile(url string, filePath, sha string, downloadStatus func(string,
 		return fmt.Errorf("failed to write file %q: %v", filePath, err)
 	}
 
+	err = os.Rename(tmpFilePath, filePath)
+	if err != nil {
+		return fmt.Errorf("failed to rename temporary file %s -> %s: %v", tmpFilePath, filePath, err)
+	}
+
 	if sha != "" {
 		// Verify SHA
 		calculatedSHA := fmt.Sprintf("%x", progress.hash.Sum(nil))