fix: resolve bugs found in pre-release review

internal/download/stream.go

@@ -5,20 +5,41 @@ import (
 	"errors"
 	"io"
 	"os"
+	"path/filepath"
 
 	"github.com/mathismqn/godeez/internal/deezer"
 )
 
-const chunkSize = 2048
+const (
+	chunkSize   = 2048
+	partPattern = ".godeez-*.part"
+)
+
+func sweepPartFiles(dir string) {
+	matches, err := filepath.Glob(filepath.Join(dir, partPattern))
+	if err != nil {
+		return
+	}
+	for _, match := range matches {
+		os.Remove(match)
+	}
+}
 
 func (d *Downloader) streamToFile(ctx context.Context, stream io.ReadCloser, outputPath string, key []byte) error {
 	defer stream.Close()
 
-	file, err := os.Create(outputPath)
+	file, err := os.CreateTemp(filepath.Dir(outputPath), partPattern)
 	if err != nil {
 		return err
 	}
-	defer file.Close()
+	tmpPath := file.Name()
+	done := false
+	defer func() {
+		if !done {
+			file.Close()
+			os.Remove(tmpPath)
+		}
+	}()
 
 	buffer := make([]byte, chunkSize)
 	for chunk := 0; ; chunk++ {
@@ -60,5 +81,16 @@ func (d *Downloader) streamToFile(ctx context.Context, stream io.ReadCloser, out
 		}
 	}
 
+	if err := file.Sync(); err != nil {
+		return err
+	}
+	if err := file.Close(); err != nil {
+		return err
+	}
+	if err := os.Rename(tmpPath, outputPath); err != nil {
+		return err
+	}
+	done = true
+
 	return nil
 }