trying to fix segmented download

util/download.go

@@ -102,14 +102,12 @@ func DownloadFileWithSegments(
 		return "", fmt.Errorf("failed to create temporary directory: %w", err)
 	}
 
-	defer os.RemoveAll(tempDir)
-
-	downloadedFiles, err := downloadSegments(ctx, segmentURLs, config)
+	downloadedFiles, err := downloadSegments(ctx, tempDir, segmentURLs, config)
 	if err != nil {
 		os.RemoveAll(tempDir)
 		return "", fmt.Errorf("failed to download segments: %w", err)
 	}
-	mergedFilePath, err := MergeSegmentFiles(ctx, downloadedFiles, fileName, config)
+	mergedFilePath, err := mergeSegmentFiles(ctx, downloadedFiles, fileName, config)
 	if err != nil {
 		os.RemoveAll(tempDir)
 		return "", fmt.Errorf("failed to merge segments: %w", err)
@@ -406,6 +404,43 @@ func downloadChunkWithRetry(
 	return nil, fmt.Errorf("all %d attempts failed: %w", config.RetryAttempts+1, lastErr)
 }
 
+func downloadFile(
+	ctx context.Context,
+	fileURL string,
+	filePath string,
+	config *models.DownloadConfig,
+) (string, error) {
+	if config == nil {
+		config = DefaultConfig()
+	}
+
+	reqCtx, cancel := context.WithTimeout(ctx, config.Timeout)
+	defer cancel()
+
+	req, err := http.NewRequestWithContext(reqCtx, http.MethodGet, fileURL, nil)
+	if err != nil {
+		return "", fmt.Errorf("failed to create request: %w", err)
+	}
+	resp, err := downloadHTTPSession.Do(req)
+	if err != nil {
+		return "", fmt.Errorf("failed to download file: %w", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return "", fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+	file, err := os.Create(filePath)
+	if err != nil {
+		return "", fmt.Errorf("failed to create file: %w", err)
+	}
+	defer file.Close()
+	_, err = io.Copy(file, resp.Body)
+	if err != nil {
+		return "", fmt.Errorf("failed to write file: %w", err)
+	}
+	return filePath, nil
+}
+
 func downloadChunk(
 	ctx context.Context,
 	fileURL string,
@@ -472,6 +507,7 @@ func createChunks(fileSize int, chunkSize int) [][2]int {
 
 func downloadSegments(
 	ctx context.Context,
+	path string,
 	segmentURLs []string,
 	config *models.DownloadConfig,
 ) ([]string, error) {
@@ -479,20 +515,9 @@ func downloadSegments(
 		config = DefaultConfig()
 	}
 
-	tempDir := filepath.Join(
-		config.DownloadDir,
-		"segments"+uuid.NewString(),
-	)
-	if err := os.MkdirAll(tempDir, 0755); err != nil {
-		return nil, fmt.Errorf("failed to create temporary directory: %w", err)
-	}
-	defer os.RemoveAll(tempDir)
-
 	semaphore := make(chan struct{}, config.Concurrency)
 	var wg sync.WaitGroup
 
-	errChan := make(chan error, len(segmentURLs))
-
 	var firstErr atomic.Value
 
 	downloadedFiles := make([]string, len(segmentURLs))
@@ -526,40 +551,45 @@ func downloadSegments(
 			defer func() { <-semaphore }()
 
 			segmentFileName := fmt.Sprintf("segment_%05d", idx)
-			segmentPath := filepath.Join(tempDir, segmentFileName)
+			segmentPath := filepath.Join(path, segmentFileName)
 
-			_, err := DownloadFile(ctx, []string{url}, segmentFileName, &models.DownloadConfig{
-				ChunkSize:       config.ChunkSize,
-				Concurrency:     3, // segments are typically small
-				Timeout:         config.Timeout,
-				DownloadDir:     tempDir,
-				RetryAttempts:   config.RetryAttempts,
-				RetryDelay:      config.RetryDelay,
-				Remux:           false, // don't remux individual segments
-				ProgressUpdater: nil,   // no progress updates for individual segments
-			})
+			filePath, err := downloadFile(
+				ctx, url, segmentPath,
+				&models.DownloadConfig{
+					Timeout: config.Timeout,
+				},
+			)
 
 			if err != nil {
 				if firstErr.Load() == nil {
 					firstErr.Store(fmt.Errorf("failed to download segment %d: %w", idx, err))
-					cancelDownload() // Cancella tutte le altre download
+					cancelDownload()
 				}
 				return
 			}
 
-			downloadedFiles[idx] = segmentPath
+			downloadedFiles[idx] = filePath
 		}(i, segmentURL)
 	}
+	wg.Wait()
 
-	go func() {
-		wg.Wait()
-		close(errChan)
-	}()
+	if err := firstErr.Load(); err != nil {
+		return nil, err.(error)
+	}
+
+	for i, file := range downloadedFiles {
+		if file == "" {
+			return nil, fmt.Errorf("segment %d was not downloaded", i)
+		}
+		if _, err := os.Stat(file); os.IsNotExist(err) {
+			return nil, fmt.Errorf("segment %d file does not exist: %w", i, err)
+		}
+	}
 
 	return downloadedFiles, nil
 }
 
-func MergeSegmentFiles(
+func mergeSegmentFiles(
 	ctx context.Context,
 	segmentPaths []string,
 	outputFileName string,
@@ -569,26 +599,14 @@ func MergeSegmentFiles(
 		config = DefaultConfig()
 	}
 
-	if err := EnsureDownloadDir(config.DownloadDir); err != nil {
-		return "", err
-	}
-
 	outputPath := filepath.Join(config.DownloadDir, outputFileName)
 	outputFile, err := os.Create(outputPath)
 	if err != nil {
 		return "", fmt.Errorf("failed to create output file: %w", err)
 	}
-	defer func() {
-		outputFile.Close()
-		if err != nil {
-			os.Remove(outputPath)
-		}
-	}()
+	defer outputFile.Close()
 
-	bufferedWriter := bufio.NewWriterSize(
-		outputFile,
-		1024*1024,
-	) // 1MB buffer
+	bufferedWriter := bufio.NewWriterSize(outputFile, 1024*1024) // 1MB buffer
 
 	var totalBytes int64
 	var processedBytes int64
@@ -606,8 +624,6 @@ func MergeSegmentFiles(
 		select {
 		case <-ctx.Done():
 			bufferedWriter.Flush()
-			outputFile.Close()
-			os.Remove(outputPath)
 			return "", ctx.Err()
 		default:
 			segmentFile, err := os.Open(segmentPath)
@@ -615,13 +631,18 @@ func MergeSegmentFiles(
 				return "", fmt.Errorf("failed to open segment %d: %w", i, err)
 			}
 
-			written, err := io.Copy(bufferedWriter, segmentFile)
+			buf := make([]byte, 4*1024*1024) // 4MB buffer
+			written, err := io.CopyBuffer(bufferedWriter, segmentFile, buf)
 			segmentFile.Close()
 
 			if err != nil {
 				return "", fmt.Errorf("failed to copy segment %d: %w", i, err)
 			}
 
+			if err := bufferedWriter.Flush(); err != nil {
+				return "", fmt.Errorf("failed to flush after segment %d: %w", i, err)
+			}
+
 			if config.ProgressUpdater != nil && totalBytes > 0 {
 				processedBytes += written
 				progress := float64(processedBytes) / float64(totalBytes)
@@ -633,6 +654,7 @@ func MergeSegmentFiles(
 	if err := bufferedWriter.Flush(); err != nil {
 		return "", fmt.Errorf("failed to flush data: %w", err)
 	}
+	outputFile.Close()
 
 	if config.Remux {
 		err := av.RemuxFile(outputPath)