Добавлена локальная загрузка снапшота

manager.go

@@ -403,6 +403,37 @@ func (data *SnapshotManagerData) UpdateSnapshotMetadata(ctx context.Context, sna
 	return nil
 }
 
+func (data *SnapshotManagerData) GetSnapshotDiffInfo(ctx context.Context, snapshotID, parentID string) (*store.DiffInfo, error) {
+	tempArchivePath, tempStagingDir, err := data.createDiffArchive(ctx, snapshotID, parentID)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create diff archive for info: %w", err)
+	}
+
+	if tempArchivePath == "" {
+		return &store.DiffInfo{SHA256: "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855", Size: 0}, nil // sha256 of empty string
+	}
+
+	defer os.Remove(tempArchivePath)
+	if tempStagingDir != "" {
+		defer os.RemoveAll(tempStagingDir)
+	}
+
+	hash, err := hash.CalculateFileHash(tempArchivePath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to calculate hash for diff archive: %w", err)
+	}
+
+	stat, err := os.Stat(tempArchivePath)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get size of diff archive: %w", err)
+	}
+
+	return &store.DiffInfo{
+		SHA256: hash,
+		Size:   stat.Size(),
+	}, nil
+}
+
 // diffArchiveReader is a wrapper around an *os.File that handles cleanup of temporary files.
 type diffArchiveReader struct {
 	*os.File
@@ -418,10 +449,10 @@ func (r *diffArchiveReader) Close() error {
 	return err
 }
 
-func (data *SnapshotManagerData) StreamSnapshotDiff(ctx context.Context, snapshotID, parentID string, offset int64) (io.ReadCloser, error) {
+func (data *SnapshotManagerData) createDiffArchive(ctx context.Context, snapshotID, parentID string) (string, string, error) {
 	targetSnap, err := data.metadataStore.GetSnapshotMetadata(ctx, snapshotID)
 	if err != nil {
-		return nil, fmt.Errorf("failed to get target snapshot metadata: %w", err)
+		return "", "", fmt.Errorf("failed to get target snapshot metadata: %w", err)
 	}
 
 	parentFiles := make(map[string]string)
@@ -449,38 +480,38 @@ func (data *SnapshotManagerData) StreamSnapshotDiff(ctx context.Context, snapsho
 	}
 
 	if len(filesToInclude) == 0 {
-		return io.NopCloser(bytes.NewReader(nil)), nil
+		return "", "", nil
 	}
 
 	tempStagingDir, err := os.MkdirTemp(data.blobStore.GetBaseDir(), "diff-staging-*")
 	if err != nil {
-		return nil, fmt.Errorf("failed to create temp staging directory: %w", err)
+		return "", "", fmt.Errorf("failed to create temp staging directory: %w", err)
 	}
 
 	targetBlobPath, err := data.blobStore.GetBlobPath(ctx, snapshotID)
 	if err != nil {
 		os.RemoveAll(tempStagingDir)
-		return nil, err
+		return "", "", err
 	}
 
 	for _, filePath := range filesToInclude {
 		destPath := filepath.Join(tempStagingDir, filePath)
 		if err := os.MkdirAll(filepath.Dir(destPath), 0755); err != nil {
 			os.RemoveAll(tempStagingDir)
-			return nil, fmt.Errorf("failed to create dir for diff file: %w", err)
+			return "", "", fmt.Errorf("failed to create dir for diff file: %w", err)
 		}
 
 		fileWriter, err := os.Create(destPath)
 		if err != nil {
 			os.RemoveAll(tempStagingDir)
-			return nil, err
+			return "", "", err
 		}
 
 		err = archive.ExtractFileFromArchive(targetBlobPath, filePath, fileWriter)
 		fileWriter.Close()
 		if err != nil {
 			os.RemoveAll(tempStagingDir)
-			return nil, fmt.Errorf("failed to extract file %s for diff: %w", filePath, err)
+			return "", "", fmt.Errorf("failed to extract file %s for diff: %w", filePath, err)
 		}
 	}
 
@@ -488,12 +519,27 @@ func (data *SnapshotManagerData) StreamSnapshotDiff(ctx context.Context, snapsho
 	if err := archive.CreateArchive(tempStagingDir, tempArchivePath); err != nil {
 		os.RemoveAll(tempStagingDir)
 		os.Remove(tempArchivePath)
-		return nil, fmt.Errorf("failed to create diff archive: %w", err)
+		return "", "", fmt.Errorf("failed to create diff archive: %w", err)
+	}
+
+	return tempArchivePath, tempStagingDir, nil
+}
+
+func (data *SnapshotManagerData) StreamSnapshotDiff(ctx context.Context, snapshotID, parentID string, offset int64) (io.ReadCloser, error) {
+	tempArchivePath, tempStagingDir, err := data.createDiffArchive(ctx, snapshotID, parentID)
+	if err != nil {
+		return nil, fmt.Errorf("failed to create diff archive for streaming: %w", err)
+	}
+
+	if tempArchivePath == "" {
+		return io.NopCloser(bytes.NewReader(nil)), nil
 	}
 
 	archiveFile, err := os.Open(tempArchivePath)
 	if err != nil {
-		os.RemoveAll(tempStagingDir)
+		if tempStagingDir != "" {
+			os.RemoveAll(tempStagingDir)
+		}
 		os.Remove(tempArchivePath)
 		return nil, err
 	}
@@ -501,7 +547,9 @@ func (data *SnapshotManagerData) StreamSnapshotDiff(ctx context.Context, snapsho
 	if offset > 0 {
 		if _, err := archiveFile.Seek(offset, io.SeekStart); err != nil {
 			archiveFile.Close()
-			os.RemoveAll(tempStagingDir)
+			if tempStagingDir != "" {
+				os.RemoveAll(tempStagingDir)
+			}
 			os.Remove(tempArchivePath)
 			return nil, fmt.Errorf("failed to seek in diff archive: %w", err)
 		}