const (
	BackendTypeOSS     = "oss"
	BackendTypeS3      = "s3"
	BackendTypeLocalFS = "localfs"
)

var (
	// We always use multipart upload for backend, and limit the
	// multipart chunk size to 500MB by default.
	MultipartChunkSize int64 = 500 * 1024 * 1024
)

type Backend interface {
	// Push pushes specified blob file to remote storage backend.
	Push(ctx context.Context, cs content.Store, desc ocispec.Descriptor) error
	// Check checks whether a blob exists in remote storage backend,
	// blob exists -> return (blobPath, nil)
	// blob not exists -> return ("", err)
	Check(blobDigest digest.Digest) (string, error)
	// Type returns backend type name.
	Type() string
}

type LocalFSBackend struct {
	// contains filtered or unexported fields
}

type OSSBackend struct {
	// contains filtered or unexported fields
}

type S3Backend struct {
	// contains filtered or unexported fields
}

type S3Config struct {
	AccessKeyID     string `json:"access_key_id,omitempty"`
	AccessKeySecret string `json:"access_key_secret,omitempty"`
	Endpoint        string `json:"endpoint,omitempty"`
	Scheme          string `json:"scheme,omitempty"`
	BucketName      string `json:"bucket_name,omitempty"`
	Region          string `json:"region,omitempty"`
	ObjectPrefix    string `json:"object_prefix,omitempty"`
}