var (
	// ErrNoToken is returned if a request is successful but the body does not
	// contain an authorization token.
	ErrNoToken = errors.New("authorization server did not include a token in the response")

	// ErrInvalidAuthorization is used when credentials are passed to a server but
	// those credentials are rejected.
	ErrInvalidAuthorization = errors.New("authorization failed")
)

type ResolverOptions struct {
	// Credentials provides username and secret given a host.
	// If username is empty but a secret is given, that secret
	// is interpretted as a long lived token.
	Credentials func(string) (string, string, error)

	// Host provides the hostname given a namespace.
	Host func(string) (string, error)

	// PlainHTTP specifies to use plain http and not https
	PlainHTTP bool

	// Client is the http client to used when making registry requests
	Client *http.Client

	// Tracker is used to track uploads to the registry. This is used
	// since the registry does not have upload tracking and the existing
	// mechanism for getting blob upload status is expensive.
	Tracker StatusTracker
}

type Status struct {
	content.Status

	// UploadUUID is used by the Docker registry to reference blob uploads
	UploadUUID string
}

type StatusTracker interface {
	GetStatus(string) (Status, error)
	SetStatus(string, Status)
}