backend

type Authority int

type B interface {
	// ServiceURL returns the service URL.
	ServiceURL(context.Context) url.URL

	// Get retrieves a single configuration.
	Get(c context.Context, configSet, path string, p Params) (*Item, error)

	// GetAll retrieves all configurations of a given type.
	GetAll(c context.Context, t GetAllTarget, path string, p Params) ([]*Item, error)

	// ConfigSetURL returns the URL for the specified config set.
	ConfigSetURL(c context.Context, configSet string, p Params) (url.URL, error)

	// GetConfigInterface returns the raw configuration interface of the backend.
	GetConfigInterface(c context.Context, a Authority) config.Interface
}

type Factory func(context.Context) B

type FormatSpec struct {
	// Formatter is the supported destination Resolver format for this item.
	// Backends (notably the format.Backend) may project the Item into this
	// format.
	//
	// An empty string means the original config service format.
	Formatter string

	// Data is additional format data describing the type. It may be empty.
	Data string
}

type GetAllTarget string

type Item struct {
	Meta

	Content string

	// FormatSpec, if non-empty, qualifies the format of the Content.
	FormatSpec FormatSpec
}

type Meta struct {
	// ConfigSet is the item's config set.
	ConfigSet string
	// Path is the item's path within its config set.
	Path string

	// ContentHash is the content hash.
	ContentHash string
	// Revision is the revision string.
	Revision string
}

type Params struct {
	// Authority is the authority to use in the request.
	Authority Authority
	// Content, if true, indicates that config content should also be fetched.
	// Otherwise, only the content hash needs to be returned.
	Content bool

	// FormatSpec, if non-empty, qualifies the format of the Content.
	FormatSpec FormatSpec
}