authentication

type AuthService interface {
	OAuthHandler
	CurrentUser(req *http.Request) (*User, error)
	LoadUserData(token *oauth2.Token, req *http.Request, res http.ResponseWriter) (*User, error)
}

type OAuthHandler interface {
	Start(res http.ResponseWriter, req *http.Request) error
	Callback(res http.ResponseWriter, req *http.Request, beforeWriteCallback func(*User) error) error
	Destroy(res http.ResponseWriter, req *http.Request) error
}

type User struct {
	AvatarURL string
	Login     string
	Email     string
}