short-d/short

package sso

import (
    "errors"

    "github.com/short-d/short/backend/app/usecase/authenticator"
)

// SingleSignOn enables sign in through external identity providers, such as
// Github, Facebook, and Google.
type SingleSignOn struct {
    identityProvider IdentityProvider
    account          Account
    accountLinker    AccountLinker
    authenticator    authenticator.Authenticator
}

// SignIn generates access token for a user using authorization code obtained
// from external identity provider.
func (o SingleSignOn) SignIn(authorizationCode string) (string, error) {
    if len(authorizationCode) < 1 {
        return "", errors.New("authorizationCode can't be empty")
    }

    accessToken, err := o.identityProvider.RequestAccessToken(authorizationCode)
    if err != nil {
        return "", err
    }

    ssoUser, err := o.account.GetSingleSignOnUser(accessToken)
    if err != nil {
        return "", err
    }

    isLinked, err := o.accountLinker.IsAccountLinked(ssoUser)
    if err != nil {
        return "", err
    }

    if !isLinked {
        err = o.accountLinker.CreateAndLinkAccount(ssoUser)
        if err != nil {
            return "", err
        }
    }

    user, err := o.accountLinker.GetShortUser(ssoUser)
    if err != nil {
        return "", err
    }
    return o.authenticator.GenerateToken(user)
}

// IsSignedIn checks whether a user is authenticated by Short.
func (o SingleSignOn) IsSignedIn(authToken string) bool {
    return o.authenticator.IsSignedIn(authToken)
}

// GetSignInLink retrieves the sign in link of the external account provider.
func (o SingleSignOn) GetSignInLink() string {
    return o.identityProvider.GetAuthorizationURL()
}

// Factory makes SingleSignOn.
type Factory struct {
    authenticator authenticator.Authenticator
}

// NewSingleSignOn creates SingleSignOn.
func (s Factory) NewSingleSignOn(
    identityProvider IdentityProvider,
    account Account,
    accountLinker AccountLinker,
) SingleSignOn {
    return SingleSignOn{
        identityProvider: identityProvider,
        account:          account,
        accountLinker:    accountLinker,
        authenticator:    s.authenticator,
    }
}

// NewFactory creates single sign on factory.
func NewFactory(
    authenticator authenticator.Authenticator,
) Factory {
    return Factory{
        authenticator: authenticator,
    }
}