Sign in with Google

GoogleDispatcher

package login
import net.liftweb.http.LiftRules
import net.liftweb.http.Req
import net.liftweb.http.GetRequest
import net.liftweb.http.S
import net.liftweb.common.Box
import net.liftweb.http.LiftResponse
import net.liftweb.util.Props
import net.liftweb.common.Full
import net.liftweb.common.Empty
import net.liftweb.http.SessionVar
import it.cataalog.model.User
import net.liftweb.common.Loggable
import com.google.api.client.googleapis.auth.oauth2.GoogleBrowserClientRequestUrl
import java.util.Arrays
import com.google.api.client.http.javanet.NetHttpTransport
import com.google.api.client.json.jackson.JacksonFactory
import com.google.api.services.oauth2.Oauth2
import com.google.api.client.googleapis.auth.oauth2.draft10.GoogleAccessProtectedResource
import com.google.api.services.oauth2.model.Userinfo
import org.bson.types.ObjectId

/**
 * Handles user login via Google.
 */
object GoogleDispatcher extends Loggable {

  /**
   * Dispatch requests for twitter. We are interested in
   * twitter/authenticate, twitter/callback and twitter/logout
   */
  def matcher: LiftRules.DispatchPF = {
    case req @ Req("google" :: "authenticate" :: Nil, _, GetRequest) =>
      () => signUpRedirect(req)
    case req @ Req("google" :: "catchtoken" :: Nil, _, GetRequest) =>
      () => processCallBack(req)
  }

  /**
   * Calls Google API to authenticate the user.
   * Post authentication Google would send the token back on callbackURL
   * @See OAuth2 with Google https://developers.google.com/accounts/docs/OAuth2UserAgent
   */
  def signUpRedirect(req: Req): Box[LiftResponse] = {
    val callbackURL = req.hostAndPath + "/google/callback"
    val url = new GoogleBrowserClientRequestUrl(Props.get("google.client.id").openOr(""),
      callbackURL, Arrays.asList("https://www.googleapis.com/auth/userinfo.email", "https://www.googleapis.com/auth/userinfo.profile")).
      setState("/").build()
    S.redirectTo(url);

  }

  /**
   * Call back from Google post authentication.
   * Login the authenticated user or 'create and login' new user.
   */
  def processCallBack(req: Req): Box[LiftResponse] = {

    // fetch user info object form Google
    val userInfo = validateTokenAndFetchUser(req)

    // process the obtained user information
    createOrLoginUser(userInfo)

    S.redirectTo("/")
  }

  /**
   * Using Google client libraries to fetch the information.
   * @See http://stackoverflow.com/questions/11328832/how-to-validate-google-oauth2-token-from-java-code
   */
  private def validateTokenAndFetchUser(req: Req) = {
    val transport = new NetHttpTransport()
    val jsonFactory = new JacksonFactory()
    val accessToken = req.param("access_token").open_!
    val refreshToken = req.param("access_token").open_!

    // TODO GoogleAccessProtectedResource is marked as deprecated, need to check the alternate
    val requestInitializer = new GoogleAccessProtectedResource(accessToken, transport, jsonFactory,
      Props.get("google.client.id").openOr(""), Props.get("google.client.secret").openOr(""), refreshToken)

    // set up global Oauth2 instance
    val oauth2 = new Oauth2.Builder(transport, jsonFactory, requestInitializer).setApplicationName("Knoldus").build()

    oauth2.userinfo().get().execute()

  }

  /**
   * If the user exists then login else create user.
   */
  private def createOrLoginUser(userInfo: Userinfo) = {
    User.findByEmail(userInfo.getEmail) match {
      case Full(user) => // needs merging
        User.logUserIn(user, true, true)

      case _ => // new user; send to register page with form pre-filled
        val user = User
        User.id(new ObjectId)
        user.name(userInfo.getName)
        user.email(userInfo.getEmail)
        user.username(userInfo.getEmail)
        user.verified(userInfo.getVerifiedEmail)
        user.save
        User.logUserIn(user, true, true)
    }
  }

}

User.logUserIn(user, true, true)