OAuth2.scala

package models

import play.api.libs.ws.WS
import play.core.parsers._
import scala.concurrent.Future
import play.api.libs.concurrent.Execution.Implicits._

case class OAuth2Settings(
  clientId: String,
  clientSecret: String,
  signInUrl: String,
  accessTokenUrl: String,
  userInfoUrl: String
)

abstract class OAuth2[T](settings: OAuth2Settings){
  def user(body: String): T
  
  import settings._
  
  lazy val signIn = signInUrl + "?client_id=" + clientId
  
  def authenticate(code: String): Future[T] = {
    val url = accessTokenUrl + "?client_id=" + clientId + "&client_secret=" + clientSecret + "&code=" + code
    
    for {
      accessToken <- WS.url(url).get()
      userInfo <- WS.url(userInfoUrl + "?access_token=" + FormUrlEncodedParser.parse(accessToken.body).get("access_token").flatMap(_.headOption).get).get()
    } yield {
      user(userInfo.body)
    }
  }
}

OAuth2Github.scala

package controllers

import lib._
import play.api.mvc._
import play.api.libs.json._
import play.api.libs.functional.syntax._

import scala.concurrent.{Future}
import scala.concurrent.ExecutionContext.Implicits.global

object OAuth2Github extends Controller {

  val GITHUB = new OAuth2[GithubUser](OAuth2Settings(
    "your_client_id",
    "your_client_secret",
    "https://github.com/login/oauth/authorize",
    "https://github.com/login/oauth/access_token",
    "https://api.github.com/user"
  )){
    def user(body: String): GithubUser = Json.parse(body).validate[GithubUser](githubUserReads).get
  }

  case class GithubUser(
    login: String,
    email: String,
    avatar_url: String,
    name: String
  )

  implicit val githubUserReads = (
    (__ \ "login").read[String] and
    (__ \ "email").read[String] and
    (__ \ "avatar_url").read[String] and
    (__ \ "name").read[String]
  )(GithubUser.apply _)

  def signin() = Action { Redirect(GITHUB.signIn) }

  def signout() = Action { Redirect(routes.Application.index()).withSession() }

  def callback(code: String) = Action.async { implicit request =>
    GITHUB.authenticate(code).map { user =>
      Redirect(routes.Application.index()).withSession("login" -> user.login)
    }
  }
}

routes

# Routes
# This file defines all application routes (Higher priority routes first)
# ~~~~

GET         /                                 controllers.Application.index

# OAuth2
GET         /signin                           controllers.OAuth2Github.signin
GET         /callback                         controllers.OAuth2Github.callback(code: String)

# Map static resources from the /public folder to the /assets URL path
GET         /assets/*file                     controllers.Assets.at(path="/public", file)