OAuth2.scala

  case class Callback(settings: Settings) extends RestHelper {
    private def exchange(request : Req)(code : String): Option[Token] = {
      val client = new DefaultHttpClient
      val request = new HttpPost(entryURL)
      val params = List(
        ("code",          code),
        ("client_id",     settings.clientId),
        ("client_secret", settings.clientSecret),
        ("redirectUri",   settings.redirectUri),
        ("grantType",     "authorization_code")).
        map(p => new BasicNameValuePair(p._1, p._2))
      request.setEntity(new UrlEncodedFormEntity(params.asInstanceOf[java.util.List[NameValuePair]]))
      val response = client.execute(request)
      def toString(entity : HttpEntity) : String = {
        val stream = entity.getContent
        val content = io.Source.fromInputStream(stream).getLines.mkString
        stream.close
        content
      }
      case class TokenParser(access_token : String,
                             refresh_token : Option[String],
                             expires_in : Integer,
                             token_type : String) {
        def toToken : Option[Token] = token_type match {
          case "Bearer" => Some(Token(
            accessToken = access_token,
            refreshToken = refresh_token,
            expiresIn = expires_in,
            tokenType = TokenType.Bearer))
          case _ => None
        }
      }
      Option(response.getEntity).map{toString(_)}.map{parse(_)}.map{_.extract[TokenParser]}.flatMap(_.toToken)
    }