ref.scala

class LoginDemo {
 
  type LoginResult = Either[UserInfo, String]
  def Success[T, E] = Left[T, E] _
  def Failure[T, E] = Right[T, E] _
 
  //@rest.Method(httpMethod = Array(POST))
  def login(request: rest.Request,
      //@rest.Param(name = "login")
      loginParam: String,
      //@rest.Param(name = "password")
      passwordParam: String): Unit =
    login(Option(loginParam), Option(passwordParam)) match {
      case Left(user) =>
        request.session("user") = user
      case Right(message) =>
        respond(UNAUTHORIZED, message)
    }
 
  def login(login: Option[String], password: Option[String]): LoginResult =
    for (login <- login.toLeft( "You should provide login" ).left;
         password <- password.toLeft( "You should provide password" ).left;
         user <- findUser(login).left;
         checkedUser <- checkUser(user).left;
         loggedUser <- doLogin(checkedUser, login, password).left
    ) yield loggedUser
 
  def findUser(login: String): LoginResult =
    AccountsStorage.find(login).toLeft( "User not found" )
 
  def checkUser(user: UserInfo): LoginResult =
    if (user.inactive) Failure("Account is inactive")
    else Success(user)
 
  def doLogin(user: UserInfo, login: String, password: String): LoginResult =
    if (user.authScheme == "PETRIVKA")
      handlePetrivkaAuthSchemeLogin(user, password)
    else
      handleUsualAuthSchemeLogin(user, login, password)
 
  def handlePetrivkaAuthSchemeLogin(user: UserInfo, password: String): LoginResult =
    if( user.passwordMatches(password) ) Success(user)
    else Failure("Authentication failed")
 
  def handleUsualAuthSchemeLogin(user: UserInfo, login: String, password: String) =
    AccessStorage.access.auth_configs.find(_.key == user.authScheme) match {
      case Some(scheme) =>
        //log.debug("authenticating with " + scheme.command)
        val exec = Runtime.getRuntime.exec(
            scheme.command replace("{login}", login) replace("{password}", password))
        if( exec.waitFor == 0 )
          Success(user)
        else
          Failure("Authentication within " + scheme + " failed")
      case None => Failure("Unknown authentication scheme: " + user.authScheme)
    }
 
  def respond(code: Int, message:String = "") = {}
 
  val UNAUTHORIZED = 401
}
 
class UserInfo {
  val inactive = false
  val authScheme = ""
 
  def passwordMatches(pwd: String) = true
}
 
object AccountsStorage {
  def find(login: String): Option[UserInfo] = None
}
 
object AccessStorage {
  object access {
    object auth_configs {
      def find(pred: {val key: String} => Boolean): Option[{val command: String}] = None
    }
  }
}
 
package rest {
  class Request {
    val session = scala.collection.mutable.Map[String, Any]()
  }
}