Exemplo de um usecase

SaveNewFriendsUsecase.scala

package com.opportunity.objectives.usecases.user

import com.opportunity.objectives.exceptions.UserInvalidException
import com.opportunity.objectives.model.{Friend, User}
import com.opportunity.objectives.persistence.adapter.user.NewUserPersistenceAdapter

class SaveNewFriendsUsecase(persistenceAdapter: NewUserPersistenceAdapter) {

  def save(user:User, friends:List[Friend]): User = {
    persistenceAdapter.findUserById(user.id) match {
      case findedUser:User => prepareFriends(findedUser, friends)
      case _ => throw new UserInvalidException(List[Map[String, String]]())
    }
  }

  private def prepareFriends(user:User, friends:List[Friend]): User = {
    val emailOfFriendsFriends:List[String] = friends.map { friend => friend.email }

    val existentFirends:List[Friend] = persistenceAdapter.findExistentFriends(emailOfFriendsFriends)

    val remainingInitialFriends = friends.takeWhile { friend => existentFirends.find{ existent => existent.email.equalsIgnoreCase(friend.email) }.isEmpty }

    val finalFriends = existentFirends ++ remainingInitialFriends

    persistenceAdapter.saveFriends(user, finalFriends)
  }
}