dddsample.scala

trait Entity[ID] {
	val id: ID
	
	// equals, hashCodeはコレクションに入れた時に検索しやすくするために定義している
 	override def equals(obj: Any): Boolean = obj match {
		case that: Entity[_] => id == that.id
        case _ => false
  	}
  	override def hashCode: Int = 31 * id.hasCode
  	
}


trait EntityIOContext

trait Repository[ID, E <: Enttity[ID]] {

	type Ctx = EntityIOContext

 	def findById(id: ID)(ctx: Ctx): Try[E]

	def store(entity: E)ctx: Ctx): Try[E]

}

case class EntityIOContextOnJDBC(sesion: DBSession) extends EntityIOContext

abstract class AbstractRepositoryOnJDBC[ID, E <: Entity[ID] extends Repository[ID, E] {

    protected def convertToEntity(resultSet: WrappedResultSet): E
    protected def convertToMap(entity: Entity): Map[String, Any]
	
    private val userDao = new UserDao
	
    private def getSession(ctx: Ctx) = ctx match {
        case EntityIOContextOnJDBC(session) => session
        case _ => throw new Exception(...)
    }

    override def findById(id: Long)(implicit ctx: Ctx) = {
        implicit val session = getSession(ctx)
        userDao.selectById(id).map(convertToEntity)
    }
 	
    override def store(entity: E)(implicit ctx: Ctx) = {
        implicit val session = getSession(ctx)
        userDao.insertOrUpdate(convertToMap(entity))
    }
	
}

abstract class AbstractRepositoryOnMemory[ID, E <: Entity[ID](entities: mutable.Map[ID, E] ) extends Repository[ID, E] {

	override def findById(id: Long)(ctx: Ctx) = Try {
		entities(id).getOrElse(throw EntityNotFoundException)
    }

	override def store(entity: E)(implicit ctx: Ctx) = {
		entities.put(id, entity)
		Success(entity)
	}
}

case class Employee(id: Long, name: String) extends Entity[Long]

case class EmployeeRepositoryOnJDBC
	extends AbstractRepositoryOnJDBC[Long, Employee]

case class EmployeeRepositoryOnMemory(entities: mutable.Map[Long, Employee] = mutable.Map.empty) 
	extends AbstractRepositoryOnMemory[Long, Employee](entities)
	
	
object Main extends App {
    
    implicit val ctx = EntityIOContextOnJDBC(AutoSession)
    
    val repository = new EmployeeRepositoryOnJDBC()
    
    val entity = Employee(1, "Junichi Kato")
    
    repository.store(entity).foreach { _ =>
        repository.findById(entity.id).foreach(println)
    }
    
}