mbank11.scala

case class AccountEntity(id: Int, state: AccountState)
    extends PersistentEntity[Int, AccountEntity] {

    override type Command = BankAccountCommand
    override type Event = BankAccountEvent
    override type State = AccountState

    // Applies the command to the current state, returning a list of events
    def processCommand(command: Command) : List[Event] = {
        command match {
            case DepositCmd(time, amount) =>
                List(DepositEvt(time, amount))
            case PurchaseCmd(time, amount) =>
                if(amount <= state.balance)
                    List(PurchaseEvt(time, amount))
                else
                    List.empty
            case AssignAccountHolderCmd(time, accountHolder) =>
                List(AssignAccountHolderEvt(time, accountHolder))
        }
    }

    // Processing an event applies changes to the current state
    // Since our entity is immutable we return a new one
    def processEvent(event: Event) : AccountEntity = {
        event match {
            case DepositEvt(time, amount) =>
                AccountEntity(id, AccountState(state.balance + amount, state.accountHolder))
            case PurchaseEvt(time, amount) =>
                AccountEntity(id, AccountState(state.balance - amount, state.accountHolder))
            case AssignAccountHolderEvt(time, accountHolder) =>
                AccountEntity(id, AccountState(state.balance, accountHolder.some))
        }
    }

}