iti_state.py

class OrderState():

    def processOrder(self, order):
        raise NotImplementedError

class PaymentState():

    _payment = None;

    def verifyPayment(self) -> None:
        raise NotImplementedError

class WaitingPaymentState(OrderState):

    def processOrder(self, order) -> OrderState:
        print("Aguardando pagamento")
        if isinstance(order.getPaymentState(), ConfirmedPaymentState):
            return PaidState()
        return self

class DoneState(OrderState):

    def processOrder(self, order) -> OrderState:
        print("Pedido finalizado")

class PaidState(OrderState):

    def processOrder(self, order) -> OrderState:
        print("Pagamento recebido")
        return DoneState()

class InitState(OrderState):

    def processOrder(self, order) -> OrderState:
        print("Pedido realizado")
        if isinstance(order.getPaymentState(), ConfirmedPaymentState):
            return PaidState()
        return WaitingPaymentState()


class UnconfirmedPaymentState(PaymentState):

    def verifyPayment(self) -> PaymentState:
        if (self._payment != True):
            return self

class ConfirmedPaymentState(PaymentState):

    def verifyPayment(self) -> PaymentState:
        if (self._payment):
            return self
        return UnconfirmedPaymentState()


class Order():

    __state: OrderState = None
    __payment: PaymentState = None

    def setOrderState(self, state: OrderState) -> None:
        self.__state = state

    def getOrderState(self) -> OrderState:
        return self.__state

    def setPaymentState(self, state: PaymentState) -> None:
        self.__payment = state

    def getPaymentState(self) -> PaymentState:
        return self.__payment

    def processOrder(self) -> None:
        self.__state = self.__state.processOrder(self)


if __name__ == "__main__":
    order: Order = Order()
    order.setPaymentState(UnconfirmedPaymentState())
    order.setOrderState(InitState())
    order.processOrder()

    print(order.getOrderState()) #WaitingPaymentState

    order.setPaymentState(ConfirmedPaymentState())
    order.processOrder()

    print(order.getOrderState()) #PaidState

    order.processOrder()

    print(order.getOrderState()) #DoneState

    order.processOrder()