saga-example.ts

const Event /* OrderProcessingEvents */ = {
  REQUESTED: "REQUESTED",
  PAYMENT_REQUESTED: "PAYMENT_REQUESTED",
  PAYMENT_REJECTED: "PAYMENT_REJECTED",
  REPLY_PAYMENT_FAILED: "REPLY_PAYMENT_FAILED",
  REPLY_PAYMENT_COMPLETED: "REPLY_PAYMENT_COMPLETED",
};

const OrderState = {
  INITIATED: "INITIATED",
  CHARGE_INITIALIZED: "CHARGE_INITIALIZED",
  CHARGE_PENDING: "CHARGE_PENDING",
  CHARGE_REJECTED: "CHARGE_REJECTED",
  INITIALIZE_CANCELLED: "INITIALIZE_CANCELLED",
  CHARGE_FAILED: "CHARGE_FAILED",
  CHARGE_COMPLETED: "CHARGE_COMPLETED",
};

class MutualFundOrderingOrchestrator {
  constructor() {
    StateMachine
      /*
        OrderState.INITIATE
          (transitionToChargeInitialized) -> OrderState.CHARGE_INITIALIZED 
      */
      .on(Event.REQUESTED, OrderCreateCommand)
      /*
        OrderState.CHARGE_INITIALIZED
          (replyTransitionToChargePending) -> OrderState.CHARGE_PENDING
          (transitionToChargeRejected) -> OrderState.CHARGE_REJECTED
      */
      .on(Event.PAYMENT_REQUESTED, OrderPaymentCreateCommand);

    StateMachine
      /*
        OrderState.CHARGE_REJECTED
          (transitionToInitializeCancelled) -> OrderState.INITIALIZE_CANCELLED
      */
      .on(Event.PAYMENT_REJECTED, OrderInitializeFailedCommand);

    StateMachine
      /*
        OrderState.CHARGE_PENDING
          (Adapter::replyPaymentFailed) -> OrderState.CHARGE_FAILED
      */
      .on(Event.REPLY_PAYMENT_FAILED, OrderPaymentFailedCommand)
      /*
        OrderState.CHARGE_PENDING
          (Adapter::replyPaymentCompleted) -> OrderState.CHARGE_COMPLETED
      */
      .on(Event.REPLY_PAYMENT_COMPLETED, OrderBookingStartCommand);
  }

  static transitionToChargeInitialized(order) {
    if (order.state !== OrderState.INITIATED)
      throw new Error("invalid state transition");

    order.state = OrderState.CHARGE_INITIALIZED;

    publish(Event.PAYMENT_REQUESTED, order);
  }

  static replyTransitionToChargePending(order) {
    if (order.state !== OrderState.CHARGE_INITIALIZED)
      throw new Error("invalid state transition");

    order.state = OrderState.CHARGE_PENDING;
  }

  static transitionToChargeRejected(order) {
    if (order.state !== OrderState.CHARGE_INITIALIZED)
      throw new Error("invalid state transition");

    order.state = OrderState.CHARGE_REJECTED;

    publish(Event.PAYMENT_REJECTED, order);
  }

  static finalTransitionToInitializeCancelled(order) {
    if (order.state !== OrderState.CHARGE_REJECTED)
      throw new Error("invalid state transition");

    order.state = OrderState.INITIALIZE_CANCELLED;
  }
}

const PaymentMethodEvent = {
  BPR_PAYMENT_COMPLETED: "BPR_PAYMENT_COMPLETED",
  BAAS_PAYMENT_COMPLETED: "BAAS_PAYMENT_COMPLETED",
};