Strategic Vision.
Relentless Execution.

// Domain-Driven Design: Order Processing Service
export class OrderService {
    constructor(
        private readonly paymentGateway: IPaymentGateway,
        private readonly orderRepository: IOrderRepository,
        private readonly eventBus: IEventBus
    ) {}

    async processCheckout(orderId: string): Promise<Result<Order, Error>> {
        // 1. Rehydrate aggregate root from event stream
        const order = await this.orderRepository.getById(orderId);
        if (!order) return Result.Fail(new OrderNotFoundError(orderId));

        // 2. Enforce invariants & domain rules
        if (!order.canBeProcessed()) {
            return Result.Fail(new InvalidOrderStateError());
        }

        // 3. Interface-driven external integration (Hexagonal Architecture)
        const paymentResult = await this.paymentGateway.charge(order.amount);
        if (paymentResult.isFailure) return Result.Fail(paymentResult.error);

        // 4. Mutate state & persist
        order.markAsPaid();
        await this.orderRepository.save(order);

        // 5. Publish domain events to async message bus
        await this.eventBus.publish(new OrderPaidEvent(order.id));

        return Result.Ok(order);
    }
}