register-customer.command-handler.ts

interface Dependencies {
  customerRepository: CustomerRepository;
}

class RegisterCustomerCommandHandler extends CommandHandler<
  RegisterCustomerCommand
> {
  constructor(private readonly dependencies: Dependencies) {
    super(REGISTER_CUSTOMER_COMMAND_TYPE);
  }

  public async execute({ payload }: RegisterCustomerCommand) {
    const { customerRepository } = this.dependencies;
    const { email } = payload;

    const existingUser = await customerRepository.findByEmail(email);

    if (existingUser) {
      throw new Error(`User with email: "${email}" already exist.`);
    }

    await customerRepository.insert(payload);
  }
}