CustomPromotion-Processor.cs

    public class MyCustomDiscountProcessor : BuyQuantityGetItemDiscountProcessor
    {
        private readonly IAccountManager _accountManager;

        public MyCustomDiscountProcessor(CollectionTargetEvaluator targetEvaluator,
            FulfillmentEvaluator fulfillmentEvaluator, LocalizationService localizationService,
            RedemptionDescriptionFactory redemptionDescriptionFactory, IAccountManager accountManager)
            : base(targetEvaluator, fulfillmentEvaluator, localizationService, redemptionDescriptionFactory)
        {
            this._accountManager = accountManager;
        }

        protected override bool CanBeFulfilled(BuyQuantityGetItemDiscount promotionData, PromotionProcessorContext context)
        {
            //We need to check whether the promotion is our extension
            MyCustomDiscount myCustomDiscount;
            if (promotionData is MyCustomDiscount)
            {
                //We cast it
                myCustomDiscount = promotionData as MyCustomDiscount;
                
                //Here we can include our custom logic to decide if we apply the promotion, or not
                if (myCustomDiscount.AccountNumber.IsNullOrEmpty())
                    return false;

                //We get the AccountNumber from our AccountManager
                string accountNumber = this._accountManager.GetAccountNumber();

                if (accountNumber == null)
                    return false;

                //And we compare it with the one on the Promotion
                if (myCustomDiscount.AccountNumber != accountNumber)
                    return false;   
            }
            
            

            //We fulfill the base type as well
            return base.CanBeFulfilled(promotionData, context);
        }
    }