CalculateCartVIPBlock.cs

namespace Sitecore.Commerce.Plugin.AdventureWorks.Pipelines.Blocks
{
    using System;
    using System.Linq;
    using System.Threading.Tasks;

    using Sitecore.Commerce.Core;
    using Sitecore.Commerce.Plugin.AdventureWorks.Components;
    using Sitecore.Commerce.Plugin.Carts;
    using Sitecore.Commerce.Plugin.Pricing;
    using Sitecore.Framework.Pipelines;

    /// <summary>
    /// The calculate cart block.
    /// </summary>
    public class CalculateCartVIPBlock : PipelineBlock<Cart, Cart, CommercePipelineExecutionContext>
    {
        /// <summary>
        /// Initializes a new instance of the <see cref="CalculateCartVIPBlock"/> class.
        /// </summary>
        /// <param name="persistEntityPersistEntityPipeline">
        /// The persist entity persist entity pipeline.
        /// </param>
        /// <param name="findEntityPipeline">
        /// The find entity pipeline.
        /// </param>
        /// <param name="serviceProvider">
        /// The service provider.
        /// </param>
        public CalculateCartVIPBlock(
            IPersistEntityPipeline persistEntityPersistEntityPipeline,
            IFindEntityPipeline findEntityPipeline,
            IServiceProvider serviceProvider)
        {

        }

        /// <summary>
        /// The run.
        /// </summary>
        /// <param name="arg">
        /// The arg.
        /// </param>
        /// <param name="context">
        /// The context.
        /// </param>
        /// <returns>
        /// The <see cref="Task"/>.
        /// </returns>
        public override Task<Cart> Run(Cart arg, CommercePipelineExecutionContext context)
        {
            /*
             * This block will be called anytime the cart is recalculated. We can now 
             * retrieve the flag on the cart and if its true do something like call a webservice that contains the VIP discount logic.
             * You could also have another block on the calculate line if the discount was set at a line level
             */
            const string AdjustmentType = "VIP";
            const string AdjustementName = "VIP Discount";

            var vipDiscountApplied = arg.Adjustments.FirstOrDefault(x => x.AdjustmentType == AdjustmentType);

            if (arg.GetComponent<CartVIPStatusComponent>().ApplyVipPricing == false)
            {
                if (vipDiscountApplied != null)
                {
                    arg.Adjustments.Remove(vipDiscountApplied);
                }

                return Task.FromResult(arg);
            }

            // Do your custom discount calculation here
            var amount = arg.Totals.SubTotal.Amount * ((decimal)0.20);
            var adjustment = new Money(context.CommerceContext.CurrentCurrency(), amount * -1);

            if (vipDiscountApplied != null)
            {
                vipDiscountApplied.Adjustment = adjustment;
            }
            else
            {
                // All the setup information should come from a policy or another system
                var awarededAdjustment = new CartLevelAwardedAdjustment
                                             {
                                                 Name = AdjustementName,
                                                 DisplayName = AdjustementName,
                                                 Adjustment = adjustment,
                                                 AdjustmentType = AdjustmentType,
                                                 AwardingBlock = this.Name,
                                                 IncludeInGrandTotal = true,
                                                 IsTaxable = false
                                             };

                arg.Adjustments.Add(awarededAdjustment);
            }

            return Task.FromResult(arg);
        }
    }
}