Search for orders using abstractions

/// <summary>
     /// Finds orders with a specific <see cref="OrderSearchFilter"/> for a specific <typeparamref name="TOrderGroup"/>.
     /// </summary>
     /// <typeparam name="TOrderGroup">The given order type for filter.</typeparam>
     /// <param name="filter">The search filter.</param>
     /// <returns>The order search results.</returns>
            OrderSearchResults Find(OrderSearchFilter filter) where TOrderGroup : class, IOrderGroup;

using EPiServer.Framework;
    using EPiServer.ServiceLocation;
    using Mediachase.Commerce.Orders;
    using Mediachase.Commerce.Orders.Search;
    using Mediachase.MetaDataPlus.Extensions;
    using System;
    using System.Linq;
    
    namespace EPiServer.Commerce.Order.Internal
      {
        /// <summary>
        /// This class is intended to be used internally by EPiServer.
        /// We do not support any backward compatibility on this.
        /// 
        /// Default implementation of .
        /// </summary>
        [ServiceConfiguration(ServiceType = typeof(IOrderSearchService), Lifecycle = ServiceInstanceScope.Singleton)]
        public class DefaultOrderSearchService : IOrderSearchService
          {
            private readonly ICartSearchService _cartSearch;
    
            public DefaultOrderSearchService(ICartSearchService cartSearch)
              {
                Validator.ThrowIfNull(nameof(cartSearch), cartSearch);
                _cartSearch = cartSearch;
              }
    
            public virtual OrderSearchResults Find(OrderSearchFilter filter) where TOrderGroup : class, IOrderGroup
              {
                Validator.ThrowIfNull(nameof(filter), filter);
                var type = typeof(TOrderGroup);
                if (IsCart(type))
                  {
                    var carts = _cartSearch.FindCarts(filter.CreatedFrom, filter.CreatedTo,
                                filter.MarketId, filter.StartingIndex ?? 0,
                                filter.RecordsToRetrieve ?? int.MaxValue,
                                out int totalRecords).OfType();
                    return new OrderSearchResults(carts, totalRecords);
                  }
    
                string sqlMetaWhereClause = $@"(META.Created BETWEEN '{(filter.CreatedFrom ?? DateTime.MinValue.TruncateToSqlDateTimeRange()).ToString("s")}' 
                                                                 AND '{(filter.CreatedTo ?? DateTime.MaxValue.TruncateToSqlDateTimeRange()).ToString("s")}')";
    
                sqlMetaWhereClause += $@" AND (META.Modified BETWEEN '{(filter.ModifiedFrom ?? DateTime.MinValue.TruncateToSqlDateTimeRange()).ToString("s")}' 
                                                                 AND '{(filter.ModifiedTo ?? DateTime.MaxValue.TruncateToSqlDateTimeRange()).ToString("s")}')";
    
                var parameters = new OrderSearchParameters() { SqlMetaWhereClause = sqlMetaWhereClause};
    
                if (!string.IsNullOrEmpty(filter.MarketId))
                  {
                    parameters.SqlWhereClause = $"MarketId = '{filter.MarketId}'";
                  }
    
                var options = new OrderSearchOptions
                  {
                    StartingRecord = filter.StartingIndex ?? 0,
                    RecordsToRetrieve = filter.RecordsToRetrieve ?? int.MaxValue
                  };
    
                if (IsPurchaseOrder(type))
                  {
                    options.Classes.Add(OrderContext.Current.PurchaseOrderMetaClass.Name);
                    var orders = OrderContext.Current.FindPurchaseOrders(parameters, options, out int totalRecords).OfType();
                    return new OrderSearchResults(orders, totalRecords);
                  }
    
                if (IsPaymentPlan(type))
                  {
                    options.Classes.Add(OrderContext.Current.PaymentPlanMetaClass.Name);
                    var paymentplans = OrderContext.Current.FindPaymentPlans(parameters, options, out int totalRecords).OfType();
                    return new OrderSearchResults(paymentplans, totalRecords);
                  }
    
                throw new InvalidOperationException($"The type {typeof(TOrderGroup)} is not supported.");
              }
    
            private static bool IsCart(Type type)
              {
                return typeof(ICart).IsAssignableFrom(type);
              }
    
            private static bool IsPurchaseOrder(Type type)
              {
                return typeof(IPurchaseOrder).IsAssignableFrom(type);
              }
    
            private static bool IsPaymentPlan(Type type)
              {
                return typeof(IPaymentPlan).IsAssignableFrom(type);
              }
          }
      }

var orderFilter = new OrderSearchFilter
      {
        CreatedFrom = DateTime.UtcNow.AddDays(-365),
        CreatedTo = DateTime.UtcNow
      };
    var orderSearchService = ServiceLocator.Current.GetInstance<IOrderSearchService>();
    var searchResult = orderSearchService.FindPurchaseOrders(orderFilter);
    var orders = searchResult.Orders;
    var totalRecords = searchResult.TotalRecords;