Initial commit

GerstITS.Examples.Logic/Shared/Search/Sorting/SortingProvider.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Reflection;
+using GerstITS.Common;
+using GerstITS.Search;
+
+namespace GerstITS.Examples.Logic.Shared.Search.Sorting
+{
+    internal class SortingProvider : ISortingProvider
+    {
+        #region ISortingProvider
+
+        public bool CanSort<TItem>(IQueryable<TItem> query)
+        {
+            return typeof(TItem).IsAssignableTo(typeof(ISortable));
+        }
+
+        public IQueryable<TItem> Sort<TItem>(IQueryable<TItem> query, ISorting sorting)
+        {
+            var propertyInfo = typeof(TItem).GetProperties()
+                                            .SingleOrDefault(i => string.Equals(i.Name, sorting.SortBy, StringComparison.InvariantCultureIgnoreCase));
+
+            if (!CanSort(query) || propertyInfo.IsNull())
+                return query;
+
+            var sortExpression = CreateSortExpression<TItem>(propertyInfo);
+
+            return (sorting.SortDirection == SortingDirections.Ascending
+                    ? query.OrderBy(sortExpression)
+                    : query.OrderByDescending(sortExpression))
+                .AsQueryable();
+        }
+
+        #endregion
+
+        #region Methods
+
+        private static Expression<Func<TItem, object>> CreateSortExpression<TItem>(MemberInfo propertyInfo)
+        {
+            var parameterExpression = Expression.Parameter(typeof(TItem), "x");
+            var propertyExpression = Expression.Property(parameterExpression, propertyInfo.Name);
+            var convertExpression = Expression.Convert(propertyExpression, typeof(object));
+
+            return Expression.Lambda<Func<TItem, object>>(convertExpression, parameterExpression);
+        } 
+        
+        #endregion
+    }
+}