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/**
 * Copyright (c) 2009, Jardel Weyrich <jweyrich@gmail.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

using System;
using System.Linq;
using System.Linq.Expressions;

namespace System.Linq
{
	public static class IQueryableOrderExtension
	{
		private static Expression<Func<T, object>> GetLambdaExpression<T>(this IQueryable<T> source, string property) {
			// The 1st lambda's parameter (obj =>)
			var param1 = Expression.Parameter(typeof(T), "obj");
			// Split member's name
			string[] properties = property.Split('.');
			// The 2nd lambda's parameter (obj.member1.member2)
			var param2 = Expression.Property(param1, properties[0]);
			for (int i = 1; i < properties.Length; i++) {
				param2 = Expression.Property(param2, properties[i]);
			}
			// Put it all together (obj => obj.member1.member2)
			return Expression.Lambda<Func<T, object>>(
				Expression.Convert(param2, typeof(object)), param1);
		}

		public static IOrderedQueryable<T> OrderBy<T>(this IQueryable<T> source, string property, bool descending) {
			var expression = GetLambdaExpression(source, property);
			return (descending)
				? source.OrderByDescending<T, object>(expression)
				: source.OrderBy<T, object>(expression);
		}

		public static IOrderedQueryable<T> OrderBy<T>(this IQueryable<T> source, string property) {
			return OrderBy(source, property, false);
		}

		public static IOrderedQueryable<T> ThenBy<T>(this IOrderedQueryable<T> source, string property, bool descending) {
			var expression = GetLambdaExpression(source, property);
			return (descending)
				? source.ThenByDescending<T, object>(expression)
				: source.ThenBy<T, object>(expression);
		}

		public static IOrderedQueryable<T> ThenBy<T>(this IOrderedQueryable<T> source, string property) {
			return ThenBy(source, property, false);
		}
	}
}