using System;
using System.Data.Objects;
using System.Data.Objects.DataClasses;
using System.Linq.Expressions;
using System.Reflection;


namespace Test.DataAccess
{
	/// <summary>
	/// See http://msmvps.com/blogs/matthieu/archive/2008/06/06/entity-framework-include-with-func-next.aspx
	/// </summary>
	public static class ObjectQueryExtension
	{
		public static ObjectQuery<T> Include<T>(this ObjectQuery<T> mainQuery, Expression<Func<T, object>> subSelector)
		{
			return mainQuery.Include(FuncToString(subSelector.Body));
		}
		private static string FuncToString(Expression selector)
		{
			switch (selector.NodeType)
			{
				case ExpressionType.MemberAccess:
					return ((selector as MemberExpression).Member as PropertyInfo).Name;
				case ExpressionType.Call:
					var method = selector as MethodCallExpression;
					return FuncToString(method.Arguments[0]) + "." + FuncToString(method.Arguments[1]);
				case ExpressionType.Quote:
					return FuncToString(((selector as UnaryExpression).Operand as LambdaExpression).Body);
			}
			throw new InvalidOperationException();
		}
		public static K Include<T, K>(this EntityCollection<T> mainQuery, Expression<Func<T, object>> subSelector)
			where T : EntityObject, IEntityWithRelationships
			where K : class
		{
			return null;
		}
		public static K Include<T, K>(this T mainQuery, Expression<Func<T, object>> subSelector)
			where T : EntityObject
			where K : class
		{
			return null;
		}
	}

}

// I'm getting a very strange compilation error because of extension methods.
// "Missing compiler required member 'System.Runtime.CompilerServices.ExtensionAttribute..ctor'"
// http://stackoverflow.com/questions/205644/error-when-using-extension-methods-in-c
// This seems to fix it...
// Sometimes it works without it (which is why you may see it commented out here...)
namespace System.Runtime.CompilerServices
{
	public class ExtensionAttribute : Attribute { }
}