using System;
using System.Linq;
using System.Linq.Expressions;
using System.Reflection;
using SqlSugar;

namespace JSMachine.WMS.Infrastructure.LambdaHelp
{
    public static class OrderExpression
    {
        public static ISugarQueryable<T> OrderByLambda<T>(this ISugarQueryable<T> source, string property, OrderByType orderByType)
        {
            return ApplyOrder<T>(source, property, orderByType.ToString());
        }

        static ISugarQueryable<T> ApplyOrder<T>(ISugarQueryable<T> source, string property, string methodName)
        {
            string[] props = property.Split('.');
            Type type = typeof(T);
            ParameterExpression arg = Expression.Parameter(type, "x");
            Expression expr = arg;
            foreach (string prop in props)
            {
                // use reflection (not ComponentModel) to mirror LINQ
                PropertyInfo pi = type.GetProperty(prop);
                expr = Expression.Property(expr, pi);
                type = pi.PropertyType;
            }
            Type delegateType = typeof(Func<,>).MakeGenericType(typeof(T), type);
            LambdaExpression lambda = Expression.Lambda(delegateType, expr, arg);

            object result = typeof(Queryable).GetMethods().Single(
                    method => method.Name == methodName
                            && method.IsGenericMethodDefinition
                            && method.GetGenericArguments().Length == 2
                            && method.GetParameters().Length == 2)
                    .MakeGenericMethod(typeof(T), type)
                    .Invoke(null, new object[] { source, lambda });
            return (ISugarQueryable<T>)result;
        }
    }
}