using System.Linq.Expressions;
using HealthMonitor.Util.QueryObjects;

namespace HealthMonitor.Core.Query.Extensions
{
    public static class OrderConditionsExt
    {
        public static IQueryable<T> OrderConditions<T>(this IQueryable<T> query, IEnumerable<OrderByCondition> conditions)
        {
            if (conditions == null) return query;

            foreach (var orderinfo in conditions)
            {
                try
                {
                    var parameter = Expression.Parameter(typeof(T));
                    Expression propertySelector = Expression.Property(parameter, orderinfo.Key);

                    //需要用Expression.Convert转换为object表达式，不然值类型的排序会报错
                    var orderby = Expression.Lambda<Func<T, object>>(Expression.Convert(propertySelector, typeof(object)), parameter);
                    if (orderinfo.IsDesc)
                        query = query.OrderByDescending(orderby);
                    else
                        query = query.OrderBy(orderby);
                }
                catch (Exception)
                {
                    continue;
                }
            }
            return query;
        }
    }
}