using System;
using System.Collections.Generic;
using System.Linq;
using System.Linq.Expressions;
using System.Text;
using System.Threading.Tasks;

namespace wispro.sp.utility
{
    public class ConditionTreeNode
    {
        public ConditionTreeNode Right { get; set; }
        public ConditionTreeNode Left { get; set; }
    }

    public class OperateNode : ConditionTreeNode
    {
        public LogicEnum Operator { get; set; }

    }

    public class FieldConditionNode : ConditionTreeNode
    {
        public FieldCondition FieldCondition { get; set; }
    }

    public class OrderField { 
        /// <summary>
        /// 排序栏位
        /// </summary>
        public string FieldName { get; set; }

        /// <summary>
        /// 排序 0：顺序；1：倒序
        /// </summary>
        public int Sort { get; set; }
    }
    public class FieldCondition
    {
        /// <summary>
        /// 字段名称
        /// </summary>
        public string FieldName { get; set; }
        /// <summary>
        /// 值
        /// </summary>
        public string Value { get; set; }
        /// <summary>
        /// 值类型
        /// </summary>
        public string ValueType { get; set; }
        /// <summary>
        /// 
        /// </summary>
        public OperatorEnum Operator { get; set; }
    }

    public enum OperatorEnum
    {
        Contains,
        Equal,
        Greater,
        GreaterEqual,
        Less,
        LessEqual,
        NotEqual,
        In,
        Between,
        StartsWith,
        EndWith,
        NotContains
    }

    public enum LogicEnum
    {
        And,
        Or
    }

    public static class EFCoreExt
    {
        public static IQueryable<T> OrderConditions<T>(this IQueryable<T> query, IList<OrderField> orderConditions)
        {
            foreach (var orderinfo in orderConditions)
            {
                var t = typeof(T);
                var propertyInfo = t.GetProperty(orderinfo.FieldName);
                var parameter = Expression.Parameter(t);
                Expression propertySelector = Expression.Property(parameter, propertyInfo);

                var orderby = Expression.Lambda<Func<T, object>>(propertySelector, parameter);
                if (orderinfo.Sort == 1)
                    query = query.OrderByDescending(orderby);
                else
                    query = query.OrderBy(orderby);

            }
            return query;
        }

        public static IQueryable<T> Pager<T>(this IQueryable<T> query, int pageindex, int pagesize, out int itemCount)
        {
            itemCount = query.Count();
            return query.Skip((pageindex - 1) * pagesize).Take(pagesize);
        }
    }
}