using Ant.Common;
using Ant.ORM;
using Ant.Utility;
using System;
using System.Collections.Generic;
using System.Linq;

namespace Ant.DbExpressions
{
    /// <summary>
    /// 
    /// </summary>
    public class DbSqlQueryExpression : DbExpression
    {
        /// <summary>
        /// 数据库SQL解析
        /// </summary>
        public DbSqlQueryExpression()
            : base(DbExpressionType.SqlQuery, UtilConstants.TypeOfVoid)
        {
            this.ColumnSegments = new List<DbColumnSegment>();
            this.GroupSegments = new List<DbExpression>();
            this.Orderings = new List<DbOrdering>();
        }
        /// <summary>
        /// TOP条数
        /// </summary>
        public int? TakeCount { get; set; }
        /// <summary>
        /// 跳过用于分页
        /// </summary>
        public int? SkipCount { get; set; }
        /// <summary>
        /// 所有列
        /// </summary>
        public List<DbColumnSegment> ColumnSegments { get; private set; }
        /// <summary>
        /// 表名
        /// </summary>
        public DbFromTableExpression Table { get; set; }
        /// <summary>
        /// 查询条件
        /// </summary>
        public DbExpression Condition { get; set; }

        /// <summary>
        /// 拼接查询条件
        /// </summary>
        public IPredicate Predicate
        {
            get;
            set;
        }

        /// <summary>
        /// 分组列表
        /// </summary>
        public List<DbExpression> GroupSegments { get; private set; }
        /// <summary>
        /// 分组条件
        /// </summary>
        public DbExpression HavingCondition { get; set; }
        /// <summary>
        /// 排序
        /// </summary>
        public List<DbOrdering> Orderings { get; private set; }
        /// <summary>
        /// 
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="visitor"></param>
        /// <returns></returns>
        public override T Accept<T>(DbExpressionVisitor<T> visitor)
        {
            return visitor.Visit(this);
        }
    }
}