using System;
using System.Text;
using System.Data.Common;
using Wood.Util;
using System.Text.RegularExpressions;
using Newtonsoft.Json.Linq;

namespace Wood.Data.Repository
{
	public class DatabasePageExtension
	{
		public static StringBuilder SqlServerPageSql(string strSql, string sort, int pageSize, int pageIndex)
		{
			CheckSqlParam(sort);

			StringBuilder sb = new StringBuilder();
			if (pageIndex == 0)
			{
				pageIndex = 1;
			}
			int startNum = (pageIndex - 1) * pageSize;
			int endNum = (pageIndex) * pageSize;
			string orderBy = string.Empty;

			if (!string.IsNullOrEmpty(sort))
			{

				orderBy = " ORDER BY " + sort;
			}
			else
			{
				orderBy = "ORDERE BY (SELECT 0)";
			}
			sb.Append("SELECT * FROM (SELECT ROW_NUMBER() Over (" + orderBy + ")");
			sb.Append(" AS ROWNUM, * From (" + strSql + ") t ) AS N WHERE ROWNUM > " + startNum + " AND ROWNUM <= " + endNum + "");
			return sb;
		}

		public static StringBuilder OraclePageSql(string strSql, string sort, int pageSize, int pageIndex)
		{
			CheckSqlParam(sort);

			StringBuilder sb = new StringBuilder();
			if (pageIndex == 0)
			{
				pageIndex = 1;
			}
			int startNum = (pageIndex - 1) * pageSize;
			int endNum = (pageIndex) * pageSize;
			string orderBy = string.Empty;

			if (!string.IsNullOrEmpty(sort))
			{
				orderBy = " ORDER BY " + sort;
			}
			sb.Append("SELECT * From (SELECT ROWNUM AS n,");
			sb.Append(" T.* From (" + strSql + orderBy + ") t )  N WHERE n > " + startNum + " AND n <= " + endNum + "");
			return sb;
		}

		public static StringBuilder MySqlPageSql(string strSql, string sort, int pageSize, int pageIndex)
		{
			CheckSqlParam(sort);

			StringBuilder sb = new StringBuilder();
			if (pageIndex == 0)
			{
				pageIndex = 1;
			}
			int num = (pageIndex - 1) * pageSize;
			string orderBy = string.Empty;

			if (!string.IsNullOrEmpty(sort))
			{
				orderBy = " ORDER BY " + sort;
			}
			sb.Append(strSql + orderBy);
			sb.Append(" LIMIT " + num + "," + pageSize + "");
			return sb;
		}

		public static string GetCountSql(string strSql)
		{
			string countSql = string.Empty;
			string strSqlCopy = strSql.ToLower();
			int selectIndex = strSqlCopy.IndexOf("SELECT ");
			int lastFromIndex = strSqlCopy.LastIndexOf(" FROM ");
			if (selectIndex >= 0 && lastFromIndex >= 0)
			{
				int backFromIndex = strSqlCopy.LastIndexOf(" FROM ", lastFromIndex);
				int backSelectIndex = strSqlCopy.LastIndexOf("SELECT ", lastFromIndex);
				if (backSelectIndex == selectIndex)
				{
					countSql = "SELECT COUNT(*) " + strSql.Substring(lastFromIndex);
					return countSql;
				}
			}
			countSql = "SELECT COUNT(1) FROM (" + strSql + ") t";
			return countSql;
		}

		private static void CheckSqlParam(string param)
		{
			if (!Regex.IsMatch(param, @"[-|;|,|\/|\(|\)|\[|\]|\}|\{|%|@|\*|!|\']"))
			{
				throw new ArgumentException("含有Sql注入的参数");
			}
		}
	}
}