/*******************************************************************************
 * Copyright © 2016 HT.Cloud.Framework 版权所有
 * Author: HT.Cloud
 * Description: WaterCloud快速开发平台
 * Website：
*********************************************************************************/

using System;
using System.Data;
using System.Text;

namespace HT.Cloud.Code
{
	public static partial class Extensions
	{
		/// <summary>
		/// 获取表里某页的数据
		/// </summary>
		/// <param name="data">表数据</param>
		/// <param name="pageIndex">当前页</param>
		/// <param name="pageSize">分页大小</param>
		/// <param name="allPage">返回总页数</param>
		/// <returns>返回当页表数据</returns>
		public static DataTable GetPage(this DataTable data, int pageIndex, int pageSize, out int allPage)
		{
			allPage = data.Rows.Count / pageSize;
			allPage += data.Rows.Count % pageSize == 0 ? 0 : 1;
			DataTable Ntable = data.Clone();
			int startIndex = pageIndex * pageSize;
			int endIndex = startIndex + pageSize > data.Rows.Count ? data.Rows.Count : startIndex + pageSize;
			if (startIndex < endIndex)
				for (int i = startIndex; i < endIndex; i++)
				{
					Ntable.ImportRow(data.Rows[i]);
				}
			return Ntable;
		}

		/// <summary>
		/// 根据字段过滤表的内容
		/// </summary>
		/// <param name="data">表数据</param>
		/// <param name="condition">条件</param>
		/// <returns></returns>
		///
		public static DataTable GetDataFilter(DataTable data, string condition)
		{
			if (data != null && data.Rows.Count > 0)
			{
				if (condition.Trim() == "")
				{
					return data;
				}
				else
				{
					DataTable newdt = new DataTable();
					newdt = data.Clone();
					DataRow[] dr = data.Select(condition);
					for (int i = 0; i < dr.Length; i++)
					{
						newdt.ImportRow((DataRow)dr[i]);
					}
					return newdt;
				}
			}
			else
			{
				return null;
			}
		}

        /// <summary>
        /// 转换为json字符串
        /// </summary>
        /// <returns></returns>
        ///
        public static string ToJson(this DataTable dt)
        {
            StringBuilder jsonString = new StringBuilder();
            jsonString.Append("[");
            DataRowCollection drc = dt.Rows;
            for (int i = 0; i < drc.Count; i++)
            {
                jsonString.Append("{");
                for (int j = 0; j < dt.Columns.Count; j++)
                {
                    string strKey = dt.Columns[j].ColumnName;
                    string strValue = drc[i][j].ToString();
                    Type type = dt.Columns[j].DataType;
                    jsonString.Append("\"" + strKey + "\":");
                    strValue = String.Format(strValue, type);
                    if (j < dt.Columns.Count - 1)
                    {
                        jsonString.Append(strValue + ",");
                    }
                    else
                    {
                        jsonString.Append(strValue);
                    }
                }
                jsonString.Append("},");
            }
            if (jsonString.Length > 1)
            {
                jsonString.Remove(jsonString.Length - 1, 1);
            }
            jsonString.Append("]");
            return jsonString.ToString();
        }
    }
}