using System;
using System.Collections;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

namespace PosDataTest
{
    class DataTableHelper
    {
        #region DataTable相关
        /// <summary>
        /// 数据行对象转化成泛型
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="dt"></param>
        /// <returns></returns>
        public static IList DataTableToIList<T>(DataTable dt)
        {
            IList list = new List<T>();
            string tempName = "";
            foreach (DataRow dr in dt.Rows)
            {
                T obj = Activator.CreateInstance<T>();
                PropertyInfo[] propertys = obj.GetType().GetProperties();
                foreach (PropertyInfo pi in propertys)
                {
                    tempName = pi.Name;
                    if (dt.Columns.Contains(tempName) && pi.CanWrite)
                    {
                        object value = dr[tempName];
                        if (value != DBNull.Value)
                        {
                            pi.SetValue(obj, value, null);
                        }
                    }
                }
                list.Add(obj);
            }
            return list;
        }
        /// <summary>
        /// 分解数据表
        /// </summary>
        /// <param name="originalTab">需要分解的表</param>
        /// <param name="rowsNum">每个表包含的数据量</param>
        /// <returns></returns>
        public DataSet SplitDataTable(DataTable originalTab, int rowsNum)
        {
            //获取所需创建的表数量
            int tableNum = (int)Math.Ceiling((decimal)originalTab.Rows.Count / rowsNum);
            //获取数据余数
            int remainder = originalTab.Rows.Count % rowsNum;

            DataSet ds = new DataSet();

            //如果只需要创建1个表，直接将原始表存入DataSet
            //if (originalTab.Rows.Count <= rowsNum)
            //{
            //    ds.Tables.Add(originalTab);
            //}
            //else
            //{
            DataTable[] tableSlice = new DataTable[tableNum];

            //Save orginal columns into new table.            
            for (int c = 0; c < tableNum; c++)
            {
                tableSlice[c] = originalTab.Clone();
            }
            //Import Rows
            for (int i = 0; i < tableNum; i++)
            {
                // if the current table is not the last one
                //if (i != tableNum - 1)
                //{
                for (int j = i * rowsNum; j < ((i + 1) * rowsNum); j++)
                {
                    if (j >= originalTab.Rows.Count)
                    {
                        break;
                    }
                    tableSlice[i].ImportRow(originalTab.Rows[j]);
                }
                //}
                //else
                //{
                //    for (int k = i * rowsNum; k < ((i + 1) * rowsNum + remainder); k++)
                //    {
                //        tableSlice[i].ImportRow(originalTab.Rows[k]);
                //    }
                //}
            }

            //add all tables into a dataset                
            foreach (DataTable dt in tableSlice)
            {
                ds.Tables.Add(dt);
            }
            //}
            return ds;
        }
        /// <summary>
        /// 获取列名
        /// </summary>
        /// <param name="Table"></param>
        /// <returns></returns>
        internal string SqlColumns(DataTable Table)
        {
            string _Columnsstr = "";
            foreach (DataColumn col in Table.Columns)
            {
                _Columnsstr += (_Columnsstr == "" ? col.ColumnName : "," + col.ColumnName);
            }
            return _Columnsstr;
        }
        /// <summary>
        /// 获取行值
        /// </summary>
        /// <param name="Table"></param>
        /// <param name="Row"></param>
        /// <returns></returns>
        internal string SqlValues(DataTable Table, DataRow Row)
        {
            string _valuesstr = "";
            for (int i = 0; i < Table.Columns.Count; i++)
            {
                if (Table.Columns[i].DataType.ToString() == "System.Decimal")
                {
                    _valuesstr += _valuesstr == "" ? (Row[i].ToString() == "" ? "NULL" : Row[i].ToString()) : "," + (Row[i].ToString() == "" ? "NULL" : Row[i].ToString());
                }
                else if (Table.Columns[i].DataType.ToString() == "System.DateTime")
                {
                    _valuesstr += _valuesstr == "" ? (Row[i].ToString() == "" ? "NULL" : "TO_DATE('" + Row[i].ToString() +
                        "','YYYY/MM/DD HH24:MI:SS')") : "," + (Row[i].ToString() == "" ? "NULL" : "TO_DATE('" + Row[i].ToString() + "','YYYY/MM/DD HH24:MI:SS')");
                }
                else
                {
                    _valuesstr += _valuesstr == "" ? (Row[i].ToString() == "" ? "NULL" : "'" + Row[i].ToString()) + "'" : "," + (Row[i].ToString() == "" ? "NULL" : "'" + Row[i].ToString() + "'");
                }
            }
            return _valuesstr;
        }

        /// <summary>
        /// 转换DataTable字段类型
        /// </summary>
        /// <param name="table"></param>
        /// <returns></returns>
        public static DataTable ConvertOraclTableToDoNetTable(DataTable table)
        {
            DataTable dt = new DataTable();
            foreach (DataColumn dc in table.Columns)
            {
                DataColumn column = new DataColumn();
                column.DataType = GetDataType(dc.DataType);
                column.ColumnName = dc.ColumnName;
                column.Caption = dc.Caption;
                dt.Columns.Add(column);
            }
            dt.TableName = table.TableName;
            dt.Merge(table, false, MissingSchemaAction.Ignore);
            return dt;
        }
        /// <summary>
        /// 字段类型
        /// </summary>
        /// <param name="dataType"></param>
        /// <returns></returns>
        public static Type GetDataType(Type dataType)
        {
            switch (dataType.ToString())
            {
                case "System.Double":
                    return System.Type.GetType("System.Decimal");
                case "System.Int32":
                    return System.Type.GetType("System.Decimal");
                case "System.Int16":
                    return System.Type.GetType("System.Decimal");
                case "System.Int64":
                    return System.Type.GetType("System.Decimal");
                default:
                    return dataType;
            }
        }
        #endregion
    }
}