using NPOI.HSSF.UserModel;
using NPOI.XSSF.UserModel;
using System;
using System.Data;
using System.IO;

namespace MainForm.ClassFile
{
    /// <summary>
    /// EXCEL操作类
    /// </summary>
    public class NPOIHelper
    {
        /// <summary>
        /// 读取指定路径的Excel文件到DataTable
        /// </summary>
        /// <param name="filePath"></param>
        /// <returns></returns>
        public static DataTable ReadExcel(string filePath)
        {
            NPOI.SS.UserModel.ISheet sheet;
            if (filePath.Contains(".xlsx"))  // 2007 xlsx
            {
                #region//初始化信息
                XSSFWorkbook hssfworkbook;
                try
                {
                    using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
                    {
                        hssfworkbook = new XSSFWorkbook(file);
                    }
                }
                catch (Exception e)
                {
                    throw e;
                }
                sheet = hssfworkbook.GetSheetAt(0);
                #endregion
                System.Collections.IEnumerator rows = sheet.GetRowEnumerator();
                DataTable dt = new DataTable();
                for (int j = 0; j < (sheet.GetRow(0).LastCellNum); j++)  // cell数
                {
                    dt.Columns.Add(Convert.ToChar(((int)'A') + j).ToString());
                }
                while (rows.MoveNext())
                {
                    XSSFRow row = (XSSFRow)rows.Current;
                    DataRow dr = dt.NewRow();
                    for (int i = 0; i < row.LastCellNum; i++)
                    {
                        NPOI.SS.UserModel.ICell cell = row.GetCell(i);
                        if (cell == null)
                        {
                            dr[i] = null;
                        }
                        else
                        {
                            dr[i] = cell.ToString();
                        }
                    }
                    dt.Rows.Add(dr);
                }
                return dt;
            }
            else  // 2003 xls
            {
                HSSFWorkbook hssfworkbook;
                try
                {
                    using (FileStream file = new FileStream(filePath, FileMode.Open, FileAccess.Read))
                    {
                        hssfworkbook = new HSSFWorkbook(file);
                    }
                }
                catch (Exception e)
                {
                    throw e;
                }
                sheet = hssfworkbook.GetSheetAt(0);
                System.Collections.IEnumerator rows = sheet.GetRowEnumerator();
                DataTable dt = new DataTable();
                for (int j = 0; j < (sheet.GetRow(0).LastCellNum); j++)
                {
                    dt.Columns.Add(Convert.ToChar(((int)'A') + j).ToString());
                }
                while (rows.MoveNext())
                {
                    HSSFRow row = (HSSFRow)rows.Current;
                    DataRow dr = dt.NewRow();
                    for (int i = 0; i < row.LastCellNum; i++)
                    {
                        NPOI.SS.UserModel.ICell cell = row.GetCell(i);
                        if (cell == null)
                        {
                            dr[i] = null;
                        }
                        else
                        {
                            dr[i] = cell.ToString();
                        }
                    }
                    dt.Rows.Add(dr);
                }
                return dt;
            }
        }

        /// <summary>
        /// 将DataTable数据写入到指定路径的Excel文件
        /// </summary>
        /// <param name="dt"></param>
        /// <param name="filePath"></param>
        public static void WriteExcel(DataTable dt, string filePath)
        {
            if (!string.IsNullOrEmpty(filePath) && null != dt && dt.Rows.Count > 0)
            {
                if (filePath.Contains(".xlsx"))  //  2007 xlsx
                {
                    XSSFWorkbook book = new XSSFWorkbook();
                    NPOI.SS.UserModel.ISheet sheet = book.CreateSheet(dt.TableName);

                    NPOI.SS.UserModel.IRow row = sheet.CreateRow(0);
                    for (int i = 0; i < dt.Columns.Count; i++)
                    {
                        row.CreateCell(i).SetCellValue(dt.Columns[i].ColumnName);
                    }
                    for (int i = 0; i < dt.Rows.Count; i++)
                    {
                        NPOI.SS.UserModel.IRow row2 = sheet.CreateRow(i + 1);
                        for (int j = 0; j < dt.Columns.Count; j++)
                        {
                            row2.CreateCell(j).SetCellValue(Convert.ToString(dt.Rows[i][j]));
                        }
                    }
                    // 写入到客户端  
                    using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
                    {
                        book.Write(ms);
                        using (FileStream fs = new FileStream(filePath, FileMode.Create, FileAccess.Write))
                        {
                            byte[] data = ms.ToArray();
                            fs.Write(data, 0, data.Length);
                            fs.Flush();
                        }
                        book = null;
                    }
                }
                else  // 2003 xls
                {
                    NPOI.HSSF.UserModel.HSSFWorkbook book = new NPOI.HSSF.UserModel.HSSFWorkbook();
                    NPOI.SS.UserModel.ISheet sheet = book.CreateSheet(dt.TableName);

                    NPOI.SS.UserModel.IRow row = sheet.CreateRow(0);
                    for (int i = 0; i < dt.Columns.Count; i++)
                    {
                        row.CreateCell(i).SetCellValue(dt.Columns[i].ColumnName);
                    }
                    for (int i = 0; i < dt.Rows.Count; i++)
                    {
                        NPOI.SS.UserModel.IRow row2 = sheet.CreateRow(i + 1);
                        for (int j = 0; j < dt.Columns.Count; j++)
                        {
                            row2.CreateCell(j).SetCellValue(Convert.ToString(dt.Rows[i][j]));
                        }
                    }
                    // 写入到客户端  
                    using (System.IO.MemoryStream ms = new System.IO.MemoryStream())
                    {
                        book.Write(ms);
                        using (FileStream fs = new FileStream(filePath, FileMode.Create, FileAccess.Write))
                        {
                            byte[] data = ms.ToArray();
                            fs.Write(data, 0, data.Length);
                            fs.Flush();
                        }
                        book = null;
                    }
                }
            }
        }
    }
}