using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using NPOI.HSSF.UserModel;
using NPOI.SS.UserModel;
using NPOI.XSSF.UserModel;

namespace Team.Utility
{
    /// <summary>
    /// poi类库实现的excel工具类
    /// excel文件到table,table到excel
    /// </summary>
    public static class ExcelUtil
    {
        /// <summary>
        /// Excel导入成Datable
        /// </summary>
        /// <param name="file">导入路径(包含文件名与扩展名)</param>
        /// <param name="isFirstRowAsHeader"></param>
        /// <returns>
        /// </returns>
        /// Exception("无效的文件扩展名"),要求xls,xlsx格式
        public static DataTable ExcelToTable(string file,bool isFirstRowAsHeader=true)
        {
            var dt = new DataTable();
            var fileExt = Path.GetExtension(file)?.ToLower();
            using var fs = new FileStream(file, FileMode.Open, FileAccess.Read,FileShare.ReadWrite);
            //XSSFWorkbook 适用XLSX格式，HSSFWorkbook 适用XLS格式
            IWorkbook workbook = fileExt switch
            {
                ".xlsx" => new XSSFWorkbook(fs),
                ".xls" => new HSSFWorkbook(fs),
                _ => throw new Exception("无效的文件扩展名")
            };
            var sheet = workbook.GetSheetAt(0);
            var columns = new List<int>();
            //表头  
            var header = sheet.GetRow(sheet.FirstRowNum);
            for (var i = 0; i < header.LastCellNum; i++)
            {
                var obj = GetValueType(header.GetCell(i));
                if (obj == null || obj.ToString() == string.Empty||!isFirstRowAsHeader)
                    dt.Columns.Add(new DataColumn("Columns" + i));
                else
                    dt.Columns.Add(new DataColumn(obj.ToString()));
                columns.Add(i);
            }

            var firstRow = isFirstRowAsHeader ? sheet.FirstRowNum + 1 : sheet.FirstRowNum;

            //数据  
            for (var i = firstRow; i <= sheet.LastRowNum; i++)
            {
                var dr = dt.NewRow();
                var hasValue = false;
                foreach (var j in columns)
                {
                    dr[j] = GetValueType(sheet.GetRow(i).GetCell(j));
                    if (dr[j] != null && dr[j].ToString() != string.Empty)
                    {
                        hasValue = true;
                    }
                }
                if (hasValue)
                {
                    dt.Rows.Add(dr);
                }
            }

            return dt;
        }

        /// <summary>
        /// Datable导出成Excel
        /// </summary>
        /// <param name="dt"></param>
        /// <param name="file">导出路径(包括文件名与扩展名)</param>
        /// <param name="isAddHeader">默认添加表头</param>
        /// Exception("无效的文件扩展名"),要求xls,xlsx格式
        public static void TableToExcel(DataTable dt, string file,bool isAddHeader=true)
        {
            var fileExt = Path.GetExtension(file)?.ToLower();
            IWorkbook workbook = fileExt switch
            {
                ".xlsx" => new XSSFWorkbook(),
                ".xls" => new HSSFWorkbook(),
                _ => throw new Exception("无效的文件扩展名")
            };

            var sheet = string.IsNullOrEmpty(dt.TableName) ? workbook.CreateSheet("Sheet1") : workbook.CreateSheet(dt.TableName);//sheet名
            if (isAddHeader)
            {
                var row = sheet.CreateRow(0);
                for (var i = 0; i < dt.Columns.Count; i++)
                {
                    var cell = row.CreateCell(i);
                    cell.SetCellValue(dt.Columns[i].ColumnName);
                }
                //数据 
            }
            for (var i = 0; i < dt.Rows.Count; i++)
            {
                var row1 = sheet.CreateRow(i + 1);
                for (var j = 0; j < dt.Columns.Count; j++)
                {
                    var cell = row1.CreateCell(j);
                    cell.SetCellValue(dt.Rows[i][j].ToString());
                }
            }
            //表头  


            //转为字节数组  
            using var stream = new MemoryStream();
            workbook.Write(stream);
            var buf = stream.ToArray();

            //保存为Excel文件  
            using var fs = new FileStream(file, FileMode.Create, FileAccess.Write);
            fs.Write(buf, 0, buf.Length);
            fs.Flush();
        }


        public static IRow ExtensionMethod(ISheet sheet,int rowIndex)
        {
            var row=  sheet.CreateRow(rowIndex);
            return row;
        }


        public static void TableToExcel(DataTable []dts, string file)
        {
            IWorkbook workbook;
            var fileExt = Path.GetExtension(file)?.ToLower();
            if (fileExt == ".xlsx") { workbook = new XSSFWorkbook(); } else if (fileExt == ".xls") { workbook = new HSSFWorkbook(); } else { workbook = null; }
            if (workbook == null) { return; }

            foreach (var dt in dts)
            {
                var sheet = string.IsNullOrEmpty(dt.TableName) ? workbook.CreateSheet($"Sheet{dts.ToList().IndexOf(dt)}") : workbook.CreateSheet(dt.TableName);
                //表头  
                var row = sheet.CreateRow(0);
                for (var i = 0; i < dt.Columns.Count; i++)
                {
                    var cell = row.CreateCell(i);
                    cell.SetCellValue(dt.Columns[i].ColumnName);
                }
                //数据  
                for (var i = 0; i < dt.Rows.Count; i++)
                {
                    var row1 = sheet.CreateRow(i + 1);
                    for (var j = 0; j < dt.Columns.Count; j++)
                    {
                        var cell = row1.CreateCell(j);
                        cell.SetCellValue(dt.Rows[i][j].ToString());
                    }
                }
            }
            

            //转为字节数组  
            var stream = new MemoryStream();
            workbook.Write(stream);
            var buf = stream.ToArray();

            //保存为Excel文件  
            using (var fs = new FileStream(file, FileMode.Create, FileAccess.Write))
            {
                fs.Write(buf, 0, buf.Length);
                fs.Flush();
            }

        }
        /// <summary>
        /// 获取单元格类型
        /// </summary>
        /// <param name="cell"></param>
        /// <returns></returns>
        private static object GetValueType(ICell cell)
        {
            if (cell == null)
                return null;
            switch (cell.CellType)
            {
                case CellType.Blank: //BLANK:  
                    return null;
                case CellType.Boolean: //BOOLEAN:  
                    return cell.BooleanCellValue;
                case CellType.Numeric: //NUMERIC:  
                    return cell.NumericCellValue;
                case CellType.String: //STRING:  
                    return cell.StringCellValue;
                case CellType.Error: //ERROR:  
                    return cell.ErrorCellValue;
                default:
                    return "=" + cell.CellFormula;
            }
        }
    }
}