using NPOI.SS.UserModel;
using System;
using System.Data;
using System.IO;

namespace YiDa_WinForm.Utils
{
    /// <summary>
    /// Excel 解析工具类
    /// </summary>
    public static class ExcelHelper
    {
        /// <summary>
        /// 读取Excel文件转换为DataTable
        /// </summary>
        /// <param name="filePath">Excel文件路径</param>
        /// <returns>解析后的DataTable</returns>
        public static DataTable GetExcelToDataTable(string filePath)
        {
            if (string.IsNullOrEmpty(filePath) || !File.Exists(filePath))
            {
                throw new FileNotFoundException("Excel文件不存在", filePath);
            }

            IWorkbook workbook = null;
            FileStream fileStream = null;

            try
            {
                fileStream = File.Open(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite);
                workbook = WorkbookFactory.Create(fileStream);

                DataTable dt = new DataTable();
                // 读取第一个Sheet（适配你的业务场景，如需多Sheet可扩展）
                ISheet sheet = workbook.GetSheetAt(0);
                if (sheet == null) return dt;

                // 读取表头构建DataTable列
                IRow headerRow = sheet.GetRow(0);
                if (headerRow == null) return dt;

                for (int i = 0; i < headerRow.LastCellNum; i++)
                {
                    string columnName = headerRow.GetCell(i)?.ToString() ?? $"列{i + 1}";
                    dt.Columns.Add(columnName);
                }

                // 读取数据行
                for (int rowIndex = 1; rowIndex <= sheet.LastRowNum; rowIndex++)
                {
                    IRow dataRow = sheet.GetRow(rowIndex);
                    if (dataRow == null) continue;

                    DataRow dr = dt.NewRow();
                    for (int colIndex = 0; colIndex < headerRow.LastCellNum; colIndex++)
                    {
                        ICell cell = dataRow.GetCell(colIndex);
                        dr[colIndex] = GetCellValue(cell);
                    }
                    dt.Rows.Add(dr);
                }

                return dt;
            }
            finally
            {
                // 手动释放资源
                if (fileStream != null)
                {
                    fileStream.Close();
                    fileStream.Dispose();
                }
                workbook = null;
            }
        }

        /// <summary>
        /// 获取Excel单元格的值（处理不同单元格类型）
        /// </summary>
        private static string GetCellValue(ICell cell)
        {
            if (cell == null) return string.Empty;

            switch (cell.CellType)
            {
                case CellType.Numeric:
                    if (DateUtil.IsCellDateFormatted(cell))
                    {
                        return cell.DateCellValue.ToString();
                    }
                    else
                    {
                        return cell.NumericCellValue.ToString();
                    }
                case CellType.String:
                    return cell.StringCellValue;
                case CellType.Boolean:
                    return cell.BooleanCellValue.ToString();
                default:
                    return cell.ToString();
            }
        }
    }
}