using System;
using System.Collections.Generic;
using System.Text;
// ref https://www.c-sharpcorner.com/article/read-excel-file-in-c-sharp-winform/
//using Microsoft.Office.Interop.Excel;
using System.Runtime.InteropServices;
using System.Data;
using Microsoft.Office.Interop;

namespace solarApp.Service
{
    public class excelHelper
    {
        void readExcel(string fname, ref System.Data.DataTable dt) {
            Microsoft.Office.Interop.Excel.Application xlApp = new Microsoft.Office.Interop.Excel.Application();
            Microsoft.Office.Interop.Excel.Workbook xlWorkbook = xlApp.Workbooks.Open(fname);
            Microsoft.Office.Interop.Excel._Worksheet xlWorksheet = xlWorkbook.Sheets[1];
            Microsoft.Office.Interop.Excel.Range xlRange = xlWorksheet.UsedRange;

            int rowCount = xlRange.Rows.Count;
            int colCount = xlRange.Columns.Count;
            DataRow mydr;
            // dt.Column = colCount;  
            //dataGridView1.ColumnCount = colCount;
            //dataGridView1.RowCount = rowCount;
            
            for (int i = 1; i <= rowCount; i++)
            {
                mydr = dt.NewRow();
                for (int j = 1; j <= colCount; j++)
                { 
                    //write the value to the Grid   
                    if (xlRange.Cells[i, j] != null && xlRange.Cells[i, j].Value2 != null)
                    { 
                        //dataGridView1.Rows[i - 1].Cells[j - 1].Value = xlRange.Cells[i, j].Value2.ToString();
                    }
                    // Console.Write(xlRange.Cells[i, j].Value2.ToString() + "\t");   
                    //add useful things here!     
                }
            }

            //cleanup  
            GC.Collect();
            GC.WaitForPendingFinalizers();

            //rule of thumb for releasing com objects:  
            //  never use two dots, all COM objects must be referenced and released individually  
            //  ex: [somthing].[something].[something] is bad  

            //release com objects to fully kill excel process from running in the background  
            Marshal.ReleaseComObject(xlRange);
            Marshal.ReleaseComObject(xlWorksheet);

            //close and release  
            xlWorkbook.Close();
            Marshal.ReleaseComObject(xlWorkbook);

            //quit and release  
            xlApp.Quit();
            Marshal.ReleaseComObject(xlApp);
        } 

        //public void ReadSample()
        //{
        //    Microsoft.Office.Interop.Excel.Application excelApp = new Microsoft.Office.Interop.Excel.Application();
        //    if (excelApp != null)
        //    {
        //        Microsoft.Office.Interop.Excel.Workbook excelWorkbook = excelApp.Workbooks.Open(@"C:\test.xls", 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
        //        Microsoft.Office.Interop.Excel.Worksheet excelWorksheet = (Microsoft.Office.Interop.Excel.Worksheet)excelWorkbook.Sheets[1];

        //        Excel.Range excelRange = excelWorksheet.UsedRange;
        //        int rowCount = excelRange.Rows.Count;
        //        int colCount = excelRange.Columns.Count;

        //        for (int i = 1; i <= rowCount; i++)
        //        {
        //            for (int j = 1; j <= colCount; j++)
        //            {
        //                Excel.Range range = (excelWorksheet.Cells[i, 1] as Excel.Range);
        //                string cellValue = range.Value.ToString();

        //                //do anything
        //            }
        //        }

        //        excelWorkbook.Close();
        //        excelApp.Quit();
        //    }
        //}
    }
}