Backend-Api/0_Framework/Excel/ExcelGenerator.cs

    using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.IO;
using System.Linq;
using System.Reflection;
using System.Threading.Tasks;

using OfficeOpenXml;
using OfficeOpenXml.Style;
using LicenseContext = OfficeOpenXml.LicenseContext;


namespace _0_Framework.Excel;

public class ExcelGenerator
{
    public ExcelGenerator()
    {
        OfficeOpenXml.ExcelPackage.License.SetNonCommercialOrganization("Gozareshgir Noncommercial organization");
    }
    public static byte[] GenerateExcel<T>(List<T> obj, string date = "") where T : class
    {
        var templatePath = Path.Combine(Directory.GetCurrentDirectory(), "wwwroot", "Test", "template (2).xlsx");

        // Open the template
        FileInfo fileInfo = new FileInfo(templatePath);
        using ExcelPackage package = new ExcelPackage(fileInfo);
        ExcelWorksheet worksheet = package.Workbook.Worksheets[0];

        var titles = GetNonEmptyDisplayNames<T>(obj);
        var col = 1;
        for (int i = 0; i < titles.Count; i++)
        {
            worksheet.Cells[1, col].Value = titles[i];
            col++;
        }

        int row = 2;
        foreach (var item in obj)
        {
            int column = 1;
            foreach (var prop in typeof(T).GetProperties())
            {
                var displayNameAttr = prop.GetCustomAttribute<DisplayNameAttribute>();
                if (displayNameAttr != null && titles.Contains(displayNameAttr.DisplayName))
                {
                    var value = prop.GetValue(item);

                    worksheet.Cells[row, column].Value = value?.ToString();
                    column++;
                }
            }

            row++;
        }

        worksheet.View.RightToLeft = true;
        worksheet.HeaderFooter.OddHeader.LeftAlignedText = !string.IsNullOrWhiteSpace(date)
            ? $"تاریخ: {date}\r\nشماره ثبت: 1727"
            : "شماره ثبت: 1727";
        return package.GetAsByteArray();
    }

    public static byte[] CreateExcel<T>(List<T> dataList)
    {
        using (var package = new ExcelPackage())
        {
            var worksheet = package.Workbook.Worksheets.Add("Sheet1");

            // Add property names as sub-header using DisplayName attribute
            var properties = typeof(T).GetProperties();
            for (int i = 0; i < properties.Length; i++)
            {
                var displayNameAttribute = properties[i].GetCustomAttribute<DisplayNameAttribute>();
                var displayName = displayNameAttribute != null ? displayNameAttribute.DisplayName : properties[i].Name;
                worksheet.Cells[3, i + 1].Value = displayName;
            }

            // Populate data and calculate column widths
            for (int i = 0; i < dataList.Count; i++)
            {
                for (int j = 0; j < properties.Length; j++)
                {
                    var cellValue = properties[j].GetValue(dataList[i]);
                    worksheet.Cells[i + 4, j + 1].Value = cellValue;
                }
            }

            // Calculate total width of all filled columns
            worksheet.Cells.AutoFitColumns(); // AutoFit columns to calculate their widths correctly
            double totalDataWidth = 0;
            for (int i = 1; i <= properties.Length; i++)
            {
                totalDataWidth += worksheet.Column(i).Width;
            }
            double headerWidth = totalDataWidth / 3.0;

            // Create dynamic headers with adjusted widths
            int totalColumns = properties.Length;
            int colEnd1 = (int)Math.Floor((double)totalColumns / 3.0);
            int colStart2 = colEnd1 + 1;
            int colEnd2 = colStart2 + (int)Math.Floor((double)totalColumns / 3.0) - 1;
            int colStart3 = colEnd2 + 1;
            int colEnd3 = totalColumns;

            worksheet.Cells[1, 1, 2, colEnd1].Merge = true;
            worksheet.Cells[1, 1, 2, colEnd1].Value = "Dynamic Header 1";
            worksheet.Column(1).Width = headerWidth;

            worksheet.Cells[1, colStart2, 2, colEnd2].Merge = true;
            worksheet.Cells[1, colStart2, 2, colEnd2].Value = "Dynamic Header 2";
            worksheet.Column(colStart2).Width = headerWidth;

            worksheet.Cells[1, colStart3, 2, colEnd3].Merge = true;
            worksheet.Cells[1, colStart3, 2, colEnd3].Value = "Dynamic Header 3";
            worksheet.Column(colStart3).Width = headerWidth;

            // Add footer
            worksheet.Cells[dataList.Count + 4, 1].Value = "Footer";
            worksheet.Cells[dataList.Count + 4, 1, dataList.Count + 4, totalColumns].Merge = true;

            // Return as byte array
            return package.GetAsByteArray();
        }
    }

    public static List<string> GetDisplayNames<T>(List<T> obj)
    {
        return typeof(T).GetProperties()
            .Select(prop => prop.GetCustomAttribute<DisplayNameAttribute>())
            .Where(attr => attr != null)
            .Select(attr => attr.DisplayName)
            .ToList();
    }

    public static List<string> GetNonEmptyDisplayNames<T>(List<T> obj)
    {
        var displayNames = new List<string>();

        var item = obj.FirstOrDefault();
        foreach (var prop in typeof(T).GetProperties())
        {
            var displayNameAttr = prop.GetCustomAttribute<DisplayNameAttribute>();

            if (displayNameAttr != null)
            {
                var value = prop.GetValue(item) as string;
                if (!string.IsNullOrEmpty(value))
                {
                    displayNames.Add(displayNameAttr.DisplayName);
                }

            }
        }


        return displayNames.Distinct().ToList(); // Using Distinct to avoid duplicate display names
    }

    public record ExcelTestVm(long Id, string Name, DateTime DateTime);

    public List<ExcelTestVm> GetDataFromExcel(Stream fileStream)
    {
        var resultList = new List<ExcelTestVm>();

        using var package = new ExcelPackage(fileStream);
        var worksheet = package.Workbook.Worksheets[0]; // Assuming first sheet

        int rows = worksheet.Dimension.Rows;
        for (int row = 2; row <= rows; row++) // Skipping the header row
        {
            var idCell = worksheet.Cells[row, 1].Text;
            var nameCell = worksheet.Cells[row, 2].Text;
            var birthDateCell = worksheet.Cells[row, 3].Text;

            // Validation
            if (string.IsNullOrEmpty(idCell) || string.IsNullOrEmpty(nameCell) ||
                string.IsNullOrEmpty(birthDateCell))
            {
                throw new Exception($"Row {row}: Missing required data.");
            }

            if (!int.TryParse(idCell, out int id))
            {
                throw new Exception($"Row {row}: Invalid data type for ID.");
            }

            if (!DateTime.TryParse(birthDateCell, out DateTime birthDate))
            {
                throw new Exception($"Row {row}: Invalid date format for Birth Date.");
            }

            var data = new ExcelTestVm(id, nameCell, birthDate);

            resultList.Add(data);
        }

        return resultList;
    }


}