SQLVision/SQLVision.Services/Exporters/ExcelExporter.cs

using ClosedXML.Excel;
using Microsoft.Extensions.Logging;
using SQLVision.Core.Models;
using System.Data;

namespace SQLVision.Services.Exporters;

public class ExcelExporter : IExportHandler
{
    private readonly ILogger<ExcelExporter> _logger;

    public string FormatName => "Excel";

    public ExcelExporter(ILogger<ExcelExporter> logger)
    {
        _logger = logger;
    }

    public async Task ExportAsync(DataTable data, string filePath, ExportOptions options)
    {
        using var workbook = new XLWorkbook();
        var worksheet = workbook.Worksheets.Add("Data");

        WriteDataToWorksheet(worksheet, data, options);

        if (options.IncludeCharts && data.Rows.Count > 0)
        {
            AddCharts(worksheet, data, options);
        }

        await Task.Run(() => workbook.SaveAs(filePath));
        _logger.LogInformation("Exported {Rows} rows to Excel: {FilePath}", data.Rows.Count, filePath);
    }

    public async Task<byte[]> ExportToMemoryAsync(DataTable data, ExportOptions options)
    {
        using var workbook = new XLWorkbook();
        var worksheet = workbook.Worksheets.Add("Data");

        WriteDataToWorksheet(worksheet, data, options);

        using var stream = new MemoryStream();
        await Task.Run(() => workbook.SaveAs(stream));
        return stream.ToArray();
    }

    private void WriteDataToWorksheet(IXLWorksheet worksheet, DataTable data, ExportOptions options)
    {
        if (options.IncludeHeaders)
        {
            for (int col = 0; col < data.Columns.Count; col++)
            {
                worksheet.Cell(1, col + 1).Value = data.Columns[col].ColumnName;
                worksheet.Cell(1, col + 1).Style.Font.Bold = true;
            }
        }

        int startRow = options.IncludeHeaders ? 2 : 1;

        for (int row = 0; row < data.Rows.Count; row++)
        {
            for (int col = 0; col < data.Columns.Count; col++)
            {
                var value = data.Rows[row][col];
                worksheet.Cell(startRow + row, col + 1).Value = ConvertValue(value);

                ApplyFormatting(worksheet.Cell(startRow + row, col + 1), value);
            }
        }

        if (options.AutoFilter)
        {
            var endRow = startRow + data.Rows.Count - 1;
            worksheet.Range(1, 1, endRow, data.Columns.Count).SetAutoFilter();
        }

        worksheet.Columns().AdjustToContents();
    }

    private XLCellValue ConvertValue(object value)
    {
        if (value == null || value == DBNull.Value) return Blank.Value;

        if (value is DateTime dateTime)
            return dateTime;

        if (value is decimal || value is double || value is float)
            return Convert.ToDouble(value);

        if (value is bool b)
            return b;

        return value.ToString();
    }

    private void ApplyFormatting(IXLCell cell, object value)
    {
        if (value is DateTime)
        {
            cell.Style.DateFormat.Format = "dd.MM.yyyy HH:mm:ss";
        }
        else if (value is decimal || value is double || value is float)
        {
            cell.Style.NumberFormat.Format = "#,##0.00";
        }
    }

    private void AddCharts(IXLWorksheet worksheet, DataTable data, ExportOptions options)
    {
        if (data.Columns.Count < 2) return;

        //TODO: chart
        /*var chartType = GetChartType(options.ChartType);
        var chart = worksheet.CreateChart(0, data.Columns.Count + 2, 20, data.Columns.Count + 10);
        chart.ChartType = chartType;

        // Добавление серий на основе данных
        for (int col = 1; col < Math.Min(5, data.Columns.Count); col++)
        {
            var series = chart.AddSeries(
                worksheet.Range(2, col + 1, data.Rows.Count + 1, col + 1),
                worksheet.Range(2, 1, data.Rows.Count + 1, 1));

            series.ChartType = chartType;
        }
        */
    }

    private XLChartType GetChartType(string? chartType) => chartType?.ToLower() switch
    {
        "line" => XLChartType.Line,
        "column" => XLChartType.ColumnClustered,
        "bar" => XLChartType.BarClustered,
        "pie" => XLChartType.Pie,
        "area" => XLChartType.Area,
        _ => XLChartType.Line
    };
}