using ClosedXML.Excel;
using System.Globalization;
using System.IO;

namespace zero.Utils;

public class ExcelCreator<T> : ITableCreator<T>
{
  private MemoryStream Stream { get; set; }

  private XLWorkbook Workbook { get; set; }

  private IEnumerable<TableColumn<T>> Columns { get; set; }

  private const string DATE_FORMAT = "dd. MM. yyyy";

  private const string DATETIME_FORMAT = "dd. MM. yyyy, HH:ii";

  private const string BOOL_YES = "yes";

  private const string BOOL_NO = "no";

  private const string LINK_NAME = "Link";

  public const string CONTENT_TYPE = "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet";

  private CultureInfo Culture = null;


  public ExcelCreator(IEnumerable<TableColumn<T>> columns)
  {
    Columns = columns;
  }


  /// <summary>
  /// Create a readable XLSX stream from a source enumerable
  /// </summary>
  public MemoryStream CreateStream(IEnumerable<T> source, CultureInfo culture)
  {
    Culture = culture;
    Workbook = Create(true, out int lineNumber);
    foreach (T item in source)
    {
      AddRow(Workbook.Worksheets.First(), lineNumber++, Columns, item);
    }
    Stream = new MemoryStream();
    Workbook.SaveAs(Stream);
    Stream.Position = 0;
    return Stream;
  }


  /// <summary>
  /// Create a readable XLSX stream from a source enumerable
  /// </summary>
  public async Task<MemoryStream> CreateStream(IAsyncEnumerable<T> source, CultureInfo culture, CancellationToken token = default)
  {
    Culture = culture;
    Workbook = Create(true, out int lineNumber);
    await foreach (T item in source.WithCancellation(token))
    {
      AddRow(Workbook.Worksheets.First(), lineNumber++, Columns, item);
    }
    Stream = new MemoryStream();
    Workbook.SaveAs(Stream);
    Stream.Position = 0;
    return Stream;
  }


  /// <summary>
  /// Create a XLSX from a source enumerable
  /// </summary>
  protected XLWorkbook Create(IEnumerable<T> source, bool headerRow = true)
  {
    XLWorkbook workbook = new XLWorkbook();
    IXLWorksheet worksheet = workbook.Worksheets.Add("Data");

    int lineNumber = 1;


    // add metadata + defaults
    workbook.RowHeight = 20;

    // add header
    if (headerRow)
    {
      AddRow(worksheet, lineNumber++, Columns, default, true);
      worksheet.Row(1).Height = 30;
    }

    // set column widths
    for (int i = 0; i < Columns.Count(); i++)
    {
      TableColumn<T> column = Columns.ElementAt(i);
      worksheet.Column(i + 1).Width = column.Width;
    }

    // add rows
    foreach (T item in source)
    {
      AddRow(worksheet, lineNumber++, Columns, item);
    }

    return workbook;
  }


  /// <summary>
  /// Create a XLSX from a source enumerable
  /// </summary>
  protected XLWorkbook Create(bool headerRow, out int lineNumber)
  {
    XLWorkbook workbook = new XLWorkbook();
    IXLWorksheet worksheet = workbook.Worksheets.Add("Data");

    lineNumber = 1;

    // add metadata + defaults
    workbook.RowHeight = 20;

    // add header
    if (headerRow)
    {
      AddRow(worksheet, lineNumber++, Columns, default, true);
      worksheet.Row(1).Height = 30;
    }

    // set column widths
    for (int i = 0; i < Columns.Count(); i++)
    {
      TableColumn<T> column = Columns.ElementAt(i);
      worksheet.Column(i + 1).Width = column.Width;
    }

    return workbook;
  }


  /// <summary>
  /// Appends a line to the XLSX
  /// </summary>
  protected void AddRow(IXLWorksheet builder, int lineNumber, IEnumerable<TableColumn<T>> columns, T item, bool isHeader = false)
  {
    int index = 0;

    foreach (TableColumn<T> column in columns)
    {
      object value = isHeader ? column.Name : (column.FieldSelector != null && column.CanRender(item) ? column.FieldSelector(item) : String.Empty);
      object property = MapProperty(value, column, out XLDataType dataType);

      IXLCell cell = builder.Cell(lineNumber, index + 1)
        .SetValue(property)
        .SetDataType(dataType);

      if (isHeader)
      {
        cell.Style.Font.SetBold();
        cell.Style.Fill.BackgroundColor = XLColor.WhiteSmoke;
      }

      cell.Style.Alignment.Vertical = XLAlignmentVerticalValues.Center;

      if (!isHeader && column.ColumnType == TableColumnType.Link)
      {
        cell.SetValue(LINK_NAME);
        cell.Hyperlink = new XLHyperlink(value.ToString());
      }
      if (column.ColumnType == TableColumnType.Currency)
      {
        cell.Style.Alignment.Horizontal = XLAlignmentHorizontalValues.Right;
      }

      index += 1;
    }

    if (!isHeader)
    {
      builder.Row(lineNumber).Height = 20;
    }
  }


  /// <summary>
  /// Map a property based on its type
  /// </summary>
  protected object MapProperty(object value, TableColumn<T> column, out XLDataType dataType)
  {
    dataType = XLDataType.Text;

    if (value == null)
    {
      return String.Empty;
    }

    if (value is bool)
    {
      return (bool)value ? BOOL_YES : BOOL_NO;
    }
    else if (value is decimal || value is float || value is double)
    {
      dataType = XLDataType.Number;
      decimal result = Decimal.Round(Convert.ToDecimal(value), 2);

      if (column.ColumnType == TableColumnType.Currency)
      {
        dataType = XLDataType.Text;
        return result.ToString("C2", Culture);
      }

      return result;
    }
    else if (value is int)
    {
      dataType = XLDataType.Number;
      return value;
    }
    else if (value is DateTime)
    {
      return ((DateTime)value).ToString(DATE_FORMAT);
    }
    else if (value is DateTime?)
    {
      var val = (DateTime?)value;
      return val.HasValue ? val.Value.ToString(DATE_FORMAT) : String.Empty;
    }
    else if (value is DateTimeOffset)
    {
      return ((DateTimeOffset)value).ToString(DATE_FORMAT);
    }
    else if (value is DateTimeOffset?)
    {
      var val = (DateTimeOffset?)value;
      return val.HasValue ? val.Value.ToString(DATE_FORMAT) : String.Empty;
    }

    return value;
  }


  public void Dispose()
  {
    Stream?.Dispose();
    Workbook?.Dispose();
  }
}