using System.Globalization;
using Avalonia.Controls;
using Avalonia.Media;

namespace Nonemm.App.Windows;

/// Stops a grid column being dragged, or sized to its cells, narrower than its
/// own heading.
public static class ColumnWidths
{
    /// What a header takes besides its text: its padding and the room the theme
    /// keeps for the sort arrow.
    private const double HeaderPadding = 40;

    /// The width of the heading in the grid's font, with the room the arrow
    /// needs.
    public static double ForHeader(DataGrid grid, string heading) =>
        new FormattedText(
            heading,
            CultureInfo.InvariantCulture,
            FlowDirection.LeftToRight,
            new Typeface(grid.FontFamily, FontStyle.Normal, FontWeight.Bold),
            grid.FontSize,
            null).Width + HeaderPadding;

    public static void KeepHeadersReadable(DataGrid grid)
    {
        foreach (DataGridColumn column in grid.Columns)
        {
            if (column.Header is string heading)
            {
                column.MinWidth = ForHeader(grid, heading);
            }
        }
    }
}