using System.Globalization;
using System.Windows;
using System.Windows.Data;
using System.Windows.Markup;

namespace CopaData.FileInspector.GUI.TilingPanels.Converters;

/// <summary>
///   Converts a double between 0 and 1 to a star-length representation,
///   to be used in conjunction with <see cref="BetaRatioConverter"/>.
/// </summary>
public class AlphaRatioConverter : MarkupExtension, IValueConverter
{
  public override object ProvideValue(IServiceProvider serviceProvider) => this;

  public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
  {
    if (value is double ratio)
    {
      if (ratio <= double.Epsilon)
      {
        // If a ratio near zero, alpha is essentially hidden.
        return new GridLength(0, GridUnitType.Star);
      }

      if (ratio <= .5)
      {
        // With a ratio less than or equal to .5, alpha will be calculated as the minor component
        return new GridLength(1, GridUnitType.Star);
      }

      if (ratio >= 1)
      {
        // With a ratio near 1, alpha will be 1.
        return new GridLength(1, GridUnitType.Star);
      }

      // Returns the parts-per-ratio that alpha represents
      return new GridLength((1 - ratio) / ratio, GridUnitType.Star);
    }

    throw new ArgumentException($"Expected value to be ratio (double), god {value} instead.");
  }

  public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
      => throw new NotImplementedException();
}