IFormattableToStringConverter.cs

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

namespace CommunityToolkit.WinUI.Converters;

/// <summary>
/// Value converter that converts an <see cref="IFormattable"/> to a formatted <see cref="string"/>.
/// The string format needs to be passed as the converter parameter.
/// </summary>
public partial class IFormattableToStringConverter : IValueConverter
{
    // TODO: Provide property to set a IFormatProvider for the 2nd parameter to ToString

    /// <summary>
    /// Convert an <see cref="IFormattable"/> value to a formatted <see cref="string"/>.
    /// </summary>
    /// <param name="value">The source data being passed to the target.</param>
    /// <param name="targetType">The type of the target property, as a type reference.</param>
    /// <param name="parameter">The format string.</param>
    /// <param name="language">The language of the conversion. Not used.</param>
    /// <returns>The formatted string.</returns>
    public object Convert(object value, Type targetType, object parameter, string language)
    {
        var formattableValue = value as IFormattable;
        var format = parameter as string;

        if (formattableValue == null || format == null)
        {
            return value;
        }

        return formattableValue.ToString(format, null);
    }

    /// <summary>
    /// Not implemented.
    /// </summary>
    /// <param name="value">The source data being passed to the target.</param>
    /// <param name="targetType">The type of the target property, as a type reference.</param>
    /// <param name="parameter">Optional parameter. Not used.</param>
    /// <param name="language">The language of the conversion. Not used.</param>
    /// <returns>The value to be passed to the target dependency property.</returns>
    public object ConvertBack(object value, Type targetType, object parameter, string language)
    {
        throw new NotImplementedException();
    }
}