nadekobot/src/NadekoBot/_common/ICurrencyProvider.cs

using System.Globalization;
using System.Numerics;

namespace NadekoBot.Common;

public interface ICurrencyProvider
{
    string GetCurrencySign();
}

public static class CurrencyHelper
{
    public static string N<T>(T cur, IFormatProvider format)
        where T : INumber<T>
        => cur.ToString("C0", format);

    public static string N<T>(T cur, CultureInfo culture, string currencySign)
        where T : INumber<T>
        => N(cur, GetCurrencyFormat(culture, currencySign));

    private static IFormatProvider GetCurrencyFormat(CultureInfo culture, string currencySign)
    {
        var flowersCurrencyCulture = (CultureInfo)culture.Clone();
        flowersCurrencyCulture.NumberFormat.CurrencySymbol = currencySign;
        flowersCurrencyCulture.NumberFormat.CurrencyNegativePattern = 5;

        return flowersCurrencyCulture;
    }
}