Billing/Billing.Shared/UI/Converters.cs

using Billing.Languages;
using Billing.Models;
using System;
using System.Globalization;
using Xamarin.Forms;

namespace Billing.UI
{
    public class TitleDateConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value is DateTime date)
            {
                return date.ToString(Resource.TitleDateFormat);
            }
            return value;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return value;
        }
    }

    public class MoneyConverter : IValueConverter
    {
        public bool MarkVisible { get; set; } = true;

        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value is decimal d)
            {
                var number = d.ToString("n2");
                if (MarkVisible)
                {
                    return "¥ " + number;
                }
                return number;
            }
            return value;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value is string s)
            {
                if (s.StartsWith("¥ "))
                {
                    s = s[2..];
                }
                if (decimal.TryParse(s, out decimal d))
                {
                    return d;
                }
                return 0m;
            }
            return value;
        }
    }

    public class NotNullConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return value != null;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return value;
        }
    }

    public class AccountCategoryConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            if (value is AccountCategory category)
            {
                return category switch
                {
                    AccountCategory.Cash => Resource.Cash,
                    AccountCategory.CreditCard => Resource.CreditCard,
                    AccountCategory.DebitCard => Resource.DebitCard,
                    AccountCategory.ElecAccount => Resource.ElecAccount,
                    _ => category.ToString()
                };
            }
            return value;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return value;
        }
    }
}