using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;
using System.Threading.Tasks;
using System.Windows.Data;

namespace Tango.Editors.Converters
{
    internal class StringFormatConverter : IMultiValueConverter
    {
        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            String stringValue = values[0].ToString();
            String format = values[1] != null ? values[1].ToString() : null;
            var resultString = Regex.Match(stringValue, @"^-?[0-9]\d*(\.\d+)?$").Value;

            if (String.IsNullOrWhiteSpace(resultString)) return "";

            if (resultString == "-") return resultString;

            return System.Convert.ToDouble(resultString).ToString(format != null ? format : "");
        }

        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
        {
            String resultString;

            if (value.ToString() == "-" || value.ToString() == ".")
            {
                resultString = value.ToString() + 0;
            }
            else
            {
                resultString = Regex.Match(value.ToString(), @"^-?[0-9]\d*(\.\d+)?$").Value;
            }
            return new object[] { System.Convert.ToDouble(String.IsNullOrWhiteSpace(resultString) ? "0" : resultString) };
        }
    }
}