using System;
using System.Globalization;
using System.Linq;
using System.Windows;
using System.Windows.Data;

namespace Project.Common.Converters
{
    public class QuantityToStringMultiValueConverter : IMultiValueConverter
    {
        private readonly DecimalConverter decimalConverter;

        public  QuantityToStringMultiValueConverter()
        {
            decimalConverter = new DecimalConverter();
        }

        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            if (values.Length != 3 || values.Any(v => v == DependencyProperty.UnsetValue))
                return null;

            string unit = (string)values[2];
            int decimalCount = (int) values[1];

            decimal quantity;
            if (values[0] is decimal)
            {
                quantity = (decimal) values[0];
            } else if (values[0] is double)
            {
                quantity = (decimal) (double)values[0];
            }
            else
            {
                throw new Exception("Unable to convert type");
            }

            return $"{decimalConverter.Convert(new object[] {quantity, decimalCount}, typeof(double))} {unit}";
        }

        public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}