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

namespace HashCalculator.GUI.Converters
{
    class MultiValueAggregateConverter : List<IValueConverter?>, IMultiValueConverter
    {
        public IMultiValueConverter? Converter { get; set; }
        public IValueConverter? PostProcess { get; set; }

        public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
        {
            if (Converter is not { } converter)
            {
                throw new InvalidOperationException($"{nameof(Converter)} of {nameof(MultiValueAggregateConverter)} is null");
            }
            if (Count > 0)
            {
                values = values.ToArray(); // 复制一份
                var length = Math.Min(Count, values.Length);
                for (var i = 0; i < length; ++i)
                {
                    if (this[i] is IValueConverter c)
                    {
                        values[i] = c.Convert(values[i], targetType, parameter, culture);
                    }
                }
            }
            var result = converter.Convert(values, targetType, parameter, culture);
            if (PostProcess is not { } postConverter)
            {
                return result;
            }
            return postConverter.Convert(result, targetType, parameter, culture);
        }

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