using System.Globalization;

using Avalonia.Data.Converters;

namespace GSS2.UI.Core.Converters;

public class DateTimeConverter : IValueConverter
{
    private static readonly string[][] FORMATS =
    {
        ["dd", "d"],
        ["."],
        ["MM", "M"],
        ["."],
        ["yyyy", "yy"],
        [" "],
        ["HH", "H"],
        [":"],
        ["mm", "m"],
        [":"],
        ["ss", "s"]
    };
    private static readonly string[] ALL_FORMATS = FORMATS
        .Aggregate(new List<string> { "" }, (acc, segments) =>
            acc.SelectMany(a => segments.Select(s => a + s)).ToList())
        .ToArray();

    public object? Convert(object? value, Type targetType, object? parameter, CultureInfo culture)
    {
        if (value is not DateTime dateTime)
            return Avalonia.Data.BindingNotification.ExtractError(new FormatException($"Не удаётся распознать значение \"{value}\" как дату и время"));

        return dateTime.ToLocalTime().ToString("dd.MM.yyyy HH:mm:ss");
    }

    public object? ConvertBack(object? value, Type targetType, object? parameter, CultureInfo culture)
    {
        if (value is not string str)
            return Avalonia.Data.BindingNotification.ExtractError(new FormatException($"Не удаётся распознать значение \"{value}\" как дату и время"));

        var success = DateTime.TryParseExact(str, ALL_FORMATS, CultureInfo.InvariantCulture, DateTimeStyles.AssumeLocal, out var dateTime);
        if (!success)
            return Avalonia.Data.BindingNotification.ExtractError(new FormatException($"Не удаётся распознать строку \"{str}\" как дату и время"));

        return dateTime.ToUniversalTime();
    }
}