Catalog/CatalogLite/ExpirationGuard.cs

using System.Globalization;
using System.Reflection;

namespace CatalogLite;

internal static class ExpirationGuard
{
    private const string MetadataKey = "CatalogLiteExpirationDate";

    public static bool IsExpired(out DateOnly? expirationDate)
    {
        expirationDate = TryReadExpirationDate();
        return expirationDate is null || DateOnly.FromDateTime(DateTime.Today) > expirationDate.Value;
    }

    private static DateOnly? TryReadExpirationDate()
    {
        var value = typeof(Program).Assembly
            .GetCustomAttributes<AssemblyMetadataAttribute>()
            .FirstOrDefault(attribute => string.Equals(attribute.Key, MetadataKey, StringComparison.Ordinal))
            ?.Value;

        return DateOnly.TryParseExact(value, "yyyy-MM-dd", CultureInfo.InvariantCulture, DateTimeStyles.None, out var date)
            ? date
            : null;
    }
}