namespace DigitalData.Core.Security.Cryptographer
{
    public static class CryptographerExtensions
    {
        public static IEnumerable<TRSACryptographer> GetByIssuer<TRSACryptographer>(this IEnumerable<TRSACryptographer> cryptographers, string issuer) where TRSACryptographer: RSACryptographer
            => cryptographers.Where(c => c.Issuer == issuer);

        public static IEnumerable<TRSACryptographer> GetByAudience<TRSACryptographer>(this IEnumerable<TRSACryptographer> cryptographers, string audience) where TRSACryptographer : RSACryptographer
            => cryptographers.Where(c => c.Audience == audience);

        public static TRSACryptographer Get<TRSACryptographer>(this IEnumerable<TRSACryptographer> cryptographers, string issuer, string audience) where TRSACryptographer : RSACryptographer
            => cryptographers.Where(c => c.Issuer == issuer && c.Audience == audience).SingleOrDefault()
            ?? throw new InvalidOperationException($"No {cryptographers.GetTypeName()} found with Issuer: {issuer} and Audience: {audience}");

        public static bool TryGet<TRSACryptographer>(this IEnumerable<TRSACryptographer> cryptographers, string issuer, string audience, out TRSACryptographer? cryptographer) where TRSACryptographer : RSACryptographer
        {
            cryptographer = cryptographers.Where(c => c.Issuer == issuer && c.Audience == audience).SingleOrDefault();
            return cryptographer is not null;
        }

        public static RSACryptographerList<TRSACryptographer> ToCryptographerList<TRSACryptographer>(this IEnumerable<TRSACryptographer> cryptographers, Func<TRSACryptographer, string> keyGenerator) where TRSACryptographer : RSACryptographer
            => new(keyGenerator: keyGenerator, cryptographers: cryptographers);

        private static string GetTypeName<TRSACryptographer>(this IEnumerable<TRSACryptographer> cryptographers) where TRSACryptographer : RSACryptographer
            => typeof(TRSACryptographer).GetType().Name.TrimStart(InterfaceIdentifierChar);

        private static readonly char InterfaceIdentifierChar = 'I';
    }
}