DigitalData.Core/DigitalData.Core.Security/Cryptographer/RSACryptographerList.cs

using DigitalData.Core.Abstractions.Security;
using System.Collections;

namespace DigitalData.Core.Security.Cryptographer
{
    public class RSACryptographerList<TRSACryptographer> : IEnumerable<TRSACryptographer> where TRSACryptographer : IRSACryptographer
    {
        private readonly Func<TRSACryptographer, string> _keyGenerator;

        private readonly IEnumerable<TRSACryptographer> _cryptographers;

        internal RSACryptographerList(Func<TRSACryptographer, string> keyGenerator, IEnumerable<TRSACryptographer> cryptographers)
        {
            _keyGenerator = keyGenerator;
            _cryptographers = cryptographers;            
        }

        public TRSACryptographer this[string key]
            => _cryptographers.SingleOrDefault(crypt => _keyGenerator(crypt) == key)
            ?? throw new InvalidOperationException($"No {typeof(TRSACryptographer).GetType().Name.TrimStart('I')} found with Key: {key}.");

        public bool TryGet(string key, out TRSACryptographer? cryptographer)
        {
            cryptographer = _cryptographers.SingleOrDefault(crypt => _keyGenerator(crypt) == key);
            return cryptographer is not null;
        }

        public IEnumerator<TRSACryptographer> GetEnumerator() => _cryptographers.GetEnumerator();

        IEnumerator IEnumerable.GetEnumerator() => GetEnumerator();
    }
}