DigitalData.Core/DigitalData.Core.Security/Cryptographer/RSACryptographer.cs

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

namespace DigitalData.Core.Security.Cryptographer
{
    public class RSACryptographer : IRSACryptographer
    {
        protected string? _pem;

        public string Pem
        {
            get => _pem
                ?? throw new InvalidOperationException($"Pem is not initialized. Please ensure that the PEM is set or properly loaded from the file. Issuer: {Issuer}, Audience: {Audience}.");
            init => _pem = value;
        }

        public string? PemPath => FileName is null ? null : Path.Combine(Directory ?? string.Empty, FileName);

        public string? Directory { get; set; }

        public string? FileName { get; set; }

        public RSAEncryptionPadding Padding { get; init; } = RSAEncryptionPadding.OaepSHA256;

        protected virtual RSA RSA { get; } = RSA.Create();

        public string Issuer { get; init; } = string.Empty;

        public string Audience { get; init; } = string.Empty;

        internal RSACryptographer() { }
        
        public virtual void UnableToInitPemEvent() => throw new InvalidOperationException(
            $"Pem is not initialized and pem file is null. Issuer is {Issuer} and audience {Audience}.");

        public virtual void FileNotFoundEvent() => throw new FileNotFoundException(
            $"Pem is not initialized and pem file is not found in {PemPath}. Issuer is {Issuer} and audience {Audience}.");

        // TODO: make file read asynchronous, consider multiple routing
        public virtual void Init()
        {
            if(_pem is null)
            {
                if(PemPath is null)
                    UnableToInitPemEvent();
                if (File.Exists(PemPath))
                    _pem = File.ReadAllText(PemPath);
                else
                    FileNotFoundEvent();
            }
        }
    }
}