using DigitalData.Core.Abstractions.Security;
using DigitalData.Core.Security.Config;
using DigitalData.Core.Security.Cryptographer;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using System.Collections;

namespace DigitalData.Core.Security
{
    public class AsymCryptService<TAsymCryptParams> : RSAFactory<TAsymCryptParams>, IAsymCryptService<TAsymCryptParams>, IRSAFactory<TAsymCryptParams>, IEnumerable<IRSADecryptor>
        where TAsymCryptParams : AsymCryptParams
    {
        public IEnumerable<IRSADecryptor> Decryptors { get; }
        
        /// <summary>
        /// It is a separate decryptor for permanently stored encrypted data. It is assigned to the first Default decryptor by default.
        /// </summary>
        public IRSADecryptor Vault { get; }

        public IRSADecryptor this[string key]
        {
            get
            {
                var key_params = key.Split(_params.KeyNameSeparator);

                if (key_params.Length != 2)
                    throw new ArgumentException($"Invalid key format. Expected two segments separated by '{_params.KeyNameSeparator}', but received: '{key}'.", nameof(key));

                return _params.Decryptors.FirstOrDefault(d => d.Issuer == key_params[0] && d.Audience == key_params[1])
                    ?? throw new KeyNotFoundException($"No decryptor found matching the issuer '{key_params[0]}' and audience '{key_params[1]}'.");
            }
        }

        public IRSADecryptor this[int index] => index < 0 || index >= Decryptors.Count()
            ? Decryptors.ElementAt(index)
            : throw new ArgumentOutOfRangeException(
                nameof(index),
                index,
                $"The index {index} is out of range. The valid indices for {GetType()} are between 0 and {Decryptors.Count() - 1} (inclusive). Please ensure the index is within this range.");

        public AsymCryptService(IOptions<TAsymCryptParams> options, ILogger<AsymCryptService<TAsymCryptParams>>? logger = null) : base(options)
        {
            logger?.LogInformation("Core.Secrets version: {Version}, Created on: {CreationDate}.", Secrets.Version, Secrets.CreationDate.ToString("dd.MM.yyyy"));

            if (!_params.Decryptors.Any())
                throw new InvalidOperationException(
                    "Any decryptor is not found. Ensure that at least one decryptor is configured in the provided parameters. " +
                    "This issue typically arises if the configuration for decryptors is incomplete or missing. " +
                    "Check the 'Decryptors' collection in the configuration and verify that it contains valid entries."
                );

            Decryptors = _params.Decryptors;

            Vault = _params.Vault ?? Decryptors.First();
        }

        public IEnumerator<IRSADecryptor> GetEnumerator() => Decryptors.GetEnumerator();

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

        public IEnumerable<IRSAEncryptor> Encryptors
        {
            get
            {
                foreach (var decryptor in Decryptors)
                    yield return decryptor.Encryptor;
            }
        }
    }
}