using Akari.Prototype.Server.Models;
using Akari.Prototype.Server.Utils;
using Isopoh.Cryptography.Argon2;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace Akari.Prototype.Server.Services
{
    public sealed class AuthManager : IAuthManager, IDisposable
    {
        public const int AuthKeysLength = 256 / 8;

        public IEnumerable<KeyValuePair<string, TimedEntry<AesGcm>>> Pairs => _keys;

        private readonly ILogger<AuthManager> _logger;
        private readonly IKeyManager _keyManager;

        private IDictionary<string, TimedEntry<AesGcm>> _keys;

        public AuthManager(ILogger<AuthManager> logger, IKeyManager keyManager)
        {
            _logger = logger;
            _keyManager = keyManager;
            _keys = new ConcurrentDictionary<string, TimedEntry<AesGcm>>();
        }

        public void Auth(string name, string token)
        {
            // Derive key and store it
            using var key = Security.Argon2idDeriveBytes(token, name, AuthKeysLength, clear: true);

            SetKey(name, new AesGcm(key.Buffer));
        }

        public bool Remove(string name)
        {
            return _keys.Remove(name);
        }

        private void SetKey(string name, AesGcm aesGcm)
        {
            _logger.LogDebug($"New fingerprint auth: {name}");

            if (_keys.TryGetValue(name, out var oldEntry))
            {
                _logger.LogDebug($"Old auth were present for '{name}', clearing it");

                oldEntry.Value.Dispose();
            }

            _keys[name] = new TimedEntry<AesGcm>(DateTime.Now, aesGcm);

            _logger.LogDebug($"New auth '{name}' at [{_keys[name].CreationDate}], expires at [{_keys[name].CreationDate + AuthLifetimeService.AuthLifetime}]");
        }

        public void Dispose()
        {
            _keys.Clear();
        }
    }
}