using Akari.Prototype.Server.Options;
using Akari.Prototype.Server.Utils;
using Isopoh.Cryptography.Argon2;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;

namespace Akari.Prototype.Server.Services
{
    public class FingerprintManager : IFingerprintManager
    {
        public const string FingerprintsPath = "fingerprints.json";

        private readonly ILogger<FingerprintManager> _logger;
        private readonly IAuthManager _authManager;
        private readonly AkariPath _akariPath;

        private IDictionary<string, string> _fingerprintsHash;

        public FingerprintManager(ILogger<FingerprintManager> logger, IAuthManager authManager, AkariPath akariPath)
        {
            _logger = logger;
            _authManager = authManager;
            _akariPath = akariPath;

            LoadFingerprints();
        }

        private void LoadFingerprints()
        {
            var path = _akariPath.GetPath(FingerprintsPath);

            // Create new
            if (!File.Exists(path))
            {
                _fingerprintsHash = new Dictionary<string, string>();

                File.WriteAllText(path, JsonSerializer.Serialize(_fingerprintsHash));
            }
            // Load
            else
            {
                _fingerprintsHash = JsonSerializer.Deserialize<IDictionary<string, string>>(File.ReadAllText(path));
            }
        }

        private void SaveFingerprints()
        {
            var path = _akariPath.GetPath(FingerprintsPath);

            File.WriteAllText(path, JsonSerializer.Serialize(_fingerprintsHash));
        }

        public bool Add(string name, string hash)
        {
            if (_fingerprintsHash.TryAdd(name, hash))
            {
                SaveFingerprints();

                _authManager.GenerateSalt(name);

                return true;
            }

            return false;
        }

        public bool Contains(string name)
        {
            return _fingerprintsHash.ContainsKey(name);
        }

        public bool Remove(string name)
        {
            if (_fingerprintsHash.Remove(name))
            {
                SaveFingerprints();

                return true;
            }

            return false;
        }

        public void Set(string name, string hash)
        {
            _fingerprintsHash[name] = hash;

            SaveFingerprints();
        }

        public IEnumerator<KeyValuePair<string, string>> GetEnumerator()
        {
            return _fingerprintsHash.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return GetEnumerator();
        }

        public void VerifyFingerprint(string name, byte[] token)
        {
            _logger.LogDebug($"Verifying hash for {name}");

            var handle = GCHandle.Alloc(token, GCHandleType.Pinned);

            if (!_fingerprintsHash.TryGetValue(name, out var hash))
            {
                _logger.LogDebug($"No fingerprint exist with the name: {name}");

                handle.Free();

                return;
            }

            if (!Argon2.Verify(hash, token))
            {
                _logger.LogDebug($"Token doesn't match stored hash: {name}");

                handle.Free();

                return;
            }

            try
            {
                _authManager.Auth(name, token);
            }
            finally
            {
                handle.Free();
            }
        }
    }
}