using Newtonsoft.Json;
using System.Net;

namespace Diligent.WebAPI.Business.Services
{

    public class UserService : IUserService
    {
        private readonly AuthorizationSettings _authSettings;
        private readonly UserManager<User> _userManager;
        private readonly IMapper _mapper;
        private readonly DatabaseContext _databaseContext;

        public UserService(IOptions<AuthorizationSettings> authSettings, UserManager<User> userManager, IMapper mapper, DatabaseContext databaseContext)
        {
            _authSettings = authSettings.Value;
            _userManager = userManager;
            _mapper = mapper;
            _databaseContext = databaseContext;
        }

        public async Task<IEnumerable<User?>> GetAll() =>
            await _userManager.Users.ToListAsync();

        public async Task<User?> GetById(int id) =>
            await _userManager.FindByIdAsync(id.ToString());

        public async Task CreateUser(CreateUserRequestDto model)
        {
            var user = _mapper.Map<User>(model);

            await _userManager.CreateAsync(user, model.Password);
        }

        private const string GoogleApiTokenInfoUrl = "https://www.googleapis.com/oauth2/v3/tokeninfo?id_token={0}";
        private string[] SupportedClientsIds = { "734219382849-nvnulsu7ibfl4bk3n164bgb7c1h5dgca.apps.googleusercontent.com" };
        private bool IsTokenValid(string providerToken)
        {
            var httpClient = new HttpClient();
            var requestUri = new Uri(string.Format(GoogleApiTokenInfoUrl, providerToken));

            HttpResponseMessage httpResponseMessage;
            try
            {
                httpResponseMessage = httpClient.GetAsync(requestUri).Result;
            }
            catch (Exception ex)
            {
                return false;
            }

            if (httpResponseMessage.StatusCode != HttpStatusCode.OK)
            {
                return false;
            }

            var response = httpResponseMessage.Content.ReadAsStringAsync().Result;
            var googleApiTokenInfo = JsonConvert.DeserializeObject<GoogleApiTokenInfo>(response);

            if (!SupportedClientsIds.Contains(googleApiTokenInfo.aud))
            {
                return false;
            }

            return true;
            //return new
            //{
            //    Email = googleApiTokenInfo.email,
            //    FirstName = googleApiTokenInfo.given_name,
            //    LastName = googleApiTokenInfo.family_name,
            //    Locale = googleApiTokenInfo.locale,
            //    Name = googleApiTokenInfo.name,
            //    ProviderUserId = googleApiTokenInfo.sub
            //};

        }

        public async Task<ServiceResponseDTO<AuthenticateResponseDto>> Authenticate(AuthenticateRequestDto model)
        {
            var user = await _userManager.FindByNameAsync(model.Username);

            // return null if user not found
            if (user == null)
            {
                return new ServiceResponseDTO<AuthenticateResponseDto>
                {
                    IsError = true,
                    ErrorMessage = "Username is not valid"
                };
            }

            var result = await _userManager.CheckPasswordAsync(user, model.Password);

            // password is not correct
            if (!result)
            {
                await _userManager.AccessFailedAsync(user);

                return new ServiceResponseDTO<AuthenticateResponseDto>
                {
                    IsError = true,
                    ErrorMessage = "Password is not correct"
                };
            }

            return await GenerateToken(user);
        }
        
        public async Task<ServiceResponseDTO<AuthenticateResponseDto>> Authenticate(GoogleApiModel model)
        {
            
            if (!IsTokenValid(model.Token))
            {
                return new ServiceResponseDTO<AuthenticateResponseDto>
                {
                    IsError = true,
                    ErrorMessage = "Invalid Google Api Token"
                };
            }
            var user = await _userManager.FindByEmailAsync(model.User.email);

            // return null if user not found
            if (user == null)
            {
                return new ServiceResponseDTO<AuthenticateResponseDto>
                {
                    IsError = true,
                    ErrorMessage = $"User with email {model.User.email} does not exist in database"
                };
            }

            return await GenerateToken(user);
        }

        private async Task<ServiceResponseDTO<AuthenticateResponseDto>> GenerateToken(User user)
        {
            var isLocked = await _userManager.IsLockedOutAsync(user);

            if (isLocked)
                return new ServiceResponseDTO<AuthenticateResponseDto>
                {
                    IsError = true,
                    ErrorMessage = "The account is locked out"
                };



            // authentication successful so generate jwt token
            var token = await GenerateJwtToken(user, true);

            var data = new AuthenticateResponseDto
            {
                Id = user.Id,
                Username = user.UserName,
                FirstName = user.FirstName,
                LastName = user.LastName,
                Token = token,
                RefreshToken = token
            };

            return new ServiceResponseDTO<AuthenticateResponseDto>
            {
                Data = data
            };
        }

        private async Task<string> GenerateJwtToken(User user, bool authenticate = false)
        {
            // generate token that is valid for 7 days
            var tokenHandler = new JwtSecurityTokenHandler();
            var key = Encoding.ASCII.GetBytes(_authSettings.Secret);
            var tokenDescriptor = new SecurityTokenDescriptor
            {
                Subject = new ClaimsIdentity(new[] {
                    new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
                    new Claim("id", user.Id.ToString())
                }),
                Expires = DateTime.UtcNow.AddMinutes(_authSettings.JwtExpiredTime),
                SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha256Signature)
            };
            var token = tokenHandler.CreateToken(tokenDescriptor);

            var writedToken = tokenHandler.WriteToken(token);

            var refreshToken = new RefreshToken
            {
                Token = writedToken,
                JwtId = token.Id,
                UserId = user.Id,
                User = user,
                CreationDate = DateTime.UtcNow,
                ExpiryDate = DateTime.UtcNow.AddMinutes(_authSettings.JwtRefreshExpiredTime)
            };

            var existRefreshToken = await _databaseContext.RefreshTokens.Where(x => x.Id == user.Id).FirstOrDefaultAsync();

            if(existRefreshToken != null)
            {
                existRefreshToken.Token = writedToken;
                existRefreshToken.JwtId = token.Id;
                existRefreshToken.CreationDate = DateTime.UtcNow;
                existRefreshToken.ExpiryDate = DateTime.UtcNow.AddMinutes(_authSettings.JwtRefreshExpiredTime);

                if (authenticate)
                {
                    existRefreshToken.Used = false;
                    existRefreshToken.Invalidated = false;
                }

                //_databaseContext.RefreshTokens.Update(existRefreshToken);
                await UpdateRefreshToken(existRefreshToken);
            }
            else
            {
                await _databaseContext.RefreshTokens.AddAsync(refreshToken);
            }

            await _databaseContext.SaveChangesAsync();

            return writedToken;
        }

        public async Task<RefreshTokenResultDto> RefreshTokenAsync(RefreshTokenRequestDto model)
        {
            var validatedToken = GetPrincipalFromToken(model.Token);

            if (validatedToken == null)
            {
                return new RefreshTokenResultDto { Error = "Invalid token" };
            }

            var expiryDateUnix = long.Parse(validatedToken.Claims.Single(x => x.Type == JwtRegisteredClaimNames.Exp).Value);

            var expiryDateTimeUtc = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc)
                .AddSeconds(expiryDateUnix);

            if (expiryDateTimeUtc > DateTime.UtcNow)
            {
                return new RefreshTokenResultDto { Error = "This token hasn't expired yet" };
            }

            var jti = validatedToken.Claims.Single(x => x.Type == JwtRegisteredClaimNames.Jti).Value;

            var storedRefreshToken = await _databaseContext.RefreshTokens.SingleOrDefaultAsync(x => x.Token == model.RefreshToken);

            if (storedRefreshToken == null)
            {
                return new RefreshTokenResultDto { Error = "This refresh token does not exist" };
            }

            if (DateTime.UtcNow > storedRefreshToken.ExpiryDate)
            {
                return new RefreshTokenResultDto { Error = "This refresh token has expired" };
            }

            if (storedRefreshToken.Invalidated)
            {
                return new RefreshTokenResultDto { Error = "This refresh token has been invalidated" };
            }

            if (storedRefreshToken.Used)
            {
                return new RefreshTokenResultDto { Error = "This refresh token has been used" };
            }

            if (storedRefreshToken.JwtId != jti)
            {
                return new RefreshTokenResultDto { Error = "This refresh token does not match this JWT" };
            }

            storedRefreshToken.Used = true;
            _databaseContext.RefreshTokens.Update(storedRefreshToken);
            await _databaseContext.SaveChangesAsync();

            var user = await _userManager.FindByIdAsync(validatedToken.Claims.Single(x => x.Type == "id").Value);

            var token =  await GenerateJwtToken(user);

            return new RefreshTokenResultDto
            {
                Token = token
            };
        }

        private ClaimsPrincipal GetPrincipalFromToken(string token)
        {
            var tokenHandler = new JwtSecurityTokenHandler();

            var key = Encoding.ASCII.GetBytes(_authSettings.Secret);
            var tokenValidationParameters = new TokenValidationParameters
            {
                ValidateIssuerSigningKey = true,
                IssuerSigningKey = new SymmetricSecurityKey(key),
                ValidateIssuer = false,
                ValidateAudience = false,
                RequireExpirationTime = false,
                ValidateLifetime = true,
                // set clockskew to zero so tokens expire exactly at token expiration time (instead of 5 minutes later)
                //ClockSkew = TimeSpan.Zero
            };

            try
            {
                var principal = tokenHandler.ValidateToken(token, tokenValidationParameters, out var validatedToken);
                if (!IsJwtWithValidSecurityAlgorithm(validatedToken))
                {
                    return null;
                }

                return principal;
            }
            catch (Exception ex)
            {
                return null;
            }
        }

        private bool IsJwtWithValidSecurityAlgorithm(SecurityToken validatedToken)
        {
            return (validatedToken is JwtSecurityToken jwtSecurityToken) &&
                jwtSecurityToken.Header.Alg.Equals(SecurityAlgorithms.HmacSha256,
                    StringComparison.InvariantCultureIgnoreCase);
        }

        public async Task<RefreshToken?> GetRefreshTokenByUserId(int userId)
        {
            return await _databaseContext.RefreshTokens.Where(x => x.UserId == userId).FirstOrDefaultAsync();
        }

        public async Task UpdateRefreshToken(RefreshToken refreshToken)
        {
            _databaseContext.RefreshTokens.Update(refreshToken);

            await _databaseContext.SaveChangesAsync();
        }
    }
}