[Route("api/[controller]")]
[ApiController]
public class AuthenticationController : ControllerBase
{
    private readonly UserManager<AppUser> _userManager;
    private readonly IUserClaimsPrincipalFactory<AppUser> _claimsFactory;
    private readonly IRepository _repository;
    private readonly IConfiguration _configuration;

    public AuthenticationController(UserManager<AppUser> userManager, IUserClaimsPrincipalFactory<AppUser> claimsPrincipalFactory, IRepository repository, IConfiguration configuration)
    {
        _repository = repository;
        _userManager = userManager;
        _claimsFactory = claimsPrincipalFactory;
        _configuration = configuration;
    }

    [HttpPost]
    [Route("Register")]
    public async Task<IActionResult> Register(UserViewModel userViewModel)
    {
        var user = await _userManager.FindByIdAsync(userViewModel.email);

        if (user == null)
        {
            user = new AppUser
            {
                Id = Guid.NewGuid().ToString(),
                UserName = userViewModel.email,
                Email = userViewModel.email
            };

            var result = await _userManager.CreateAsync(user, userViewModel.password);

            if (result.Errors.Count() > 0) return StatusCode(StatusCodes.Status500InternalServerError, "Internal Server Error. Please contact support.");
        }
        else
        {
            return Forbid("Account already exists.");
        }

        return Ok();
    }

    [HttpPost]
    [Route("Login")]
    public async Task<ActionResult> Login(UserViewModel uvm)
    {
        var user = await _userManager.FindByNameAsync(uvm.email);

        if (user != null && await _userManager.CheckPasswordAsync(user, uvm.password))
        {
            try
            {
                var userPrincipal = await _claimsFactory.CreateAsync(user);
                return GenerateJWTToken(user);
            }
            catch (Exception)
            {
                return StatusCode(StatusCodes.Status500InternalServerError, "Internal Server Error. Please contact support.");
            }
        }
        else
        {
            return NotFound("Does not exist");
        }
    }

    [HttpGet]
    private ActionResult GenerateJWTToken(AppUser user)
    {
        // Create JWT Token
        var userClaims = new[]
        {
            new Claim(JwtRegisteredClaimNames.Sub, user.Email),
            new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString()),
            new Claim(JwtRegisteredClaimNames.UniqueName, user.UserName)
        };

        var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_configuration["Tokens:Key"]));
        var credentials = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);

        var token = new JwtSecurityToken(
            _configuration["Tokens:Issuer"],
            _configuration["Tokens:Audience"],
            userClaims  ,
            signingCredentials: credentials,
            expires: DateTime.UtcNow.AddHours(3)
        );

        return Created("", new
        {
            token = new JwtSecurityTokenHandler().WriteToken(token),
            user = user.UserName
        });
    }
}