sledgemapper/Sledgemapper.Api/Controllers/AuthManagementController.cs

using AutoMapper;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Options;
using Microsoft.IdentityModel.Tokens;
using Sledgemapper.Entities;
using Sledgemapper.Models.Users;
using System;
using System.Collections.Generic;
using System.IdentityModel.Tokens.Jwt;
using System.Linq;
using System.Security.Claims;
using System.Text;
using System.Threading.Tasks;

namespace Sledgemapper.Api.Controllers
{
    [Route("[controller]")] // api/authmanagement
    [ApiController]
    public class AuthManagementController : ControllerBase
    {
        private readonly UserManager<User> _userManager;
        private readonly JwtConfig _jwtConfig;
        private readonly IMapper _mapper;

        public AuthManagementController(UserManager<User> userManager,
                                        IOptionsMonitor<JwtConfig> optionsMonitor,
                                        IMapper mapper)
        {
            _userManager = userManager;
            _jwtConfig = optionsMonitor.CurrentValue;
            _mapper = mapper;
        }

        [HttpPost]
        [Route("Register")]
        public async Task<IActionResult> Register([FromBody] RegisterModel user)
        {
            // Check if the incoming request is valid
            if (ModelState.IsValid)
            {
                // check i the user with the same email exist
                var existingUser = await _userManager.FindByEmailAsync(user.Email);

                if (existingUser != null)
                {
                    return BadRequest(new RegistrationResponse()
                    {
                        Result = false,
                        Errors = new List<string>(){
                                            "Email already exist"
                                        }
                    });
                }

                var newUser = _mapper.Map<User>(user);
                // var newUser = new User() { Email = user.Email, UserName = user.UserName };
                var isCreated = await _userManager.CreateAsync(newUser, user.Password);
                if (isCreated.Succeeded)
                {
                    var jwtToken = GenerateJwtToken(newUser);

                    return Ok(new RegistrationResponse()
                    {
                        Result = true,
                        Token = jwtToken
                    });
                }

                return new JsonResult(new RegistrationResponse()
                {
                    Result = false,
                    Errors = isCreated.Errors.Select(x => x.Description).ToList()
                }
                        )
                { StatusCode = 500 };
            }

            return BadRequest(new RegistrationResponse()
            {
                Result = false,
                Errors = new List<string>(){
                                            "Invalid payload"
                                        }
            });
        }

        [HttpPost]
        [Route("Login")]
        public async Task<IActionResult> Login([FromBody] UserLoginRequest user)
        {
            if (ModelState.IsValid)
            {
                // check if the user with the same email exist
                var existingUser = await _userManager.FindByEmailAsync(user.Email);

                if (existingUser == null)
                {
                    // We dont want to give to much information on why the request has failed for security reasons
                    return BadRequest(new RegistrationResponse()
                    {
                        Result = false,
                        Errors = new List<string>(){
                                        "Invalid authentication request"
                                    }
                    });
                }

                // Now we need to check if the user has inputed the right password
                var isCorrect = await _userManager.CheckPasswordAsync(existingUser, user.Password);

                if (isCorrect)
                {
                    var jwtToken = GenerateJwtToken(existingUser);

                    return Ok(new LoginResponse()
                    {
                        Result = true,
                        Token = jwtToken,
                        Username = existingUser.Email,
                        Initials = existingUser.Initials,
                        Id = existingUser.Id
                    });
                }
                else
                {
                    // We dont want to give to much information on why the request has failed for security reasons
                    return BadRequest(new RegistrationResponse()
                    {
                        Result = false,
                        Errors = new List<string>(){
                                         "Invalid authentication request"
                                    }
                    });
                }
            }

            return BadRequest(new RegistrationResponse()
            {
                Result = false,
                Errors = new List<string>(){
                                        "Invalid payload"
                                    }
            });
        }

        private string GenerateJwtToken(User user)
        {
            // Now its ime to define the jwt token which will be responsible of creating our tokens
            var jwtTokenHandler = new JwtSecurityTokenHandler();

            // We get our secret from the appsettings
            var key = Encoding.ASCII.GetBytes(_jwtConfig.Secret);

            // we define our token descriptor
            // We need to utilise claims which are properties in our token which gives information about the token
            // which belong to the specific user who it belongs to
            // so it could contain their id, name, email the good part is that these information
            // are generated by our server and identity framework which is valid and trusted
            var tokenDescriptor = new SecurityTokenDescriptor
            {

                Subject = new ClaimsIdentity(new[]
                {
                new Claim("Id", user.Id.ToString()),
                new Claim(JwtRegisteredClaimNames.Sub, user.Email),
                new Claim(JwtRegisteredClaimNames.Email, user.Email),
                // the JTI is used for our refresh token which we will be convering in the next video
                new Claim(JwtRegisteredClaimNames.Jti, Guid.NewGuid().ToString())
            }),
                // the life span of the token needs to be shorter and utilise refresh token to keep the user signedin
                // but since this is a demo app we can extend it to fit our current need
                Expires = DateTime.UtcNow.AddHours(6),
                // here we are adding the encryption alogorithim information which will be used to decrypt our token
                SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha512Signature)
            };

            var token = jwtTokenHandler.CreateToken(tokenDescriptor);

            var jwtToken = jwtTokenHandler.WriteToken(token);

            return jwtToken;
        }
    }
}