emall-api/FutureMailAPI/Helpers/JwtHelper.cs

using Microsoft.IdentityModel.Tokens;
using System.IdentityModel.Tokens.Jwt;
using System.Security.Claims;
using System.Text;
using FutureMailAPI.Models;

namespace FutureMailAPI.Helpers
{
    public interface IJwtHelper
    {
        string GenerateToken(User user);
        string GenerateToken(int userId, string username, string email);
        ClaimsPrincipal? ValidateToken(string token);
    }
    
    public class JwtHelper : IJwtHelper
    {
        private readonly IConfiguration _configuration;
        
        public JwtHelper(IConfiguration configuration)
        {
            _configuration = configuration;
        }
        
        public string GenerateToken(User user)
        {
            var tokenHandler = new JwtSecurityTokenHandler();
            var key = Encoding.ASCII.GetBytes(_configuration["Jwt:Key"]!);
            var tokenDescriptor = new SecurityTokenDescriptor
            {
                Subject = new ClaimsIdentity(new[]
                {
                    new Claim(ClaimTypes.NameIdentifier, user.Id.ToString()),
                    new Claim(ClaimTypes.Name, user.Username),
                    new Claim(ClaimTypes.Email, user.Email)
                }),
                Expires = DateTime.UtcNow.AddDays(7),
                Issuer = _configuration["Jwt:Issuer"],
                Audience = _configuration["Jwt:Audience"],
                SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha256Signature)
            };
            
            var token = tokenHandler.CreateToken(tokenDescriptor);
            return tokenHandler.WriteToken(token);
        }
        
        public string GenerateToken(int userId, string username, string email)
        {
            var tokenHandler = new JwtSecurityTokenHandler();
            var key = Encoding.ASCII.GetBytes(_configuration["Jwt:Key"]!);
            var tokenDescriptor = new SecurityTokenDescriptor
            {
                Subject = new ClaimsIdentity(new[]
                {
                    new Claim(ClaimTypes.NameIdentifier, userId.ToString()),
                    new Claim(ClaimTypes.Name, username),
                    new Claim(ClaimTypes.Email, email)
                }),
                Expires = DateTime.UtcNow.AddDays(7),
                Issuer = _configuration["Jwt:Issuer"],
                Audience = _configuration["Jwt:Audience"],
                SigningCredentials = new SigningCredentials(new SymmetricSecurityKey(key), SecurityAlgorithms.HmacSha256Signature)
            };
            
            var token = tokenHandler.CreateToken(tokenDescriptor);
            return tokenHandler.WriteToken(token);
        }
        
        public ClaimsPrincipal? ValidateToken(string token)
        {
            try
            {
                var tokenHandler = new JwtSecurityTokenHandler();
                var key = Encoding.ASCII.GetBytes(_configuration["Jwt:Key"]!);
                
                var validationParameters = new TokenValidationParameters
                {
                    ValidateIssuerSigningKey = true,
                    IssuerSigningKey = new SymmetricSecurityKey(key),
                    ValidateIssuer = true,
                    ValidIssuer = _configuration["Jwt:Issuer"],
                    ValidateAudience = true,
                    ValidAudience = _configuration["Jwt:Audience"],
                    ValidateLifetime = true,
                    ClockSkew = TimeSpan.Zero
                };
                
                var principal = tokenHandler.ValidateToken(token, validationParameters, out SecurityToken validatedToken);
                return principal;
            }
            catch
            {
                return null;
            }
        }
    }
}