Login IKIMINA

using Microsoft.AspNetCore.Authentication.Cookies;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.RazorPages;
using System.Data.SqlClient;
using System.Security.Claims;

namespace IKIMINA_CYACU.Pages.Users
{
    public class LoginModel : PageModel
    {
        string conString = "Data Source=JN-JUSTE\\SQLEXPRESS;Initial Catalog=IKIMINACYACUProject;Integrated Security=True;Encrypt=False";
        public string message = "";
        public void OnGet()
        {
        }

        private bool AuthenticateUser(string username, string password, out string userRole)
        {
            userRole = null;

            try
            {
                using (SqlConnection con = new SqlConnection(conString))
                {
                    string qry = "SELECT UserName, Role FROM USERS WHERE UserName = @username AND Password = @password";
                    con.Open();

                    using (SqlCommand cmd = new SqlCommand(qry, con))
                    {
                        cmd.Parameters.AddWithValue("@username", username);
                        cmd.Parameters.AddWithValue("@password", password);

                        using (SqlDataReader reader = cmd.ExecuteReader())
                        {
                            if (reader.Read())
                            {
                                userRole = reader.GetString(reader.GetOrdinal("Role"));
                                return true; // Authentication successful
                            }
                            else
                            {
                                return false; // Authentication failed
                            }
                        }
                    }
                }
            }
            catch (Exception)
            {
                throw;
            }
        }
        public IActionResult OnPost()
        {
            try
            {
                string enteredUsername = Request.Form["username"];
                string enteredPassword = Request.Form["password"];

                if (AuthenticateUser(enteredUsername, enteredPassword, out string userRole))
                {
                    var claims = new List<Claim>
                    {
                        new Claim(ClaimTypes.Name, enteredUsername),
                        new Claim(ClaimTypes.Role, userRole),
                    };

                    var userIdentity = new ClaimsIdentity(claims, "login");
                    var userPrincipal = new ClaimsPrincipal(userIdentity);

                    HttpContext.SignInAsync(CookieAuthenticationDefaults.AuthenticationScheme, userPrincipal);

                    if (userRole.Equals("ADMIN", StringComparison.OrdinalIgnoreCase))
                    {
                        message = $"Welcome dear {userRole} {enteredUsername}!";
                        return RedirectToPage("/Users/CreateUser");
                    }
                    else if (userRole.Equals("MEMBER", StringComparison.OrdinalIgnoreCase))
                    {
                        message = $"Welcome dear {userRole} {enteredUsername}!";
                        return RedirectToPage("/Index");
                    }
                    else
                    {
                        message = "Invalid role for user";
                        return Page();
                    }
                }
                else
                {
                    message = "Invalid username or password";
                    return Page();
                }
            }
            catch (Exception ex)
            {
                message = "There's a problem: " + ex.Message;
                return Page();
            }
        }
    }
}