<?php
include("config.php");
session_start();

if($_SERVER["REQUEST_METHOD"] == "POST") {

  $myusername = mysqli_real_escape_string($db,$_POST['username']);
  $mypassword = mysqli_real_escape_string($db,$_POST['password']);

  $sql = "SELECT * FROM user WHERE username = '$myusername' and password = '$mypassword'";
  $result = mysqli_query($db,$sql);
  $row = mysqli_fetch_array($result,MYSQLI_ASSOC);
  $active = isset($row['active']);
  $count = mysqli_num_rows($result);

  $role = isset($row['role']);

    if($role = 'admin'){
        $link = 'admin.php';
    }
    elseif($role = 'user'){
        $link = 'user.php';
    }
    elseif($role = 'expert'){
        $link = 'expert.php';
    }
    else{
        $link = '404.php';
    }

  if($count == 1) {
    $_SESSION['username'] = $myusername;

    header("Location: ".$link."");
    exit();
  }else {
     $error = "Your Login Name or Password is invalid";
  }
}
?>