<div class="row justify-content-center">
<div class="col-6">
<h1><?php echo $title ?></h1>
<?php echo form_open('users/changePassword', array('id' => 'passwordForm'))?>
<div class="form-group">
<input type="password" name="oldpass" id="oldpass" class="form-control" placeholder="Old Password" />
<?php echo form_error('oldpass', '<div class="error">', '</div>')?>
</div>
<div class="form-group">
<input type="password" name="newpass" id="newpass" class="form-control" placeholder="New Password" />
<?php echo form_error('newpass', '<div class="error">', '</div>')?>
</div>
<div class="form-group">
<input type="password" name="passconf" id="passconf" class="form-control" placeholder="Confirm Password" />
<?php echo form_error('passconf', '<div class="error">', '</div>')?>
</div>
<div class="form-group">
<button type="submit" class="btn btn-success">Change Password</button>
</div>
<?php echo form_close(); ?>
</div>
</div>

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Users extends CI_Controller{

public function __construct()
{
parent::__construct();
$this->load->helper('form');
$this->load->library('form_validation');
$this->load->model('users_model');
}

private function logged_in()
{
if( ! $this->session->userdata('authenticated')){
redirect('users/login');
}
}

public function changePassword()
{
$this->logged_in();

$data['title'] = 'Change Password';

$this->load->library('form_validation');

$this->form_validation->set_rules('oldpass', 'old password', 'callback_password_check');
$this->form_validation->set_rules('newpass', 'new password', 'required');
$this->form_validation->set_rules('passconf', 'confirm password', 'required|matches[newpass]');

$this->form_validation->set_error_delimiters('<div class="error">', '</div>');

if($this->form_validation->run() == false) {
$this->load->view('header', $data);
$this->load->view('users/change_password', $data);
$this->load->view('footer', $data);
}
else {

$id = $this->session->userdata('id');

$newpass = $this->input->post('newpass');

$this->users_model->update_user($id, array('password' => md5($newpass)));

redirect('users/logout');
}
}

public function password_check($oldpass)
{
$id = $this->session->userdata('id');
$user = $this->users_model->get_user($id);

if($user->password !== md5($oldpass)) {
$this->form_validation->set_message('password_check', 'The {field} does not match');
return false;
}

return true;
}
}
?>

<?php
defined('BASEPATH') OR exit('No direct script access allowed');

class Users_model extends CI_Model{

public function get_user($id)
{
$this->db->where('id', $id);
$query = $this->db->get('users');
return $query->row();
}

public function update_user($id, $userdata)
{
$this->db->where('id', $id);
$this->db->update('users', $userdata);
}
}
?>