Use avatar from file or url

[eluser]Sein Kraft[/eluser]
Hi everyone. I've a simple file uploader wich set the avatar for the user but i want also add an input for set the avatar from url. The question is vallidate and use the url if the user havent selected a file but for that i should remove the avatar callback.

More than a problem is a performance question I think. What I should do?

This my code:

Code:

function _set_avatar(){
    
        $this->form_validation->set_rules('avatar_file', 'Avatar', 'callback__avatar_check');
        $this->form_validation->set_rules('avatar_url', 'Avatar', 'trim|min_length[5]');
            
        $this->form_validation->set_error_delimiters('<div class="error">', '</div>');
        
        if ($this->form_validation->run() == FALSE)
        {            
            $this->load->view('users/profile');
        }
        else
        {
            //Agregar aviso de error durante la subida del avatar.        
            $config_avatar['upload_path'] = './temp/';
            $config_avatar['allowed_types'] = 'gif|jpg|png';
            $config_avatar['overwrite'] = TRUE;
            $config_avatar['max_size']    = '100';
            $config_avatar['max_width']  = '100';
            $config_avatar['max_height']  = '100';
            
            $this->load->library('upload', $config_avatar);
        
            if (!$this->upload->do_upload('avatar_file'))
            {
                //I suppose that the code for the url should be here
            }    
            else
            {
                $data = array('upload_data' => $this->upload->data());
                $upload_data = $this->upload->data();
                
                $this->load->model('mUsers','', TRUE);
                $users = $this->mUsers->get_user('id', $this->session->userdata('id'));
                
                $temp_file = './temp/'.$upload_data['file_name'];
                $new_file = './accounts/'.$users->user.'/avatar'.$upload_data['file_ext'];
                
                //We delete the olda avatar to create the new one.
                unlink($new_file);
                rename($temp_file , $new_file);
                                
                $user_data['id'] = $users->id;
                $user_data['avatar'] = $this->mConfig->get_config('subdomain_accounts').$users->user.'/avatar'.$upload_data['file_ext'];
                
                $this->mUsers->set_avatar($user_data);
                
                redirect('users/profile');
            }
        }
        
        $this->load->view('footer');
    }
    
    
    
    /*
    - Check if the field of the avatar is not empty.
    */
    function _avatar_check(){
        if($_FILES['avatar_file']['error'] == 4){
            $this->form_validation->set_message('_avatar_check','File to use as avatar is required.');
            return FALSE;
        }
        else{
            return TRUE;
        }
    }