$this->load->library('form_validation');
    $this->form_validation->set_rules('username','Username','required');
    $this->form_validation->set_rules('password','Password','required');

    if($this->form_validation->run()){
        //variables
        $username = $this->input->post('username');
        $password = md5($this->input->post('password'));
        //model function
        $this->load->model('main_model');
        if($this->main_model->can_login($username,$password)){
            $session_data = array(
                `username` => $username
            );
            $this->session->set_userdata($session_data);
            redirect(base_url() . 'home/admin');
        }
        else{
            $this->session->set_flashdata('error','Invalid Username and Password');
            redirect(base_url() . 'home/index');
        }
    }
    else{
        $this->index();
    }