parts.php

<?php

abstract class Controller_Parts extends Controller_Template {

  /**
   * @var  Array  Ordered list of steps in the form <step name> => <function to execute>
   */
  protected $steps = array(
    'make'     => 'vcdb',
    'year'     => 'vcdb',
    'model'    => 'vcdb',
    'submodel' => 'vcdb',
  );

  /**
   * The main vehicle selector action. This should generall be the same for all
   * implementing controllers. The particular steps can be overridden via
   * $this->steps.
   */
  public function action_index()
  {

    $params = Input::get('vehicle');
    $completed_steps = array_keys($params);
    $options = array();

    $count = 0;
    foreach ($this->steps as $step => $function)
    {
      // Even if the user has already selected this, we still need the
      // option data to populate the select
      $options[$step] = $this->{"step_{$function}"}($step, array_slice($params, 0, $count, true));

      $count++;
      // But stop at the first unknown
      if ( ! in_array($step, $completed_steps))
      {
        break;
      }
    }

    $data = compact('params', 'options');
    $this->template->content = View::factory('parts/vehicle_selector.jade', $data);
  }

  /**
   * Implementation for the 'make' step.
   */
  protected function step_vcdb($step, $params)
  {
    return Model_Vehicle::distinct($step, $params);
  }

}