Inject facet block in views exposed form

exposed_facets.php

<?php

function MODULE_get_exposed_facet_token($delta) {
  return "<!-- FACET:$delta -->";
}

/**
 * Implements hook_form_FORM_ID_alter().
 */
function MODULE_form_views_exposed_form_alter(&$form, &$form_state, $form_id) {

  $facets['{VIEW}:{DISPLAY}'] = 'search_api@{INDEX}:block:{FIELD_NAME}';

  $view_name = $form_state['view']->name . ':' . $form_state['view']->current_display;

  if(isset($facets[$view_name])) {
    $delta = array_search($facets[$view_name], facetapi_get_delta_map());
    $form_state['view']->exposed_facets[$delta] = $facets[$view_name];

    $form['facets'] = array(
      '#markup' => MODULE_get_exposed_facet_token($delta)
    );
  }
}

/**
 * Implements hook_preprocess_HOOK().
 */
function MODULE_preprocess_views_view(&$vars) {
  $placeholders = !empty($vars['view']->exposed_facets) ? $vars['view']->exposed_facets : array();
  foreach($placeholders as $delta => $facet) {
    $token = MODULE_get_exposed_facet_token($delta);
    $block = facetapi_block_view($delta);
    // @todo inject views-ajax-link class
    $vars['exposed'] = str_replace($token, drupal_render($block), $vars['exposed']);
  }
}