Extending Facet API for Mime Type 1

gistfile1.php

<?php
function MYMODULE_facetapi_facet_info($searcher_info) {
  $facets = array();
  
  $facets['mime'] = array(
     'label' => t('Mime Type'),
     'description' => t('Filter by mime type.'),
     //indexed field from solr 
     'field' => 'ss_filemime',
     'map callback' => 'MYMODULE_map_mime',
     'facet mincount allowed' => TRUE,
     'dependency plugins' => array('bundle', 'role'),
   );
   
  return $facets;
}