Kirby CMS: Collect files sharing the same name / different extension for HTML5 Video handling

kirby-group-files.php

<?php

  //build lookup array for files with the same name but a different extension
  $fileGroups = [];
  foreach($page->files() as $file) {
    if (!isset($fileGroups[$file->name()])) {
      $fileGroups[$file->name()] = [];
    }
    array_push($fileGroups[$file->name()], $file->extension());
  }
  
  //remove all files with only 1 extension – no duplicates, no videos
  foreach($fileGroups as $fileName => $extensions) {
    if (count($extensions) <= 1) {
      unset($fileGroups[$fileName]);
    }
  }
  
  //custom filter, as recommended by @distantnative
  //http://forum.getkirby.com/t/filter-files-by-multiple-file-extensions/697/4
  $GLOBALS['fileGroups'] = $fileGroups; //TODO: hacky, because resorting to globals
  $files = $page->files()->filter(function($file) {
    $fileGroups = $GLOBALS['fileGroups'];
    return
        //filter files with multiple extensions + keep only images
        (empty($fileGroups[$file->name()])) and ($file->type() == 'image')
      or
        //multiple extensions means: video, means: use only .mp4 file
        $file->extension() == 'mp4'
      ;
  });