media_entity.module

<?php

/**
 * @file
 * Provides media entities.
 */

use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function media_entity_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    case 'help.page.media_entity':
      $output = '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('The <a href=":media_entity_url">Media Entity</a> module provides a "base" entity for media. This is a very basic entity which can reference to all kinds of media-objects (local files, YouTube videos, Tweets, Instagram photos, ...). Media entity provides a relation between your website and the media resource. You can reference to/use this entity within any other entity on your site. For more information, see the <a href=":media_entity_handbook">online documentation for the Media Entity module</a>.',
          [
            ':media_entity_url' => 'https://www.drupal.org/project/media_entity',
            ':media_entity_handbook' => 'https://drupal-media.gitbooks.io/drupal8-guide/content/modules/media_entity/intro.html',
          ]) . '</p>';
      $output .= '<h3>' . t('Uses') . '</h3>';
      $output .= '<p>' . t('For detailed information about the usage of this module please refer to <a href=":media_entity_handbook">the official documentation</a>.',
          [
            ':media_entity_handbook' => 'https://drupal-media.gitbooks.io/drupal8-guide/content/modules/media_entity/intro.html',
          ]) . '</p>';

      return $output;
  }
}

/**
 * Implements hook_theme().
 */
function media_entity_theme() {
  return [
    'media' => [
      'render element' => 'elements',
      'file' => 'media_entity.theme.inc',
      'template' => 'media',
    ],
  ];
}

/**
 * Implements hook_theme_suggestions_HOOK().
 */
function media_entity_theme_suggestions_media(array $variables) {
  $suggestions = [];
  $media = $variables['elements']['#media'];
  $sanitized_view_mode = strtr($variables['elements']['#view_mode'], '.', '_');

  $suggestions[] = 'media__' . $sanitized_view_mode;
  $suggestions[] = 'media__' . $media->bundle();
  $suggestions[] = 'media__' . $media->bundle() . '__' . $sanitized_view_mode;
  $suggestions[] = 'media__' . $media->id();
  $suggestions[] = 'media__' . $media->id() . '__' . $sanitized_view_mode;

  return $suggestions;
}

/**
 * Copy the media file icons to files directory for use with image styles.
 *
 * @param string $source
 *   Source folder.
 * @param string $destination
 *   Destination folder.
 *
 * @throws Exception
 */
function media_entity_copy_icons($source, $destination) {
  if (!file_prepare_directory($destination, FILE_CREATE_DIRECTORY | FILE_MODIFY_PERMISSIONS)) {
    throw new Exception("Unable to create directory $destination.");
  }

  $files = file_scan_directory($source, '/.*\.(png|jpg)$/');
  foreach ($files as $file) {
    $result = file_unmanaged_copy($file->uri, $destination, FILE_EXISTS_REPLACE);
    if (!$result) {
      throw new Exception("Unable to copy {$file->uri} to $destination.");
    }
  }
}