--- /dev/null
+<?php
+
+namespace Drupal\media\Plugin\media\Source;
+
+use Drupal\file\FileInterface;
+use Drupal\media\MediaInterface;
+use Drupal\media\MediaTypeInterface;
+use Drupal\media\MediaSourceBase;
+
+/**
+ * File entity media source.
+ *
+ * @see \Drupal\file\FileInterface
+ *
+ * @MediaSource(
+ * id = "file",
+ * label = @Translation("File"),
+ * description = @Translation("Use local files for reusable media."),
+ * allowed_field_types = {"file"},
+ * default_thumbnail_filename = "generic.png"
+ * )
+ */
+class File extends MediaSourceBase {
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getMetadataAttributes() {
+ return [];
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function getMetadata(MediaInterface $media, $attribute_name) {
+ /** @var \Drupal\file\FileInterface $file */
+ $file = $media->get($this->configuration['source_field'])->entity;
+ // If the source field is not required, it may be empty.
+ if (!$file) {
+ return parent::getMetadata($media, $attribute_name);
+ }
+ switch ($attribute_name) {
+ case 'default_name':
+ return $file->getFilename();
+
+ case 'thumbnail_uri':
+ return $this->getThumbnail($file) ?: parent::getMetadata($media, $attribute_name);
+
+ default:
+ return parent::getMetadata($media, $attribute_name);
+ }
+ }
+
+ /**
+ * Gets the thumbnail image URI based on a file entity.
+ *
+ * @param \Drupal\file\FileInterface $file
+ * A file entity.
+ *
+ * @return string
+ * File URI of the thumbnail image or NULL if there is no specific icon.
+ */
+ protected function getThumbnail(FileInterface $file) {
+ $icon_base = $this->configFactory->get('media.settings')->get('icon_base_uri');
+
+ // We try to automatically use the most specific icon present in the
+ // $icon_base directory, based on the MIME type. For instance, if an
+ // icon file named "pdf.png" is present, it will be used if the file
+ // matches this MIME type.
+ $mimetype = $file->getMimeType();
+ $mimetype = explode('/', $mimetype);
+
+ $icon_names = [
+ $mimetype[0] . '--' . $mimetype[1],
+ $mimetype[1],
+ $mimetype[0],
+ ];
+ foreach ($icon_names as $icon_name) {
+ $thumbnail = $icon_base . '/' . $icon_name . '.png';
+ if (is_file($thumbnail)) {
+ return $thumbnail;
+ }
+ }
+
+ return NULL;
+ }
+
+ /**
+ * {@inheritdoc}
+ */
+ public function createSourceField(MediaTypeInterface $type) {
+ return parent::createSourceField($type)->set('settings', ['file_extensions' => 'txt doc docx pdf']);
+ }
+
+}