<?php

namespace Drupal\custom_forms_default_fields\EventSubscriber;

use Drupal\Core\Logger\LoggerChannelFactoryInterface;
use Drupal\Core\StringTranslation\StringTranslationTrait;
use Drupal\file\Entity\File;
use Drupal\file\FileUsage\FileUsageInterface;
use Drupal\state_machine\Event\WorkflowTransitionEvent;
use Symfony\Component\EventDispatcher\EventDispatcherInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

/**
 * Class SubmissionEventSubscriber
 *
 * @package Drupal\custom_forms_default_fields\EventSubscriber
 */
class SubmissionEventSubscriber implements EventSubscriberInterface {
  use StringTranslationTrait;

  /**
   * The logger channel factory.
   *
   * @var \Drupal\Core\Logger\LoggerChannelInterface
   */
  protected $logger;

  /**
   * The event dispatcher service.
   *
   * @var \Symfony\Component\EventDispatcher\EventDispatcherInterface
   */
  protected $eventDispatcher;

  /**
   * The file usage service.
   *
   * @var \Drupal\file\FileUsage\FileUsageInterface
   */
  protected $fileUsage;

  public function __construct(LoggerChannelFactoryInterface $logger_factory, EventDispatcherInterface $event_dispatcher, FileUsageInterface $file_usage) {
    $this->logger = $logger_factory->get('Custom Forms');
    $this->eventDispatcher = $event_dispatcher;
    $this->fileUsage = $file_usage;
  }

  /**
   * Returns an array of event names this subscriber wants to listen to.
   *
   * The array keys are event names and the value can be:
   *
   *  * The method name to call (priority defaults to 0)
   *  * An array composed of the method name to call and the priority
   *  * An array of arrays composed of the method names to call and respective
   *    priorities, or 0 if unset
   *
   * For instance:
   *
   *  * ['eventName' => 'methodName']
   *  * ['eventName' => ['methodName', $priority]]
   *  * ['eventName' => [['methodName1', $priority], ['methodName2']]]
   *
   * @return array
   *   The event names to listen to.
   */
  public static function getSubscribedEvents() : array {
    return [
      'custom_form.initialize.post_transition'  => ['setFileUsage', -100],
    ];
  }

  /**
   * Set the file usage of any attached files to be associated with
   * the submission that added them.
   *
   * @param \Drupal\state_machine\Event\WorkflowTransitionEvent $event
   *   The transition event.
   */
  public function setFileUsage(WorkflowTransitionEvent $event) : void {
    /** @var \Drupal\custom_forms\Entity\CustomFormSubmissionInterface $submission */
    $submission = $event->getEntity();
    $values = $submission->getData();

    // Return if file usage processing is disabled or no files defined.
    if (empty($values['_process_file_usage']) && empty($values['_files'])) {
      return;
    }

    foreach ($values['_files'] as $machine_name => $file_data) {
      /** @var \Drupal\file\FileInterface $file */
      $file = File::load($file_data['fid']);

      // If file failed to load, log error and skip it.
      if ($file === NULL) {
        $message = $this->t('Failed loading file with id @fid when processing file usage.',
          ['@fid' => $file_data['fid']]
        );
        $this->logger->error($message);
        continue;
      }

      // Add the file usage so the uploaded file doesn't get removed by
      // garbage collection.
      $this->fileUsage->add($file, 'custom_forms_submission', 'image_upload', $submission->id(), 1);
    }

    // Remove the processing tag, as we don't need it any more.
    unset($values['_process_file_usage']);

    $submission->setDataArray($values);
  }

}