<?php

namespace Drupal\cdesai_migrate\Plugin\migrate\process;

use Drupal\migrate\MigrateSkipRowException;
use Drupal\migrate\Row;
use Drupal\migrate\ProcessPluginBase;
use Drupal\migrate\MigrateExecutableInterface;
use Drush\Drush;

/**
 * Provides a 'Extract File Contents' migrate process plugin.
 *
 * Extracts contents of a file.
 *
 * @MigrateProcessPlugin(
 *  id = "extract_file_contents"
 * )
 */
class ExtractFileContents extends ProcessPluginBase {

  /**
   * {@inheritdoc}
   *
   * @throws \Drupal\migrate\MigrateSkipRowException
   */
  public function transform($value, MigrateExecutableInterface $migrate_executable, Row $row, $destination_property) {
    $error = FALSE;
    $page = $row->get('page');

    if (is_null($value) || trim($value) === '') {
      $error = "Skipping because content filepath is empty for {$page}.";
    }
    elseif (!is_file($value)) {
      $error = "Skipping because content file is missing for {$page}.";
    }
    else {
      $contents = file_get_contents($value);
      if ($contents !== FALSE) {
        return $contents;
      }

      $error = "Skipping because content file is unreadable for {$page}.";
    }

    if ($error) {
      Drush::output()->writeln($error);
      throw new MigrateSkipRowException($error);
    }

    return '';
  }

}