<?php

namespace Drupal\some_module;

use Drupal\Core\Entity\EntityTypeManagerInterface;
use Drupal\node\NodeInterface;

/**
 * Class SomeOrgJobManger.
 */
class SomeOrgJobManger {

  /**
   * The node storage service.
   *
   * @var \Drupal\Core\Entity\EntityStorageInterface
   */
  protected $nodeStorage;

  /**
   * A node entity query object.
   *
   * @var \Drupal\Core\Entity\Query\QueryAggregateInterface
   */
  protected $nodeAggregateQuery;

  /**
   * SomeOrgJobManger constructor.
   *
   * @param \Drupal\Core\Entity\EntityTypeManagerInterface $entity_type_manager
   *   The entity storage interface.
   */
  public function __construct(EntityTypeManagerInterface $entity_type_manager) {
    $this->nodeStorage = $entity_type_manager->getStorage('node');
    $this->nodeAggregateQuery = $this->nodeStorage->getAggregateQuery();
  }

  /**
   *
   */
  public function getStatesWithAvailableJobs() {
    $result = [];

    $job_results = $this->nodeAggregateQuery
      ->aggregate('nid', 'MIN')
      ->groupBy('field_country_region')
      ->condition('status', NodeInterface::PUBLISHED)
      ->condition('type', 'job_posting')
      ->execute();

    foreach ($job_results as $job_info) {
      if (!empty($job_info['field_country_region_target_id'])) {
        $region_node = $this->nodeStorage->load($job_info['field_country_region_target_id']);
        $state_abbrev = $region_node->field_state_province_abbr->value;
        if (!empty($state_abbrev)) {
          $result[$state_abbrev] = $region_node->label();
        }
      }
    }

    // TODO: Remove the following proof of concept code.
    $nodeQuery = $this->nodeStorage->getQuery();
    $test_states = [];
    $test_result = $nodeQuery
      ->condition('type', 'job_posting')
      ->condition('status', NodeInterface::PUBLISHED)
      ->execute();
    foreach ($test_result as $nid) {
      $test_job_node = $this->nodeStorage->load($nid);
      if (!empty($test_job_node) && isset($test_job_node->field_country_region)) {
        $test_region = $test_job_node->field_country_region->entity;
        if (isset($test_region->field_state_province_abbr)) {
          $state_abbrev = $test_region->field_state_province_abbr->value;
          if (!empty($state_abbrev)) {
            $test_states[$state_abbrev] = $test_region->label();
          }
        }
      }
    }
    $diff = array_diff($result, $test_states);
    if (!empty($diff)) {
      drupal_set_message('SomeOrgJobManger::getStatesWithAvailableJobs is incorrect.');
    }
    // TODO: End remove.

    return $result;
  }

}