<?php

namespace Civi\Mailinglistsync;

use CRM_Mailinglistsync_ExtensionUtil as E;
use Civi\Mailinglistsync\Exceptions\MailinglistException;
use Civi\Mailinglistsync\Exceptions\MailinglistSyncException;
use CRM_Queue_Queue;

class QueueHelper {

  /**
   * Singleton instances.
   *
   * @var array
   */
  private static array $instances = [];

  private CRM_Queue_Queue $groupQueue;
  private CRM_Queue_Queue $eventQueue;
  private CRM_Queue_Queue $emailQueue;

  private array $groups;

  private array $events;

  private array $emails;

  /**
   * Protect singleton from being instantiated.
   */
  protected function __construct() {
    // Get queues
    $this->groupQueue = \Civi::queue(
      'propeace-mailinglist-group-queue', [
      'type' => 'SqlParallel',
      'is_autorun' => FALSE,
      'reset' => FALSE,
      'error' => 'drop',
    ]);
    $this->eventQueue = \Civi::queue(
      'propeace-mailinglist-group-queue', [
      'type' => 'SqlParallel',
      'is_autorun' => FALSE,
      'reset' => FALSE,
      'error' => 'drop',
    ]);
    $this->emailQueue = \Civi::queue(
      'propeace-mailinglist-group-queue', [
      'type' => 'SqlParallel',
      'is_autorun' => FALSE,
      'reset' => FALSE,
      'error' => 'drop',
    ]);
  }

  /**
   * Protect singleton from being cloned.
   */
  protected function __clone() { }

  /**
   * Protect unserialize method to prevent cloning of the instance.
   * @throws \Exception
   */
  public function __wakeup()
  {
    throw new MailinglistSyncException(
      "Cannot unserialize a singleton.",
      MailinglistSyncException::ERROR_CODE_UNSERIALIZE_SINGLETON
    );
  }

  /**
   * Returns the singleton instance.
   *
   * @return \Civi\Mailinglistsync\QueueHelper
   */
  public static function getInstance(): QueueHelper
  {
    $cls = static::class;
    if (!isset(self::$instances[$cls])) {
      self::$instances[$cls] = new static();
      \Civi::log()->debug(E::LONG_NAME . ": Created new instance of $cls");
    }

    return self::$instances[$cls];
  }

  /**
   * Getter for the group queue.
   *
   * @return \CRM_Queue_Queue
   */
  public function getGroupQueue(): CRM_Queue_Queue {
    return $this->groupQueue;
  }

  /**
   * Getter for the event queue.
   *
   * @return \CRM_Queue_Queue
   */
  public function getEventQueue(): CRM_Queue_Queue {
    return $this->eventQueue;
  }

  /**
   * Getter for the email queue.
   *
   * @return \CRM_Queue_Queue
   */
  public function getEmailQueue(): CRM_Queue_Queue {
    return $this->emailQueue;
  }

  public function getGroups(): array {
    return $this->groups;
  }

  public function addToGroups(GroupMailingList $group): void {
    $this->groups[] = $group;
  }

  public function getEvents(): array {
    return $this->events;
  }

  public function addToEvents(EventMailingList $event): void {
    $this->events[] = $event;
  }

  public function getEmails(): array {
    return $this->emails;
  }

  public function addToEmails(string $email): void {
    $this->emails[] = $email;
  }

  /**
   * Stores an instance of the given class in the queue helper singleton.
   * Meant to be passed as callback to the queue.
   *
   * @param int $entityId
   * @param string $class
   *
   * @return void
   * @throws \Civi\Mailinglistsync\Exceptions\MailinglistException
   */
  public static function storeInstance(int $entityId, string $class): void {

    // Throw exception if class is invalid
    if ($class != GroupMailingList::class &&
      $class != ADGroupMailingList::class &&
      $class != EventMailingList::class) {
      throw new MailinglistException(
        "Invalid class '$class'",
        MailinglistException::ERROR_CODE_INVALID_CLASS
      );
    }

    // Instantiate the mailing list object
    $instance = new $class();
    $instance->load($entityId);

    // Store instance in the queue helper singleton
    match ($class) {
      GroupMailingList::class, ADGroupMailingList::class => self::getInstance()->addToGroups($instance),
      EventMailingList::class => self::getInstance()->addToEvents($instance),
      default => throw new MailinglistException(
        "Invalid class '$class'",
        MailinglistException::ERROR_CODE_INVALID_CLASS
      ),
    };
  }
}