<?php

/**
 * SPDX-FileCopyrightText: 2016-2024 Nextcloud GmbH and Nextcloud contributors
 * SPDX-FileCopyrightText: 2016 ownCloud, Inc.
 * SPDX-License-Identifier: AGPL-3.0-only
 */
namespace OC;

use OC\Tagging\TagMapper;
use OCP\Db\Exception as DBException;
use OCP\DB\QueryBuilder\IQueryBuilder;
use OCP\EventDispatcher\Event;
use OCP\EventDispatcher\IEventDispatcher;
use OCP\EventDispatcher\IEventListener;
use OCP\Files\IRootFolder;
use OCP\IDBConnection;
use OCP\ITagManager;
use OCP\ITags;
use OCP\IUserManager;
use OCP\IUserSession;
use OCP\User\Events\UserDeletedEvent;
use Psr\Log\LoggerInterface;

/**
 * @template-implements IEventListener<UserDeletedEvent>
 */
class TagManager implements ITagManager, IEventListener {

	public function __construct(
		private TagMapper $mapper,
		private IUserSession $userSession,
		private IUserManager $userManager,
		private IDBConnection $connection,
		private LoggerInterface $logger,
		private IEventDispatcher $dispatcher,
		private IRootFolder $rootFolder,
	) {
	}

	/**
	 * Create a new \OCP\ITags instance and load tags from db.
	 *
	 * @see \OCP\ITags
	 * @param string $type The type identifier e.g. 'contact' or 'event'.
	 * @param array $defaultTags An array of default tags to be used if none are stored.
	 * @param boolean $includeShared Whether to include tags for items shared with this user by others.
	 * @param string $userId user for which to retrieve the tags, defaults to the currently
	 *                       logged in user
	 * @return \OCP\ITags
	 *
	 * since 20.0.0 $includeShared isn't used anymore
	 */
	public function load($type, $defaultTags = [], $includeShared = false, $userId = null) {
		if (is_null($userId)) {
			$user = $this->userSession->getUser();
			if ($user === null) {
				// nothing we can do without a user
				return null;
			}
			$userId = $this->userSession->getUser()->getUId();
		}
		$userFolder = $this->rootFolder->getUserFolder($userId);
		return new Tags($this->mapper, $userId, $type, $this->logger, $this->connection, $this->dispatcher, $this->userManager, $userFolder, $defaultTags);
	}

	/**
	 * Get all users who favorited an object
	 *
	 * @param string $objectType
	 * @param int $objectId
	 * @return array
	 */
	public function getUsersFavoritingObject(string $objectType, int $objectId): array {
		$query = $this->connection->getQueryBuilder();
		$query->select('uid')
			->from('vcategory_to_object', 'o')
			->innerJoin('o', 'vcategory', 'c', $query->expr()->eq('o.categoryid', 'c.id'))
			->where($query->expr()->eq('objid', $query->createNamedParameter($objectId, IQueryBuilder::PARAM_INT)))
			->andWhere($query->expr()->eq('c.type', $query->createNamedParameter($objectType)))
			->andWhere($query->expr()->eq('c.category', $query->createNamedParameter(ITags::TAG_FAVORITE)));

		$result = $query->executeQuery();
		$users = $result->fetchAll(\PDO::FETCH_COLUMN);
		$result->closeCursor();

		return $users;
	}

	public function handle(Event $event): void {
		if (!($event instanceof UserDeletedEvent)) {
			return;
		}

		// Find all objectid/tagId pairs.
		$user = $event->getUser();
		$qb = $this->connection->getQueryBuilder();
		$qb->select('id')
			->from('vcategory')
			->where($qb->expr()->eq('uid', $qb->createNamedParameter($user->getUID())));
		try {
			$result = $qb->executeQuery();
		} catch (DBException $e) {
			$this->logger->error($e->getMessage(), [
				'app' => 'core',
				'exception' => $e,
			]);
			return;
		}

		$tagsIds = array_map(fn (array $row) => (int)$row['id'], $result->fetchAll());
		$result->closeCursor();

		if (count($tagsIds) === 0) {
			return;
		}

		// Clean vcategory_to_object table
		$qb = $this->connection->getQueryBuilder();
		$qb = $qb->delete('vcategory_to_object')
			->where($qb->expr()->in('categoryid', $qb->createParameter('chunk')));

		// Clean vcategory
		$qb1 = $this->connection->getQueryBuilder();
		$qb1 = $qb1->delete('vcategory')
			->where($qb1->expr()->in('uid', $qb1->createParameter('chunk')));

		foreach (array_chunk($tagsIds, 1000) as $tagChunk) {
			$qb->setParameter('chunk', $tagChunk, IQueryBuilder::PARAM_INT_ARRAY);
			$qb1->setParameter('chunk', $tagChunk, IQueryBuilder::PARAM_INT_ARRAY);
			try {
				$qb->executeStatement();
				$qb1->executeStatement();
			} catch (DBException $e) {
				$this->logger->error($e->getMessage(), [
					'app' => 'core',
					'exception' => $e,
				]);
			}
		}
	}
}
