<?php

declare(strict_types=1);

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

use OC\DB\Exceptions\DbalException;
use OCP\DB\QueryBuilder\IQueryBuilder;
use OCP\Files\Storage\IStorage;
use OCP\IDBConnection;
use OCP\Server;
use Psr\Log\LoggerInterface;

/**
 * Handle the mapping between the string and numeric storage ids
 *
 * Each storage has 2 different ids
 * 	a string id which is generated by the storage backend and reflects the configuration of the storage (e.g. 'smb://user@host/share')
 * 	and a numeric storage id which is referenced in the file cache
 *
 * A mapping between the two storage ids is stored in the database and accessible through this class
 *
 * @package OC\Files\Cache
 */
class Storage {
	private static ?StorageGlobal $globalCache = null;

	private string $storageId;

	private int $numericId;

	public static function getGlobalCache(): StorageGlobal {
		if (is_null(self::$globalCache)) {
			self::$globalCache = new StorageGlobal(Server::get(IDBConnection::class));
		}

		return self::$globalCache;
	}

	/**
	 * @throws \RuntimeException
	 */
	public function __construct(
		IStorage|string $storage,
		bool $isAvailable,
		IDBConnection $connection,
	) {
		$this->storageId = $storage instanceof IStorage ? $storage->getId() : $storage;

		$this->storageId = self::adjustStorageId($this->storageId);

		if ($row = self::getStorageById($this->storageId)) {
			$this->numericId = $row['numeric_id'];
		} else {
			$available = $isAvailable ? 1 : 0;

			try {
				$qb = $connection->getQueryBuilder();
				$qb->insert('storages')
					->values([
						'id' => $qb->createNamedParameter($this->storageId),
						'available' => $qb->createNamedParameter($available),
					])
					->executeStatement();
				$this->numericId = $qb->getLastInsertId();
			} catch (DbalException $e) {
				if ($e->getReason() === DbalException::REASON_UNIQUE_CONSTRAINT_VIOLATION) {
					$qb = $connection->getQueryBuilder();
					$result = $qb->select('numeric_id')
						->from('storages')
						->where($qb->expr()->eq('id', $qb->createNamedParameter($this->storageId)))
						->executeQuery();
					/** @var false|string|int $row */
					$row = $result->fetchOne();
					if ($row === false) {
						throw new \RuntimeException('Storage could neither be inserted nor be selected from the database: ' . $this->storageId, $e->getCode(), $e);
					}

					$this->numericId = (int)$row;
				}

				throw $e;
			}
		}
	}

	/**
	 * @return array{id: string, numeric_id: int, available: bool, last_checked: int}|null
	 */
	public static function getStorageById(string $storageId): ?array {
		return self::getGlobalCache()->getStorageInfo($storageId);
	}

	/**
	 * Adjusts the storage id to use md5 if too long
	 * @param string $storageId storage id
	 * @return string unchanged $storageId if its length is less than 64 characters,
	 *                else returns the md5 of $storageId
	 */
	public static function adjustStorageId(string $storageId): string {
		if (strlen($storageId) > 64) {
			return md5($storageId);
		}

		return $storageId;
	}

	/**
	 * Get the numeric id for the storage
	 */
	public function getNumericId(): int {
		return $this->numericId;
	}

	/**
	 * Get the string id for the storage
	 *
	 * @return string|null either the storage id string or null if the numeric id is not known
	 */
	public static function getStorageId(int $numericId): ?string {
		$storage = self::getGlobalCache()->getStorageInfoByNumericId($numericId);
		return $storage['id'] ?? null;
	}

	/**
	 * @return array{available: bool, last_checked: int}
	 */
	public function getAvailability(): array {
		if ($row = self::getStorageById($this->storageId)) {
			return [
				'available' => (int)$row['available'] === 1,
				'last_checked' => $row['last_checked']
			];
		}

		return [
			'available' => true,
			'last_checked' => time(),
		];
	}

	/**
	 * @param int $delay amount of seconds to delay reconsidering that storage further
	 */
	public function setAvailability(bool $isAvailable, int $delay = 0): void {
		$available = $isAvailable ? 1 : 0;
		if (!$isAvailable) {
			Server::get(LoggerInterface::class)->info('Storage with ' . $this->storageId . ' marked as unavailable', ['app' => 'lib']);
		}

		$query = Server::get(IDBConnection::class)->getQueryBuilder();
		$query->update('storages')
			->set('available', $query->createNamedParameter($available))
			->set('last_checked', $query->createNamedParameter(time() + $delay))
			->where($query->expr()->eq('id', $query->createNamedParameter($this->storageId)));
		$query->executeStatement();
	}

	/**
	 * Remove the entry for the storage by the mount id.
	 */
	public static function cleanByMountId(int $mountId): void {
		$db = Server::get(IDBConnection::class);

		try {
			$db->beginTransaction();

			$query = $db->getQueryBuilder();
			$query->select('storage_id')
				->from('mounts')
				->where($query->expr()->eq('mount_id', $query->createNamedParameter($mountId, IQueryBuilder::PARAM_INT)));
			$storageIds = $query->executeQuery()->fetchAll(\PDO::FETCH_COLUMN);
			$storageIds = array_unique($storageIds);

			$query = $db->getQueryBuilder();
			$query->delete('filecache')
				->where($query->expr()->in('storage', $query->createNamedParameter($storageIds, IQueryBuilder::PARAM_INT_ARRAY)))
				->runAcrossAllShards()
				->executeStatement();

			$query = $db->getQueryBuilder();
			$query->delete('storages')
				->where($query->expr()->in('numeric_id', $query->createNamedParameter($storageIds, IQueryBuilder::PARAM_INT_ARRAY)))
				->executeStatement();

			$query = $db->getQueryBuilder();
			$query->delete('mounts')
				->where($query->expr()->eq('mount_id', $query->createNamedParameter($mountId, IQueryBuilder::PARAM_INT)))
				->executeStatement();

			$db->commit();
		} catch (\Exception $exception) {
			$db->rollBack();
			throw $exception;
		}
	}
}