<?php

/**
 * SPDX-FileCopyrightText: 2017 Nextcloud GmbH and Nextcloud contributors
 * SPDX-License-Identifier: AGPL-3.0-or-later
 */

namespace OCA\Guests;

use OCP\DB\QueryBuilder\IQueryBuilder;
use OCP\EventDispatcher\IEventDispatcher;
use OCP\IConfig;
use OCP\IDBConnection;
use OCP\IUser;
use OCP\IUserManager;
use OCP\IUserSession;
use OCP\Security\Events\GenerateSecurePasswordEvent;
use OCP\Security\ICrypto;
use OCP\Security\ISecureRandom;
use OCP\Share\IManager;
use OCP\Share\IShare;

class GuestManager {
	public function __construct(
		private IConfig $config,
		private UserBackend $userBackend,
		private ISecureRandom $secureRandom,
		private ICrypto $crypto,
		private IManager $shareManager,
		private IDBConnection $connection,
		private IUserSession $userSession,
		private IEventDispatcher $eventDispatcher,
		private IUserManager $userManager,
	) {
	}

	/**
	 * @param IUser|string $user
	 * @return bool
	 */
	public function isGuest($user = null): bool {
		if (is_null($user)) {
			$user = $this->userSession->getUser();
			return ($user !== null) && $this->userBackend->userExists($user->getUID());
		}
		if (is_string($user)) {
			return $this->userBackend->userExists($user);
		} elseif ($user instanceof IUser) {
			return $this->userBackend->userExists($user->getUID());
		}
		return false;
	}

	public function createGuest(?IUser $createdBy, string $userId, string $email, string $displayName = '', string $language = '', ?string $initialPassword = null) : IUser {
		if ($initialPassword === null) {
			$passwordEvent = new GenerateSecurePasswordEvent();
			$this->eventDispatcher->dispatchTyped($passwordEvent);
			$password = $passwordEvent->getPassword() ?? $this->secureRandom->generate(20);
		} else {
			$password = $initialPassword;
		}

		/** @var IUser */
		$user = $this->userManager->createUserFromBackend(
			$userId,
			$password,
			$this->userBackend
		);

		$user->setSystemEMailAddress($email);
		if ($createdBy) {
			$this->config->setUserValue($userId, 'guests', 'created_by', $createdBy->getUID());
		}

		if ($displayName) {
			$user->setDisplayName($displayName);
		}

		if ($language) {
			$this->config->setUserValue($userId, 'core', 'lang', $language);
		}

		if ($initialPassword === null) {
			// generate token for lost password so that a link can be sent by email
			$token = $this->secureRandom->generate(
				21,
				ISecureRandom::CHAR_DIGITS
				. ISecureRandom::CHAR_LOWER
				. ISecureRandom::CHAR_UPPER);

			$endOfTime = PHP_INT_MAX - 50000;
			$token = sprintf('%s:%s', $endOfTime, $token);

			$encryptedValue = $this->crypto->encrypt($token, strtolower($email) . $this->config->getSystemValue('secret'));

			$this->config->setUserValue(
				$userId,
				'core',
				'lostpassword',
				$encryptedValue
			);
		}

		$user->setQuota('0 B');

		return $user;
	}

	public function listGuests(): array {
		return $this->userBackend->getUsers();
	}

	public function getGuestsInfo(): array {
		$displayNames = $this->userBackend->getDisplayNames();
		$guests = array_keys($displayNames);
		$shareCounts = $this->getShareCountForUsers($guests);
		$createdBy = $this->config->getUserValueForUsers('guests', 'created_by', $guests);
		return array_map(function ($uid) use ($createdBy, $displayNames, $shareCounts) {
			$allSharesCount = count(array_merge(
				$this->shareManager->getSharedWith($uid, IShare::TYPE_USER, null, -1, 0),
				$this->shareManager->getSharedWith($uid, IShare::TYPE_GROUP, null, -1, 0),
				$this->shareManager->getSharedWith($uid, IShare::TYPE_CIRCLE, null, -1, 0),
				$this->shareManager->getSharedWith($uid, IShare::TYPE_GUEST, null, -1, 0),
				$this->shareManager->getSharedWith($uid, IShare::TYPE_ROOM, null, -1, 0),
			));
			return [
				'email' => $uid,
				'display_name' => $displayNames[$uid] ?? $uid,
				'created_by' => $createdBy[$uid] ?? '',
				'share_count' => isset($shareCounts[$uid]) ? $shareCounts[$uid] : 0,
				'share_count_with_circles' => $allSharesCount,
			];
		}, $guests);
	}

	private function getShareCountForUsers(array $guests): array {
		$query = $this->connection->getQueryBuilder();
		$query->select('share_with', $query->func()->count('*', 'count'))
			->from('share')
			->where($query->expr()->in('share_with', $query->createNamedParameter($guests, IQueryBuilder::PARAM_STR_ARRAY)))
			->groupBy('share_with');
		$result = $query->executeQuery();
		$data = [];
		while ($row = $result->fetch()) {
			$data[$row['share_with']] = $row['count'];
		}
		$result->closeCursor();

		return $data;
	}

	public function getGuestInfo(string $userId): array {
		$shares = array_merge(
			$this->shareManager->getSharedWith($userId, IShare::TYPE_USER, null, -1, 0),
			$this->shareManager->getSharedWith($userId, IShare::TYPE_GROUP, null, -1, 0),
			$this->shareManager->getSharedWith($userId, IShare::TYPE_CIRCLE, null, -1, 0),
			$this->shareManager->getSharedWith($userId, IShare::TYPE_GUEST, null, -1, 0),
			$this->shareManager->getSharedWith($userId, IShare::TYPE_ROOM, null, -1, 0)
		);
		return [
			'shares' => array_map(function (IShare $share) {
				return [
					'id' => $share->getId(),
					'shared_by' => $share->getSharedBy(),
					'mime_type' => $share->getNodeCacheEntry()->getMimeType(),
					'name' => $share->getNodeCacheEntry()->getName(),
					'time' => $share->getShareTime()->getTimestamp(),
				];
			}, $shares),
		];
	}
}