<?php
/************************************************************************
 * This file is part of EspoCRM.
 *
 * EspoCRM - Open Source CRM application.
 * Copyright (C) 2014-2021 Yurii Kuznietsov, Taras Machyshyn, Oleksii Avramenko
 * Website: https://www.espocrm.com
 *
 * EspoCRM is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * EspoCRM is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with EspoCRM. If not, see http://www.gnu.org/licenses/.
 *
 * The interactive user interfaces in modified source and object code versions
 * of this program must display Appropriate Legal Notices, as required under
 * Section 5 of the GNU General Public License version 3.
 *
 * In accordance with Section 7(b) of the GNU General Public License version 3,
 * these Appropriate Legal Notices must retain the display of the "EspoCRM" word.
 ************************************************************************/

namespace Espo\Services;

use Laminas\Mail\Storage;

use Espo\ORM\Entity;

use Espo\Repositories\UserData as UserDataRepository;

use Espo\Core\{
    Exceptions\Error,
    Exceptions\Forbidden,
    Exceptions\BadRequest,
    Mail\Importer,
    Mail\ImporterData,
    Mail\MessageWrapper,
    Mail\Mail\Storage\Imap,
    Mail\Parser,
    Mail\ParserFactory,
    Record\CreateParams,
};

use Espo\Entities\{
    EmailAccount as EmailAccountEntity,
    User,
    Email as EmailEntity,
    UserData,
};

use Espo\Core\Di;

use RecursiveIteratorIterator;
use Exception;
use Throwable;
use DateTime;
use DateTimeZone;
use stdClass;

class EmailAccount extends Record implements

    Di\CryptAware
{
    use Di\CryptSetter;

    protected $storageClassName = Imap::class;

    protected const PORTION_LIMIT = 10;

    protected function filterInput($data)
    {
        parent::filterInput($data);

        if (property_exists($data, 'password')) {
            $data->password = $this->crypt->encrypt($data->password);
        }

        if (property_exists($data, 'smtpPassword')) {
            $data->smtpPassword = $this->crypt->encrypt($data->smtpPassword);
        }
    }

    public function processValidation(Entity $entity, $data)
    {
        parent::processValidation($entity, $data);

        if ($entity->get('useImap')) {
            if (!$entity->get('fetchSince')) {
                throw new BadRequest("EmailAccount validation: fetchSince is required.");
            }
        }
    }

    public function getFolders(array $params): array
    {
        $userId = $params['userId'] ?? null;

        if ($userId) {
            if (!$this->getUser()->isAdmin() && $userId !== $this->getUser()->getId()) {
                throw new Forbidden();
            }
        }

        $password = $params['password'];

        if (!empty($params['id'])) {
            $entity = $this->entityManager->getEntity('EmailAccount', $params['id']);
            if ($entity) {
                $params['password'] = $this->crypt->decrypt($entity->get('password'));
                $params['imapHandler'] = $entity->get('imapHandler');
            }
        }

        $storage = $this->createStorage($params);

        $foldersArr = [];

        $folders = new RecursiveIteratorIterator($storage->getFolders(), RecursiveIteratorIterator::SELF_FIRST);

        foreach ($folders as $name => $folder) {
            $foldersArr[] = mb_convert_encoding($folder->getGlobalName(), 'UTF-8', 'UTF7-IMAP');
        }

        return $foldersArr;
    }

    public function testConnection(array $params)
    {
        if (!empty($params['id'])) {
            $account = $this->entityManager->getEntity('EmailAccount', $params['id']);

            if ($account) {
                $params['imapHandler'] = $account->get('imapHandler');
            }
        }

        $storage = $this->createStorage($params);

        $userId = $params['userId'] ?? null;

        if ($userId) {
            if (!$this->getUser()->isAdmin() && $userId !== $this->getUser()->getId()) {
                throw new Forbidden();
            }
        }

        if ($storage->getFolders()) {
            return true;
        }

        throw new Error();
    }

    protected function createStorage(array $params)
    {
        $emailAddress = $params['emailAddress'] ?? null;

        $userId = $params['userId'] ?? null;

        $handler = null;

        $imapParams = null;

        $handlerClassName = $params['imapHandler'] ?? null;

        if ($handlerClassName && !empty($params['id'])) {
            try {
                $handler = $this->injectableFactory->create($handlerClassName);
            } catch (Throwable $e) {
                $this->log->error(
                    "EmailAccount: Could not create Imap Handler. Error: " . $e->getMessage()
                );
            }

            if (method_exists($handler, 'prepareProtocol')) {
                // for backward compatibility
                $params['ssl'] = $params['security'];

                $imapParams = $handler->prepareProtocol($params['id'], $params);
            }
        }

        if ($emailAddress && $userId && !$handlerClassName) {
            $emailAddress = strtolower($emailAddress);

            $userData = $this->getUserDataRepository()->getByUserId($userId);

            if ($userData) {
                $imapHandlers = $userData->get('imapHandlers') ?? (object) [];

                if (is_object($imapHandlers)) {
                    if (isset($imapHandlers->$emailAddress)) {
                        $handlerClassName = $imapHandlers->$emailAddress;

                        try {
                            $handler = $this->injectableFactory->create($handlerClassName);
                        }
                        catch (Throwable $e) {
                            $this->log->error(
                                "EmailAccount: Could not create Imap Handler for {$emailAddress}. Error: " .
                                    $e->getMessage()
                            );
                        }

                        if (method_exists($handler, 'prepareProtocol')) {
                            $imapParams = $handler->prepareProtocol($userId, $emailAddress, $params);
                        }
                    }
                }
            }
        }

        if (!$imapParams) {
            $imapParams = [
                'host' => $params['host'],
                'port' => $params['port'],
                'user' => $params['username'],
                'password' => $params['password'],
            ];

            if (!empty($params['security'])) {
                $imapParams['ssl'] = $params['security'];
            }
        }

        $storage = new $this->storageClassName($imapParams);

        return $storage;
    }

    public function create(stdClass $data, CreateParams $params): Entity
    {
        if (!$this->user->isAdmin()) {
            $count = $this->entityManager
                ->getRDBRepository('EmailAccount')
                ->where([
                    'assignedUserId' => $this->getUser()->getId()
                ])
                ->count();

            if ($count >= $this->getConfig()->get('maxEmailAccountCount', \PHP_INT_MAX)) {
                throw new Forbidden();
            }
        }

        $entity = parent::create($data, $params);

        if (!$this->getUser()->isAdmin()) {
            $entity->set('assignedUserId', $this->getUser()->getId());
        }

        $this->entityManager->saveEntity($entity);

        return $entity;
    }

    public function storeSentMessage(Entity $emailAccount, $message)
    {
        $storage = $this->getStorage($emailAccount);

        $folder = $emailAccount->get('sentFolder');
        if (empty($folder)) {
            throw new Error("No sent folder for Email Account: " . $emailAccount->getId() . ".");
        }

        $storage->appendMessage($message->toString(), $folder);
    }

    protected function getStorage(Entity $emailAccount)
    {
        $params = [
            'host' => $emailAccount->get('host'),
            'port' => $emailAccount->get('port'),
            'username' => $emailAccount->get('username'),
            'password' => $this->crypt->decrypt($emailAccount->get('password')),
            'emailAddress' => $emailAccount->get('emailAddress'),
            'userId' => $emailAccount->get('assignedUserId'),
        ];

        if ($emailAccount->get('security')) {
            $params['security'] = $emailAccount->get('security');
        }

        $params['imapHandler'] = $emailAccount->get('imapHandler');
        $params['id'] = $emailAccount->getId();

        $storage = $this->createStorage($params);

        return $storage;
    }

    protected function createParser(): Parser
    {
        return $this->injectableFactory->create(ParserFactory::class)->create();
    }

    protected function createImporter(): Importer
    {
        return $this->injectableFactory->create(Importer::class);
    }

    public function fetchFromMailServer(EmailAccountEntity $emailAccount)
    {
        if ($emailAccount->get('status') != 'Active' || !$emailAccount->get('useImap')) {
            throw new Error("Email Account {$emailAccount->getId()} is not active.");
        }

        $importer = $this->createImporter();

        $user = $this->entityManager->getEntity('User', $emailAccount->get('assignedUserId'));

        if (!$user) {
            throw new Error();
        }

        $userId = $user->getId();
        $teamId = $user->get('defaultTeamId');
        $teamIdList = [];

        if (!empty($teamId)) {
            $teamIdList[] = $teamId;
        }

        $filterCollection = $this->entityManager
            ->getRDBRepository('EmailFilter')
            ->where([
                'action' => 'Skip',
                'OR' => [
                    [
                        'parentType' => $emailAccount->getEntityType(),
                        'parentId' => $emailAccount->getId(),
                    ],
                    [
                        'parentId' => null
                    ]
                ]
            ])
            ->find();

        $fetchData = $emailAccount->get('fetchData');

        if (empty($fetchData)) {
            $fetchData = (object) [];
        }

        $fetchData = clone $fetchData;

        if (!property_exists($fetchData, 'lastUID')) {
            $fetchData->lastUID = (object) [];
        }

        if (!property_exists($fetchData, 'lastDate')) {
            $fetchData->lastDate = (object) [];
        }

        if (!property_exists($fetchData, 'byDate')) {
            $fetchData->byDate = (object) [];
        }

        $fetchData->lastUID = clone $fetchData->lastUID;
        $fetchData->lastDate = clone $fetchData->lastDate;
        $fetchData->byDate = clone $fetchData->byDate;

        $storage = $this->getStorage($emailAccount);

        $monitoredFolders = $emailAccount->get('monitoredFolders');

        if (empty($monitoredFolders)) {
            throw new Error("No monitored folders for email account.");
        }

        foreach ($monitoredFolders as $folder) {
            $folder = mb_convert_encoding(trim($folder), 'UTF7-IMAP', 'UTF-8');

            $portionLimit = $this->getConfig()->get('personalEmailMaxPortionSize', self::PORTION_LIMIT);

            try {
                $storage->selectFolder($folder);
            }
            catch (Exception $e) {
                $this->log->error(
                    'EmailAccount '.$emailAccount->getId().' (Select Folder) [' . $e->getCode() . '] ' .
                    $e->getMessage()
                );

                continue;
            }

            $lastUID = 0;
            $lastDate = 0;

            if (!empty($fetchData->lastUID->$folder)) {
                $lastUID = $fetchData->lastUID->$folder;
            }

            if (!empty($fetchData->lastDate->$folder)) {
                $lastDate = $fetchData->lastDate->$folder;
            }
            $forceByDate = !empty($fetchData->byDate->$folder);

            if ($forceByDate) {
                $portionLimit = 0;
            }

            $previousLastUID = $lastUID;
            $previousLastDate = $lastDate;

            if (!empty($lastUID) && !$forceByDate) {
                $idList = $storage->getIdsFromUID($lastUID);
            }
            else {
                $fetchSince = $emailAccount->get('fetchSince');

                if ($lastDate) {
                    $fetchSince = $lastDate;
                }

                $dt = null;

                try {
                    $dt = new DateTime($fetchSince);
                }
                catch (Exception $e) {}

                if ($dt) {
                    $idList = $storage->getIdsFromDate($dt->format('d-M-Y'));
                }
                else {
                    return false;
                }
            }

            if (count($idList) === 1 && !empty($lastUID)) {
                if ($storage->getUniqueId($idList[0]) === $lastUID) {
                    continue;
                }
            }

            $k = 0;

            foreach ($idList as $i => $id) {
                if ($k == count($idList) - 1) {
                    $lastUID = $storage->getUniqueId($id);
                }

                if ($forceByDate && $previousLastUID) {
                    $uid = $storage->getUniqueId($id);

                    if ($uid <= $previousLastUID) {
                        $k++;

                        continue;
                    }
                }

                $fetchOnlyHeader = $this->checkFetchOnlyHeader($storage, $id);

                $folderData = [];

                if ($emailAccount->get('emailFolderId')) {
                    $folderData[$userId] = $emailAccount->get('emailFolderId');
                }

                $message = null;
                $email = null;
                $flags = null;

                try {
                    $parser = $this->createParser();

                    $message = new MessageWrapper($storage, $id, $parser);

                    if ($message->isFetched() && $emailAccount->get('keepFetchedEmailsUnread')) {
                        $flags = $message->getFlags();
                    }

                    $importerData = ImporterData
                        ::create()
                        ->withTeamIdList($teamIdList)
                        ->withUserIdList([$userId])
                        ->withFilterList($filterCollection)
                        ->withFetchOnlyHeader($fetchOnlyHeader)
                        ->withFolderData($folderData);

                    $email = $this->importMessage(
                        $importer,
                        $emailAccount,
                        $message,
                        $importerData
                    );

                    if ($emailAccount->get('keepFetchedEmailsUnread')) {
                        if (is_array($flags) && empty($flags[Storage::FLAG_SEEN])) {
                            unset($flags[Storage::FLAG_RECENT]);

                            $storage->setFlags($id, $flags);
                        }
                    }

                } catch (Throwable $e) {
                    $this->log->error(
                        'EmailAccount '.$emailAccount->getId().
                        ' (Get Message): [' . $e->getCode() . '] ' .$e->getMessage()
                    );
                }

                if (!empty($email)) {
                    $this->entityManager->getRDBRepository('EmailAccount')->relate($emailAccount, 'emails', $email);

                    if (!$email->isFetched()) {
                        $this->noteAboutEmail($email);
                    }
                }

                if ($k === count($idList) - 1 || $k === $portionLimit - 1) {
                    $lastUID = $storage->getUniqueId($id);

                    if ($email && $email->get('dateSent')) {
                        $dt = null;

                        try {
                            $dt = new DateTime($email->get('dateSent'));
                        }
                        catch (Exception $e) {}

                        if ($dt) {
                            $nowDt = new DateTime();

                            if ($dt->getTimestamp() >= $nowDt->getTimestamp()) {
                                $dt = $nowDt;
                            }

                            $dateSent = $dt->setTimezone(new DateTimeZone('UTC'))->format('Y-m-d H:i:s');

                            $lastDate = $dateSent;
                        }
                    }

                    break;
                }

                $k++;
            }

            if ($forceByDate) {
                $nowDt = new DateTime();
                $lastDate = $nowDt->format('Y-m-d H:i:s');
            }

            $fetchData->lastDate->$folder = $lastDate;
            $fetchData->lastUID->$folder = $lastUID;

            if ($forceByDate) {
                if ($previousLastUID) {
                    $idList = $storage->getIdsFromUID($previousLastUID);

                    if (count($idList)) {
                        $uid1 = $storage->getUniqueId($idList[0]);

                        if ($uid1 && $uid1 > $previousLastUID) {
                            unset($fetchData->byDate->$folder);
                        }
                    }
                }
            } else {
                if ($previousLastUID && count($idList) && $previousLastUID >= $lastUID) {
                     $fetchData->byDate->$folder = true;
                }
            }

            $emailAccount->set('fetchData', $fetchData);

            $this->entityManager->saveEntity($emailAccount, ['silent' => true]);
        }

        $storage->close();

        return true;
    }

    protected function importMessage(
        Importer $importer,
        EmailAccountEntity $emailAccount,
        MessageWrapper $message,
        ImporterData $data
    ): ?EmailEntity {

        try {
            return $importer->import($message, $data);
        }
        catch (Throwable $e) {
            $this->log->error(
                'EmailAccount '.$emailAccount->getId().' (Import Message): [' . $e->getCode() . '] ' .
                $e->getMessage()
            );

            if ($this->entityManager->getLocker()->isLocked()) {
                $this->entityManager->getLocker()->rollback();
            }
        }

        return null;
    }

    protected function noteAboutEmail($email)
    {
        if ($email->get('parentType') && $email->get('parentId')) {
            $parent = $this->entityManager->getEntity($email->get('parentType'), $email->get('parentId'));

            if ($parent) {
                $this->getStreamService()->noteEmailReceived($parent, $email);

                return;
            }
        }
    }

    /**
     * @return EmailAccountEntity|null
     */
    public function findAccountForUser(User $user, string $address)
    {
        $emailAccount = $this->entityManager
            ->getRDBRepository('EmailAccount')
            ->where([
                'emailAddress' => $address,
                'assignedUserId' => $user->getId(),
                'status' => 'Active',
            ])
            ->findOne();

        return $emailAccount;
    }

    public function getSmtpParamsFromAccount(EmailAccountEntity $emailAccount): ?array
    {
        $smtpParams = [];

        $smtpParams['server'] = $emailAccount->get('smtpHost');

        if ($smtpParams['server']) {
            $smtpParams['port'] = $emailAccount->get('smtpPort');
            $smtpParams['auth'] = $emailAccount->get('smtpAuth');
            $smtpParams['security'] = $emailAccount->get('smtpSecurity');

            if ($emailAccount->get('smtpAuth')) {
                $smtpParams['username'] = $emailAccount->get('smtpUsername');
                $smtpParams['password'] = $emailAccount->get('smtpPassword');
                $smtpParams['authMechanism'] = $emailAccount->get('smtpAuthMechanism');
            }

            if (array_key_exists('password', $smtpParams)) {
                $smtpParams['password'] = $this->crypt->decrypt($smtpParams['password']);
            }

            $this->applySmtpHandler($emailAccount, $smtpParams);

            return $smtpParams;
        }

        return null;
    }

    public function applySmtpHandler(EmailAccountEntity $emailAccount, array &$params)
    {
        $handlerClassName = $emailAccount->get('smtpHandler');

        if (!$handlerClassName) {
            return;
        }

        $handler = null;

        try {
            $handler = $this->injectableFactory->create($handlerClassName);
        }
        catch (Throwable $e) {
            $this->log->error(
                "EmailAccount: Could not create Smtp Handler for account {$emailAccount->getId()}. Error: " .
                $e->getMessage()
            );
        }

        if (method_exists($handler, 'applyParams')) {
            $handler->applyParams($emailAccount->getId(), $params);
        }
    }

    protected function checkFetchOnlyHeader(Imap $storage, string $id): bool
    {
        $maxSize = $this->getConfig()->get('emailMessageMaxSize');

        if (!$maxSize) {
            return false;
        }

        try {
            $size = $storage->getSize((int) $id);
        }
        catch (Throwable $e) {
            return false;
        }

        if (!is_int($size)) {
            return false;
        }

        if ($size > $maxSize * 1024 * 1024) {
            return true;
        }

        return false;
    }

    private function getUserDataRepository(): UserDataRepository
    {
        /** @var UserDataRepository */
        return $this->entityManager->getRepository(UserData::ENTITY_TYPE);
    }
}