feat: mail filters

Co-authored-by: Hamza Mahjoubi <[email protected]>
Signed-off-by: Daniel Kesselberg <[email protected]>

REUSE.toml

@@ -101,6 +101,12 @@ precedence = "aggregate"
 SPDX-FileCopyrightText = "2024 Nextcloud GmbH and Nextcloud contributors"
 SPDX-License-Identifier = "AGPL-3.0-or-later"
 
+[[annotations]]
+path = ["tests/data/mail-filter/*"]
+precedence = "aggregate"
+SPDX-FileCopyrightText = "2024 Nextcloud GmbH and Nextcloud contributors"
+SPDX-License-Identifier = "AGPL-3.0-or-later"
+
 [[annotations]]
 path = ".github/CODEOWNERS"
 precedence = "aggregate"

lib/Controller/FilterController.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Controller;
+
+use OCA\Mail\AppInfo\Application;
+use OCA\Mail\Service\AccountService;
+use OCA\Mail\Service\FilterService;
+use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\Attribute\Route;
+use OCP\AppFramework\Http\JSONResponse;
+use OCP\AppFramework\OCSController;
+use OCP\IRequest;
+
+class FilterController extends OCSController {
+	private string $currentUserId;
+
+	public function __construct(
+		IRequest $request,
+		string $userId,
+		private FilterService $mailFilterService,
+		private AccountService $accountService,
+	) {
+		parent::__construct(Application::APP_ID, $request);
+		$this->currentUserId = $userId;
+	}
+
+	#[Route(Route::TYPE_FRONTPAGE, verb: 'GET', url: '/api/filter/{accountId}', requirements: ['accountId' => '[\d]+'])]
+	public function getFilters(int $accountId) {
+		$account = $this->accountService->findById($accountId);
+
+		if ($account->getUserId() !== $this->currentUserId) {
+			return new JSONResponse([], Http::STATUS_NOT_FOUND);
+		}
+
+		$result = $this->mailFilterService->parse($account->getMailAccount());
+
+		return new JSONResponse($result->getFilters());
+	}
+
+	#[Route(Route::TYPE_FRONTPAGE, verb: 'PUT', url: '/api/filter/{accountId}', requirements: ['accountId' => '[\d]+'])]
+	public function updateFilters(int $accountId, array $filters) {
+		$account = $this->accountService->findById($accountId);
+
+		if ($account->getUserId() !== $this->currentUserId) {
+			return new JSONResponse([], Http::STATUS_NOT_FOUND);
+		}
+
+		$this->mailFilterService->update($account->getMailAccount(), $filters);
+
+		return new JSONResponse([]);
+	}
+}

lib/Exception/FilterParserException.php

@@ -0,0 +1,29 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Exception;
+
+use Exception;
+
+class FilterParserException extends Exception {
+
+	public static function invalidJson(\Throwable $exception): FilterParserException {
+		return new self(
+			'Failed to parse filter state json: ' . $exception->getMessage(),
+			0,
+			$exception,
+		);
+	}
+
+	public static function invalidState(): FilterParserException {
+		return new self(
+			'Reached an invalid state',
+		);
+	}
+}

lib/Service/AllowedRecipientsService.php

@@ -0,0 +1,34 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Service;
+
+use OCA\Mail\Db\MailAccount;
+
+class AllowedRecipientsService {
+
+	public function __construct(
+		private AliasesService $aliasesService,
+	) {
+	}
+
+	/**
+	 * Return a list of allowed recipients for a given mail account
+	 *
+	 * @return string[] email addresses
+	 */
+	public function get(MailAccount $mailAccount): array {
+		$aliases = array_map(
+			static fn ($alias) => $alias->getAlias(),
+			$this->aliasesService->findAll($mailAccount->getId(), $mailAccount->getUserId())
+		);
+
+		return array_merge([$mailAccount->getEmail()], $aliases);
+	}
+}

lib/Service/FilterService.php

@@ -0,0 +1,88 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Service;
+
+use Horde\ManageSieve\Exception as ManageSieveException;
+use JsonException;
+use OCA\Mail\Db\MailAccount;
+use OCA\Mail\Exception\ClientException;
+use OCA\Mail\Exception\CouldNotConnectException;
+use OCA\Mail\Exception\FilterParserException;
+use OCA\Mail\Exception\OutOfOfficeParserException;
+use OCA\Mail\Service\MailFilter\FilterBuilder;
+use OCA\Mail\Service\MailFilter\FilterParser;
+use OCA\Mail\Service\MailFilter\FilterParserResult;
+use OCA\Mail\Service\OutOfOffice\OutOfOfficeParser;
+use OCA\Mail\Service\OutOfOffice\OutOfOfficeState;
+use Psr\Log\LoggerInterface;
+
+class FilterService {
+
+	public function __construct(
+		private AllowedRecipientsService $allowedRecipientsService,
+		private OutOfOfficeParser $outOfOfficeParser,
+		private FilterParser $filterParser,
+		private FilterBuilder $filterBuilder,
+		private SieveService $sieveService,
+		private LoggerInterface $logger,
+	) {
+	}
+
+	/**
+	 * @throws ClientException
+	 * @throws ManageSieveException
+	 * @throws CouldNotConnectException
+	 * @throws FilterParserException
+	 */
+	public function parse(MailAccount $account): FilterParserResult {
+		$script = $this->sieveService->getActiveScript($account->getUserId(), $account->getId());
+		return $this->filterParser->parseFilterState($script->getScript());
+	}
+
+	/**
+	 * @throws CouldNotConnectException
+	 * @throws JsonException
+	 * @throws ClientException
+	 * @throws OutOfOfficeParserException
+	 * @throws ManageSieveException
+	 * @throws FilterParserException
+	 */
+	public function update(MailAccount $account, array $filters): void {
+		$script = $this->sieveService->getActiveScript($account->getUserId(), $account->getId());
+
+		$oooResult = $this->outOfOfficeParser->parseOutOfOfficeState($script->getScript());
+		$filterResult = $this->filterParser->parseFilterState($oooResult->getUntouchedSieveScript());
+
+		$newScript = $this->filterBuilder->buildSieveScript(
+			$filters,
+			$filterResult->getUntouchedSieveScript()
+		);
+
+		$oooState = $oooResult->getState();
+
+		if ($oooState instanceof OutOfOfficeState) {
+			$newScript = $this->outOfOfficeParser->buildSieveScript(
+				$oooState,
+				$newScript,
+				$this->allowedRecipientsService->get($account),
+			);
+		}
+
+		try {
+			$this->sieveService->updateActiveScript($account->getUserId(), $account->getId(), $newScript);
+		} catch (ManageSieveException $e) {
+			$this->logger->error('Failed to save sieve script: ' . $e->getMessage(), [
+				'exception' => $e,
+				'script' => $newScript,
+			]);
+			throw $e;
+		}
+	}
+}

lib/Service/MailFilter/FilterBuilder.php

@@ -0,0 +1,165 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Service\MailFilter;
+
+use OCA\Mail\Exception\ImapFlagEncodingException;
+use OCA\Mail\IMAP\ImapFlag;
+use OCA\Mail\Sieve\SieveUtils;
+
+class FilterBuilder {
+	private const SEPARATOR = '### Nextcloud Mail: Filters ### DON\'T EDIT ###';
+	private const DATA_MARKER = '# FILTER: ';
+	private const SIEVE_NEWLINE = "\r\n";
+
+	public function __construct(
+		private ImapFlag $imapFlag,
+	) {
+	}
+
+
+	public function buildSieveScript(array $filters, string $untouchedScript): string {
+		$commands = [];
+		$extensions = [];
+
+		foreach ($filters as $filter) {
+			if ($filter['enable'] === false) {
+				continue;
+			}
+
+			$commands[] = '# ' . $filter['name'];
+
+			$tests = [];
+			foreach ($filter['tests'] as $test) {
+				if ($test['field'] === 'subject') {
+					$tests[] = sprintf(
+						'header :%s "Subject" %s',
+						$test['operator'],
+						SieveUtils::stringList($test['values']),
+					);
+				}
+				if ($test['field'] === 'to') {
+					$tests[] = sprintf(
+						'address :%s :all "To" %s',
+						$test['operator'],
+						SieveUtils::stringList($test['values']),
+					);
+				}
+				if ($test['field'] === 'from') {
+					$tests[] = sprintf(
+						'address :%s :all "From" %s',
+						$test['operator'],
+						SieveUtils::stringList($test['values']),
+					);
+				}
+			}
+
+			if (count($tests) === 0) {
+				// skip filter without tests
+				$commands[] = '# No valid tests found';
+				continue;
+			}
+
+			$actions = [];
+			foreach ($filter['actions'] as $action) {
+				if ($action['type'] === 'fileinto') {
+					$extensions[] = 'fileinto';
+					$actions[] = sprintf(
+						'fileinto "%s";',
+						SieveUtils::escapeString($action['mailbox'])
+					);
+				}
+				if ($action['type'] === 'addflag') {
+					$extensions[] = 'imap4flags';
+					$actions[] = sprintf(
+						'addflag "%s";',
+						SieveUtils::escapeString($this->sanitizeFlag($action['flag']))
+					);
+				}
+				if ($action['type'] === 'keep') {
+					$actions[] = 'keep;';
+				}
+				if ($action['type'] === 'stop') {
+					$actions[] = 'stop;';
+				}
+			}
+
+			if (count($tests) > 1) {
+				$ifTest = sprintf('%s (%s)', $filter['operator'], implode(', ', $tests));
+			} else {
+				$ifTest = $tests[0];
+			}
+
+			$actions = array_map(
+				static fn ($action) => "\t" . $action,
+				$actions
+			);
+
+			$ifBlock = sprintf(
+				"if %s {\r\n%s\r\n}",
+				$ifTest,
+				implode(self::SIEVE_NEWLINE, $actions)
+			);
+
+			$commands[] = $ifBlock;
+		}
+
+		$lines = [];
+
+		$extensions = array_unique($extensions);
+		if (count($extensions) > 0) {
+			$lines[] = self::SEPARATOR;
+			$lines[] = 'require ' . SieveUtils::stringList($extensions) . ';';
+			$lines[] = self::SEPARATOR;
+		}
+
+		/*
+		 * Using implode("\r\n", $lines) may introduce an extra newline if the original script already ends with one.
+		 * There may be a cleaner solution, but I couldn't find one that works seamlessly with Filter and Autoresponder.
+		 * Feel free to give it a try!
+		 */
+		if (str_ends_with($untouchedScript, self::SIEVE_NEWLINE . self::SIEVE_NEWLINE)) {
+			$untouchedScript = substr($untouchedScript, 0, -2);
+		}
+		$lines[] = $untouchedScript;
+
+		if (count($filters) > 0) {
+			$lines[] = self::SEPARATOR;
+			$lines[] = self::DATA_MARKER . json_encode($this->sanitizeDefinition($filters), JSON_THROW_ON_ERROR);
+			array_push($lines, ...$commands);
+			$lines[] = self::SEPARATOR;
+		}
+
+		return implode(self::SIEVE_NEWLINE, $lines);
+	}
+
+	private function sanitizeFlag(string $flag): string {
+		try {
+			return $this->imapFlag->create($flag);
+		} catch (ImapFlagEncodingException) {
+			return 'placeholder_for_invalid_label';
+		}
+	}
+
+	private function sanitizeDefinition(array $filters): array {
+		return array_map(static function ($filter) {
+			unset($filter['accountId'], $filter['id']);
+			$filter['tests'] = array_map(static function ($test) {
+				unset($test['id']);
+				return $test;
+			}, $filter['tests']);
+			$filter['actions'] = array_map(static function ($action) {
+				unset($action['id']);
+				return $action;
+			}, $filter['actions']);
+			$filter['priority'] = (int)$filter['priority'];
+			return $filter;
+		}, $filters);
+	}
+}