feature: mail provider backend

lib/AppInfo/Application.php

@@ -53,6 +53,7 @@
 use OCA\Mail\Listener\SpamReportListener;
 use OCA\Mail\Listener\UserDeletedListener;
 use OCA\Mail\Notification\Notifier;
+use OCA\Mail\Provider\MailProvider;
 use OCA\Mail\Search\FilteringProvider;
 use OCA\Mail\Search\Provider;
 use OCA\Mail\Service\Attachment\AttachmentService;
@@ -156,6 +157,9 @@ public function register(IRegistrationContext $context): void {
 			$context->registerSearchProvider(Provider::class);
 		}
 
+		// Added in version 4.0.0
+		$context->registerMailProvider(MailProvider::class);
+
 		$context->registerNotifierService(Notifier::class);
 
 		// bypass Horde Translation system

lib/Db/MailAccountMapper.php

@@ -83,6 +83,27 @@ public function findByUserId(string $userId): array {
 		return $this->findEntities($query);
 	}
 
+	/**
+	 * Finds a mail account(s) by user id and mail address
+	 *
+	 * @since 4.0.0
+	 *
+	 * @param string $userId system user id
+	 * @param string $address mail address (e.g. test@example.com)
+	 *
+	 * @return MailAccount[]
+	 */
+	public function findByUserIdAndAddress(string $userId, string $address): array {
+		$qb = $this->db->getQueryBuilder();
+		$query = $qb
+			->select('*')
+			->from($this->getTableName())
+			->where($qb->expr()->eq('user_id', $qb->createNamedParameter($userId)))
+			->andWhere($qb->expr()->eq('email', $qb->createNamedParameter($address)));
+
+		return $this->findEntities($query);
+	}
+
 	/**
 	 * @throws DoesNotExistException
 	 * @throws MultipleObjectsReturnedException

lib/Provider/Command/MessageSend.php

@@ -0,0 +1,151 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\Mail\Provider\Command;
+
+use OCA\Mail\Db\LocalAttachment;
+use OCA\Mail\Db\LocalMessage;
+use OCA\Mail\Exception\ClientException;
+use OCA\Mail\Exception\UploadException;
+use OCA\Mail\Service\AccountService;
+use OCA\Mail\Service\Attachment\AttachmentService;
+use OCA\Mail\Service\OutboxService;
+use OCP\AppFramework\Utility\ITimeFactory;
+use OCP\Mail\Provider\Exception\SendException;
+use OCP\Mail\Provider\IAddress;
+use OCP\Mail\Provider\IMessage;
+
+class MessageSend {
+
+	public function __construct(
+		protected ITimeFactory $time,
+		protected AccountService $accountService,
+		protected OutboxService $outboxService,
+		protected AttachmentService $attachmentService
+	) {
+	}
+
+	/**
+	 * Performs send operation
+	 *
+	 * @since 4.0.0
+	 *
+	 * @param string $userId system user id
+	 * @param string $serviceId mail account id
+	 * @param IMessage $message mail message object with all required parameters to send a message
+	 * @param array $options array of options reserved for future use
+	 *
+	 * @return LocalMessage
+	 *
+	 * @throws SendException on failure, check message for reason
+	 *
+	 */
+	public function perform(string $userId, string $serviceId, IMessage $message, array $options = []): LocalMessage {
+		// validate that at least one To address is present
+		if (count($message->getTo()) === 0) {
+			throw new SendException('Invalid Message Parameter: MUST contain at least one TO address with a valid address');
+		}
+		// validate that all To, CC and BCC have email address
+		$entries = array_merge($message->getTo(), $message->getCc(), $message->getBcc());
+		array_walk($entries, function ($entry) {
+			if (empty($entry->getAddress())) {
+				throw new SendException('Invalid Message Parameter: All TO, CC and BCC addresses MUST contain at least an email address');
+			}
+		});
+		// validate that all attachments have a name, type, and contents
+		$entries = $message->getAttachments();
+		array_walk($entries, function ($entry) {
+			if (empty($entry->getName()) || empty($entry->getType()) || empty($entry->getContents())) {
+				throw new SendException('Invalid Attachment Parameter: MUST contain values for Name, Type and Contents');
+			}
+		});
+		// retrieve user mail account details
+		try {
+			$account = $this->accountService->find($userId, (int)$serviceId);
+		} catch (ClientException $e) {
+			throw new SendException('Error: occurred while retrieving mail account details', 0, $e);
+		}
+		// convert mail provider message to mail app message
+		$localMessage = new LocalMessage();
+		$localMessage->setType($localMessage::TYPE_OUTGOING);
+		$localMessage->setAccountId($account->getId());
+		$localMessage->setSubject((string)$message->getSubject());
+		$localMessage->setBody((string)$message->getBody());
+		// disabled due to issues caused by opening these messages in gui
+		//$localMessage->setEditorBody($message->getBody());
+		$localMessage->setHtml(true);
+		$localMessage->setSendAt($this->time->getTime());
+		// convert mail provider addresses to recipient addresses
+		$to = $this->convertAddressArray($message->getTo());
+		$cc = $this->convertAddressArray($message->getCc());
+		$bcc = $this->convertAddressArray($message->getBcc());
+		// save attachments
+		$attachments = [];
+		try {
+			foreach ($message->getAttachments() as $entry) {
+				$attachments[] = $this->attachmentService->addFileFromString(
+					$userId,
+					(string)$entry->getName(),
+					(string)$entry->getType(),
+					(string)$entry->getContents()
+				);
+			}
+		} catch (UploadException $e) {
+			$this->purgeSavedAttachments($attachments);
+			throw new SendException('Error: occurred while saving mail message attachment', 0, $e);
+		}
+		// save message
+		$localMessage = $this->outboxService->saveMessage(
+			$account,
+			$localMessage,
+			$to,
+			$cc,
+			$bcc,
+			array_map(static fn (LocalAttachment $attachment) => $attachment->jsonSerialize(), $attachments)
+		);
+		// send message
+		try {
+			$localMessage = $this->outboxService->sendMessage($localMessage, $account);
+		} catch (\Throwable $e) {
+			throw new SendException('Error: occurred while sending mail message', 0, $e);
+		}
+
+		return $localMessage;
+	}
+
+	/**
+	 * Converts IAddress objects collection to plain array
+	 *
+	 * @since 4.0.0
+	 *
+	 * @param array<int,IAddress> $addresses collection of IAddress objects
+	 *
+	 * @return array<int, array{email: string, label?: string}> collection of addresses and labels
+	 */
+	protected function convertAddressArray(array $addresses): array {
+		return array_map(static function (IAddress $address) {
+			return !empty($address->getLabel())
+				? ['email' => (string)$address->getAddress(), 'label' => (string)$address->getLabel()]
+				: ['email' => (string)$address->getAddress()];
+		}, $addresses);
+	}
+
+	/**
+	 * Removes attachments from data store
+	 *
+	 * @since 4.0.0
+	 *
+	 * @param array<int, LocalAttachment> $attachments collection of local attachment objects
+	 */
+	protected function purgeSavedAttachments(array $attachments): void {
+		foreach ($attachments as $attachment) {
+			$this->attachmentService->deleteAttachment($attachment->getUserId(), $attachment->getId());
+		}
+	}
+
+}

lib/Provider/MailProvider.php

@@ -0,0 +1,167 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2024 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+namespace OCA\Mail\Provider;
+
+use OCA\Mail\Account;
+use OCA\Mail\Exception\ClientException;
+use OCA\Mail\Service\AccountService;
+use OCP\IL10N;
+use OCP\Mail\Provider\Address as MailAddress;
+use OCP\Mail\Provider\IProvider;
+use OCP\Mail\Provider\IService;
+use Psr\Container\ContainerInterface;
+use Psr\Log\LoggerInterface;
+
+class MailProvider implements IProvider {
+
+	public function __construct(
+		protected ContainerInterface $container,
+		protected AccountService $accountService,
+		protected LoggerInterface $logger,
+		protected IL10N $l10n
+	) {
+	}
+
+	/**
+	 * Arbitrary unique text string identifying this provider
+	 *
+	 * @since 4.0.0
+	 *
+	 * @return string id of this provider (e.g. UUID or 'IMAP/SMTP' or anything else)
+	 */
+	public function id(): string {
+		return 'mail-application';
+	}
+
+	/**
+	 * Localized human friendly name of this provider
+	 *
+	 * @since 4.0.0
+	 *
+	 * @return string label/name of this provider (e.g. Plain Old IMAP/SMTP)
+	 */
+	public function label(): string {
+		return $this->l10n->t('Mail Application');
+	}
+
+	/**
+	 * Determine if any services are configured for a specific user
+	 *
+	 * @since 4.0.0
+	 *
+	 * @param string $userId system user id
+	 *
+	 * @return bool true if any services are configure for the user
+	 */
+	public function hasServices(string $userId): bool {
+		return (count($this->listServices($userId)) > 0);
+	}
+
+	/**
+	 * Retrieve collection of services for a specific user
+	 *
+	 * @since 4.0.0
+	 *
+	 * @param string $userId system user id
+	 *
+	 * @return array<string,IService> collection of service id and object ['1' => IServiceObject]
+	 */
+	public function listServices(string $userId): array {
+		// retrieve service(s) details from data store
+		$accounts = $this->accountService->findByUserId($userId);
+		// construct temporary collection
+		$services = [];
+		// add services to collection
+		foreach ($accounts as $entry) {
+			$services[(string)$entry->getId()] = $this->serviceFromAccount($userId, $entry);
+		}
+		// return list of services for user
+		return $services;
+	}
+
+	/**
+	 * Retrieve a service with a specific id
+	 *
+	 * @since 4.0.0
+	 *
+	 * @param string $userId system user id
+	 * @param string $serviceId mail account id
+	 *
+	 * @return IService|null returns service object or null if none found
+	 *
+	 */
+	public function findServiceById(string $userId, string $serviceId): IService|null {
+		// determine if a valid user and service id was submitted
+		if (empty($userId) && !ctype_digit($serviceId)) {
+			return null;
+		}
+		// retrieve service details from data store
+		try {
+			$account = $this->accountService->find($userId, (int)$serviceId);
+		} catch(ClientException $e) {
+			$this->logger->error('Error occurred while retrieving mail account details', [ 'exception' => $e ]);
+			return null;
+		}
+		// return mail service object
+		return $this->serviceFromAccount($userId, $account);
+	}
+
+	/**
+	 * Retrieve a service for a specific mail address
+	 *
+	 * @since 4.0.0
+	 *
+	 * @param string $userId system user id
+	 * @param string $address mail address (e.g. test@example.com)
+	 *
+	 * @return IService|null returns service object or null if none found
+	 */
+	public function findServiceByAddress(string $userId, string $address): IService|null {
+		// retrieve service details from data store
+		$accounts = $this->accountService->findByUserIdAndAddress($userId, $address);
+		// evaluate if service details where found
+		if (count($accounts) > 0) {
+			// return mail service object
+			return $this->serviceFromAccount($userId, $accounts[0]);
+		}
+
+		return null;
+	}
+
+	/**
+	 * Construct a new fresh service object
+	 *
+	 * @since 4.0.0
+	 *
+	 * @return IService fresh service object
+	 */
+	public function initiateService(): IService {
+		return new MailService($this->container);
+	}
+
+	/**
+	 * Construct a service object from a mail account
+	 *
+	 * @since 4.0.0
+	 *
+	 * @param string $userId system user id
+	 * @param Account $account mail account
+	 *
+	 * @return IService service object
+	 */
+	protected function serviceFromAccount(string $userId, Account $account): IService {
+		// extract values
+		$serviceId = (string)$account->getId();
+		$serviceLabel = $account->getName();
+		$serviceAddress = new MailAddress($account->getEmail(), $account->getName());
+		// return mail service object
+		return new MailService($this->container, $userId, $serviceId, $serviceLabel, $serviceAddress);
+	}
+
+}