feat: add delegation backend

Signed-off-by: Hamza <hamzamahjoubi221@gmail.com>

Author: hamza221

lib/Db/Delegation.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Db;
+
+use JsonSerializable;
+use OCP\AppFramework\Db\Entity;
+use ReturnTypeWillChange;
+
+/**
+ * @method int getAccountId()
+ * @method void setAccountId(int $accountId)
+ * @method string getUserId()
+ * @method void setUserId(string $userId)
+ */
+class Delegation extends Entity implements JsonSerializable {
+	protected $accountId;
+	protected $userId;
+
+	public function __construct() {
+		$this->addType('userId', 'string');
+		$this->addType('accountId', 'integer');
+	}
+
+	#[ReturnTypeWillChange]
+	public function jsonSerialize() {
+		return [
+			'id' => $this->getId(),
+			'accountId' => $this->getAccountId(),
+			'userId' => $this->getUserId(),
+		];
+	}
+}

lib/Db/DelegationMapper.php

@@ -0,0 +1,62 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Db;
+
+use OCP\AppFramework\Db\DoesNotExistException;
+use OCP\AppFramework\Db\QBMapper;
+use OCP\IDBConnection;
+
+/**
+ * @template-extends QBMapper<Delegation>
+ */
+class DelegationMapper extends QBMapper {
+	public function __construct(IDBConnection $db) {
+		parent::__construct($db, 'mail_delegations');
+	}
+
+	public function findDelegatedAccountsForUser(string $uid): array {
+		$qb = $this->db->getQueryBuilder();
+
+		$select = $qb->select('account_id')
+			->from($this->getTableName())
+			->where(
+				$qb->expr()->eq('user_id', $qb->createNamedParameter($uid))
+			);
+
+		$rows = $this->findEntities($select);
+
+		return $rows;
+	}
+
+    public function findDelegatedToUsers(string $accountId) : array {
+        $qb = $this->db->getQueryBuilder();
+
+		$select = $qb->select('user_id')
+			->from($this->getTableName())
+			->where(
+				$qb->expr()->eq('account_id', $qb->createNamedParameter($accountId))
+			);
+
+		$rows = $this->findEntities($select);
+		return $rows;
+    }
+
+    /**
+	 * @throws DoesNotExistException
+	 */
+	public function find(int $accountId, string $uid): Actions {
+		$qb = $this->db->getQueryBuilder();
+		$qb->select('*')
+			->from($this->getTableName())
+			->where($qb->expr()->eq('user_id', $qb->createNamedParameter($uid)))
+			->andWhere($qb->expr()->eq('account_id', $qb->createNamedParameter($accountId)));
+		return $this->findEntity($qb);
+	}
+}

lib/Migration/Version5007Date20260312152753.php

@@ -0,0 +1,58 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCA\Mail\Migration;
+
+use Closure;
+use OCP\DB\ISchemaWrapper;
+use OCP\Migration\IOutput;
+use OCP\Migration\SimpleMigrationStep;
+use Override;
+
+class Version5007Date20260312152753 extends SimpleMigrationStep {
+
+	/**
+	 * @param IOutput $output
+	 * @param Closure(): ISchemaWrapper $schemaClosure
+	 * @param array $options
+	 * @return null|ISchemaWrapper
+	 */
+	#[Override]
+	public function changeSchema(IOutput $output, Closure $schemaClosure, array $options): ?ISchemaWrapper {
+		$schema = $schemaClosure();
+
+		if (!$schema->hasTable('mail_delegations')) {
+			$table = $schema->createTable('mail_delegations');
+			$table->addColumn('id', Types::INTEGER, [
+				'autoincrement' => true,
+				'notnull' => true,
+			]);
+			$table->addColumn('account_id', Types::INTEGER, [
+				'notnull' => true,
+				'length' => 20,
+			]);
+			$table->addColumn('user_id', Types::STRING, [
+				'notnull' => true,
+				'length' => 64,
+			]);
+		}
+		$table->setPrimaryKey(['id']);
+		if ($schema->hasTable('mail_accounts')) {
+			$table->addForeignKeyConstraint(
+				$schema->getTable('mail_accounts'),
+				['account_id'],
+				['id'],
+				[
+					'onDelete' => 'CASCADE',
+				]
+			);
+		}
+	}
+
+}

lib/Service/DelegationService.php

@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+namespace OCA\Mail\Service;
+
+use OCP\AppFramework\Db\DoesNotExistException;
+use Psr\Log\LoggerInterface;
+use OCA\Mail\Db\Delegation;
+use  OCA\Mail\Db\DelegationMapper;
+
+class DelegationService {
+
+
+    public function __construct(
+        private DelegationMapper $delegationMapper,
+        private LoggerInterface $logger
+    ){}
+
+    public function delegate(int $accountId, string $userId){
+        $delegation = new Delegation(); 
+        $delegation->setAccountId($accountId); 
+        $delegation->setUserId($userId);
+        $this->delegationMapper->insert($delegation);
+    }
+
+    public function findDelgatedAccountForUser(string $userId): array {
+        return $this->delegationMapper->findDelegatedAccountsForUser($userId);
+    }
+
+    public function findDelegatedToUsersForAccount(string $accountId): array {
+        return $this->delegationMapper->findDelegatedToUsers($accountId);
+    }
+
+    public function unDelegate(int $accountId, string $userId) {
+        try {
+            $delegation = $this->delegationMapper->find($accountId,$userId);
+
+        } catch (DoesNotExistException $e) {
+            $this->logger->warning("Delegation of account:$accountId not found for user: $userId", ['exception' => $e]);
+        }
+        if( !$delegation ){
+            return; 
+        }
+        $this->delegationMapper->delete($delegation);
+        
+    }
+
+}