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<?php

namespace Doctrine\DBAL\Connections;

use Doctrine\Common\EventManager;

use Doctrine\DBAL\Configuration;

use Doctrine\DBAL\Connection;

use Doctrine\DBAL\Driver;

use Doctrine\DBAL\Driver\Connection as DriverConnection;

use Doctrine\DBAL\Driver\Exception as DriverException;

use Doctrine\DBAL\DriverManager;

use Doctrine\DBAL\Event\ConnectionEventArgs;

use Doctrine\DBAL\Events;

use Doctrine\DBAL\Exception;

use Doctrine\DBAL\Statement;

use Doctrine\Deprecations\Deprecation;

use InvalidArgumentException;

use function array_rand;

use function count;

/**

 * Primary-Replica Connection

 *

 * Connection can be used with primary-replica setups.

 *

 * Important for the understanding of this connection should be how and when

 * it picks the replica or primary.

 *

 * 1. Replica if primary was never picked before and ONLY if 'getWrappedConnection'

 *    or 'executeQuery' is used.

 * 2. Primary picked when 'executeStatement', 'insert', 'delete', 'update', 'createSavepoint',

 *    'releaseSavepoint', 'beginTransaction', 'rollback', 'commit' or 'prepare' is called.

 * 3. If Primary was picked once during the lifetime of the connection it will always get picked afterwards.

 * 4. One replica connection is randomly picked ONCE during a request.

 *

 * ATTENTION: You can write to the replica with this connection if you execute a write query without

 * opening up a transaction. For example:

 *

 *      $conn = DriverManager::getConnection(...);

 *      $conn->executeQuery("DELETE FROM table");

 *

 * Be aware that Connection#executeQuery is a method specifically for READ

 * operations only.

 *

 * Use Connection#executeStatement for any SQL statement that changes/updates

 * state in the database (UPDATE, INSERT, DELETE or DDL statements).

 *

 * This connection is limited to replica operations using the

 * Connection#executeQuery operation only, because it wouldn't be compatible

 * with the ORM or SchemaManager code otherwise. Both use all the other

 * operations in a context where writes could happen to a replica, which makes

 * this restricted approach necessary.

 *

 * You can manually connect to the primary at any time by calling:

 *

 *      $conn->ensureConnectedToPrimary();

 *

 * Instantiation through the DriverManager looks like:

 *

 * @psalm-import-type Params from DriverManager

 * @example

 *

 * $conn = DriverManager::getConnection(array(

 *    'wrapperClass' => 'Doctrine\DBAL\Connections\PrimaryReadReplicaConnection',

 *    'driver' => 'pdo_mysql',

 *    'primary' => array('user' => '', 'password' => '', 'host' => '', 'dbname' => ''),

 *    'replica' => array(

 *        array('user' => 'replica1', 'password', 'host' => '', 'dbname' => ''),

 *        array('user' => 'replica2', 'password', 'host' => '', 'dbname' => ''),

 *    )

 * ));

 *

 * You can also pass 'driverOptions' and any other documented option to each of this drivers

 * to pass additional information.

 */

class PrimaryReadReplicaConnection extends Connection

{

    /**

     * Primary and Replica connection (one of the randomly picked replicas).

     *

     * @var DriverConnection[]|null[]

     */

    protected $connections = ['primary' => null, 'replica' => null];

    /**

     * You can keep the replica connection and then switch back to it

     * during the request if you know what you are doing.

     *

     * @var bool

     */

    protected $keepReplica = false;

    /**

     * Creates Primary Replica Connection.

     *

     * @internal The connection can be only instantiated by the driver manager.

     *

     * @param array<string,mixed> $params

     * @psalm-param Params $params

     *

     * @throws Exception

     * @throws InvalidArgumentException

     */

    public function __construct(

        array $params,

        Driver $driver,

        ?Configuration $config = null,

        ?EventManager $eventManager = null

    ) {

        if (! isset($params['replica'], $params['primary'])) {

            throw new InvalidArgumentException('primary or replica configuration missing');

        }

        if (count($params['replica']) === 0) {

            throw new InvalidArgumentException('You have to configure at least one replica.');

        }

        if (isset($params['driver'])) {

            $params['primary']['driver'] = $params['driver'];

            foreach ($params['replica'] as $replicaKey => $replica) {

                $params['replica'][$replicaKey]['driver'] = $params['driver'];

            }

        }

        $this->keepReplica = (bool) ($params['keepReplica'] ?? false);

        parent::__construct($params, $driver, $config, $eventManager);

    }

    /**

     * Checks if the connection is currently towards the primary or not.

     */

    public function isConnectedToPrimary(): bool

    {

        return $this->_conn !== null && $this->_conn === $this->connections['primary'];

    }

    /**

     * @param string|null $connectionName

     *

     * @return bool

     */

    public function connect($connectionName = null)

    {

        if ($connectionName !== null) {

            throw new InvalidArgumentException(

                'Passing a connection name as first argument is not supported anymore.'

                    . ' Use ensureConnectedToPrimary()/ensureConnectedToReplica() instead.',

            );

        }

        return $this->performConnect();

    }

    protected function performConnect(?string $connectionName = null): bool

    {

        $requestedConnectionChange = ($connectionName !== null);

        $connectionName            = $connectionName ?? 'replica';

        if ($connectionName !== 'replica' && $connectionName !== 'primary') {

            throw new InvalidArgumentException('Invalid option to connect(), only primary or replica allowed.');

        }

        // If we have a connection open, and this is not an explicit connection

        // change request, then abort right here, because we are already done.

        // This prevents writes to the replica in case of "keepReplica" option enabled.

        if ($this->_conn !== null && ! $requestedConnectionChange) {

            return false;

        }

        $forcePrimaryAsReplica = false;

        if ($this->getTransactionNestingLevel() > 0) {

            $connectionName        = 'primary';

            $forcePrimaryAsReplica = true;

        }

        if (isset($this->connections[$connectionName])) {

            $this->_conn = $this->connections[$connectionName];

            if ($forcePrimaryAsReplica && ! $this->keepReplica) {

                $this->connections['replica'] = $this->_conn;

            }

            return false;

        }

        if ($connectionName === 'primary') {

            $this->connections['primary'] = $this->_conn = $this->connectTo($connectionName);

            // Set replica connection to primary to avoid invalid reads

            if (! $this->keepReplica) {

                $this->connections['replica'] = $this->connections['primary'];

            }

        } else {

            $this->connections['replica'] = $this->_conn = $this->connectTo($connectionName);

        }

        if ($this->_eventManager->hasListeners(Events::postConnect)) {

            Deprecation::trigger(

                'doctrine/dbal',

                'https://github.com/doctrine/dbal/issues/5784',

                'Subscribing to %s events is deprecated. Implement a middleware instead.',

                Events::postConnect,

            );

            $eventArgs = new ConnectionEventArgs($this);

            $this->_eventManager->dispatchEvent(Events::postConnect, $eventArgs);

        }

        return true;

    }

    /**

     * Connects to the primary node of the database cluster.

     *

     * All following statements after this will be executed against the primary node.

     */

    public function ensureConnectedToPrimary(): bool

    {

        return $this->performConnect('primary');

    }

    /**

     * Connects to a replica node of the database cluster.

     *

     * All following statements after this will be executed against the replica node,

     * unless the keepReplica option is set to false and a primary connection

     * was already opened.

     */

    public function ensureConnectedToReplica(): bool

    {

        return $this->performConnect('replica');

    }

    /**

     * Connects to a specific connection.

     *

     * @param string $connectionName

     *

     * @return DriverConnection

     *

     * @throws Exception

     */

    protected function connectTo($connectionName)

    {

        $params = $this->getParams();

        $connectionParams = $this->chooseConnectionConfiguration($connectionName, $params);

        try {

            return $this->_driver->connect($connectionParams);

        } catch (DriverException $e) {

            throw $this->convertException($e);

        }

    }

    /**

     * @param string  $connectionName

     * @param mixed[] $params

     *

     * @return mixed

     */

    protected function chooseConnectionConfiguration($connectionName, $params)

    {

        if ($connectionName === 'primary') {

            return $params['primary'];

        }

        $config = $params['replica'][array_rand($params['replica'])];

        if (! isset($config['charset']) && isset($params['primary']['charset'])) {

            $config['charset'] = $params['primary']['charset'];

        }

        return $config;

    }

    /**

     * {@inheritDoc}

     */

    public function executeStatement($sql, array $params = [], array $types = [])

    {

        $this->ensureConnectedToPrimary();

        return parent::executeStatement($sql, $params, $types);

    }

    /**

     * {@inheritDoc}

     */

    public function beginTransaction()

    {

        $this->ensureConnectedToPrimary();

        return parent::beginTransaction();

    }

    /**

     * {@inheritDoc}

     */

    public function commit()

    {

        $this->ensureConnectedToPrimary();

        return parent::commit();

    }

    /**

     * {@inheritDoc}

     */

    public function rollBack()

    {

        $this->ensureConnectedToPrimary();

        return parent::rollBack();

    }

    /**

     * {@inheritDoc}

     */

    public function close()

    {

        unset($this->connections['primary'], $this->connections['replica']);

        parent::close();

        $this->_conn       = null;

        $this->connections = ['primary' => null, 'replica' => null];

    }

    /**

     * {@inheritDoc}

     */

    public function createSavepoint($savepoint)

    {

        $this->ensureConnectedToPrimary();

        parent::createSavepoint($savepoint);

    }

    /**

     * {@inheritDoc}

     */

    public function releaseSavepoint($savepoint)

    {

        $this->ensureConnectedToPrimary();

        parent::releaseSavepoint($savepoint);

    }

    /**

     * {@inheritDoc}

     */

    public function rollbackSavepoint($savepoint)

    {

        $this->ensureConnectedToPrimary();

        parent::rollbackSavepoint($savepoint);

    }

    public function prepare(string $sql): Statement

    {

        $this->ensureConnectedToPrimary();

        return parent::prepare($sql);

    }

}