<?php
/*
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * This software consists of voluntary contributions made by many individuals
 * and is licensed under the MIT license. For more information, see
 * <http://www.doctrine-project.org>.
 */

namespace Doctrine\ODM\MongoDB;

use Doctrine\ODM\MongoDB\Mapping\ClassMetadata;
use Doctrine\ODM\MongoDB\Mapping\ClassMetadataFactory;
use const E_USER_DEPRECATED;
use function in_array;
use function sprintf;
use function trigger_error;

/**
 * @final
 */
class SchemaManager
{
    /**
     * @internal For internal use only. This constant will be private in 2.0.
     */
    const MONGODB_ERROR_ILLEGAL_OPERATION = 20;

    /**
     * @internal For internal use only. This constant will be private in 2.0.
     */
    const MONGODB_ERROR_ALREADY_INITIALIZED = 23;

    /**
     * @var DocumentManager
     */
    protected $dm;

    /**
     *
     * @var ClassMetadataFactory
     */
    protected $metadataFactory;

    /**
     * @param DocumentManager $dm
     * @param ClassMetadataFactory $cmf
     */
    public function __construct(DocumentManager $dm, ClassMetadataFactory $cmf)
    {
        if (self::class !== static::class) {
            @trigger_error(sprintf('The class "%s" extends "%s" which will be final in doctrine/mongodb-odm 2.0.', static::class, self::class), E_USER_DEPRECATED);
        }
        $this->dm = $dm;
        $this->metadataFactory = $cmf;
    }

    /**
     * Ensure indexes are created for all documents that can be loaded with the
     * metadata factory.
     *
     * @param integer $timeout Timeout (ms) for acknowledged index creation
     */
    public function ensureIndexes($timeout = null)
    {
        foreach ($this->metadataFactory->getAllMetadata() as $class) {
            if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
                continue;
            }
            $this->ensureDocumentIndexes($class->name, $timeout);
        }
    }

    /**
     * Ensure indexes exist for all mapped document classes.
     *
     * Indexes that exist in MongoDB but not the document metadata will be
     * deleted.
     *
     * @param integer $timeout Timeout (ms) for acknowledged index creation
     */
    public function updateIndexes($timeout = null)
    {
        foreach ($this->metadataFactory->getAllMetadata() as $class) {
            if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
                continue;
            }
            $this->updateDocumentIndexes($class->name, $timeout);
        }
    }

    /**
     * Ensure indexes exist for the mapped document class.
     *
     * Indexes that exist in MongoDB but not the document metadata will be
     * deleted.
     *
     * @param string $documentName
     * @param integer $timeout Timeout (ms) for acknowledged index creation
     * @throws \InvalidArgumentException
     */
    public function updateDocumentIndexes($documentName, $timeout = null)
    {
        $class = $this->dm->getClassMetadata($documentName);

        if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
            throw new \InvalidArgumentException('Cannot update document indexes for mapped super classes, embedded documents or aggregation result documents.');
        }

        $documentIndexes = $this->getDocumentIndexes($documentName);
        $collection = $this->dm->getDocumentCollection($documentName);
        $mongoIndexes = $collection->getIndexInfo();

        /* Determine which Mongo indexes should be deleted. Exclude the ID index
         * and those that are equivalent to any in the class metadata.
         */
        $self = $this;
        $mongoIndexes = array_filter($mongoIndexes, function ($mongoIndex) use ($documentIndexes, $self) {
            if ('_id_' === $mongoIndex['name']) {
                return false;
            }

            foreach ($documentIndexes as $documentIndex) {
                if ($self->isMongoIndexEquivalentToDocumentIndex($mongoIndex, $documentIndex)) {
                    return false;
                }
            }

            return true;
        });

        // Delete indexes that do not exist in class metadata
        foreach ($mongoIndexes as $mongoIndex) {
            if (isset($mongoIndex['name'])) {
                /* Note: MongoCollection::deleteIndex() cannot delete
                 * custom-named indexes, so use the deleteIndexes command.
                 */
                $collection->getDatabase()->command(array(
                    'deleteIndexes' => $collection->getName(),
                    'index' => $mongoIndex['name'],
                ));
            }
        }

        $this->ensureDocumentIndexes($documentName, $timeout);
    }

    /**
     * @param string $documentName
     * @return array
     */
    public function getDocumentIndexes($documentName)
    {
        $visited = array();
        return $this->doGetDocumentIndexes($documentName, $visited);
    }

    /**
     * @param string $documentName
     * @param array $visited
     * @return array
     */
    private function doGetDocumentIndexes($documentName, array &$visited)
    {
        if (isset($visited[$documentName])) {
            return array();
        }

        $visited[$documentName] = true;

        $class = $this->dm->getClassMetadata($documentName);
        $indexes = $this->prepareIndexes($class);
        $embeddedDocumentIndexes = array();

        // Add indexes from embedded & referenced documents
        foreach ($class->fieldMappings as $fieldMapping) {
            if (isset($fieldMapping['embedded'])) {
                if (isset($fieldMapping['targetDocument'])) {
                    $possibleEmbeds = array($fieldMapping['targetDocument']);
                } elseif (isset($fieldMapping['discriminatorMap'])) {
                    $possibleEmbeds = array_unique($fieldMapping['discriminatorMap']);
                } else {
                    continue;
                }

                foreach ($possibleEmbeds as $embed) {
                    if (isset($embeddedDocumentIndexes[$embed])) {
                        $embeddedIndexes = $embeddedDocumentIndexes[$embed];
                    } else {
                        $embeddedIndexes = $this->doGetDocumentIndexes($embed, $visited);
                        $embeddedDocumentIndexes[$embed] = $embeddedIndexes;
                    }

                    foreach ($embeddedIndexes as $embeddedIndex) {
                        foreach ($embeddedIndex['keys'] as $key => $value) {
                            $embeddedIndex['keys'][$fieldMapping['name'] . '.' . $key] = $value;
                            unset($embeddedIndex['keys'][$key]);
                        }

                        if (isset($embeddedIndex['options']['name'])) {
                            $embeddedIndex['options']['name'] = sprintf('%s_%s', $fieldMapping['name'], $embeddedIndex['options']['name']);
                        }

                        $indexes[] = $embeddedIndex;
                    }
                }
            } elseif (isset($fieldMapping['reference']) && isset($fieldMapping['targetDocument'])) {
                foreach ($indexes as $idx => $index) {
                    $newKeys = array();
                    foreach ($index['keys'] as $key => $v) {
                        if ($key == $fieldMapping['name']) {
                            $key = ClassMetadata::getReferenceFieldName($fieldMapping['storeAs'], $key);
                        }

                        $newKeys[$key] = $v;
                    }

                    $indexes[$idx]['keys'] = $newKeys;
                }
            }
        }

        return $indexes;
    }

    /**
     * @param ClassMetadata $class
     * @return array
     */
    private function prepareIndexes(ClassMetadata $class)
    {
        $persister = $this->dm->getUnitOfWork()->getDocumentPersister($class->name);
        $indexes = $class->getIndexes();
        $newIndexes = array();

        foreach ($indexes as $index) {
            $newIndex = array(
                'keys' => array(),
                'options' => $index['options']
            );
            foreach ($index['keys'] as $key => $value) {
                $key = $persister->prepareFieldName($key);
                if ($class->hasField($key)) {
                    $mapping = $class->getFieldMapping($key);
                    $newIndex['keys'][$mapping['name']] = $value;
                } else {
                    $newIndex['keys'][$key] = $value;
                }
            }

            $newIndexes[] = $newIndex;
        }

        return $newIndexes;
    }

    /**
     * Ensure the given document's indexes are created.
     *
     * @param string $documentName
     * @param integer $timeout Timeout (ms) for acknowledged index creation
     * @throws \InvalidArgumentException
     */
    public function ensureDocumentIndexes($documentName, $timeout = null)
    {
        $class = $this->dm->getClassMetadata($documentName);
        if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
            throw new \InvalidArgumentException('Cannot create document indexes for mapped super classes, embedded documents or query result documents.');
        }
        if ($indexes = $this->getDocumentIndexes($documentName)) {
            $collection = $this->dm->getDocumentCollection($class->name);
            foreach ($indexes as $index) {
                $keys = $index['keys'];
                $options = $index['options'];

                if ( ! isset($options['safe']) && ! isset($options['w'])) {
                    $options['w'] = 1;
                }

                if (isset($options['safe']) && ! isset($options['w'])) {
                    $options['w'] = is_bool($options['safe']) ? (integer) $options['safe'] : $options['safe'];
                    unset($options['safe']);
                }

                if ( ! isset($options['timeout']) && isset($timeout)) {
                    $options['timeout'] = $timeout;
                }

                $collection->ensureIndex($keys, $options);
            }
        }
    }

    /**
     * Delete indexes for all documents that can be loaded with the
     * metadata factory.
     */
    public function deleteIndexes()
    {
        foreach ($this->metadataFactory->getAllMetadata() as $class) {
            if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
                continue;
            }
            $this->deleteDocumentIndexes($class->name);
        }
    }

    /**
     * Delete the given document's indexes.
     *
     * @param string $documentName
     * @throws \InvalidArgumentException
     */
    public function deleteDocumentIndexes($documentName)
    {
        $class = $this->dm->getClassMetadata($documentName);
        if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
            throw new \InvalidArgumentException('Cannot delete document indexes for mapped super classes, embedded documents or query result documents.');
        }
        $this->dm->getDocumentCollection($documentName)->deleteIndexes();
    }

    /**
     * Create all the mapped document collections in the metadata factory.
     */
    public function createCollections()
    {
        foreach ($this->metadataFactory->getAllMetadata() as $class) {
            if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
                continue;
            }
            $this->createDocumentCollection($class->name);
        }
    }

    /**
     * Create the document collection for a mapped class.
     *
     * @param string $documentName
     * @throws \InvalidArgumentException
     */
    public function createDocumentCollection($documentName)
    {
        $class = $this->dm->getClassMetadata($documentName);

        if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
            throw new \InvalidArgumentException('Cannot create document collection for mapped super classes, embedded documents or query result documents.');
        }

        if ($class->isFile()) {
            $this->dm->getDocumentDatabase($documentName)->createCollection($class->getCollection() . '.files');
            $this->dm->getDocumentDatabase($documentName)->createCollection($class->getCollection() . '.chunks');

            return;
        }

        $this->dm->getDocumentDatabase($documentName)->createCollection(
            $class->getCollection(),
            $class->getCollectionCapped(),
            $class->getCollectionSize(),
            $class->getCollectionMax()
        );
    }

    /**
     * Drop all the mapped document collections in the metadata factory.
     */
    public function dropCollections()
    {
        foreach ($this->metadataFactory->getAllMetadata() as $class) {
            if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
                continue;
            }
            $this->dropDocumentCollection($class->name);
        }
    }

    /**
     * Drop the document collection for a mapped class.
     *
     * @param string $documentName
     * @throws \InvalidArgumentException
     */
    public function dropDocumentCollection($documentName)
    {
        $class = $this->dm->getClassMetadata($documentName);
        if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
            throw new \InvalidArgumentException('Cannot delete document indexes for mapped super classes, embedded documents or query result documents.');
        }
        $this->dm->getDocumentCollection($documentName)->drop();
    }

    /**
     * Drop all the mapped document databases in the metadata factory.
     */
    public function dropDatabases()
    {
        foreach ($this->metadataFactory->getAllMetadata() as $class) {
            if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
                continue;
            }
            $this->dropDocumentDatabase($class->name);
        }
    }

    /**
     * Drop the document database for a mapped class.
     *
     * @param string $documentName
     * @throws \InvalidArgumentException
     */
    public function dropDocumentDatabase($documentName)
    {
        $class = $this->dm->getClassMetadata($documentName);
        if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
            throw new \InvalidArgumentException('Cannot drop document database for mapped super classes, embedded documents or query result documents.');
        }
        $this->dm->getDocumentDatabase($documentName)->drop();
    }

    /**
     * Create all the mapped document databases in the metadata factory.
     *
     * @deprecated Databases are created automatically by MongoDB (>= 3.0). Deprecated since ODM 1.2, to be removed in ODM 2.0.
     */
    public function createDatabases()
    {
        @trigger_error(
            sprintf('The method "%s" was deprecated in doctrine/mongodb-odm 1.2 and will be removed in 2.0. Databases are created automatically by MongoDB (>= 3.0).', __METHOD__),
            E_USER_DEPRECATED
        );
        foreach ($this->metadataFactory->getAllMetadata() as $class) {
            if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
                continue;
            }
            $this->createDocumentDatabase($class->name);
        }
    }

    /**
     * Create the document database for a mapped class.
     *
     * @param string $documentName
     * @throws \InvalidArgumentException
     *
     * @deprecated A database is created automatically by MongoDB (>= 3.0). Deprecated since ODM 1.2, to be removed in ODM 2.0.
     */
    public function createDocumentDatabase($documentName)
    {
        @trigger_error(
            sprintf('The "%s" method was deprecated in doctrine/mongodb-odm 1.2 and will be removed in 2.0. Databases are created automatically by MongoDB (>= 3.0).', __METHOD__),
            E_USER_DEPRECATED
        );
        $class = $this->dm->getClassMetadata($documentName);
        if ($class->isMappedSuperclass || $class->isEmbeddedDocument || $class->isQueryResultDocument) {
            throw new \InvalidArgumentException('Cannot create databases for mapped super classes, embedded documents or query result documents.');
        }

        $this->dm->getDocumentDatabase($documentName)->execute('function() { return true; }');
    }

    /**
     * Determine if an index returned by MongoCollection::getIndexInfo() can be
     * considered equivalent to an index in class metadata.
     *
     * Indexes are considered different if:
     *
     *   (a) Key/direction pairs differ or are not in the same order
     *   (b) Sparse or unique options differ
     *   (c) Mongo index is unique without dropDups and mapped index is unique
     *       with dropDups
     *   (d) Geospatial options differ (bits, max, min)
     *   (e) The partialFilterExpression differs
     *
     * Regarding (c), the inverse case is not a reason to delete and
     * recreate the index, since dropDups only affects creation of
     * the unique index. Additionally, the background option is only
     * relevant to index creation and is not considered.
     *
     * @param array $mongoIndex Mongo index data.
     * @param array $documentIndex Document index data.
     * @return bool True if the indexes are equivalent, otherwise false.
     */
    public function isMongoIndexEquivalentToDocumentIndex($mongoIndex, $documentIndex)
    {
        $documentIndexOptions = $documentIndex['options'];

        if (! $this->isEquivalentIndexKeys($mongoIndex, $documentIndex)) {
            return false;
        }

        if (empty($mongoIndex['sparse']) xor empty($documentIndexOptions['sparse'])) {
            return false;
        }

        if (empty($mongoIndex['unique']) xor empty($documentIndexOptions['unique'])) {
            return false;
        }

        if ( ! empty($mongoIndex['unique']) && empty($mongoIndex['dropDups']) &&
            ! empty($documentIndexOptions['unique']) && ! empty($documentIndexOptions['dropDups'])) {

            return false;
        }

        foreach (array('bits', 'max', 'min') as $option) {
            if (isset($mongoIndex[$option]) xor isset($documentIndexOptions[$option])) {
                return false;
            }

            if (isset($mongoIndex[$option]) && isset($documentIndexOptions[$option]) &&
                $mongoIndex[$option] !== $documentIndexOptions[$option]) {

                return false;
            }
        }

        if (empty($mongoIndex['partialFilterExpression']) xor empty($documentIndexOptions['partialFilterExpression'])) {
            return false;
        }

        if (isset($mongoIndex['partialFilterExpression']) && isset($documentIndexOptions['partialFilterExpression']) &&
            $mongoIndex['partialFilterExpression'] !== $documentIndexOptions['partialFilterExpression']) {

            return false;
        }

        if (isset($mongoIndex['weights']) && ! $this->isEquivalentTextIndexWeights($mongoIndex, $documentIndex)) {
            return false;
        }

        foreach (['default_language', 'language_override', 'textIndexVersion'] as $option) {
            /* Text indexes will always report defaults for these options, so
             * only compare if we have explicit values in the document index. */
            if (isset($mongoIndex[$option]) && isset($documentIndexOptions[$option]) &&
                $mongoIndex[$option] !== $documentIndexOptions[$option]) {

                return false;
            }
        }

        return true;
    }

    /**
     * Determine if the keys for a MongoDB index can be considered equivalent to
     * those for an index in class metadata.
     *
     * @param array $mongoIndex Mongo index data.
     * @param array $documentIndex Document index data.
     * @return bool True if the indexes have equivalent keys, otherwise false.
     */
    private function isEquivalentIndexKeys(array $mongoIndex, array $documentIndex)
    {
        $mongoIndexKeys    = $mongoIndex['key'];
        $documentIndexKeys = $documentIndex['keys'];

        /* If we are dealing with text indexes, we need to unset internal fields
         * from the MongoDB index and filter out text fields from the document
         * index. This will leave only non-text fields, which we can compare as
         * normal. Any text fields in the document index will be compared later
         * with isEquivalentTextIndexWeights(). */
        if (isset($mongoIndexKeys['_fts']) && $mongoIndexKeys['_fts'] === 'text') {
            unset($mongoIndexKeys['_fts'], $mongoIndexKeys['_ftsx']);

            $documentIndexKeys = array_filter($documentIndexKeys, function($type) {
                return $type !== 'text';
            });
        }

        return $mongoIndexKeys == $documentIndexKeys;
    }

    /**
     * Determine if the text index weights for a MongoDB index can be considered
     * equivalent to those for an index in class metadata.
     *
     * @param array $mongoIndex Mongo index data.
     * @param array $documentIndex Document index data.
     * @return bool True if the indexes have equivalent weights, otherwise false.
     */
    private function isEquivalentTextIndexWeights(array $mongoIndex, array $documentIndex)
    {
        $mongoIndexWeights    = $mongoIndex['weights'];
        $documentIndexWeights = isset($documentIndex['options']['weights'])
            ? $documentIndex['options']['weights']
            : [];

        // If not specified, assign a default weight for text fields
        foreach ($documentIndex['keys'] as $key => $type) {
            if ($type === 'text' && ! isset($documentIndexWeights[$key])) {
                $documentIndexWeights[$key] = 1;
            }
        }

        /* MongoDB returns the weights sorted by field name, but we'll sort both
         * arrays in case that is internal behavior not to be relied upon. */
        ksort($mongoIndexWeights);
        ksort($documentIndexWeights);

        return $mongoIndexWeights == $documentIndexWeights;
    }

    /**
     * Ensure collections are sharded for all documents that can be loaded with the
     * metadata factory.
     *
     * @param array $indexOptions Options for `ensureIndex` command. It's performed on an existing collections
     *
     * @throws MongoDBException
     */
    public function ensureSharding(array $indexOptions = array())
    {
        if (! empty($indexOptions)) {
            @trigger_error(sprintf('The "indexOptions" argument in "%s" is deprecated and will be removed in doctrine/mongodb-odm 2.0.', __METHOD__), E_USER_DEPRECATED);
        }

        foreach ($this->metadataFactory->getAllMetadata() as $class) {
            if ($class->isMappedSuperclass || !$class->isSharded()) {
                continue;
            }

            $this->ensureDocumentSharding($class->name, $indexOptions);
        }
    }

    /**
     * Ensure sharding for collection by document name.
     *
     * @param string $documentName
     * @param array  $indexOptions Options for `ensureIndex` command. It's performed on an existing collections.
     *
     * @throws MongoDBException
     */
    public function ensureDocumentSharding($documentName, array $indexOptions = array())
    {
        if (! empty($indexOptions)) {
            @trigger_error(sprintf('The "indexOptions" argument in "%s" is deprecated and will be removed in doctrine/mongodb-odm 2.0.', __METHOD__), E_USER_DEPRECATED);
        }

        $class = $this->dm->getClassMetadata($documentName);
        if ( ! $class->isSharded()) {
            return;
        }

        $this->enableShardingForDbByDocumentName($documentName);

        $try = 0;
        do {
            $result = $this->runShardCollectionCommand($documentName);
            $done = true;

            // Need to check error message because MongoDB 3.0 does not return a code for this error
            if ($result['ok'] != 1 && strpos($result['errmsg'], 'please create an index that starts') !== false) {
                // The proposed key is not returned when using mongo-php-adapter with ext-mongodb.
                // See https://github.com/mongodb/mongo-php-driver/issues/296 for details
                if (isset($result['proposedKey'])) {
                    $key = $result['proposedKey'];
                } else {
                    $key = $this->dm->getClassMetadata($documentName)->getShardKey()['keys'];
                }

                $this->dm->getDocumentCollection($documentName)->ensureIndex($key, $indexOptions);
                $done = false;
                $try++;
            }
        } while (! $done && $try < 2);

        // For MongoDB 3.2 and newer, this command returns code 20 when a collection is already sharded.
        // For MongoDB 4.0 and newer, this command returns code 23 when a collection is already sharded.
        // For older MongoDB versions, we check the error message
        if ($result['ok'] == 1 || (isset($result['code']) && in_array($result['code'], [self::MONGODB_ERROR_ILLEGAL_OPERATION, self::MONGODB_ERROR_ALREADY_INITIALIZED])) || $result['errmsg'] == 'already sharded') {
            return;
        }

        throw MongoDBException::failedToEnsureDocumentSharding($documentName, $result['errmsg']);
    }

    /**
     * Enable sharding for database which contains documents with given name.
     *
     * @param string $documentName
     *
     * @throws MongoDBException
     */
    public function enableShardingForDbByDocumentName($documentName)
    {
        $dbName = $this->dm->getDocumentDatabase($documentName)->getName();
        $adminDb = $this->dm->getConnection()->selectDatabase('admin');
        $result = $adminDb->command(array('enableSharding' => $dbName));

        // Error code is only available with MongoDB 3.2. MongoDB 3.0 only returns a message
        // Thus, check code if it exists and fall back on error message
        if ($result['ok'] == 1 || (isset($result['code']) && $result['code'] == self::MONGODB_ERROR_ALREADY_INITIALIZED) || $result['errmsg'] == 'already enabled') {
            return;
        }

        throw MongoDBException::failedToEnableSharding($dbName, $result['errmsg']);
    }

    /**
     * @param $documentName
     *
     * @return array
     */
    private function runShardCollectionCommand($documentName)
    {
        $class = $this->dm->getClassMetadata($documentName);
        $dbName = $this->dm->getDocumentDatabase($documentName)->getName();
        $shardKey = $class->getShardKey();
        $adminDb = $this->dm->getConnection()->selectDatabase('admin');

        $shardKeyPart = array();
        foreach ($shardKey['keys'] as $key => $order) {
            if ($class->hasField($key)) {
                $mapping = $class->getFieldMapping($key);
                $fieldName = $mapping['name'];

                if ($class->isSingleValuedReference($key)) {
                    $fieldName = ClassMetadata::getReferenceFieldName($mapping['storeAs'], $fieldName);
                }
            } else {
                $fieldName = $key;
            }

            $shardKeyPart[$fieldName] = $order;
        }

        $result = $adminDb->command(
            array(
                'shardCollection' => $dbName . '.' . $class->getCollection(),
                'key'             => $shardKeyPart,
            )
        );

        return $result;
    }
}