class EntityPatcher {

    /**
     * @since 0.4
     *
     * @param string $entityType
     *
     * @return EntityDiffer
     */
    public static function newForType( $entityType ) {
        if ( $entityType === Item::ENTITY_TYPE ) {
            $class = '\Wikibase\ItemPatcher';
        }
        else {
            $class = __CLASS__;
        }

        return new $class( new MapPatcher( true ) );
    }

    /**
     * @since 0.4
     *
     * @var MapPatcher
     */
    protected $mapPatcher;

    /**
     * @since 0.4
     *
     * @param boolean $throwErrors
     */
    public function __construct( MapPatcher $mapPatcher ) {
        $this->mapPatcher = $mapPatcher;
    }

    /**
     * @since 0.4
     *
     * @param Entity $oldEntity
     * @param EntityDiff $patch
     *
     * @return Entity
     * @throws MWException
     */
    public final function getPatchedEntity( Entity $entity, EntityDiff $patch ) {
        $newEntity = $this->entityToArray( $entity );
        $newEntity = $this->mapPatcher->patch( $newEntity, $patch );

        return $this->entityFromArray( $newEntity, $entity );
    }

    /**
     * @since 0.4
     *
     * @param array $entity
     * @param Entity $originalEntity
     *
     * @return Entity
     */
    protected final function entityFromArray( array $entity, Entity $originalEntity ) {
        $originalEntity->clear();

        foreach ( $entity['aliases'] as $langCode => $aliases ) {
            $originalEntity->setAliases( $langCode, $aliases );
        }

        foreach ( $entity['label'] as $langCode => $label ) {
            $originalEntity->setLabel( $langCode, $label );
        }

        foreach ( $entity['description'] as $langCode => $description ) {
            $originalEntity->setDescription( $langCode, $description );
        }

        // TODO: claims

        $this->setSpecificObjectFields( $entity, $originalEntity );

        return $originalEntity;
    }

    /**
     * @since 0.4
     *
     * @param array $entityArray
     * @param Entity $entityObject
     */
    protected function setSpecificObjectFields( array $entityArray, Entity &$entityObject ) {
        // No-op, meant to be overridden in deriving classes to add specific behaviour
    }

    /**
     * @since 0.4
     *
     * @param Entity $entity
     *
     * @return array
     */
    protected final function entityToArray( Entity $entity ) {
        $array = array();

        $array['aliases'] = $entity->getAllAliases();
        $array['label'] = $entity->getLabels();
        $array['description'] = $entity->getDescriptions();

        // TODO: claims

        $this->setSpecificArrayFields( $array, $entity );

        return $array;
    }

    /**
     * @since 0.4
     *
     * @param array $entityArray
     * @param Entity $entityObject
     */
    protected function setSpecificArrayFields( array &$entityArray, Entity $entityObject ) {
        // No-op, meant to be overridden in deriving classes to add specific behaviour
    }

}