Flow2Lab/EventSourcing

<?php
namespace Flow2Lab\EventSourcing;

use Flow2Lab\EventSourcing\Event\DomainEvent;
use Flow2Lab\EventSourcing\Exception\EmptyStreamException;

trait AggregateSourcing
{

    use EventSourcing;

    /**
     * @var integer
     */
    protected $version = -1;

    /**
     * @param DomainEvent[] $stream
     * @return static
     * @throws EmptyStreamException
     * @throws Exception\EventNotAppliedException
     */
    public static function loadFromEventStream(array $stream = [])
    {
        if (count($stream) === 0) {
            throw new EmptyStreamException('Unable to load aggregate "' . get_called_class() . '" with an empty event stream.', 1427292049);
        }

        /** @var AggregateSourcing $aggregate */
        $aggregate = unserialize('O:' . strlen(get_called_class()) . ':"' . get_called_class() . '":0:{}');

        /** @var DomainEvent $event */
        foreach ($stream as $event) {
            $aggregate->apply($event);
        }

        $aggregate->version = $event->version;

        return $aggregate;
    }

    /**
     * @param DomainEvent $event
     */
    protected function applyNewEvent(DomainEvent $event)
    {
        $event->version = $this->getNextVersion();

        $this->apply($event);
        $this->uncommittedEvents[] = $event;
    }

    /**
     * @param EntityInterface $entity
     */
    protected function registerEntity(EntityInterface $entity)
    {
        $aggregate = $this;
        $entityIdentifier = $entity->getIdentifier();

        if (array_key_exists($entityIdentifier, $this->entities) === TRUE) {
            throw new \InvalidArgumentException('The entity with identifier "' . $entityIdentifier . '" is already registered.', 1426251092);
        }

        $entity->setAggregateRoot($this);
        $entity->setVersionGenerator(function () use ($aggregate) {
            return $aggregate->getNextVersion();
        });

        $this->entities[$entityIdentifier] = $entity;
    }

    /**
     * @return integer
     */
    protected function getNextVersion()
    {
        return ++$this->version;
    }

}