class DefaultLazyPluginCollection

class DefaultLazyPluginCollection extends LazyPluginCollection {
    use DependencySerializationTrait;
    
    /**
     * The manager used to instantiate the plugins.
     *
     * @var \Drupal\Component\Plugin\PluginManagerInterface
     */
    protected $manager;
    
    /**
     * The initial configuration for each plugin in the collection.
     *
     * @var array
     *   An associative array containing the initial configuration for each plugin
     *   in the collection, keyed by plugin instance ID.
     */
    protected $configurations = [];
    
    /**
     * The key within the plugin configuration that contains the plugin ID.
     *
     * @var string
     */
    protected $pluginKey = 'id';
    
    /**
     * The original order of the instances.
     *
     * @var array
     */
    protected $originalOrder = [];
    
    /**
     * Constructs a new DefaultLazyPluginCollection object.
     *
     * @param \Drupal\Component\Plugin\PluginManagerInterface $manager
     *   The manager to be used for instantiating plugins.
     * @param array $configurations
     *   (optional) An associative array containing the initial configuration for
     *   each plugin in the collection, keyed by plugin instance ID.
     */
    public function __construct(PluginManagerInterface $manager, array $configurations = []) {
        $this->manager = $manager;
        $this->configurations = $configurations;
        if (!empty($configurations)) {
            $instance_ids = array_keys($configurations);
            $this->instanceIds = array_combine($instance_ids, $instance_ids);
            // Store the original order of the instance IDs for export.
            $this->originalOrder = $this->instanceIds;
        }
    }
    
    /**
     * {@inheritdoc}
     */
    protected function initializePlugin($instance_id) {
        $configuration = $this->configurations[$instance_id] ?? [];
        if (!isset($configuration[$this->pluginKey])) {
            throw new PluginNotFoundException($instance_id);
        }
        $this->set($instance_id, $this->manager
            ->createInstance($configuration[$this->pluginKey], $configuration));
    }
    
    /**
     * Sorts all plugin instances in this collection.
     *
     * @return $this
     */
    public function sort() {
        uasort($this->instanceIds, [
            $this,
            'sortHelper',
        ]);
        return $this;
    }
    
    /**
     * Provides uasort() callback to sort plugins.
     */
    public function sortHelper($aID, $bID) {
        $a = $this->get($aID);
        $b = $this->get($bID);
        return strnatcasecmp($a->getPluginId(), $b->getPluginId());
    }
    
    /**
     * {@inheritdoc}
     */
    public function getConfiguration() {
        $instances = [];
        // Store the current order of the instances.
        $current_order = $this->instanceIds;
        // Reorder the instances to match the original order, adding new instances
        // to the end.
        $this->instanceIds = $this->originalOrder + $current_order;
        foreach ($this as $instance_id => $instance) {
            if ($instance instanceof ConfigurableInterface) {
                $instances[$instance_id] = $instance->getConfiguration();
            }
            else {
                $instances[$instance_id] = $this->configurations[$instance_id];
            }
        }
        // Restore the current order.
        $this->instanceIds = $current_order;
        return $instances;
    }
    
    /**
     * {@inheritdoc}
     */
    public function setConfiguration(array $configuration) {
        // Track each instance ID as it is updated.
        $unprocessed_instance_ids = $this->getInstanceIds();
        foreach ($configuration as $instance_id => $instance_configuration) {
            $this->setInstanceConfiguration($instance_id, $instance_configuration);
            // Remove this instance ID from the list being updated.
            unset($unprocessed_instance_ids[$instance_id]);
        }
        // Remove remaining instances that had no configuration specified for them.
        foreach ($unprocessed_instance_ids as $unprocessed_instance_id) {
            $this->removeInstanceId($unprocessed_instance_id);
        }
        return $this;
    }
    
    /**
     * Updates the configuration for a plugin instance.
     *
     * If there is no plugin instance yet, a new will be instantiated. Otherwise,
     * the existing instance is updated with the new configuration.
     *
     * @param string $instance_id
     *   The ID of a plugin to set the configuration for.
     * @param array $configuration
     *   The plugin configuration to set.
     */
    public function setInstanceConfiguration($instance_id, array $configuration) {
        if (isset($this->pluginInstances[$instance_id]) && isset($configuration[$this->pluginKey]) && isset($this->configurations[$instance_id][$this->pluginKey]) && $configuration[$this->pluginKey] !== $this->configurations[$instance_id][$this->pluginKey]) {
            // If the plugin has already been instantiated by the configuration was
            // for a different plugin then we need to unset the instantiated plugin.
            unset($this->pluginInstances[$instance_id]);
        }
        $this->configurations[$instance_id] = $configuration;
        $instance = $this->get($instance_id);
        if ($instance instanceof ConfigurableInterface) {
            $instance->setConfiguration($configuration);
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function addInstanceId($id, $configuration = NULL) {
        parent::addInstanceId($id);
        if ($configuration !== NULL) {
            $this->setInstanceConfiguration($id, $configuration);
        }
        if (!isset($this->originalOrder[$id])) {
            $this->originalOrder[$id] = $id;
        }
    }
    
    /**
     * {@inheritdoc}
     */
    public function removeInstanceId($instance_id) {
        parent::removeInstanceId($instance_id);
        unset($this->originalOrder[$instance_id]);
        unset($this->configurations[$instance_id]);
    }

}