class LayoutPluginManager

class LayoutPluginManager extends DefaultPluginManager implements LayoutPluginManagerInterface {
    use FilteredPluginManagerTrait;
    
    /**
     * The theme handler.
     *
     * @var \Drupal\Core\Extension\ThemeHandlerInterface
     */
    protected $themeHandler;
    
    /**
     * LayoutPluginManager constructor.
     *
     * @param \Traversable $namespaces
     *   An object that implements \Traversable which contains the root paths
     *   keyed by the corresponding namespace to look for plugin implementations.
     * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
     *   Cache backend instance to use.
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
     *   The module handler to invoke the alter hook with.
     * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
     *   The theme handler to invoke the alter hook with.
     */
    public function __construct(\Traversable $namespaces, CacheBackendInterface $cache_backend, ModuleHandlerInterface $module_handler, ThemeHandlerInterface $theme_handler) {
        parent::__construct('Plugin/Layout', $namespaces, $module_handler, LayoutInterface::class, Layout::class);
        $this->themeHandler = $theme_handler;
        $type = $this->getType();
        $this->setCacheBackend($cache_backend, $type);
        $this->alterInfo($type);
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getType() {
        return 'layout';
    }
    
    /**
     * {@inheritdoc}
     */
    protected function providerExists($provider) {
        return $this->moduleHandler
            ->moduleExists($provider) || $this->themeHandler
            ->themeExists($provider);
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getDiscovery() {
        if (!$this->discovery) {
            $discovery = new AnnotatedClassDiscovery($this->subdir, $this->namespaces, $this->pluginDefinitionAnnotationName, $this->additionalAnnotationNamespaces);
            $discovery = new YamlDiscoveryDecorator($discovery, 'layouts', $this->moduleHandler
                ->getModuleDirectories() + $this->themeHandler
                ->getThemeDirectories());
            $discovery->addTranslatableProperty('label')
                ->addTranslatableProperty('description')
                ->addTranslatableProperty('category');
            $discovery = new AnnotationBridgeDecorator($discovery, $this->pluginDefinitionAnnotationName);
            $discovery = new ContainerDerivativeDiscoveryDecorator($discovery);
            $this->discovery = $discovery;
        }
        return $this->discovery;
    }
    
    /**
     * {@inheritdoc}
     */
    public function processDefinition(&$definition, $plugin_id) {
        parent::processDefinition($definition, $plugin_id);
        if (!$definition instanceof LayoutDefinition) {
            throw new InvalidPluginDefinitionException($plugin_id, sprintf('The "%s" layout definition must extend %s', $plugin_id, LayoutDefinition::class));
        }
        // Add the module or theme path to the 'path'.
        $provider = $definition->getProvider();
        if ($this->moduleHandler
            ->moduleExists($provider)) {
            $base_path = $this->moduleHandler
                ->getModule($provider)
                ->getPath();
        }
        elseif ($this->themeHandler
            ->themeExists($provider)) {
            $base_path = $this->themeHandler
                ->getTheme($provider)
                ->getPath();
        }
        else {
            $base_path = '';
        }
        $path = $definition->getPath();
        $path = !empty($path) ? $base_path . '/' . $path : $base_path;
        $definition->setPath($path);
        // Add the base path to the icon path.
        if ($icon_path = $definition->getIconPath()) {
            $definition->setIconPath($path . '/' . $icon_path);
        }
        // Add a dependency on the provider of the library.
        if ($library = $definition->getLibrary()) {
            $config_dependencies = $definition->getConfigDependencies();
            list($library_provider) = explode('/', $library, 2);
            if ($this->moduleHandler
                ->moduleExists($library_provider)) {
                $config_dependencies['module'][] = $library_provider;
            }
            elseif ($this->themeHandler
                ->themeExists($library_provider)) {
                $config_dependencies['theme'][] = $library_provider;
            }
            $definition->setConfigDependencies($config_dependencies);
        }
        // If 'template' is set, then we'll derive 'template_path' and 'theme_hook'.
        $template = $definition->getTemplate();
        if (!empty($template)) {
            $template_parts = explode('/', $template);
            $template = array_pop($template_parts);
            $template_path = $path;
            if (count($template_parts) > 0) {
                $template_path .= '/' . implode('/', $template_parts);
            }
            $definition->setTemplate($template);
            $definition->setThemeHook(strtr($template, '-', '_'));
            $definition->setTemplatePath($template_path);
        }
        if (!$definition->getDefaultRegion()) {
            $definition->setDefaultRegion(key($definition->getRegions()));
        }
        // Makes sure region names are translatable.
        $regions = array_map(function ($region) {
            if (!$region['label'] instanceof TranslatableMarkup) {
                // Region labels from YAML discovery needs translation.
                $region['label'] = new TranslatableMarkup($region['label'], [], [
                    'context' => 'layout_region',
                ]);
            }
            return $region;
        }, $definition->getRegions());
        $definition->setRegions($regions);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getThemeImplementations() {
        $hooks = [];
        $hooks['layout'] = [
            'render element' => 'content',
        ];
        
        /** @var \Drupal\Core\Layout\LayoutDefinition[] $definitions */
        $definitions = $this->getDefinitions();
        foreach ($definitions as $definition) {
            if ($template = $definition->getTemplate()) {
                $hooks[$definition->getThemeHook()] = [
                    'render element' => 'content',
                    'base hook' => 'layout',
                    'template' => $template,
                    'path' => $definition->getTemplatePath(),
                ];
            }
        }
        return $hooks;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCategories() {
        // Fetch all categories from definitions and remove duplicates.
        $categories = array_unique(array_values(array_map(function (LayoutDefinition $definition) {
            return $definition->getCategory();
        }, $this->getDefinitions())));
        natcasesort($categories);
        return $categories;
    }
    
    /**
     * {@inheritdoc}
     *
     * @return \Drupal\Core\Layout\LayoutDefinition[]
     */
    public function getSortedDefinitions(array $definitions = NULL, $label_key = 'label') {
        // Sort the plugins first by category, then by label.
        $definitions = isset($definitions) ? $definitions : $this->getDefinitions();
        // Suppress errors because PHPUnit will indirectly modify the contents,
        // triggering https://bugs.php.net/bug.php?id=50688.
        @uasort($definitions, function (LayoutDefinition $a, LayoutDefinition $b) {
            if ($a->getCategory() != $b->getCategory()) {
                return strnatcasecmp($a->getCategory(), $b->getCategory());
            }
            return strnatcasecmp($a->getLabel(), $b->getLabel());
        });
        return $definitions;
    }
    
    /**
     * {@inheritdoc}
     *
     * @return \Drupal\Core\Layout\LayoutDefinition[][]
     */
    public function getGroupedDefinitions(array $definitions = NULL, $label_key = 'label') {
        $definitions = $this->getSortedDefinitions(isset($definitions) ? $definitions : $this->getDefinitions(), $label_key);
        $grouped_definitions = [];
        foreach ($definitions as $id => $definition) {
            $grouped_definitions[(string) $definition->getCategory()][$id] = $definition;
        }
        return $grouped_definitions;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getLayoutOptions() {
        $layout_options = [];
        foreach ($this->getGroupedDefinitions() as $category => $layout_definitions) {
            foreach ($layout_definitions as $name => $layout_definition) {
                $layout_options[$category][$name] = $layout_definition->getLabel();
            }
        }
        return $layout_options;
    }

}