class BreakpointManager

class BreakpointManager extends DefaultPluginManager implements BreakpointManagerInterface {
    use StringTranslationTrait;
    
    /**
     * {@inheritdoc}
     */
    protected $defaults = [
        // Human readable label for breakpoint.
'label' => '',
        // The media query for the breakpoint.
'mediaQuery' => '',
        // Weight used for ordering breakpoints.
'weight' => 0,
        // Breakpoint multipliers.
'multipliers' => [],
        // The breakpoint group.
'group' => '',
        // Default class for breakpoint implementations.
'class' => 'Drupal\\breakpoint\\Breakpoint',
        // The plugin id. Set by the plugin system based on the top-level YAML key.
'id' => '',
    ];
    
    /**
     * The theme handler.
     *
     * @var \Drupal\Core\Extension\ThemeHandlerInterface
     */
    protected $themeHandler;
    
    /**
     * Static cache of breakpoints keyed by group.
     *
     * @var array
     */
    protected $breakpointsByGroup;
    
    /**
     * The plugin instances.
     *
     * @var array
     */
    protected $instances = [];
    
    /**
     * Constructs a new BreakpointManager instance.
     *
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
     *   The module handler.
     * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
     *   The theme handler.
     * @param \Drupal\Core\Cache\CacheBackendInterface $cache_backend
     *   The cache backend.
     * @param \Drupal\Core\StringTranslation\TranslationInterface $string_translation
     *   The string translation service.
     */
    public function __construct(ModuleHandlerInterface $module_handler, ThemeHandlerInterface $theme_handler, CacheBackendInterface $cache_backend, TranslationInterface $string_translation) {
        $this->factory = new ContainerFactory($this);
        $this->moduleHandler = $module_handler;
        $this->themeHandler = $theme_handler;
        $this->setStringTranslation($string_translation);
        $this->alterInfo('breakpoints');
        $this->setCacheBackend($cache_backend, 'breakpoints', [
            'breakpoints',
        ]);
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getDiscovery() {
        if (!isset($this->discovery)) {
            $this->discovery = new YamlDiscovery('breakpoints', $this->moduleHandler
                ->getModuleDirectories() + $this->themeHandler
                ->getThemeDirectories());
            $this->discovery = new ContainerDerivativeDiscoveryDecorator($this->discovery);
        }
        return $this->discovery;
    }
    
    /**
     * {@inheritdoc}
     */
    public function processDefinition(&$definition, $plugin_id) {
        parent::processDefinition($definition, $plugin_id);
        // Allow custom groups and therefore more than one group per extension.
        if (empty($definition['group'])) {
            $definition['group'] = $definition['provider'];
        }
        // Ensure a 1x multiplier exists.
        if (!in_array('1x', $definition['multipliers'])) {
            $definition['multipliers'][] = '1x';
        }
        // Ensure that multipliers are sorted correctly.
        sort($definition['multipliers']);
    }
    
    /**
     * {@inheritdoc}
     */
    protected function providerExists($provider) {
        return $this->moduleHandler
            ->moduleExists($provider) || $this->themeHandler
            ->themeExists($provider);
    }
    
    /**
     * {@inheritdoc}
     */
    public function getBreakpointsByGroup($group) {
        if (!isset($this->breakpointsByGroup[$group])) {
            if ($cache = $this->cacheBackend
                ->get($this->cacheKey . ':' . $group)) {
                $this->breakpointsByGroup[$group] = $cache->data;
            }
            else {
                $breakpoints = [];
                foreach ($this->getDefinitions() as $plugin_id => $plugin_definition) {
                    if ($plugin_definition['group'] == $group) {
                        $breakpoints[$plugin_id] = $plugin_definition;
                    }
                }
                uasort($breakpoints, [
                    'Drupal\\Component\\Utility\\SortArray',
                    'sortByWeightElement',
                ]);
                $this->cacheBackend
                    ->set($this->cacheKey . ':' . $group, $breakpoints, Cache::PERMANENT, [
                    'breakpoints',
                ]);
                $this->breakpointsByGroup[$group] = $breakpoints;
            }
        }
        $instances = [];
        foreach ($this->breakpointsByGroup[$group] as $plugin_id => $definition) {
            if (!isset($this->instances[$plugin_id])) {
                $this->instances[$plugin_id] = $this->createInstance($plugin_id);
            }
            $instances[$plugin_id] = $this->instances[$plugin_id];
        }
        return $instances;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getGroups() {
        // Use a double colon so as to not clash with the cache for each group.
        if ($cache = $this->cacheBackend
            ->get($this->cacheKey . '::groups')) {
            $groups = $cache->data;
        }
        else {
            $groups = [];
            foreach ($this->getDefinitions() as $plugin_definition) {
                if (!isset($groups[$plugin_definition['group']])) {
                    $groups[$plugin_definition['group']] = $plugin_definition['group'];
                }
            }
            $this->cacheBackend
                ->set($this->cacheKey . '::groups', $groups, Cache::PERMANENT, [
                'breakpoints',
            ]);
        }
        // Get the labels. This is not cacheable due to translation.
        $group_labels = [];
        foreach ($groups as $group) {
            $group_labels[$group] = $this->getGroupLabel($group);
        }
        asort($group_labels);
        return $group_labels;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getGroupProviders($group) {
        $providers = [];
        $breakpoints = $this->getBreakpointsByGroup($group);
        foreach ($breakpoints as $breakpoint) {
            $provider = $breakpoint->getProvider();
            $extension = FALSE;
            if ($this->moduleHandler
                ->moduleExists($provider)) {
                $extension = $this->moduleHandler
                    ->getModule($provider);
            }
            elseif ($this->themeHandler
                ->themeExists($provider)) {
                $extension = $this->themeHandler
                    ->getTheme($provider);
            }
            if ($extension) {
                $providers[$extension->getName()] = $extension->getType();
            }
        }
        return $providers;
    }
    
    /**
     * {@inheritdoc}
     */
    public function clearCachedDefinitions() {
        parent::clearCachedDefinitions();
        $this->breakpointsByGroup = NULL;
        $this->instances = [];
    }
    
    /**
     * Gets the label for a breakpoint group.
     *
     * @param string $group
     *   The breakpoint group.
     *
     * @return string
     *   The label.
     */
    protected function getGroupLabel($group) {
        // Extension names are not translatable.
        if ($this->moduleHandler
            ->moduleExists($group)) {
            $label = $this->moduleHandler
                ->getName($group);
        }
        elseif ($this->themeHandler
            ->themeExists($group)) {
            $label = $this->themeHandler
                ->getName($group);
        }
        else {
            // Custom group label that should be translatable.
            $label = $this->t($group, [], [
                'context' => 'breakpoint',
            ]);
        }
        return $label;
    }

}