class AssetResolver

class AssetResolver implements AssetResolverInterface {
    
    /**
     * The library discovery service.
     *
     * @var \Drupal\Core\Asset\LibraryDiscoveryInterface
     */
    protected $libraryDiscovery;
    
    /**
     * The library dependency resolver.
     *
     * @var \Drupal\Core\Asset\LibraryDependencyResolverInterface
     */
    protected $libraryDependencyResolver;
    
    /**
     * The module handler.
     *
     * @var \Drupal\Core\Extension\ModuleHandlerInterface
     */
    protected $moduleHandler;
    
    /**
     * The theme manager.
     *
     * @var \Drupal\Core\Theme\ThemeManagerInterface
     */
    protected $themeManager;
    
    /**
     * The language manager.
     *
     * @var \Drupal\Core\Language\LanguageManagerInterface
     */
    protected $languageManager;
    
    /**
     * The cache backend.
     *
     * @var \Drupal\Core\Cache\CacheBackendInterface
     */
    protected $cache;
    
    /**
     * The theme handler service.
     *
     * @var \Drupal\Core\Extension\ThemeHandlerInterface
     */
    protected $themeHandler;
    
    /**
     * Constructs a new AssetResolver instance.
     *
     * @param \Drupal\Core\Asset\LibraryDiscoveryInterface $library_discovery
     *   The library discovery service.
     * @param \Drupal\Core\Asset\LibraryDependencyResolverInterface $library_dependency_resolver
     *   The library dependency resolver.
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $module_handler
     *   The module handler.
     * @param \Drupal\Core\Theme\ThemeManagerInterface $theme_manager
     *   The theme manager.
     * @param \Drupal\Core\Language\LanguageManagerInterface $language_manager
     *   The language manager.
     * @param \Drupal\Core\Cache\CacheBackendInterface $cache
     *   The cache backend.
     * @param \Drupal\Core\Extension\ThemeHandlerInterface $theme_handler
     *   The theme handler service.
     */
    public function __construct(LibraryDiscoveryInterface $library_discovery, LibraryDependencyResolverInterface $library_dependency_resolver, ModuleHandlerInterface $module_handler, ThemeManagerInterface $theme_manager, LanguageManagerInterface $language_manager, CacheBackendInterface $cache, ?ThemeHandlerInterface $theme_handler = NULL) {
        if ($theme_handler === NULL) {
            @trigger_error('Calling ' . __METHOD__ . ' without the $theme_handler argument is deprecated in drupal:11.1.0 and it will be required in drupal:12.0.0. See https://www.drupal.org/project/drupal/issues/3451667', E_USER_DEPRECATED);
            $theme_handler = \Drupal::service('theme_handler');
        }
        $this->libraryDiscovery = $library_discovery;
        $this->libraryDependencyResolver = $library_dependency_resolver;
        $this->moduleHandler = $module_handler;
        $this->themeManager = $theme_manager;
        $this->languageManager = $language_manager;
        $this->cache = $cache;
        $this->themeHandler = $theme_handler;
    }
    
    /**
     * Returns the libraries that need to be loaded.
     *
     * For example, with core/a depending on core/c and core/b on core/d:
     * @code
     * $assets = new AttachedAssets();
     * $assets->setLibraries(['core/a', 'core/b', 'core/c']);
     * $assets->setAlreadyLoadedLibraries(['core/c']);
     * $resolver->getLibrariesToLoad($assets, 'js') === ['core/a', 'core/b', 'core/d']
     * @endcode
     *
     * The attached assets tend to be in the order that libraries were attached
     * during a request. To minimize the number of unique aggregated asset URLs
     * and files, we normalize the list by filtering out libraries that don't
     * include the asset type being built as well as ensuring a reliable order of
     * the libraries based on their dependencies.
     *
     * @param \Drupal\Core\Asset\AttachedAssetsInterface $assets
     *   The assets attached to the current response.
     * @param string|null $asset_type
     *   The asset type to load.
     *
     * @return string[]
     *   A list of libraries and their dependencies, in the order they should be
     *   loaded, excluding any libraries that have already been loaded.
     */
    protected function getLibrariesToLoad(AttachedAssetsInterface $assets, ?string $asset_type = NULL) {
        // @see Drupal\FunctionalTests\Core\Asset\AssetOptimizationTestUmami
        // @todo https://www.drupal.org/project/drupal/issues/1945262
        $libraries_to_load = array_diff($this->libraryDependencyResolver
            ->getLibrariesWithDependencies($assets->getLibraries()), $this->libraryDependencyResolver
            ->getLibrariesWithDependencies($assets->getAlreadyLoadedLibraries()));
        if ($asset_type) {
            $libraries_to_load = $this->filterLibrariesByType($libraries_to_load, $asset_type);
        }
        // We now have a complete list of libraries requested. However, this list
        // could be in any order depending on when libraries were attached during
        // the page request, which can result in different file contents and URLs
        // even for an otherwise identical set of libraries. To ensure that any
        // particular set of libraries results in the same aggregate URL, sort the
        // libraries, then generate the minimum representative set again.
        sort($libraries_to_load);
        $minimum_libraries = $this->libraryDependencyResolver
            ->getMinimalRepresentativeSubset($libraries_to_load);
        $libraries_to_load = array_diff($this->libraryDependencyResolver
            ->getLibrariesWithDependencies($minimum_libraries), $this->libraryDependencyResolver
            ->getLibrariesWithDependencies($assets->getAlreadyLoadedLibraries()));
        // Now remove any libraries without the relevant asset type again, since
        // they have been brought back in via dependencies.
        if ($asset_type) {
            $libraries_to_load = $this->filterLibrariesByType($libraries_to_load, $asset_type);
        }
        return $libraries_to_load;
    }
    
    /**
     * Filter libraries that don't contain an asset type.
     *
     * @param array $libraries
     *   An array of library definitions.
     * @param string $asset_type
     *   The type of asset, either 'js' or 'css'.
     *
     * @return array
     *   The filtered libraries array.
     */
    protected function filterLibrariesByType(array $libraries, string $asset_type) : array {
        foreach ($libraries as $key => $library) {
            [
                $extension,
                $name,
            ] = explode('/', $library, 2);
            $definition = $this->libraryDiscovery
                ->getLibraryByName($extension, $name);
            if (empty($definition[$asset_type])) {
                unset($libraries[$key]);
            }
        }
        return $libraries;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getCssAssets(AttachedAssetsInterface $assets, $optimize, ?LanguageInterface $language = NULL) {
        if (!$assets->getLibraries()) {
            return [];
        }
        // Get the complete list of libraries to load including dependencies.
        $libraries_to_load = $this->getLibrariesToLoad($assets, 'css');
        if (!$libraries_to_load) {
            return [];
        }
        if (!isset($language)) {
            $language = $this->languageManager
                ->getCurrentLanguage();
        }
        // Add the active theme name to the cache key since active themes may
        // implement hook_library_info_alter().
        $active_theme = $this->themeManager
            ->getActiveTheme()
            ->getName();
        // Add the default theme name to the cache key since css generated for an
        // active admin theme may include the default theme's ckeditor5-stylesheets
        // and default themes may be set conditionally and dynamically.
        $default_theme = $this->themeHandler
            ->getDefault();
        $cid = 'css:' . $active_theme . ':' . $default_theme . ':' . $language->getId() . Crypt::hashBase64(serialize($libraries_to_load)) . (int) $optimize;
        if ($cached = $this->cache
            ->get($cid)) {
            return $cached->data;
        }
        $css = [];
        $default_options = [
            'type' => 'file',
            'group' => CSS_AGGREGATE_DEFAULT,
            'weight' => 0,
            'media' => 'all',
            'preprocess' => TRUE,
        ];
        foreach ($libraries_to_load as $library) {
            [
                $extension,
                $name,
            ] = explode('/', $library, 2);
            $definition = $this->libraryDiscovery
                ->getLibraryByName($extension, $name);
            foreach ($definition['css'] as $options) {
                $options += $default_options;
                // Copy the asset library license information to each file.
                $options['license'] = $definition['license'];
                // Files with a query string cannot be preprocessed.
                if ($options['type'] === 'file' && $options['preprocess'] && str_contains($options['data'], '?')) {
                    $options['preprocess'] = FALSE;
                }
                // Always add a tiny value to the weight, to conserve the insertion
                // order.
                $options['weight'] += count($css) / 30000;
                // CSS files are being keyed by the full path.
                $css[$options['data']] = $options;
            }
        }
        // Allow modules and themes to alter the CSS assets.
        $this->moduleHandler
            ->alter('css', $css, $assets, $language);
        $this->themeManager
            ->alter('css', $css, $assets, $language);
        if (!empty($css)) {
            // Sort CSS items, so that they appear in the correct order.
            uasort($css, [
                static::class,
                'sort',
            ]);
            if ($optimize) {
                $css = \Drupal::service('asset.css.collection_optimizer')->optimize($css, array_values($libraries_to_load), $language);
            }
        }
        $this->cache
            ->set($cid, $css, CacheBackendInterface::CACHE_PERMANENT, [
            'library_info',
        ]);
        return $css;
    }
    
    /**
     * Returns the JavaScript settings assets for this response's libraries.
     *
     * Gathers all drupalSettings from all libraries in the attached assets
     * collection and merges them.
     *
     * @param \Drupal\Core\Asset\AttachedAssetsInterface $assets
     *   The assets attached to the current response.
     *
     * @return array
     *   A (possibly optimized) collection of JavaScript assets.
     */
    protected function getJsSettingsAssets(AttachedAssetsInterface $assets) {
        $settings = [];
        foreach ($this->getLibrariesToLoad($assets, 'js') as $library) {
            [
                $extension,
                $name,
            ] = explode('/', $library, 2);
            $definition = $this->libraryDiscovery
                ->getLibraryByName($extension, $name);
            if (isset($definition['drupalSettings'])) {
                $settings = NestedArray::mergeDeepArray([
                    $settings,
                    $definition['drupalSettings'],
                ], TRUE);
            }
        }
        return $settings;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getJsAssets(AttachedAssetsInterface $assets, $optimize, ?LanguageInterface $language = NULL) {
        if (!$assets->getLibraries() && !$assets->getSettings()) {
            return [
                [],
                [],
            ];
        }
        if (!isset($language)) {
            $language = $this->languageManager
                ->getCurrentLanguage();
        }
        $theme_info = $this->themeManager
            ->getActiveTheme();
        // Get the complete list of libraries to load including dependencies.
        $libraries_to_load = $this->getLibrariesToLoad($assets, 'js');
        // Collect all libraries that contain JS assets and are in the header.
        $header_js_libraries = [];
        foreach ($libraries_to_load as $key => $library) {
            [
                $extension,
                $name,
            ] = explode('/', $library, 2);
            $definition = $this->libraryDiscovery
                ->getLibraryByName($extension, $name);
            if (!empty($definition['header'])) {
                $header_js_libraries[] = $library;
            }
        }
        // If all the libraries to load contained only CSS, there is nothing further
        // to do here, so return early.
        if (!$libraries_to_load && !$assets->getSettings()) {
            return [
                [],
                [],
            ];
        }
        // Add the theme name to the cache key since themes may implement
        // hook_library_info_alter(). Additionally add the current language to
        // support translation of JavaScript files via hook_js_alter().
        $cid = 'js:' . $theme_info->getName() . ':' . $language->getId() . ':' . Crypt::hashBase64(serialize($libraries_to_load)) . (int) (count($assets->getSettings()) > 0) . (int) $optimize;
        if ($cached = $this->cache
            ->get($cid)) {
            [
                $js_assets_header,
                $js_assets_footer,
                $settings,
                $settings_in_header,
            ] = $cached->data;
        }
        else {
            $javascript = [];
            $default_options = [
                'type' => 'file',
                'group' => JS_DEFAULT,
                'weight' => 0,
                'cache' => TRUE,
                'preprocess' => TRUE,
                'attributes' => [],
                'version' => NULL,
            ];
            // The current list of header JS libraries are only those libraries that
            // are in the header, but their dependencies must also be loaded for them
            // to function correctly, so update the list with those.
            $header_js_libraries = $this->libraryDependencyResolver
                ->getLibrariesWithDependencies($header_js_libraries);
            foreach ($libraries_to_load as $library) {
                [
                    $extension,
                    $name,
                ] = explode('/', $library, 2);
                $definition = $this->libraryDiscovery
                    ->getLibraryByName($extension, $name);
                foreach ($definition['js'] as $options) {
                    $options += $default_options;
                    // Copy the asset library license information to each file.
                    $options['license'] = $definition['license'];
                    // 'scope' is a calculated option, based on which libraries are
                    // marked to be loaded from the header (see above).
                    $options['scope'] = in_array($library, $header_js_libraries) ? 'header' : 'footer';
                    // Preprocess can only be set if caching is enabled and no
                    // attributes are set.
                    $options['preprocess'] = $options['cache'] && empty($options['attributes']) ? $options['preprocess'] : FALSE;
                    // Always add a tiny value to the weight, to conserve the insertion
                    // order.
                    $options['weight'] += count($javascript) / 30000;
                    // Local and external files must keep their name as the associative
                    // key so the same JavaScript file is not added twice.
                    $javascript[$options['data']] = $options;
                }
            }
            // Allow modules and themes to alter the JavaScript assets.
            $this->moduleHandler
                ->alter('js', $javascript, $assets, $language);
            $this->themeManager
                ->alter('js', $javascript, $assets, $language);
            // Sort JavaScript assets, so that they appear in the correct order.
            uasort($javascript, [
                static::class,
                'sort',
            ]);
            // Prepare the return value: filter JavaScript assets per scope.
            $js_assets_header = [];
            $js_assets_footer = [];
            foreach ($javascript as $key => $item) {
                if ($item['scope'] == 'header') {
                    $js_assets_header[$key] = $item;
                }
                elseif ($item['scope'] == 'footer') {
                    $js_assets_footer[$key] = $item;
                }
            }
            if ($optimize) {
                $collection_optimizer = \Drupal::service('asset.js.collection_optimizer');
                $js_assets_header = $collection_optimizer->optimize($js_assets_header, $libraries_to_load);
                $js_assets_footer = $collection_optimizer->optimize($js_assets_footer, $libraries_to_load);
            }
            // If the core/drupalSettings library is being loaded or is already
            // loaded, get the JavaScript settings assets, and convert them into a
            // single "regular" JavaScript asset.
            $libraries_to_load = $this->getLibrariesToLoad($assets);
            $settings_required = in_array('core/drupalSettings', $libraries_to_load) || in_array('core/drupalSettings', $this->libraryDependencyResolver
                ->getLibrariesWithDependencies($assets->getAlreadyLoadedLibraries()));
            $settings_have_changed = count($libraries_to_load) > 0 || count($assets->getSettings()) > 0;
            // Initialize settings to FALSE since they are not needed by default. This
            // distinguishes between an empty array which must still allow
            // hook_js_settings_alter() to be run.
            $settings = FALSE;
            if ($settings_required && $settings_have_changed) {
                $settings = $this->getJsSettingsAssets($assets);
                // Allow modules to add cached JavaScript settings.
                $this->moduleHandler
                    ->invokeAllWith('js_settings_build', function (callable $hook, string $module) use (&$settings, $assets) {
                    $hook($settings, $assets);
                });
            }
            $settings_in_header = in_array('core/drupalSettings', $header_js_libraries);
            $this->cache
                ->set($cid, [
                $js_assets_header,
                $js_assets_footer,
                $settings,
                $settings_in_header,
            ], CacheBackendInterface::CACHE_PERMANENT, [
                'library_info',
            ]);
        }
        if ($settings !== FALSE) {
            // Attached settings override both library definitions and
            // hook_js_settings_build().
            $settings = NestedArray::mergeDeepArray([
                $settings,
                $assets->getSettings(),
            ], TRUE);
            // Allow modules and themes to alter the JavaScript settings.
            $this->moduleHandler
                ->alter('js_settings', $settings, $assets);
            $this->themeManager
                ->alter('js_settings', $settings, $assets);
            // Update the $assets object accordingly, so that it reflects the final
            // settings.
            $assets->setSettings($settings);
            // Convert ajaxPageState to a compressed string from an array, since it is
            // used by ajax.js to pass to AJAX requests as a query parameter.
            if (isset($settings['ajaxPageState']['libraries'])) {
                $settings['ajaxPageState']['libraries'] = UrlHelper::compressQueryParameter($settings['ajaxPageState']['libraries']);
            }
            $settings_as_inline_javascript = [
                'type' => 'setting',
                'group' => JS_SETTING,
                'weight' => 0,
                'data' => $settings,
            ];
            $settings_js_asset = [
                'drupalSettings' => $settings_as_inline_javascript,
            ];
            // Prepend to the list of JS assets, to render it first. Preferably in
            // the footer, but in the header if necessary.
            if ($settings_in_header) {
                $js_assets_header = $settings_js_asset + $js_assets_header;
            }
            else {
                $js_assets_footer = $settings_js_asset + $js_assets_footer;
            }
        }
        return [
            $js_assets_header,
            $js_assets_footer,
        ];
    }
    
    /**
     * Sorts CSS and JavaScript resources.
     *
     * Callback for uasort().
     *
     * This sort order helps optimize front-end performance while providing
     * modules and themes with the necessary control for ordering the CSS and
     * JavaScript appearing on a page.
     *
     * @param array $a
     *   First item for comparison. The compared items should be associative
     *   arrays of member items.
     * @param array $b
     *   Second item for comparison.
     *
     * @return int
     *   The comparison result for uasort().
     */
    public static function sort(array $a, array $b) {
        // First order by group, so that all items in the CSS_AGGREGATE_DEFAULT
        // group appear before items in the CSS_AGGREGATE_THEME group. Modules may
        // create additional groups by defining their own constants.
        if ($a['group'] < $b['group']) {
            return -1;
        }
        elseif ($a['group'] > $b['group']) {
            return 1;
        }
        elseif ($a['weight'] < $b['weight']) {
            return -1;
        }
        elseif ($a['weight'] > $b['weight']) {
            return 1;
        }
        else {
            return 0;
        }
    }

}