class AdvaggJsCollectionGrouper

class AdvaggJsCollectionGrouper extends JsCollectionGrouper implements AssetCollectionGrouperInterface {
    
    /**
     * Construct the grouper instance.
     *
     * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
     *   A config factory for retrieving required config objects.
     */
    public function __construct(ConfigFactoryInterface $config_factory) {
        $this->config = $config_factory->get('advagg_bundler.settings');
    }
    
    /**
     * {@inheritdoc}
     */
    public function group(array $js_assets) {
        $max = $this->config
            ->get('js.max');
        // Only modify core grouping if bundler is enabled.
        if (!$this->config
            ->get('active') || !$max) {
            return parent::group($js_assets);
        }
        $logic = $this->config
            ->get('js.logic');
        $preprocess_count = count(array_filter(array_column($js_assets, 'preprocess')));
        $target = max($max - (count($js_assets) - $preprocess_count), 1);
        if ($logic === 0) {
            $split = round($preprocess_count / $target);
        }
        else {
            $split = array_sum(array_column($js_assets, 'size')) / $target;
        }
        $groups = [];
        // If a group can contain multiple items, we track the information that must
        // be the same for each item in the group, so that when we iterate the next
        // item, we can determine if it can be put into the current group, or if a
        // new group needs to be made for it.
        $current_group_keys = NULL;
        $current_size = 0;
        $index = -1;
        foreach ($js_assets as $item) {
            // The browsers for which the JavaScript item needs to be loaded is part
            // of the information that determines when a new group is needed, but the
            // order of keys in the array doesn't matter, and we don't want a new
            // group if all that's different is that order.
            ksort($item['browsers']);
            switch ($item['type']) {
                case 'file':
                    // Group file items if their 'preprocess' flag is TRUE.
                    // Help ensure maximum reuse of aggregate files by only grouping
                    // together items that share the same 'group' value.
                    $arrayItems = [
                        $item['type'],
                        $item['group'],
                        $item['browsers'],
                    ];
                    $group_keys = $item['preprocess'] ? $arrayItems : FALSE;
                    break;
                case 'external':
                    // Do not group external items.
                    $group_keys = FALSE;
                    break;
            }
            // If the group keys don't match the most recent group we're working with,
            // then a new group must be made.
            if ($group_keys !== $current_group_keys) {
                $index++;
                // Initialize the new group with the same properties as the first item
                // being placed into it. The item's 'data' and 'weight' properties are
                // unique to the item and should not be carried over to the group.
                $groups[$index] = $item;
                unset($groups[$index]['data'], $groups[$index]['weight']);
                $groups[$index]['items'] = [];
                $current_group_keys = $group_keys ? $group_keys : NULL;
            }
            // Add the item to the current group.
            $groups[$index]['items'][] = $item;
            if ($current_group_keys) {
                if ($logic === 0) {
                    if (count($groups[$index]['items']) >= $split) {
                        $current_group_keys = NULL;
                    }
                }
                else {
                    $current_size += isset($item['size']) ? $item['size'] : 0;
                    if ($current_size >= $split) {
                        $current_size = 0;
                        $current_group_keys = NULL;
                    }
                }
            }
            else {
                $current_size = 0;
            }
        }
        return $groups;
    }

}