Feature Request: getChildPagesTagsRecursive()

[NicoHood]

It would be nice to also get the tags of the pages below. This is useful when using '@self.descendants' as item collection.

[NicoHood]

I am no php expert, so the following code should be reviewed first. That is my first time hacking php. Feel free to adapt it!

    /**
     * Get taxonomy list with only tags of the child pages.
     * @param bool Include also recursively descendants of the child pages.
     *
     * @return array
     */
    public function getChildPagesTags(bool $recursive = false)
    {
        $current = Grav::instance()['page'];
        $taxonomies = $this->getChildPagesTagsInternal([], $current, $recursive);

        return $taxonomies;
    }

    /**
     * @internal
     * @param array $taxonomies
     * @param \Grav\Common\Page\Page $page
     * @return array
     */
    protected function getChildPagesTagsInternal(array $taxonomies, \Grav\Common\Page\Page $page, bool $recursive = false)
    {
        // Also parse all sub pages
        if($recursive == true)
        {
            foreach ($page->children()->published() as $child) {
                $taxonomies = $this->getChildPagesTagsInternal($taxonomies, $child, $recursive);
            }
        }

        // Parse current page
        foreach($this->build($page->taxonomy()) as $taxonomyName => $taxonomyValue) {
            if (!isset($taxonomies[$taxonomyName])) {
                $taxonomies[$taxonomyName] = $taxonomyValue;
            } else {
                foreach ($taxonomyValue as $value => $count) {
                    if (!isset($taxonomies[$taxonomyName][$value])) {
                        $taxonomies[$taxonomyName][$value] = $count;
                    } else {
                        $taxonomies[$taxonomyName][$value] += $count;
                    }
                }
            }
        }

        return $taxonomies;
    }