class SvgExtractor

class SvgExtractor extends IconExtractorWithFinder {
    
    /**
     * {@inheritdoc}
     */
    public function discoverIcons() : array {
        // Check is included in getFilesFromSources(), but we need to disallow
        // remote sources before.
        $this->checkRequiredConfigSources();
        $this->configuration['config']['sources'] = array_filter($this->configuration['config']['sources'], function ($source) {
            return empty(parse_url($source, PHP_URL_SCHEME));
        });
        if (empty($this->configuration['config']['sources'])) {
            return [];
        }
        $files = $this->getFilesFromSources();
        if (empty($files)) {
            return [];
        }
        $icons = [];
        foreach ($files as $file) {
            if (!isset($file['absolute_path']) || empty($file['absolute_path'])) {
                continue;
            }
            $id = IconDefinition::createIconId($this->configuration['id'], $file['icon_id']);
            $icons[$id] = [
                'absolute_path' => $file['absolute_path'],
                'source' => $file['source'],
                'group' => $file['group'] ?? NULL,
            ];
        }
        return $icons;
    }
    
    /**
     * {@inheritdoc}
     */
    public function loadIcon(array $icon_data) : ?IconDefinitionInterface {
        if (!isset($icon_data['icon_id']) || !isset($icon_data['source']) || !isset($icon_data['absolute_path'])) {
            return NULL;
        }
        if (!($svg_data = $this->extractSvg($icon_data['absolute_path']))) {
            return NULL;
        }
        return $this->createIcon($icon_data['icon_id'], $icon_data['source'], $icon_data['group'] ?? NULL, $svg_data);
    }
    
    /**
     * Extract svg values, simply exclude parent <svg>.
     *
     * @param string $source
     *   Local path or url to the svg file.
     *
     * @return array|null
     *   The SVG `content` as string and `viewbox` value if any.
     */
    private function extractSvg(string $source) : ?array {
        if (!($content = $this->iconFinder
            ->getFileContents($source))) {
            return NULL;
        }
        libxml_use_internal_errors(TRUE);
        if (!($svg = simplexml_load_string((string) $content))) {
            // @todo do we need to log a warning with the xml error?
            return NULL;
        }
        $return = [
            'content' => '',
            'attributes' => new Attribute(),
        ];
        foreach ($svg as $child) {
            $return['content'] .= $child->asXML();
        }
        if (empty($return['content'])) {
            return NULL;
        }
        // Content contain xml data and will be printed, we need to not escape it
        // for rendering.
        $return['content'] = new FormattableMarkup($return['content'], []);
        // Add svg attributes to be available in the template.
        foreach ($svg->attributes() as $name => $value) {
            $return['attributes']->setAttribute($name, (string) $value);
        }
        return $return;
    }

}