Generating Previews with PHP

link-preview.php

public function link_preview_post()
{
    $post = json_decode($this->security->xss_clean($this->input->raw_input_stream));
    $url = $post->url;

    $is_facebook_url = false;
    $no_data = false;


    $array = [
        'status' => false,
        'tags' => '',
    ];

    if($url) {
        // As previews don't change that often it would be good to save them for quick fetch results than scraping it all over again
        $this->load->model('PreviewModel');
                
        $result = $this->PreviewModel->getByURL($url);

        if($result) {
            $array = $result;
        } else {
            $res = $this->curl_get($url, []);
            $html = $res[1];
            $newurl = $res[0];

            $rmetas = [];
            
            // Fetching meta tags from the URL given
            $doc = new DomDocument();
            @$doc->loadHTML(html_entity_decode(mb_convert_encoding($html, 'HTML-ENTITIES', 'UTF-8')));
            $xpath = new DOMXPath($doc);
            $query = '//*/meta';

            $metas = $xpath->query($query);
            foreach ($metas as $meta) {
                $property = $meta->getAttribute('property');
                $content = is_string($meta->getAttribute('content')) ? $meta->getAttribute('content') : is_string($meta->getAttribute('property')) ? $meta->getAttribute('property') : '';
                if($property) {
                    $rmetas[$property] = $content;
                }
            }
            
            // formatting the data as required
            foreach( $doc->getElementsByTagName('meta') as $m){
                $name = is_string($m->getAttribute('name')) ? $m->getAttribute('name') : '';
                $property = is_string($m->getAttribute('property')) ? $m->getAttribute('property') : '';
                $content = is_string($m->getAttribute('content')) ? $m->getAttribute('content') : '';

                if($property && (strpos('og:', $property) == 0 || strpos(':', $property) > 0)) {
                    $rmetas[$property] = $content ? $content : '';
                } elseif($name && (strpos('og:', $name) == 0 || strpos('twitter:', $name) == 0)) {
                    $rmetas[$name] = $property ? $property : $content;
                }
            }
            
            // Most of the meta tags get fetched from this method but some tags like facebook with colon are not attained from previous methods so we use default php methods for meta tags 
            $meta_tags = @get_meta_tags($newurl);

            if(empty($rmetas) && empty($meta_tags)) {
                $no_data = true;
            } else {
                $meta_tags = array_merge($rmetas, is_array($meta_tags) ? $meta_tags : []);
            }

            $meta_tags['url'] = $url;

            $pattern = '/fb.watch|facebook.com/i';
            
            // in case you need to know if the url is facebook video
            if(preg_match($pattern, $url)) {
                $is_facebook_url = true;
            }

            if(!$no_data || ($no_data && $is_facebook_url)) {
                $array = [
                    'status' => true,                        
                    'all_tags' => $meta_tags, // unformatted data
                    'tags' => $this->getLinkData($meta_tags), // formatted data
                ];

                if(empty($array['tags']['title'])) {
                    $array['status'] = false;
                    $array['tags'] = null;
                    $array['all_tags'] = null;
                }
            }
            
            // saving the data in database for further repetitive fetching
            $this->PreviewModel->save(['url' => $url, 'json_data' => json_encode($array, true), 'createdDtm' => date('y-m-d H:i:s')]);
        }
    }

    $this->response($array, REST_Controller::HTTP_OK);
}