486663 Joomla share on Facebook preview thumbnail and text fix

We have Joomla 1.5.11 and we need a script to fix that problem: when sharing a document on facebook the preview is set to the first image or the text it founds and that sometimes is not the same of the article. I've found a script for wordpress but we need something similar for Joomla. function set_default_image(){ global $post; $image = str_img_src($post->post_content); if($image != ""){ echo '<link rel="image_src" href="'. $image . '" />' . "\n"; } } add_action('wp_head', 'set_default_image'); function str_img_src($html) { if (strpos($html, '<img') !== false) { $imgsrc_regex = '#<\s*img [^\>]*src\s*=\s*(["\'])(.*?)\1#im'; preg_match($imgsrc_regex, $html, $matches); unset($imgsrc_regex); unset($html); if (is_array($matches) && !empty($matches)) { return $matches[2]; } else { return false; } } else { return false; } }