if ( isset($HTTP_GET_VARS[POST_TOPIC_URL]) ) 
{ 
      $topic_id = intval($HTTP_GET_VARS[POST_TOPIC_URL]); 
} 
else if ( isset($HTTP_GET_VARS['topic']) ) 
{ 
      $topic_id = intval($HTTP_GET_VARS['topic']); 
} 

$topic_id = $post_id = false; 

$join_sql_table = ( !isset($post_id) ) ? '' : ", " . POSTS_TABLE . " p, " . POSTS_TABLE . " p2 "; 
$join_sql = ( !isset($post_id) ) ? "t.topic_id = $topic_id" : "p.post_id = $post_id AND t.topic_id = p.topic_id AND p2.topic_id = p.topic_id AND p2.post_id <= $post_id"; 
$count_sql = ( !isset($post_id) ) ? '' : ", COUNT(p2.post_id) AS prev_posts"; 

$order_sql = ( !isset($post_id) ) ? '' : "GROUP BY p.post_id, t.topic_id, t.topic_title, t.topic_status, t.topic_replies, t.topic_time, t.topic_type, t.topic_vote, t.topic_last_post_id, f.forum_name, f.forum_status, f.forum_id, f.auth_view, f.auth_read, f.auth_post, f.auth_reply, f.auth_edit, f.auth_delete, f.auth_sticky, f.auth_announce, f.auth_pollcreate, f.auth_vote, f.auth_attachments ORDER BY p.post_id ASC"; 

$join_sql_table = ( empty($post_id) ) ? '' : ", " . POSTS_TABLE . " p, " . POSTS_TABLE . " p2 "; 
$join_sql = ( empty($post_id) ) ? "t.topic_id = $topic_id" : "p.post_id = $post_id AND t.topic_id = p.topic_id AND p2.topic_id = p.topic_id AND p2.post_id <= $post_id"; 
$count_sql = ( empty($post_id) ) ? '' : ", COUNT(p2.post_id) AS prev_posts"; 

$order_sql = ( empty($post_id) ) ? '' : "GROUP BY p.post_id, t.topic_id, t.topic_title, t.topic_status, t.topic_replies, t.topic_time, t.topic_type, t.topic_vote, t.topic_last_post_id, f.forum_name, f.forum_status, f.forum_id, f.auth_view, f.auth_read, f.auth_post, f.auth_reply, f.auth_edit, f.auth_delete, f.auth_sticky, f.auth_announce, f.auth_pollcreate, f.auth_vote, f.auth_attachments ORDER BY p.post_id ASC"; 

$bbcode_tpl['url4'] = str_replace('{URL}', 'http://\\1', $bbcode_tpl['url']); 
   $bbcode_tpl['url4'] = str_replace('{DESCRIPTION}', '\\5', $bbcode_tpl['url4']);

$bbcode_tpl['url4'] = str_replace('{URL}', 'http://\\1', $bbcode_tpl['url']); 
   $bbcode_tpl['url4'] = str_replace('{DESCRIPTION}', '\\3', $bbcode_tpl['url4']);

// matches a xxxx://www.phpbb.com code.. 
   $patterns[] = "#\[url\]([\w]+?://.*?[^ \"\n\r\t<]*?)\[/url\]#is"; 
   $replacements[] = $bbcode_tpl['url1']; 

   // www.phpbb.com code.. (no xxxx:// prefix). 
   $patterns[] = "#\[url\]((www|ftp)\.([\w\-]+\.)*?[\w\-]+\.[a-z]{2,4}(:?[0-9]*?/[^ \"\n\r\t<]*)?)\[/url\]#is"; 
   $replacements[] = $bbcode_tpl['url2']; 

   // phpBB code.. 
   $patterns[] = "#\+?://.*?[^ \"\n\r\t<]*?)\](.*?)\[/url\]#is"; 
   $replacements[] = $bbcode_tpl['url3']; 

   // [url=www.phpbb.com]phpBB code.. (no xxxx:// prefix). 
   $patterns[] = "#\+\.)*?[\w\-]+\.[a-z]{2,4}(:?[0-9]*?/[^ \"\n\r\t<]*)?)\](.*?)\[/url\]#is";
   $replacements[] = $bbcode_tpl['url4'];

// matches a [url]xxxx://www.phpbb.com code.. 
   $patterns[] = "#\[url\]([\w]+?://[^ \"\n\r\t<]*?)\[/url\]#is"; 
   $replacements[] = $bbcode_tpl['url1']; 

   // www.phpbb.com code.. (no xxxx:// prefix). 
   $patterns[] = "#\[url\]((www|ftp)\.[^ \"\n\r\t<]*?)\[/url\]#is"; 
   $replacements[] = $bbcode_tpl['url2']; 

   // phpBB code.. 
   $patterns[] = "#\+?://[^ \"\n\r\t<]*?)\](.*?)\[/url\]#is"; 
   $replacements[] = $bbcode_tpl['url3']; 

   // [url=www.phpbb.com]phpBB code.. (no xxxx:// prefix). 
   $patterns[] = "#\[url=((www|ftp)\.[^ \"\n\r\t<]*?)\](.*?)\[/url\]#is"; 
   $replacements[] = $bbcode_tpl['url4'];

// matches an "xxxx://yyyy" URL at the start of a line, or after a space. 
   // xxxx can only be alpha characters. 
   // yyyy is anything up to the first space, newline, comma, double quote or < 
   $ret = preg_replace("#(^|[\n ])([\w]+?://.*?[^ \"\n\r\t<]*)#is", "\\1<a href=\"\\2\" target=\"_blank\">\\2</a>", $ret); 

   // matches a "www|ftp.xxxx.yyyy[/zzzz]" kinda lazy URL thing 
   // Must contain at least 2 dots. xxxx contains either alphanum, or "-" 
   // zzzz is optional.. will contain everything up to the first space, newline, 
   // comma, double quote or <. 
   $ret = preg_replace("#(^|[\n ])((www|ftp)\.[\w\-]+\.[\w\-.\~]+(?:/[^ \"\t\n\r<]*)?)#is", "\\1<a href=\"http://\\2\" target=\"_blank\">\\2</a>", $ret);

// matches an "xxxx://yyyy" URL at the start of a line, or after a space. 
   // xxxx can only be alpha characters. 
   // yyyy is anything up to the first space, newline, comma, double quote or < 
   $ret = preg_replace("#(^|[\n ])([\w]+?://.*?[^ \"\n\r\t<]*)#is", "\\1<a href=\"\\2\" target=\"_blank\">\\2</a>", $ret); 

   // matches a "www|ftp.xxxx.yyyy[/zzzz]" kinda lazy URL thing 
   // Must contain at least 2 dots. xxxx contains either alphanum, or "-" 
   // zzzz is optional.. will contain everything up to the first space, newline, 
   // comma, double quote or <. 
   $ret = preg_replace("#(^|[\n ])((www|ftp)\.[\w\-]+\.[\w\-.\~]+(?:/[^ \"\t\n\r<]*)?)#is", "\\1<a href=\"http://\\2\" target=\"_blank\">\\2</a>", $ret);