I’m in the process of upgrading my site’s engine. The new version does not support bbcodes, and all my forum posts and articles are created using it.

I want to make a script to convert all text with bbdodes to html. But I’ve run into a problem and I’m not sure how to proceed. Please take a look at my code and suggest how I can improve it.

Functions:

function bbcodeconvert($text)
    {

    $text = " ".$text;

    $bbcodes = array(
        '[b]' => '<strong>',
        '[/b]' => '</strong>'
    );

  foreach($bbcodes as $bbcode => $bbcodehtml)
            { $text = str_replace($bbcode,$bbcodehtml,$text); }

    $bbcodes2 = array(
        '\[img\]([^\';?([]*).(jpg|jpeg|gif|png)\[/img\]' => '<img src="\1.\2" alt="">',
        '\[img=([^\';?([]*).(jpg|jpeg|gif|png)\]([^\[]*).(jpg|jpeg|gif|png)\[/img\]' => '<a href="\1.\2" data-lightbox="spic"><img src="\3.\4" alt=""></a>',
        '\[youtube\]([^\([]*)\[/youtube\]' => '<iframe width="540" height="320" src="https://www.youtube.com/embed/\1?wmode=opaque" frameborder="0" allowfullscreen></iframe>',
        '\[colleft\]([^\[]*)\[/colleft\]' => '<div class="colleft">\1</div>',
        '\[colright\]([^\[]*)\[/colright\]' => '<div class="colright">\1</div>'
           );
        
        foreach($bbcodes2 as $bbcode => $bbcodehtml)
        { $text = preg_replace($bbcode,$bbcodehtml,$text); }

        return(mb_substr($text,1));
}

function oldparse($text)
    {
    global  $sys, $L;

    $text = ' '.$text;
    $code = array();
    $unique_seed = $sys['unique'];
    $ii = 5000;

        $p1 = 1;
        $p2 = 1;
        while ($p1 > 0 && $p2 > 0 && $ii < 5031)
            {
            $ii++;
            $p1 = mb_strpos($text, '[code]');
            $p2 = mb_strpos($text, '[/code]');
            if ($p2 > $p1 && $p1 > 0)
                {
                $key = '**'.$ii.$unique_seed.'**';
                $code[$key]= mb_substr ($text, $p1 + 6, ($p2 - $p1) - 6);
                $code_len = mb_strlen($code[$key]) + 13;
                $code[$key] = str_replace('t','   ', $code[$key]);
                $code[$key] = str_replace('  ', '  ', $code[$key]);
                $code[$key] = str_replace('  ', '  ', $code[$key]);
                $code[$key] = str_replace(
                array('{', '<', '>' , ''', '"', "<!--", '$' ),
                array('{', '<', '>', ''', '"', '"<!--"', '$' ),$code[$key]);
        $code[$key] = "<div class="codetitle">".$L['bbcodes_code'].":</div><div class="code">".trim($code[$key])."</div>"; 
                $text = substr_replace($text, $key, $p1, $code_len);
                }
            }

    $text = sed_bbcode($text);

       return(mb_substr($text, 1));
    }

Execution example:

$sql = sql_query("SELECT some_text FROM forum_posts WHERE topicid='$s' LIMIT 1");

     while ($row = sql_fetchassoc($sql)) {
          $post_text = oldparse($row['some_text']);
                            }
$output = "Converted text:$post_text";   

I have no problem with a first part where I use “str_replace”, but can’t figure out segment with “preg_replace” for more complicated bbcodes. Any suggestions?