WordPress code plugin, a quick solution

I’m slowly copying the markdown versions of my posts after my recent move of this blog. It really is tedious, and I don’t think I’ll finish anytime soon, so in the meantime I created a plugin to output the [ code] shortcode that wordpress.com put in my post export in the same way that markdown does. This is the first plugin and shortcode I’ve created in a long while, but it was relatively quick to do working off of my posts on plugins and shortcodes. The biggest time consumer was figuring out how to deal with whitespace issues. Apparently, WordPress sometimes will add <p> and <br /> to shortcode content. Also, there were leading and trailing line breaks adding unnecessary space. My quick solution:

Plugin Name: tjm-code
Plugin URI:  https://www.tobymackenzie.com/blog/2016/04/06/wordpress-code-plugin/
Description: Simple handler of 'code' shorttag
Version: 0.1
Author: Toby Mackenzie
Author URI: https://www.tobymackenzie.com
License: licenseName

add_shortcode('code', function($args = null, $content = null){
    $content = trim($content);
    $content = str_replace('<br />', '', $content);
    $content = str_replace('<p>', '', $content);
    $content = str_replace('</p>', '', $content);
    if(ord($content{0}) === 10){
        $content = substr($content, 1);
    if($args && isset($args['lang'])){
        return '<pre><code>' . $content . '</code></pre>';
        return '<pre><code>' . $content . '</code></pre>';

I still have to find a solution for syntax highlighting. I haven’t liked the plugins I’ve tried so far.