another-syntax-highlighter.php

<?php
/**
 * Plugin Name: Another Syntax Highlighter
 * Version: 0.1
 * Plugin URI: https://norbertvajda.wordpress.com/
 * Description: Just another syntax highligher plugin. It works with prism.js (https://prismjs.com/).
 * Author: Norbert Vajda
 * Author URI: https://norbertvajda.wordpress.com/
 * Network: false
 * Text Domain: ash
 * Domain Path: /languages
 */

/**
 * @author Norbert Vajda
 * @copyright Norbert Vajda, 2019, All Rights Reserved
 * This code is released under the GPL licence version 3 or later, available here
 * https://www.gnu.org/licenses/gpl.txt
 */

 // If this file is called directly, abort.
if ( ! defined( 'WPINC' ) ) {
	die;
}

/**
 * Admin Page
 */

function another_Syntax_Highlighter_setup_menu(){
    add_menu_page(
	    'Another Syntax Highlighter page', 
	    'Another Syntax Highlighter', 
	    'manage_options', 
	    'another-syntax-highlighter', 
	    'ash_admin_init', 
	    'dashicons-editor-code', 
	    66
    );
}

function ash_admin_init() {
    ?>
    <div class="wrap">
        <h1>Another Syntax Highlighter Settings</h1>
        <form action="post" action="options.php">
            <?php settings_fields( 'myoption-group' ); ?>

            <?php submit_button("Let's go!"); ?>
        </form>
    </div>
    <?php
}

add_action('admin_menu', 'another_Syntax_Highlighter_setup_menu');

/**
 * bind prism.js and prism.css, when post / page has this shortcode 
 */
function highlighter_enqueue_scripts() {
    global $post;
	if( is_a( $post, 'WP_Post' ) && has_shortcode( $post->post_content, 'another-syntax-highlighter') ) {
        wp_register_style( 'prism-stylesheet',  plugin_dir_url( __FILE__ ) . 'assets/css/prism.css' );
        wp_register_script( 'prism-script', plugin_dir_url( __FILE__ ) . 'assets/js/prism.js' );
        wp_enqueue_style( 'prism-stylesheet' );
        wp_enqueue_script( 'prism-script' );
	}
}
add_action( 'wp_enqueue_scripts', 'highlighter_enqueue_scripts');

function another_Syntax_Highlighter( $atts, $content = null, $tag = '' ) {
    // normalize attribute keys, lowercase
	$atts = array_change_key_case( (array)$atts, CASE_LOWER );
	
	extract( shortcode_atts(
			array(
				'lang' => '',
			),
			$atts,
			'another-syntax-highlighter'
    ) );
    
    // only the following attributes values
    if( in_array( $lang, array( 'markup', 'html', 'xml', 'svg', 'mathml', 'css', 'clike', 'javascript', 'js' ) ) ){
        $value = esc_attr($lang);
    } else {
        $value = 'css';
    }
    
    
    $output = '<pre><code class="language-' . esc_attr($lang) . '">' . $content . '</code></pre>';
    
    return $output;
}

function shortcode_init() {
    add_shortcode('another-syntax-highlighter', 'another_Syntax_Highlighter');
}

add_action('init', 'shortcode_init');