Plugin Tweaks: Support the Code Syntax Block

mu-plugins/helpers/helpers.php

@@ -1,6 +1,7 @@
 <?php
 
 namespace WordPressdotorg\MU_Plugins\Helpers;
+
 defined( 'WPINC' ) || die();
 
 /**
@@ -22,3 +23,30 @@ function natural_language_join( array $list, $conjunction = 'and' ) : string {
 
 	return $last;
 }
+
+/**
+ * Check if a plugin is active on the current site.
+ *
+ * Clone of core's `is_plugin_active` and `is_plugin_active_for_network`, so
+ * they can be used on the frontend.
+ *
+ * @param string $plugin Path to the plugin file relative to the plugins directory.
+ * @return bool True, if in the active plugins list. False, not in the list.
+ */
+function is_plugin_active( $plugin ) {
+	// Single-site active.
+	if ( in_array( $plugin, (array) get_option( 'active_plugins', array() ), true ) ) {
+		return true;
+	}
+
+	if ( ! is_multisite() ) {
+		return false;
+	}
+
+	$plugins = get_site_option( 'active_sitewide_plugins' );
+	if ( isset( $plugins[ $plugin ] ) ) {
+		return true;
+	}
+
+	return false;
+}

mu-plugins/plugin-tweaks/code-syntax-block/index.php

@@ -0,0 +1,148 @@
+<?php
+/**
+ * Code Syntax Block Tweaks
+ *
+ * Adds support for the shortcodes provided by SyntaxHighlighter Evolved.
+ * This allows the current content (with shortcodes) to use the new design's
+ * syntax highlighting style & behavior.
+ *
+ * Also injects the stylesheet with our custom styles.
+ */
+
+namespace WordPressdotorg\MU_Plugins\Plugin_Tweaks\CodeSyntaxBlock;
+
+use function WordPressdotorg\MU_Plugins\Helpers\is_plugin_active;
+
+add_action( 'init', __NAMESPACE__ . '\maybe_init' );
+add_filter( 'mkaz_code_syntax_force_loading', '__return_true' );
+add_filter( 'mkaz_prism_css_url', __NAMESPACE__ . '\update_prism_css_url' );
+
+/**
+ * Initialize the shortcode replacements only if the Code Syntax Block is active.
+ */
+function maybe_init() {
+	if ( ! is_plugin_active( 'code-syntax-block/index.php' ) ) {
+		return;
+	}
+
+	add_shortcode( 'php', __NAMESPACE__ . '\do_shortcode_php' );
+	add_shortcode( 'js', __NAMESPACE__ . '\do_shortcode_js' );
+	add_shortcode( 'css', __NAMESPACE__ . '\do_shortcode_css' );
+	add_shortcode( 'code', __NAMESPACE__ . '\do_shortcode_code' );
+
+	add_filter(
+		'no_texturize_shortcodes',
+		function ( $shortcodes ) {
+			$shortcodes[] = 'php';
+			$shortcodes[] = 'js';
+			$shortcodes[] = 'css';
+			$shortcodes[] = 'code';
+			return $shortcodes;
+		}
+	);
+}
+
+/**
+ * Customize the syntax highlighter style.
+ * See https://github.com/PrismJS/prism-themes.
+ *
+ * @param string $url Absolute URL of the default CSS file you want to enqueue.
+ * @return string
+ */
+function update_prism_css_url( $url ) {
+	return plugins_url( 'prism.css', __FILE__ );
+}
+
+/**
+ * Render the php shortcode using the Code Syntax Block syntax.
+ *
+ * @param array|string $attr    Shortcode attributes array or empty string.
+ * @param string       $content Shortcode content.
+ * @param string       $tag     Shortcode name.
+ * @return string
+ */
+function do_shortcode_php( $attr, $content, $tag ) {
+	$attr = is_array( $attr ) ? $attr : array();
+	$attr['lang'] = 'php';
+
+	return do_shortcode_code( $attr, $content, $tag );
+}
+
+/**
+ * Render the js shortcode using the Code Syntax Block syntax.
+ *
+ * @param array|string $attr    Shortcode attributes array or empty string.
+ * @param string       $content Shortcode content.
+ * @param string       $tag     Shortcode name.
+ * @return string
+ */
+function do_shortcode_js( $attr, $content, $tag ) {
+	$attr = is_array( $attr ) ? $attr : array();
+	$attr['lang'] = 'js';
+
+	return do_shortcode_code( $attr, $content, $tag );
+}
+
+/**
+ * Render the css shortcode using the Code Syntax Block syntax.
+ *
+ * @param array|string $attr    Shortcode attributes array or empty string.
+ * @param string       $content Shortcode content.
+ * @param string       $tag     Shortcode name.
+ * @return string
+ */
+function do_shortcode_css( $attr, $content, $tag ) {
+	$attr = is_array( $attr ) ? $attr : array();
+	$attr['lang'] = 'css';
+
+	return do_shortcode_code( $attr, $content, $tag );
+}
+
+/**
+ * Render the code shortcode using the Code Syntax Block syntax.
+ *
+ * @param array|string $attr    Shortcode attributes array or empty string.
+ * @param string       $content Shortcode content.
+ * @param string       $tag     Shortcode name.
+ * @return string
+ */
+function do_shortcode_code( $attr, $content, $tag ) {
+	// Use an allowedlist of languages, falling back to PHP.
+	// This should account for all languages used in the handbooks.
+	$lang_list = [ 'js', 'json', 'sh', 'bash', 'html', 'css', 'scss', 'php', 'markdown', 'yaml' ];
+	$lang = in_array( $attr['lang'] ?? '', $lang_list ) ? $attr['lang'] ?? '' : 'php';
+
+	$content = _trim_code( $content );
+	// Hides numbers if <= 4 lines of code (last line has no linebreak).
+	$show_line_numbers = substr_count( $content, "\n" ) > 3;
+
+	// Shell is flagged with `sh` or `bash` in the handbooks, but Prism uses `shell`.
+	if ( 'sh' === $lang || 'bash' === $lang ) {
+		$lang = 'shell';
+	}
+
+	return do_blocks(
+		sprintf(
+			'<!-- wp:code {"lineNumbers":%3$s} --><pre class="wp-block-code"><code lang="%1$s" class="language-%1$s %4$s">%2$s</code></pre><!-- /wp:code -->',
+			$lang,
+			$content,
+			$show_line_numbers ? 'true' : 'false',
+			$show_line_numbers ? 'line-numbers' : ''
+		)
+	);
+}
+
+/**
+ * Trim off any extra space, including initial new lines.
+ * Strip out <br /> and <p> added by WordPress.
+ *
+ * @param string $content Shortcode content.
+ * @return string
+ */
+function _trim_code( $content ) {
+	$content = preg_replace( '/<br \/>/', '', $content );
+	$content = preg_replace( '/<\/p>\s*<p>/', "\n\n", $content );
+	// Trim everything except leading spaces.
+	$content = trim( $content, "\n\r\t\v\x00" );
+	return $content;
+}