Incorporate logic from contact-form-7-conditional-enqueues.php mini p…

…lugin

* Use template_redirect action rather than wp to prevent accidental admin usage.
* Add version check for CF7.
* Add conditional enqueueing for styles in addition to scripts.
* Override filters for wpcf7_load_js and wpcf7_load_css to return false.
* Prevent re-enqueueing scripts after they have been enqueued.

inc/ThirdParty/Plugins/ContactForm7.php

@@ -4,25 +4,58 @@
 use WP_Rocket\Event_Management\Subscriber_Interface;
 
 class ContactForm7 implements Subscriber_Interface {
+
+	/**
+	 * Required CF6 version.
+	 *
+	 * Version in which the wpcf7_shortcode_callback action was introduced.
+	 *
+	 * @var string
+	 */
+	const REQUIRED_CF7_VERSION = '5.8.1';
+
 	/**
 	 * Subscribed events.
 	 */
 	public static function get_subscribed_events() {
 		return [
-			'wp' => [ 'maybe_optimize_contact_form_7', 10 ],
+			'template_redirect' => [ 'maybe_optimize_contact_form_7', 10 ],
 		];
 	}
 
 	/**
 	 * Optimize ContactForm7 scripts.
-	 *
-	 * @return array
 	 */
 	public function maybe_optimize_contact_form_7() {
-		if ( defined( 'WPCF7_LOAD_JS' ) && WPCF7_LOAD_JS && ! has_action( 'wpcf7_shortcode_callback' ) ) {
-			// Only load the frontend scripts on the new 'wpcf7_shortcode_callback' hook.
-			add_filter( 'wpcf7_load_js', '__return_false' );
-			add_action( 'wpcf7_shortcode_callback', 'wpcf7_enqueue_scripts' );
+		// The wpcf7_shortcode_callback action was added in CF7 version 5.8.1.
+		if ( ! defined( 'WPCF7_VERSION' ) || version_compare( WPCF7_VERSION, self::REQUIRED_CF7_VERSION, '<' ) ) {
+			return;
+		}
+
+		// Force scripts and styles to not load by default.
+		add_filter( 'wpcf7_load_js', '__return_false', PHP_INT_MAX );
+		add_filter( 'wpcf7_load_css', '__return_false', PHP_INT_MAX );
+
+		// Conditionally enqueue scripts
+		add_action( 'wpcf7_shortcode_callback', [ $this, 'conditionally_enqueue_scripts' ] );
+		add_action( 'wpcf7_shortcode_callback',  [ $this, 'conditionally_enqueue_styles' ] );
+	}
+
+	/**
+	 * Enqueue scripts if not already enqueued.
+	 */
+	function conditionally_enqueue_scripts() {
+		if ( ! did_action( 'wpcf7_enqueue_scripts' ) ) { // Prevent double-enqueueing when multiple forms present.
+			wpcf7_enqueue_scripts();
+		}
+	}
+
+	/**
+	 * Enqueue styles if not already enqueued.
+	 */
+	function conditionally_enqueue_styles() {
+		if ( ! did_action( 'wpcf7_enqueue_styles' ) ) { // Prevent double-enqueueing when multiple forms present.
+			wpcf7_enqueue_styles();
 		}
 	}
 }