Add default option for automatic rules enabled for backwards compat

projects/packages/waf/src/class-compatibility.php

@@ -0,0 +1,55 @@
+<?php
+/**
+ * Class used to manage backwards-compatibility of the package
+ *
+ * @package automattic/jetpack-waf
+ */
+
+namespace Automattic\Jetpack\Waf;
+
+/**
+ * Defines methods for ensuring backwards compatibility.
+ */
+class Waf_Compatibility {
+
+	/**
+	 * Add compatibilty hooks
+	 *
+	 * @since 0.8.0
+	 *
+	 * @return void
+	 */
+	public static function add_compatibility_hooks() {
+		add_filter( 'default_option_' . Waf_Runner::AUTOMATIC_RULES_ENABLED_OPTION_NAME, __CLASS__ . '::default_option_waf_automatic_rules', 10, 3 );
+	}
+
+	/**
+	 * Provides a default value for sites that installed the WAF
+	 * before the automatic rules option was introduced.
+	 *
+	 * @since 0.8.0
+	 *
+	 * @param mixed  $default         The default value to return if the option does not exist in the database.
+	 * @param string $option          Option name.
+	 * @param bool   $passed_default  Was get_option() passed a default value.
+	 *
+	 * @return mixed The default value to return if the option does not exist in the database.
+	 */
+	public static function default_option_waf_automatic_rules( $default, $option, $passed_default ) {
+		// Allow get_option() to override this default value
+		if ( $passed_default ) {
+			return $default;
+		}
+
+		return self::get_default_automatic_rules_option();
+	}
+
+	/**
+	 * If the option is not available, use the WAF module status
+	 * to determine whether or not to run automatic rules
+	 */
+	public static function get_default_automatic_rules_option() {
+		return Waf_Runner::is_enabled();
+	}
+
+}

projects/packages/waf/src/class-waf-initializer.php

@@ -34,6 +34,9 @@ public static function init() {
 		add_action( 'jetpack_activate_module_waf', __CLASS__ . '::on_activation' );
 		add_action( 'jetpack_deactivate_module_waf', __CLASS__ . '::on_deactivation' );
 
+		// Ensure backwards compatibility
+		Waf_Compatibility::add_compatibility_hooks();
+
 		// Run the WAF
 		Waf_Runner::initialize();
 	}