Refactor GES integration with bbPress.

This is an addendum to commit 681830d.  Instead of using BPMFP's hook, we
use GES' new 'bp_ass_send_activity_notification_for_user' filter available
as of GES v3.6.0.

This is better and paves the way to removing the extend_activity_listener()
method in a future version.

includes/bp-rbe-extend-bbpress.php

@@ -93,8 +93,8 @@ private function custom_hooks() {
 		add_action( 'bbp_new_topic_post_extras',         array( $this, 'clear_global_cache' ) );
 		add_action( 'bbp_new_reply_post_extras',         array( $this, 'clear_global_cache' ) );
 
-		// BPMFP support.
-		add_action( 'bpmfp_before_send', array( $this, 'bpmfp_support' ) );
+		// New GES support.
+		add_filter( 'bp_ass_send_activity_notification_for_user', array( $this, 'ges_support' ), 9999, 2 );
 	}
 
 	/**
@@ -1307,35 +1307,65 @@ public function get_forum_encoded_email_address() {
 	}
 
 	/**
-	 * Add support for the BP Multiple Forum Post plugin.
+	 * Add support for the BP Group Email Subscription plugin.
+	 *
+	 * This is the new way to add support for GES 3.6+.
 	 *
 	 * @since 1.0-RC4
 	 *
-	 * @param BP_Activity_Activity $activity
+	 * @param bool                 $retval   Whether GES should send the current email.
+	 * @param BP_Activity_Activity $activity Activity object GES is using.
 	 */
-	public function bpmfp_support( $activity ) {
-		// Temporarily save activity object so we can reference it in the bpmfp_support() method.
+	public function ges_support( $retval, $activity ) {
+		if ( false === $retval ) {
+			return $retval;
+		}
+
+		/*
+		 * Temporarily save activity object so we can reference it in the
+		 * ges_extend_listener() method.
+		 */
 		$this->temp_activity = $activity;
 
 		// Extend RBE's listener to add RBE support.
-		add_action( 'bp_rbe_extend_listener', array( $this, 'bpmfp_extend_listener' ) );
+		add_action( 'bp_rbe_extend_listener', array( $this, 'ges_extend_listener' ) );
+
+		return $retval;
 	}
 
 	/**
-	 * Register support for BPMFP with RBE.
+	 * Register support for GES with RBE.
 	 *
-	 * Since BPMFP works by delaying email sending to remove duplicate emails
-	 * {@see bpmfp_interrupt_original_activity_notification()}, we must tell RBE
-	 * about this on the 'bp_rbe_extend_listener' hook.
+	 * Since other GES plugins like BP Multiple Forum Post works by delaying GES
+	 * email sending to remove duplicate emails {@see bpmfp_interrupt_original_activity_notification()},
+	 * we need to let RBE's listener know about it.
 	 *
 	 * @since 1.0-RC4
 	 *
 	 * @param BP_Reply_By_Email $rbe
 	 */
-	public function bpmfp_extend_listener( $rbe ) {
+	public function ges_extend_listener( $rbe ) {
+		// We've already done this, so stop!
+		// @todo Remove this once we're ready to drop extend_activity_listener().
+		if ( isset( $rbe->listener ) && $this->id === $rbe->listener->component ) {
+			return;
+		}
+
+		// If activity type does not match our bbPress types, stop now!
+		if ( $this->temp_activity->type != $this->activity_type && $this->temp_activity->type != 'bbp_topic_create' ) {
+			return;
+		}
+
 		$rbe->listener->component         = $this->id;
 		$rbe->listener->item_id           = $this->temp_activity->item_id;
 		$rbe->listener->secondary_item_id = $this->temp_activity->secondary_item_id;
+		$rbe->listener->reply_to_id       = $this->temp_activity->secondary_item_id;
 		$rbe->listener->user_id           = $this->temp_activity->user_id;
+
+		// If activity type is a bbPress reply, we need to grab the topic ID manually.
+		if ( $this->temp_activity->type === $this->activity_type ) {
+			$rbe->listener->secondary_item_id = bbp_get_reply_topic_id( $this->temp_activity->secondary_item_id );
+			$rbe->listener->reply_to_id       = get_post_field( 'post_parent', $this->temp_activity->secondary_item_id );
+		}
 	}
 }