bp_activity_get_permalink( int $activity_id, object|bool $activity_obj = false )

function bp_activity_get_permalink( $activity_id, $activity_obj = false ) {
	$bp = buddypress();

	if ( empty( $activity_obj ) ) {
		$activity_obj = new BP_Activity_Activity( $activity_id );
	}

	if ( isset( $activity_obj->current_comment ) ) {
		$activity_obj = $activity_obj->current_comment;
	}

	$use_primary_links = array(
		'new_blog_post',
		'new_blog_comment',
		'new_forum_topic',
		'new_forum_post',
	);

	if ( ! empty( $bp->activity->track ) ) {
		$use_primary_links = array_merge( $use_primary_links, array_keys( $bp->activity->track ) );
	}

	if ( false !== array_search( $activity_obj->type, $use_primary_links ) ) {
		$link = $activity_obj->primary_link;
	} else {
		if ( 'activity_comment' == $activity_obj->type ) {
			$link = bp_get_root_domain() . '/' . bp_get_activity_root_slug() . '/p/' . $activity_obj->item_id . '/#acomment-' . $activity_obj->id;
		} else {
			$link = bp_get_root_domain() . '/' . bp_get_activity_root_slug() . '/p/' . $activity_obj->id . '/';
		}
	}

	/**
	 * Filters the activity permalink for the specified activity item.
	 *
	 * @since BuddyPress 1.2.0
	 *
	 * @param array $array Array holding activity permalink and activity item object.
	 */
	return apply_filters_ref_array( 'bp_activity_get_permalink', array( $link, &$activity_obj ) );
}