BP_Invitation_Manager::accept_invitation( $args = array() )

	 public function accept_invitation( $args = array() ) {

		/*
		 * Some basic info is required to accept an invitation,
		 * because we'll need to mark all similar invitations and requests.
		 * The following, except the optional 'secondary_item_id', are required.
		 */
		$r = bp_parse_args( $args, array(
			'user_id'           => 0,
			'invitee_email'     => '',
			'item_id'           => null,
			'secondary_item_id' => null,
			'invite_sent'       => 'sent',
		), 'accept_invitation' );
		$r['class'] = $this->class_name;

		if ( ! ( ( $r['user_id'] || $r['invitee_email'] ) && $r['class'] && $r['item_id'] ) ) {
			return false;
		}

		if ( ! $this->invitation_exists( $r ) ) {
			return false;
		}

		$success = $this->run_acceptance_action( 'invite', $r );
		if ( $success ) {
			// Mark invitations & requests to this item for this user.
			$this->mark_accepted( $r );

			// Allow plugins an opportunity to act on the change.
			do_action( 'bp_invitations_accepted_invite', $r );
		}
		return $success;
	}