BP_Invitation_Manager::send_invitation_by_id( int $invitation_id )

	public function send_invitation_by_id( $invitation_id = 0 ) {
		$updated = false;

		$invitation = new BP_Invitation( $invitation_id );

		if ( ! $invitation->id ) {
			return false;
		}

		/**
		 * Fires before an invitation is sent.
		 *
		 * @since BuddyBoss 1.3.5
		 *
		 * @param BP_Invitation object $invitation Invitation about to be sent.
		 */
		do_action( 'bp_invitations_send_invitation_by_id_before_send', $invitation );

		/*
		 * Before sending an invitation, check for outstanding requests to the same item.
		 * A sent invitation + a request = acceptance.
		 */
		$request_args = array(
			'user_id'           => $invitation->user_id,
			'invitee_email'     => $invitation->invitee_email,
			'item_id'           => $invitation->item_id,
			'secondary_item_id' => $invitation->secondary_item_id,
		);
		$request = $this->request_exists( $request_args );

		if ( ! empty( $request ) ) {
			// Accept the request.
			return $this->accept_request( $request_args );
		}

		// Perform the send action.
		$this->run_send_action( $invitation );

		$updated = BP_Invitation::mark_sent( $invitation->id );

		return $updated;
	}