<?php

class VigiloDepends extends VigiloXml

{

    protected $host;

    protected $service;

    public function __construct($host = null, $service = null)

    {

        if (null === $host && null === $service) {

            throw new Exception('Invalid dependency');

        }

        if ('' === $host || '' === $service || !is_string($host) || !is_string($service)) {

            throw new Exception('Invalid dependency');

        }

        $this->host     = $host;

        $this->service  = $service;

    }

    public function __toString()

    {

        if (null === $this->host) {

            return "<depends service=\"{$this->service}\"/>";

        }

        if (null === $this->service) {

            return "<depends host=\"{$this->host}\"/>";

        }

        return "<depends host=\"{$this->host}\" service=\"{$this->service}\"/>";

    }

}