<?php

/*
* This file is part of the Symfony package.
*
* (c) Fabien Potencier <fabien@symfony.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/

namespace Symfony\Component\Process;

use Symfony\Component\Process\Exception\RuntimeException;

/**
* Provides a way to continuously write to the input of a Process until the InputStream is closed.
*
* @author Nicolas Grekas <p@tchwork.com>
*/
class InputStream implements \IteratorAggregate
{
private $onEmpty = null;
private $input = array();
private $open = true;

/**
* Sets a callback that is called when the write buffer becomes empty.
*/
public function onEmpty(callable $onEmpty = null)
{
$this->onEmpty = $onEmpty;
}

/**
* Appends an input to the write buffer.
*
* @param resource|scalar|\Traversable|null The input to append as stream resource, scalar or \Traversable
*/
public function write($input)
{
if (null === $input) {
return;
}
if ($this->isClosed()) {
throw new RuntimeException(sprintf('%s is closed', static::class));
}
$this->input[] = ProcessUtils::validateInput(__METHOD__, $input);
}

/**
* Closes the write buffer.
*/
public function close()
{
$this->open = false;
}

/**
* Tells whether the write buffer is closed or not.
*/
public function isClosed()
{
return !$this->open;
}

public function getIterator()
{
$this->open = true;

while ($this->open || $this->input) {
if (!$this->input) {
yield '';
continue;
}
$current = array_shift($this->input);

if ($current instanceof \Iterator) {
foreach ($current as $cur) {
yield $cur;
}
} else {
yield $current;
}
if (!$this->input && $this->open && null !== $onEmpty = $this->onEmpty) {
$this->write($onEmpty($this));
}
}
}
}