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<?php
/**
*
* This file is part of Aura for PHP.
*
* @license http://opensource.org/licenses/bsd-license.php BSD
*
*/
namespace Aura\Accept;
use ArrayIterator;
use IteratorAggregate;
/**
*
* Represents a collection of `Accept*` header values, sorted in quality order.
*
* @package Aura.Accept
*
*/
abstract class AbstractNegotiator implements IteratorAggregate
{
/**
*
* An array of objects representing acceptable values from the header.
*
* @var array
*
*/
protected $acceptable = array();
/**
*
* The $_SERVER key to use when populating acceptable values.
*
* @var string
*
*/
protected $server_key;
/**
*
* A factory to create value objects.
*
* @var ValueFactory
*
*/
protected $value_factory;
/**
*
* The type of value object to create using the ValueFactory.
*
* @var string
*
*/
protected $value_type;
/**
*
* Constructor.
*
* @param ValueFactory $value_factory A factory for value objects.
*
* @param array $server A copy of $_SERVER for finding acceptable values.
*
*/
public function __construct(
ValueFactory $value_factory,
array $server = array()
) {
$this->value_factory = $value_factory;
if (isset($server[$this->server_key])) {
$this->set($server[$this->server_key]);
}
}
/**
*
* Returns a value object by its sorted quality position.
*
* @param int $key The sorted position.
*
* @return Value\AbstractValue
*
*/
public function get($key = null)
{
if ($key === null) {
return $this->acceptable;
}
return $this->acceptable[$key];
}
/**
*
* Sets the collection to one or more acceptable values, overwriting all
* previous values.
*
* @param string|array $acceptable An `Accept*` string value; e.g.,
* `text/plain;q=0.5,text/html,text/*;q=0.1`.
*
* @return null
*
*/
public function set($acceptable = null)
{
$this->acceptable = array();
$this->add($acceptable);
}
/**
*
* Adds one or more acceptable values to this collection.
*
* @param string|array $acceptable One or more `Accept*` string values;
* e.g., the string `'text/plain;q=0.5,text/html,text/*;q=0.1'` and
* `array('text/plain;q=0.5','text/html','text/*;q=0.1')` are
* equivalent.
*
* @return null
*
* @todo Allow this to take an array so we can parse-and-sort in one pass.
*
*/
public function add($acceptable = null)
{
foreach ((array) $acceptable as $string) {
$this->parse($string);
}
$this->sort();
}
/**
*
* Parses an acceptable string value into the `$acceptable` property.
*
* @param string $string An `Accept*` string value; e.g.,
* `text/plain;q=0.5,text/html,text/*;q=0.1`.
*
* @return array
*
*/
protected function parse($string)
{
$acceptable = explode(',', $string);
foreach ($acceptable as $value) {
$pairs = explode(';', $value);
$value = $pairs[0];
unset($pairs[0]);
$parameters = array();
foreach ($pairs as $pair) {
$param = array();
preg_match(
'/^(?P<name>.+?)=(?P<quoted>"|\')?(?P<value>.*?)(?:\k<quoted>)?$/',
$pair,
$param
);
$parameters[$param['name']] = $param['value'];
}
$quality = 1.0;
if (isset($parameters['q'])) {
$quality = $parameters['q'];
unset($parameters['q']);
}
$this->acceptable[] = $this->value_factory->newInstance(
$this->value_type,
trim($value),
(float) $quality,
$parameters
);
}
}
/**
*
* Sorts the `$acceptable` values according to quality levels.
*
* This is an unusual sort. Normally we'd think a reverse-sort would
* order the array by q values from 1 to 0, but the problem is that
* an implicit 1.0 on more than one value means that those values will
* be reverse from what the header specifies, which seems unexpected
* when negotiating later.
*
*/
protected function sort()
{
// q-value buckets
$bucket = array();
// sort into q-value buckets
foreach ($this->acceptable as $value) {
$bucket[(string)$value->getQuality()][] = $value;
}
// reverse-sort the buckets so that q=1 is first and q=0 is last,
// but the values in the buckets stay in the original order.
krsort($bucket);
// flatten the buckets back into the acceptable array
$this->acceptable = array();
foreach ($bucket as $q => $acceptable) {
foreach ($acceptable as $value) {
$this->acceptable[] = $value;
}
}
}
/**
*
* IteratorInterface: returns the iterator for this object.
*
* @return ArrayIterator
*
*/
public function getIterator()
{
return new ArrayIterator($this->acceptable);
}
/**
*
* Negotiates between acceptable and available values. On success, the
* return value is a plain old PHP object with the matching negotiated
* `$acceptable` and `$available` value objects; these are to be inspected
* by the calling code.
*
* @param array $available Available values in preference order, if any.
*
* @return mixed A plain-old PHP object with negotiated `$acceptable` and
* `$available` value objects on success, or false on failure.
*
*/
public function negotiate(array $available = null)
{
// if none available, no possible match
if (! $available) {
return false;
}
// convert to object
$clone = clone $this;
$clone->set($available);
$available = $clone;
// if nothing acceptable specified, use first available
if (! $this->acceptable) {
return (object) array(
'acceptable' => false,
'available' => $available->get(0),
);
}
// loop through acceptable values
foreach ($this->acceptable as $accept) {
// if the acceptable quality is zero, skip it
if ($accept->getQuality() == 0) {
continue;
}
// if acceptable value is "anything" return the first available
if ($accept->isWildcard()) {
return (object) array(
'acceptable' => $accept,
'available' => $available->get(0),
);
}
// if acceptable value is available, use it
foreach ($available as $avail) {
if ($accept->match($avail)) {
return (object) array(
'acceptable' => $accept,
'available' => $avail,
);
}
}
}
return false;
}
}
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