<?php
namespace enshrined\svgSanitize\ElementReference;
use enshrined\svgSanitize\data\XPath;
use enshrined\svgSanitize\Exceptions\NestingException;
use enshrined\svgSanitize\Helper;
class Resolver
{
/**
* @var XPath
*/
protected $xPath;
/**
* @var Subject[]
*/
protected $subjects = [];
/**
* @var array DOMElement[]
*/
protected $elementsToRemove = [];
/**
* @var int
*/
protected $useNestingLimit;
public function __construct(XPath $xPath, $useNestingLimit)
{
$this->xPath = $xPath;
$this->useNestingLimit = $useNestingLimit;
}
public function collect()
{
$this->collectIdentifiedElements();
$this->processReferences();
$this->determineInvalidSubjects();
}
/**
* Resolves one subject by element.
*
* @param \DOMElement $element
* @param bool $considerChildren Whether to search in Subject's children as well
* @return Subject|null
*/
public function findByElement(\DOMElement $element, $considerChildren = false)
{
foreach ($this->subjects as $subject) {
if (
$element === $subject->getElement()
|| $considerChildren && Helper::isElementContainedIn($element, $subject->getElement())
) {
return $subject;
}
}
return null;
}
/**
* Resolves subjects (plural!) by element id - in theory malformed
* DOM might have same ids assigned to different elements and leaving
* it to client/browser implementation which element to actually use.
*
* @param string $elementId
* @return Subject[]
*/
public function findByElementId($elementId)
{
return array_filter(
$this->subjects,
function (Subject $subject) use ($elementId) {
return $elementId === $subject->getElementId();
}
);
}
/**
* Collects elements having `id` attribute (those that can be referenced).
*/
protected function collectIdentifiedElements()
{
/** @var \DOMNodeList|\DOMElement[] $elements */
$elements = $this->xPath->query('//*[@id]');
foreach ($elements as $element) {
$this->subjects[$element->getAttribute('id')] = new Subject($element, $this->useNestingLimit);
}
}
/**
* Processes references from and to elements having `id` attribute concerning
* their occurrence in `<use ... xlink:href="#identifier">` statements.
*/
protected function processReferences()
{
$useNodeName = $this->xPath->createNodeName('use');
foreach ($this->subjects as $subject) {
$useElements = $this->xPath->query(
$useNodeName . '[@href or @xlink:href]',
$subject->getElement()
);
/** @var \DOMElement $useElement */
foreach ($useElements as $useElement) {
$useId = Helper::extractIdReferenceFromHref(
Helper::getElementHref($useElement)
);
if ($useId === null || !isset($this->subjects[$useId])) {
continue;
}
$subject->addUse($this->subjects[$useId]);
$this->subjects[$useId]->addUsedIn($subject);
}
}
}
/**
* Determines and tags infinite loops.
*/
protected function determineInvalidSubjects()
{
foreach ($this->subjects as $subject) {
if (in_array($subject->getElement(), $this->elementsToRemove)) {
continue;
}
$useId = Helper::extractIdReferenceFromHref(
Helper::getElementHref($subject->getElement())
);
try {
if ($useId === $subject->getElementId()) {
$this->markSubjectAsInvalid($subject);
} elseif ($subject->hasInfiniteLoop()) {
$this->markSubjectAsInvalid($subject);
}
} catch (NestingException $e) {
$this->elementsToRemove[] = $e->getElement();
$this->markSubjectAsInvalid($subject);
}
}
}
/**
* Get all the elements that caused a nesting exception.
*
* @return array
*/
public function getElementsToRemove() {
return $this->elementsToRemove;
}
/**
* The Subject is invalid for some reason, therefore we should
* remove it and all it's child usages.
*
* @param Subject $subject
*/
protected function markSubjectAsInvalid(Subject $subject) {
$this->elementsToRemove = array_merge(
$this->elementsToRemove,
$subject->clearInternalAndGetAffectedElements()
);
}
}