SKZH
/
ITSSTOOLS


			
				
					
						
						
							123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219220221222223224225226227228229230231232233234235236237238239240241242243244245246247248249250251252253254255256257258259260261262263264265266267268269270271272273274275276277278279280281282283284285286287288289290291292293294295296297298299300301302303304305306307308309310311312313314315316317318319320321322323324325326327328329330331332333334335336337338339340341342343344345346347348349350351352353354355356357358359360361362363364365366367368369370371372373374375376377378379380381382383384385386387388389390391392393394395396397398399400401402403404405406407408409410411412413414415416417418419420421422423424425426427428429430431432433434435436437438439440441442443444445446447448449450451452453454455456457458459460461462463464465466467468469470471472473474475476477478479480481482483484485486487488489490491492493494495496497498499500501502503504505506507508509510511512513514515516517518519520521522523524525526527528529530531532533534535536537538539540541542543544545546547548549550551552553554555556557558559560561562563564565566567568569570571572573574575576577578579580581582583584585586587588589590591592593594595596597598599600601602603604605606607608609610611612613614615616617618619620621622623624625626627628629630631632633634635636637638639640641642643644645646647648649650651652653654655656657658659660661662663664665666667668669670671672673674675676677678679680681682683684685686687688689690691692693694695696697698699700701702703704705706707708709710711712713714715716717718719720721722723724725726727728729730731732733734735736737738739740741742743744745746747748749750751752753754755756757758759760761762763764765766767768769770771772773774775776777778779780781782783784785786787788789790791792793794795796797798799800801802803804805806807808809810811812813814815816817818819820821822823824825826827828829830831832833834835836837838839840841842843844845846847848849850851852853854855856857858859860861862863864865866867868869870871872873874875876877878879880881882883884885886887888889890891892893894895896897898899900901902903904905906907908909910911912913914915916917918919920921922923924925926927928929930931932933934935936937938939940941942943944945946947948949950951952953954955956957958959960961962963964965966967968969970971972973974975976977978979980981982983984985986987988989990991992993994995996997998999100010011002100310041005100610071008100910101011101210131014101510161017101810191020
							<?php
namespace Pelago;

/**
 * This class provides functions for converting CSS styles into inline style attributes in your HTML code.
 *
 * For more information, please see the README.md file.
 *
 * @version 1.0.0
 *
 * @author Cameron Brooks
 * @author Jaime Prado
 * @author Oliver Klee <typo3-coding@oliverklee.de>
 * @author Roman Ožana <ozana@omdesign.cz>
 */
class Emogrifier
{
    /**
     * @var int
     */
    const CACHE_KEY_CSS = 0;
    /**
     * @var int
     */
    const CACHE_KEY_SELECTOR = 1;
    /**
     * @var int
     */
    const CACHE_KEY_XPATH = 2;
    /**
     * @var int
     */
    const CACHE_KEY_CSS_DECLARATIONS_BLOCK = 3;
    /**
     * @var int
     */
    const CACHE_KEY_COMBINED_STYLES = 4;
    /**
     * for calculating nth-of-type and nth-child selectors
     *
     * @var int
     */
    const INDEX = 0;
    /**
     * for calculating nth-of-type and nth-child selectors
     *
     * @var int
     */
    const MULTIPLIER = 1;
    /**
     * @var string
     */
    const ID_ATTRIBUTE_MATCHER = '/(\\w+)?\\#([\\w\\-]+)/';
    /**
     * @var string
     */
    const CLASS_ATTRIBUTE_MATCHER = '/(\\w+|[\\*\\]])?((\\.[\\w\\-]+)+)/';
    /**
     * @var string
     */
    const CONTENT_TYPE_META_TAG = '<meta http-equiv="Content-Type" content="text/html; charset=utf-8">';
    /**
     * @var string
     */
    const DEFAULT_DOCUMENT_TYPE = '<!DOCTYPE html>';
    /**
     * @var string
     */
    private $html = '';
    /**
     * @var string
     */
    private $css = '';
    /**
     * @var bool[]
     */
    private $excludedSelectors = array();
    /**
     * @var string[]
     */
    private $unprocessableHtmlTags = array('wbr');
    /**
     * @var bool[]
     */
    private $allowedMediaTypes = array('all' => true, 'screen' => true, 'print' => true);
    /**
     * @var array[]
     */
    private $caches = array(self::CACHE_KEY_CSS => array(), self::CACHE_KEY_SELECTOR => array(), self::CACHE_KEY_XPATH => array(), self::CACHE_KEY_CSS_DECLARATIONS_BLOCK => array(), self::CACHE_KEY_COMBINED_STYLES => array());
    /**
     * the visited nodes with the XPath paths as array keys
     *
     * @var \DOMElement[]
     */
    private $visitedNodes = array();
    /**
     * the styles to apply to the nodes with the XPath paths as array keys for the outer array
     * and the attribute names/values as key/value pairs for the inner array
     *
     * @var array[]
     */
    private $styleAttributesForNodes = array();
    /**
     * Determines whether the "style" attributes of tags in the the HTML passed to this class should be preserved.
     * If set to false, the value of the style attributes will be discarded.
     *
     * @var bool
     */
    private $isInlineStyleAttributesParsingEnabled = true;
    /**
     * Determines whether the <style> blocks in the HTML passed to this class should be parsed.
     *
     * If set to true, the <style> blocks will be removed from the HTML and their contents will be applied to the HTML
     * via inline styles.
     *
     * If set to false, the <style> blocks will be left as they are in the HTML.
     *
     * @var bool
     */
    private $isStyleBlocksParsingEnabled = true;
    /**
     * Determines whether elements with the `display: none` property are
     * removed from the DOM.
     *
     * @var bool
     */
    private $shouldKeepInvisibleNodes = true;
    /**
     * The constructor.
     *
     * @param string $html the HTML to emogrify, must be UTF-8-encoded
     * @param string $css the CSS to merge, must be UTF-8-encoded
     */
    public function __construct($html = '', $css = '')
    {
        $this->setHtml($html);
        $this->setCss($css);
    }
    /**
     * The destructor.
     */
    public function __destruct()
    {
        $this->purgeVisitedNodes();
    }
    /**
     * Sets the HTML to emogrify.
     *
     * @param string $html the HTML to emogrify, must be UTF-8-encoded
     *
     * @return void
     */
    public function setHtml($html)
    {
        $this->html = $html;
    }
    /**
     * Sets the CSS to merge with the HTML.
     *
     * @param string $css the CSS to merge, must be UTF-8-encoded
     *
     * @return void
     */
    public function setCss($css)
    {
        $this->css = $css;
    }
    /**
     * Applies $this->css to $this->html and returns the HTML with the CSS
     * applied.
     *
     * This method places the CSS inline.
     *
     * @return string
     *
     * @throws \BadMethodCallException
     */
    public function emogrify()
    {
        if ($this->html === '') {
            throw new \BadMethodCallException('Please set some HTML first before calling emogrify.', 1390393096);
        }
        $xmlDocument = $this->createXmlDocument();
        $this->process($xmlDocument);
        return $xmlDocument->saveHTML();
    }
    /**
     * Applies $this->css to $this->html and returns only the HTML content
     * within the <body> tag.
     *
     * This method places the CSS inline.
     *
     * @return string
     *
     * @throws \BadMethodCallException
     */
    public function emogrifyBodyContent()
    {
        if ($this->html === '') {
            throw new \BadMethodCallException('Please set some HTML first before calling emogrify.', 1390393096);
        }
        $xmlDocument = $this->createXmlDocument();
        $this->process($xmlDocument);
        $innerDocument = new \DOMDocument();
        foreach ($xmlDocument->documentElement->getElementsByTagName('body')->item(0)->childNodes as $childNode) {
            $innerDocument->appendChild($innerDocument->importNode($childNode, true));
        }
        return $innerDocument->saveHTML();
    }
    /**
     * Applies $this->css to $xmlDocument.
     *
     * This method places the CSS inline.
     *
     * @param \DOMDocument $xmlDocument
     *
     * @return void
     */
    protected function process(\DOMDocument $xmlDocument)
    {
        $xpath = new \DOMXPath($xmlDocument);
        $this->clearAllCaches();
        // Before be begin processing the CSS file, parse the document and normalize all existing CSS attributes.
        // This changes 'DISPLAY: none' to 'display: none'.
        // We wouldn't have to do this if DOMXPath supported XPath 2.0.
        // Also store a reference of nodes with existing inline styles so we don't overwrite them.
        $this->purgeVisitedNodes();
        $nodesWithStyleAttributes = $xpath->query('//*[@style]');
        if ($nodesWithStyleAttributes !== false) {
            /** @var \DOMElement $node */
            foreach ($nodesWithStyleAttributes as $node) {
                if ($this->isInlineStyleAttributesParsingEnabled) {
                    $this->normalizeStyleAttributes($node);
                } else {
                    $node->removeAttribute('style');
                }
            }
        }
        // grab any existing style blocks from the html and append them to the existing CSS
        // (these blocks should be appended so as to have precedence over conflicting styles in the existing CSS)
        $allCss = $this->css;
        if ($this->isStyleBlocksParsingEnabled) {
            $allCss .= $this->getCssFromAllStyleNodes($xpath);
        }
        $cssParts = $this->splitCssAndMediaQuery($allCss);
        $excludedNodes = $this->getNodesToExclude($xpath);
        $cssRules = $this->parseCssRules($cssParts['css']);
        foreach ($cssRules as $cssRule) {
            // query the body for the xpath selector
            $nodesMatchingCssSelectors = $xpath->query($this->translateCssToXpath($cssRule['selector']));
            // ignore invalid selectors
            if ($nodesMatchingCssSelectors === false) {
                continue;
            }
            /** @var \DOMElement $node */
            foreach ($nodesMatchingCssSelectors as $node) {
                if (in_array($node, $excludedNodes, true)) {
                    continue;
                }
                // if it has a style attribute, get it, process it, and append (overwrite) new stuff
                if ($node->hasAttribute('style')) {
                    // break it up into an associative array
                    $oldStyleDeclarations = $this->parseCssDeclarationsBlock($node->getAttribute('style'));
                } else {
                    $oldStyleDeclarations = array();
                }
                $newStyleDeclarations = $this->parseCssDeclarationsBlock($cssRule['declarationsBlock']);
                $node->setAttribute('style', $this->generateStyleStringFromDeclarationsArrays($oldStyleDeclarations, $newStyleDeclarations));
            }
        }
        if ($this->isInlineStyleAttributesParsingEnabled) {
            $this->fillStyleAttributesWithMergedStyles();
        }
        if ($this->shouldKeepInvisibleNodes) {
            $this->removeInvisibleNodes($xpath);
        }
        $this->copyCssWithMediaToStyleNode($xmlDocument, $xpath, $cssParts['media']);
    }
    /**
     * Extracts and parses the individual rules from a CSS string.
     *
     * @param string $css a string of raw CSS code
     *
     * @return string[][] an array of string sub-arrays with the keys
     *         "selector" (the CSS selector(s), e.g., "*" or "h1"),
     *         "declarationsBLock" (the semicolon-separated CSS declarations for that selector(s),
     *         e.g., "color: red; height: 4px;"),
     *         and "line" (the line number e.g. 42)
     */
    private function parseCssRules($css)
    {
        $cssKey = md5($css);
        if (!isset($this->caches[self::CACHE_KEY_CSS][$cssKey])) {
            // process the CSS file for selectors and definitions
            preg_match_all('/(?:^|[\\s^{}]*)([^{]+){([^}]*)}/mis', $css, $matches, PREG_SET_ORDER);
            $cssRules = array();
            /** @var string[] $cssRule */
            foreach ($matches as $key => $cssRule) {
                $cssDeclaration = trim($cssRule[2]);
                if ($cssDeclaration === '') {
                    continue;
                }
                $selectors = explode(',', $cssRule[1]);
                foreach ($selectors as $selector) {
                    // don't process pseudo-elements and behavioral (dynamic) pseudo-classes;
                    // only allow structural pseudo-classes
                    if (strpos($selector, ':') !== false && !preg_match('/:\\S+\\-(child|type\\()/i', $selector)) {
                        continue;
                    }
                    $cssRules[] = array('selector' => trim($selector), 'declarationsBlock' => $cssDeclaration, 'line' => $key);
                }
            }
            usort($cssRules, array($this, 'sortBySelectorPrecedence'));
            $this->caches[self::CACHE_KEY_CSS][$cssKey] = $cssRules;
        }
        return $this->caches[self::CACHE_KEY_CSS][$cssKey];
    }
    /**
     * Disables the parsing of inline styles.
     *
     * @return void
     */
    public function disableInlineStyleAttributesParsing()
    {
        $this->isInlineStyleAttributesParsingEnabled = false;
    }
    /**
     * Disables the parsing of <style> blocks.
     *
     * @return void
     */
    public function disableStyleBlocksParsing()
    {
        $this->isStyleBlocksParsingEnabled = false;
    }
    /**
     * Disables the removal of elements with `display: none` properties.
     *
     * @return void
     */
    public function disableInvisibleNodeRemoval()
    {
        $this->shouldKeepInvisibleNodes = false;
    }
    /**
     * Clears all caches.
     *
     * @return void
     */
    private function clearAllCaches()
    {
        $this->clearCache(self::CACHE_KEY_CSS);
        $this->clearCache(self::CACHE_KEY_SELECTOR);
        $this->clearCache(self::CACHE_KEY_XPATH);
        $this->clearCache(self::CACHE_KEY_CSS_DECLARATIONS_BLOCK);
        $this->clearCache(self::CACHE_KEY_COMBINED_STYLES);
    }
    /**
     * Clears a single cache by key.
     *
     * @param int $key the cache key, must be CACHE_KEY_CSS, CACHE_KEY_SELECTOR, CACHE_KEY_XPATH
     *                 or CACHE_KEY_CSS_DECLARATION_BLOCK
     *
     * @return void
     *
     * @throws \InvalidArgumentException
     */
    private function clearCache($key)
    {
        $allowedCacheKeys = array(self::CACHE_KEY_CSS, self::CACHE_KEY_SELECTOR, self::CACHE_KEY_XPATH, self::CACHE_KEY_CSS_DECLARATIONS_BLOCK, self::CACHE_KEY_COMBINED_STYLES);
        if (!in_array($key, $allowedCacheKeys, true)) {
            throw new \InvalidArgumentException('Invalid cache key: ' . $key, 1391822035);
        }
        $this->caches[$key] = array();
    }
    /**
     * Purges the visited nodes.
     *
     * @return void
     */
    private function purgeVisitedNodes()
    {
        $this->visitedNodes = array();
        $this->styleAttributesForNodes = array();
    }
    /**
     * Marks a tag for removal.
     *
     * There are some HTML tags that DOMDocument cannot process, and it will throw an error if it encounters them.
     * In particular, DOMDocument will complain if you try to use HTML5 tags in an XHTML document.
     *
     * Note: The tags will not be removed if they have any content.
     *
     * @param string $tagName the tag name, e.g., "p"
     *
     * @return void
     */
    public function addUnprocessableHtmlTag($tagName)
    {
        $this->unprocessableHtmlTags[] = $tagName;
    }
    /**
     * Drops a tag from the removal list.
     *
     * @param string $tagName the tag name, e.g., "p"
     *
     * @return void
     */
    public function removeUnprocessableHtmlTag($tagName)
    {
        $key = array_search($tagName, $this->unprocessableHtmlTags, true);
        if ($key !== false) {
            unset($this->unprocessableHtmlTags[$key]);
        }
    }
    /**
     * Marks a media query type to keep.
     *
     * @param string $mediaName the media type name, e.g., "braille"
     *
     * @return void
     */
    public function addAllowedMediaType($mediaName)
    {
        $this->allowedMediaTypes[$mediaName] = true;
    }
    /**
     * Drops a media query type from the allowed list.
     *
     * @param string $mediaName the tag name, e.g., "braille"
     *
     * @return void
     */
    public function removeAllowedMediaType($mediaName)
    {
        if (isset($this->allowedMediaTypes[$mediaName])) {
            unset($this->allowedMediaTypes[$mediaName]);
        }
    }
    /**
     * Adds a selector to exclude nodes from emogrification.
     *
     * Any nodes that match the selector will not have their style altered.
     *
     * @param string $selector the selector to exclude, e.g., ".editor"
     *
     * @return void
     */
    public function addExcludedSelector($selector)
    {
        $this->excludedSelectors[$selector] = true;
    }
    /**
     * No longer excludes the nodes matching this selector from emogrification.
     *
     * @param string $selector the selector to no longer exclude, e.g., ".editor"
     *
     * @return void
     */
    public function removeExcludedSelector($selector)
    {
        if (isset($this->excludedSelectors[$selector])) {
            unset($this->excludedSelectors[$selector]);
        }
    }
    /**
     * This removes styles from your email that contain display:none.
     * We need to look for display:none, but we need to do a case-insensitive search. Since DOMDocument only
     * supports XPath 1.0, lower-case() isn't available to us. We've thus far only set attributes to lowercase,
     * not attribute values. Consequently, we need to translate() the letters that would be in 'NONE' ("NOE")
     * to lowercase.
     *
     * @param \DOMXPath $xpath
     *
     * @return void
     */
    private function removeInvisibleNodes(\DOMXPath $xpath)
    {
        $nodesWithStyleDisplayNone = $xpath->query('//*[contains(translate(translate(@style," ",""),"NOE","noe"),"display:none")]');
        if ($nodesWithStyleDisplayNone->length === 0) {
            return;
        }
        // The checks on parentNode and is_callable below ensure that if we've deleted the parent node,
        // we don't try to call removeChild on a nonexistent child node
        /** @var \DOMNode $node */
        foreach ($nodesWithStyleDisplayNone as $node) {
            if ($node->parentNode && is_callable(array($node->parentNode, 'removeChild'))) {
                $node->parentNode->removeChild($node);
            }
        }
    }
    /**
     * Normalizes the value of the "style" attribute and saves it.
     *
     * @param \DOMElement $node
     *
     * @return void
     */
    private function normalizeStyleAttributes(\DOMElement $node)
    {
        $normalizedOriginalStyle = preg_replace_callback('/[A-z\\-]+(?=\\:)/S', function (array $m) {
            return strtolower($m[0]);
        }, $node->getAttribute('style'));
        // in order to not overwrite existing style attributes in the HTML, we
        // have to save the original HTML styles
        $nodePath = $node->getNodePath();
        if (!isset($this->styleAttributesForNodes[$nodePath])) {
            $this->styleAttributesForNodes[$nodePath] = $this->parseCssDeclarationsBlock($normalizedOriginalStyle);
            $this->visitedNodes[$nodePath] = $node;
        }
        $node->setAttribute('style', $normalizedOriginalStyle);
    }
    /**
     * Merges styles from styles attributes and style nodes and applies them to the attribute nodes
     *
     * @return void
     */
    private function fillStyleAttributesWithMergedStyles()
    {
        foreach ($this->styleAttributesForNodes as $nodePath => $styleAttributesForNode) {
            $node = $this->visitedNodes[$nodePath];
            $currentStyleAttributes = $this->parseCssDeclarationsBlock($node->getAttribute('style'));
            $node->setAttribute('style', $this->generateStyleStringFromDeclarationsArrays($currentStyleAttributes, $styleAttributesForNode));
        }
    }
    /**
     * This method merges old or existing name/value array with new name/value array
     * and then generates a string of the combined style suitable for placing inline.
     * This becomes the single point for CSS string generation allowing for consistent
     * CSS output no matter where the CSS originally came from.
     *
     * @param string[] $oldStyles
     * @param string[] $newStyles
     *
     * @return string
     */
    private function generateStyleStringFromDeclarationsArrays(array $oldStyles, array $newStyles)
    {
        $combinedStyles = array_merge($oldStyles, $newStyles);
        $cacheKey = serialize($combinedStyles);
        if (isset($this->caches[self::CACHE_KEY_COMBINED_STYLES][$cacheKey])) {
            return $this->caches[self::CACHE_KEY_COMBINED_STYLES][$cacheKey];
        }
        foreach ($oldStyles as $attributeName => $attributeValue) {
            if (isset($newStyles[$attributeName]) && strtolower(substr($attributeValue, -10)) === '!important') {
                $combinedStyles[$attributeName] = $attributeValue;
            }
        }
        $style = '';
        foreach ($combinedStyles as $attributeName => $attributeValue) {
            $style .= strtolower(trim($attributeName)) . ': ' . trim($attributeValue) . '; ';
        }
        $trimmedStyle = rtrim($style);
        $this->caches[self::CACHE_KEY_COMBINED_STYLES][$cacheKey] = $trimmedStyle;
        return $trimmedStyle;
    }
    /**
     * Applies $css to $xmlDocument, limited to the media queries that actually apply to the document.
     *
     * @param \DOMDocument $xmlDocument the document to match against
     * @param \DOMXPath $xpath
     * @param string $css a string of CSS
     *
     * @return void
     */
    private function copyCssWithMediaToStyleNode(\DOMDocument $xmlDocument, \DOMXPath $xpath, $css)
    {
        if ($css === '') {
            return;
        }
        $mediaQueriesRelevantForDocument = array();
        foreach ($this->extractMediaQueriesFromCss($css) as $mediaQuery) {
            foreach ($this->parseCssRules($mediaQuery['css']) as $selector) {
                if ($this->existsMatchForCssSelector($xpath, $selector['selector'])) {
                    $mediaQueriesRelevantForDocument[] = $mediaQuery['query'];
                    break;
                }
            }
        }
        $this->addStyleElementToDocument($xmlDocument, implode($mediaQueriesRelevantForDocument));
    }
    /**
     * Extracts the media queries from $css.
     *
     * @param string $css
     *
     * @return string[][] numeric array with string sub-arrays with the keys "css" and "query"
     */
    private function extractMediaQueriesFromCss($css)
    {
        preg_match_all('#(?<query>@media[^{]*\\{(?<css>(.*?)\\})(\\s*)\\})#s', $css, $mediaQueries);
        $result = array();
        foreach (array_keys($mediaQueries['css']) as $key) {
            $result[] = array('css' => $mediaQueries['css'][$key], 'query' => $mediaQueries['query'][$key]);
        }
        return $result;
    }
    /**
     * Checks whether there is at least one matching element for $cssSelector.
     *
     * @param \DOMXPath $xpath
     * @param string $cssSelector
     *
     * @return bool
     */
    private function existsMatchForCssSelector(\DOMXPath $xpath, $cssSelector)
    {
        $nodesMatchingSelector = $xpath->query($this->translateCssToXpath($cssSelector));
        return $nodesMatchingSelector !== false && $nodesMatchingSelector->length !== 0;
    }
    /**
     * Returns CSS content.
     *
     * @param \DOMXPath $xpath
     *
     * @return string
     */
    private function getCssFromAllStyleNodes(\DOMXPath $xpath)
    {
        $styleNodes = $xpath->query('//style');
        if ($styleNodes === false) {
            return '';
        }
        $css = '';
        /** @var \DOMNode $styleNode */
        foreach ($styleNodes as $styleNode) {
            $css .= '

' . $styleNode->nodeValue;
            $styleNode->parentNode->removeChild($styleNode);
        }
        return $css;
    }
    /**
     * Adds a style element with $css to $document.
     *
     * This method is protected to allow overriding.
     *
     * @see https://github.com/jjriv/emogrifier/issues/103
     *
     * @param \DOMDocument $document
     * @param string $css
     *
     * @return void
     */
    protected function addStyleElementToDocument(\DOMDocument $document, $css)
    {
        $styleElement = $document->createElement('style', $css);
        $styleAttribute = $document->createAttribute('type');
        $styleAttribute->value = 'text/css';
        $styleElement->appendChild($styleAttribute);
        $head = $this->getOrCreateHeadElement($document);
        $head->appendChild($styleElement);
    }
    /**
     * Returns the existing or creates a new head element in $document.
     *
     * @param \DOMDocument $document
     *
     * @return \DOMNode the head element
     */
    private function getOrCreateHeadElement(\DOMDocument $document)
    {
        $head = $document->getElementsByTagName('head')->item(0);
        if ($head === null) {
            $head = $document->createElement('head');
            $html = $document->getElementsByTagName('html')->item(0);
            $html->insertBefore($head, $document->getElementsByTagName('body')->item(0));
        }
        return $head;
    }
    /**
     * Splits input CSS code to an array where:
     *
     * - key "css" will be contains clean CSS code
     * - key "media" will be contains all valuable media queries
     *
     * Example:
     *
     * The CSS code
     *
     *   "@import "file.css"; h1 { color:red; } @media { h1 {}} @media tv { h1 {}}"
     *
     * will be parsed into the following array:
     *
     *   "css" => "h1 { color:red; }"
     *   "media" => "@media { h1 {}}"
     *
     * @param string $css
     *
     * @return string[]
     */
    private function splitCssAndMediaQuery($css)
    {
        $cssWithoutComments = preg_replace('/\\/\\*.*\\*\\//sU', '', $css);
        $mediaTypesExpression = '';
        if (!empty($this->allowedMediaTypes)) {
            $mediaTypesExpression = '|' . implode('|', array_keys($this->allowedMediaTypes));
        }
        $media = '';
        $cssForAllowedMediaTypes = preg_replace_callback('#@media\\s+(?:only\\s)?(?:[\\s{\\(]' . $mediaTypesExpression . ')\\s?[^{]+{.*}\\s*}\\s*#misU', function ($matches) use(&$media) {
            $media .= $matches[0];
        }, $cssWithoutComments);
        // filter the CSS
        $search = array('import directives' => '/^\\s*@import\\s[^;]+;/misU', 'remaining media enclosures' => '/^\\s*@media\\s[^{]+{(.*)}\\s*}\\s/misU');
        $cleanedCss = preg_replace($search, '', $cssForAllowedMediaTypes);
        return array('css' => $cleanedCss, 'media' => $media);
    }
    /**
     * Creates a DOMDocument instance with the current HTML.
     *
     * @return \DOMDocument
     */
    private function createXmlDocument()
    {
        $xmlDocument = new \DOMDocument();
        $xmlDocument->encoding = 'UTF-8';
        $xmlDocument->strictErrorChecking = false;
        $xmlDocument->formatOutput = true;
        $libXmlState = libxml_use_internal_errors(true);
        $xmlDocument->loadHTML($this->getUnifiedHtml());
        libxml_clear_errors();
        libxml_use_internal_errors($libXmlState);
        $xmlDocument->normalizeDocument();
        return $xmlDocument;
    }
    /**
     * Returns the HTML with the unprocessable HTML tags removed and
     * with added document type and Content-Type meta tag if needed.
     *
     * @return string the unified HTML
     *
     * @throws \BadMethodCallException
     */
    private function getUnifiedHtml()
    {
        $htmlWithoutUnprocessableTags = $this->removeUnprocessableTags($this->html);
        $htmlWithDocumentType = $this->ensureDocumentType($htmlWithoutUnprocessableTags);
        return $this->addContentTypeMetaTag($htmlWithDocumentType);
    }
    /**
     * Removes the unprocessable tags from $html (if this feature is enabled).
     *
     * @param string $html
     *
     * @return string the reworked HTML with the unprocessable tags removed
     */
    private function removeUnprocessableTags($html)
    {
        if (empty($this->unprocessableHtmlTags)) {
            return $html;
        }
        $unprocessableHtmlTags = implode('|', $this->unprocessableHtmlTags);
        return preg_replace('/<\\/?(' . $unprocessableHtmlTags . ')[^>]*>/i', '', $html);
    }
    /**
     * Makes sure that the passed HTML has a document type.
     *
     * @param string $html
     *
     * @return string HTML with document type
     */
    private function ensureDocumentType($html)
    {
        $hasDocumentType = stripos($html, '<!DOCTYPE') !== false;
        if ($hasDocumentType) {
            return $html;
        }
        return self::DEFAULT_DOCUMENT_TYPE . $html;
    }
    /**
     * Adds a Content-Type meta tag for the charset.
     *
     * @param string $html
     *
     * @return string the HTML with the meta tag added
     */
    private function addContentTypeMetaTag($html)
    {
        $hasContentTypeMetaTag = stristr($html, 'Content-Type') !== false;
        if ($hasContentTypeMetaTag) {
            return $html;
        }
        // We are trying to insert the meta tag to the right spot in the DOM.
        // If we just prepended it to the HTML, we would lose attributes set to the HTML tag.
        $hasHeadTag = stripos($html, '<head') !== false;
        $hasHtmlTag = stripos($html, '<html') !== false;
        if ($hasHeadTag) {
            $reworkedHtml = preg_replace('/<head(.*?)>/i', '<head$1>' . self::CONTENT_TYPE_META_TAG, $html);
        } elseif ($hasHtmlTag) {
            $reworkedHtml = preg_replace('/<html(.*?)>/i', '<html$1><head>' . self::CONTENT_TYPE_META_TAG . '</head>', $html);
        } else {
            $reworkedHtml = self::CONTENT_TYPE_META_TAG . $html;
        }
        return $reworkedHtml;
    }
    /**
     * @param string[] $a
     * @param string[] $b
     *
     * @return int
     */
    private function sortBySelectorPrecedence(array $a, array $b)
    {
        $precedenceA = $this->getCssSelectorPrecedence($a['selector']);
        $precedenceB = $this->getCssSelectorPrecedence($b['selector']);
        // We want these sorted in ascending order so selectors with lesser precedence get processed first and
        // selectors with greater precedence get sorted last.
        $precedenceForEquals = $a['line'] < $b['line'] ? -1 : 1;
        $precedenceForNotEquals = $precedenceA < $precedenceB ? -1 : 1;
        return $precedenceA === $precedenceB ? $precedenceForEquals : $precedenceForNotEquals;
    }
    /**
     * @param string $selector
     *
     * @return int
     */
    private function getCssSelectorPrecedence($selector)
    {
        $selectorKey = md5($selector);
        if (!isset($this->caches[self::CACHE_KEY_SELECTOR][$selectorKey])) {
            $precedence = 0;
            $value = 100;
            // ids: worth 100, classes: worth 10, elements: worth 1
            $search = array('\\#', '\\.', '');
            foreach ($search as $s) {
                if (trim($selector) === '') {
                    break;
                }
                $number = 0;
                $selector = preg_replace('/' . $s . '\\w+/', '', $selector, -1, $number);
                $precedence += $value * $number;
                $value /= 10;
            }
            $this->caches[self::CACHE_KEY_SELECTOR][$selectorKey] = $precedence;
        }
        return $this->caches[self::CACHE_KEY_SELECTOR][$selectorKey];
    }
    /**
     * Maps a CSS selector to an XPath query string.
     *
     * @see http://plasmasturm.org/log/444/
     *
     * @param string $cssSelector a CSS selector
     *
     * @return string the corresponding XPath selector
     */
    private function translateCssToXpath($cssSelector)
    {
        $paddedSelector = ' ' . $cssSelector . ' ';
        $lowercasePaddedSelector = preg_replace_callback('/\\s+\\w+\\s+/', function (array $matches) {
            return strtolower($matches[0]);
        }, $paddedSelector);
        $trimmedLowercaseSelector = trim($lowercasePaddedSelector);
        $xpathKey = md5($trimmedLowercaseSelector);
        if (!isset($this->caches[self::CACHE_KEY_XPATH][$xpathKey])) {
            $cssSelectorMatches = array('child' => '/\\s+>\\s+/', 'adjacent sibling' => '/\\s+\\+\\s+/', 'descendant' => '/\\s+/', ':first-child' => '/([^\\/]+):first-child/i', ':last-child' => '/([^\\/]+):last-child/i', 'attribute only' => '/^\\[(\\w+|\\w+\\=[\'"]?\\w+[\'"]?)\\]/', 'attribute' => '/(\\w)\\[(\\w+)\\]/', 'exact attribute' => '/(\\w)\\[(\\w+)\\=[\'"]?(\\w+)[\'"]?\\]/');
            $xPathReplacements = array('child' => '/', 'adjacent sibling' => '/following-sibling::*[1]/self::', 'descendant' => '//', ':first-child' => '\\1/*[1]', ':last-child' => '\\1/*[last()]', 'attribute only' => '*[@\\1]', 'attribute' => '\\1[@\\2]', 'exact attribute' => '\\1[@\\2="\\3"]');
            $roughXpath = '//' . preg_replace($cssSelectorMatches, $xPathReplacements, $trimmedLowercaseSelector);
            $xpathWithIdAttributeMatchers = preg_replace_callback(self::ID_ATTRIBUTE_MATCHER, array($this, 'matchIdAttributes'), $roughXpath);
            $xpathWithIdAttributeAndClassMatchers = preg_replace_callback(self::CLASS_ATTRIBUTE_MATCHER, array($this, 'matchClassAttributes'), $xpathWithIdAttributeMatchers);
            // Advanced selectors are going to require a bit more advanced emogrification.
            // When we required PHP 5.3, we could do this with closures.
            $xpathWithIdAttributeAndClassMatchers = preg_replace_callback('/([^\\/]+):nth-child\\(\\s*(odd|even|[+\\-]?\\d|[+\\-]?\\d?n(\\s*[+\\-]\\s*\\d)?)\\s*\\)/i', array($this, 'translateNthChild'), $xpathWithIdAttributeAndClassMatchers);
            $finalXpath = preg_replace_callback('/([^\\/]+):nth-of-type\\(\\s*(odd|even|[+\\-]?\\d|[+\\-]?\\d?n(\\s*[+\\-]\\s*\\d)?)\\s*\\)/i', array($this, 'translateNthOfType'), $xpathWithIdAttributeAndClassMatchers);
            $this->caches[self::CACHE_KEY_SELECTOR][$xpathKey] = $finalXpath;
        }
        return $this->caches[self::CACHE_KEY_SELECTOR][$xpathKey];
    }
    /**
     * @param string[] $match
     *
     * @return string
     */
    private function matchIdAttributes(array $match)
    {
        return ($match[1] !== '' ? $match[1] : '*') . '[@id="' . $match[2] . '"]';
    }
    /**
     * @param string[] $match
     *
     * @return string
     */
    private function matchClassAttributes(array $match)
    {
        return ($match[1] !== '' ? $match[1] : '*') . '[contains(concat(" ",@class," "),concat(" ","' . implode('"," "))][contains(concat(" ",@class," "),concat(" ","', explode('.', substr($match[2], 1))) . '"," "))]';
    }
    /**
     * @param string[] $match
     *
     * @return string
     */
    private function translateNthChild(array $match)
    {
        $parseResult = $this->parseNth($match);
        if (isset($parseResult[self::MULTIPLIER])) {
            if ($parseResult[self::MULTIPLIER] < 0) {
                $parseResult[self::MULTIPLIER] = abs($parseResult[self::MULTIPLIER]);
                $xPathExpression = sprintf('*[(last() - position()) mod %u = %u]/self::%s', $parseResult[self::MULTIPLIER], $parseResult[self::INDEX], $match[1]);
            } else {
                $xPathExpression = sprintf('*[position() mod %u = %u]/self::%s', $parseResult[self::MULTIPLIER], $parseResult[self::INDEX], $match[1]);
            }
        } else {
            $xPathExpression = sprintf('*[%u]/self::%s', $parseResult[self::INDEX], $match[1]);
        }
        return $xPathExpression;
    }
    /**
     * @param string[] $match
     *
     * @return string
     */
    private function translateNthOfType(array $match)
    {
        $parseResult = $this->parseNth($match);
        if (isset($parseResult[self::MULTIPLIER])) {
            if ($parseResult[self::MULTIPLIER] < 0) {
                $parseResult[self::MULTIPLIER] = abs($parseResult[self::MULTIPLIER]);
                $xPathExpression = sprintf('%s[(last() - position()) mod %u = %u]', $match[1], $parseResult[self::MULTIPLIER], $parseResult[self::INDEX]);
            } else {
                $xPathExpression = sprintf('%s[position() mod %u = %u]', $match[1], $parseResult[self::MULTIPLIER], $parseResult[self::INDEX]);
            }
        } else {
            $xPathExpression = sprintf('%s[%u]', $match[1], $parseResult[self::INDEX]);
        }
        return $xPathExpression;
    }
    /**
     * @param string[] $match
     *
     * @return int[]
     */
    private function parseNth(array $match)
    {
        if (in_array(strtolower($match[2]), array('even', 'odd'), true)) {
            // we have "even" or "odd"
            $index = strtolower($match[2]) === 'even' ? 0 : 1;
            return array(self::MULTIPLIER => 2, self::INDEX => $index);
        }
        if (stripos($match[2], 'n') === false) {
            // if there is a multiplier
            $index = (int) str_replace(' ', '', $match[2]);
            return array(self::INDEX => $index);
        }
        if (isset($match[3])) {
            $multipleTerm = str_replace($match[3], '', $match[2]);
            $index = (int) str_replace(' ', '', $match[3]);
        } else {
            $multipleTerm = $match[2];
            $index = 0;
        }
        $multiplier = str_ireplace('n', '', $multipleTerm);
        if ($multiplier === '') {
            $multiplier = 1;
        } elseif ($multiplier === '0') {
            return array(self::INDEX => $index);
        } else {
            $multiplier = (int) $multiplier;
        }
        while ($index < 0) {
            $index += abs($multiplier);
        }
        return array(self::MULTIPLIER => $multiplier, self::INDEX => $index);
    }
    /**
     * Parses a CSS declaration block into property name/value pairs.
     *
     * Example:
     *
     * The declaration block
     *
     *   "color: #000; font-weight: bold;"
     *
     * will be parsed into the following array:
     *
     *   "color" => "#000"
     *   "font-weight" => "bold"
     *
     * @param string $cssDeclarationsBlock the CSS declarations block without the curly braces, may be empty
     *
     * @return string[]
     *         the CSS declarations with the property names as array keys and the property values as array values
     */
    private function parseCssDeclarationsBlock($cssDeclarationsBlock)
    {
        if (isset($this->caches[self::CACHE_KEY_CSS_DECLARATIONS_BLOCK][$cssDeclarationsBlock])) {
            return $this->caches[self::CACHE_KEY_CSS_DECLARATIONS_BLOCK][$cssDeclarationsBlock];
        }
        $properties = array();
        $declarations = preg_split('/;(?!base64|charset)/', $cssDeclarationsBlock);
        foreach ($declarations as $declaration) {
            $matches = array();
            if (!preg_match('/^([A-Za-z\\-]+)\\s*:\\s*(.+)$/', trim($declaration), $matches)) {
                continue;
            }
            $propertyName = strtolower($matches[1]);
            $propertyValue = $matches[2];
            $properties[$propertyName] = $propertyValue;
        }
        $this->caches[self::CACHE_KEY_CSS_DECLARATIONS_BLOCK][$cssDeclarationsBlock] = $properties;
        return $properties;
    }
    /**
     * Find the nodes that are not to be emogrified.
     *
     * @param \DOMXPath $xpath
     *
     * @return \DOMElement[]
     */
    private function getNodesToExclude(\DOMXPath $xpath)
    {
        $excludedNodes = array();
        foreach (array_keys($this->excludedSelectors) as $selectorToExclude) {
            foreach ($xpath->query($this->translateCssToXpath($selectorToExclude)) as $node) {
                $excludedNodes[] = $node;
            }
        }
        return $excludedNodes;
    }
}