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<?php

namespace Pelago\Emogrifier;

use
Pelago\Emogrifier\HtmlProcessor\AbstractHtmlProcessor;
use
Pelago\Emogrifier\Utilities\CssConcatenator;
use
Symfony\Component\CssSelector\CssSelectorConverter;
use
Symfony\Component\CssSelector\Exception\SyntaxErrorException;

/**
 * This class provides functions for converting CSS styles into inline style attributes in your HTML code.
 *
 * For Emogrifier 3.0.0, this will be the successor to the \Pelago\Emogrifier class (which then will be deprecated).
 *
 * For more information, please see the README.md file.
 *
 * @author Cameron Brooks
 * @author Jaime Prado
 * @author Oliver Klee <github@oliverklee.de>
 * @author Roman Ožana <ozana@omdesign.cz>
 * @author Sander Kruger <s.kruger@invessel.com>
 * @author Zoli Szabó <zoli.szabo+github@gmail.com>
 */
class CssInliner extends AbstractHtmlProcessor
{
   
/**
     * @var int
     */
   
const CACHE_KEY_CSS = 0;

   
/**
     * @var int
     */
   
const CACHE_KEY_SELECTOR = 1;

   
/**
     * @var int
     */
   
const CACHE_KEY_CSS_DECLARATIONS_BLOCK = 2;

   
/**
     * @var int
     */
   
const CACHE_KEY_COMBINED_STYLES = 3;

   
/**
     * Regular expression component matching a static pseudo class in a selector, without the preceding ":",
     * for which the applicable elements can be determined (by converting the selector to an XPath expression).
     * (Contains alternation without a group and is intended to be placed within a capturing, non-capturing or lookahead
     * group, as appropriate for the usage context.)
     *
     * @var string
     */
   
const PSEUDO_CLASS_MATCHER
       
= 'empty|(?:first|last|nth(?:-last)?+|only)-child|(?:first|last|nth(?:-last)?+)-of-type|not\\([[:ascii:]]*\\)';

   
/**
     * @var bool[]
     */
   
private $excludedSelectors = [];

   
/**
     * @var bool[]
     */
   
private $allowedMediaTypes = ['all' => true, 'screen' => true, 'print' => true];

   
/**
     * @var mixed[]
     */
   
private $caches = [
       
self::CACHE_KEY_CSS => [],
       
self::CACHE_KEY_SELECTOR => [],
       
self::CACHE_KEY_CSS_DECLARATIONS_BLOCK => [],
       
self::CACHE_KEY_COMBINED_STYLES => [],
    ];

   
/**
     * @var CssSelectorConverter
     */
   
private $cssSelectorConverter = null;

   
/**
     * the visited nodes with the XPath paths as array keys
     *
     * @var \DOMElement[]
     */
   
private $visitedNodes = [];

   
/**
     * 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 string[][]
     */
   
private $styleAttributesForNodes = [];

   
/**
     * 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;

   
/**
     * For calculating selector precedence order.
     * Keys are a regular expression part to match before a CSS name.
     * Values are a multiplier factor per match to weight specificity.
     *
     * @var int[]
     */
   
private $selectorPrecedenceMatchers = [
       
// IDs: worth 10000
       
'\\#' => 10000,
       
// classes, attributes, pseudo-classes (not pseudo-elements) except `:not`: worth 100
       
'(?:\\.|\\[|(?<!:):(?!not\\())' => 100,
       
// elements (not attribute values or `:not`), pseudo-elements: worth 1
       
'(?:(?<![="\':\\w\\-])|::)' => 1,
    ];

   
/**
     * array of data describing CSS rules which apply to the document but cannot be inlined, in the format returned by
     * `parseCssRules`
     *
     * @var string[][]
     */
   
private $matchingUninlinableCssRules = null;

   
/**
     * Emogrifier will throw Exceptions when it encounters an error instead of silently ignoring them.
     *
     * @var bool
     */
   
private $debug = false;

   
/**
     * Inlines the given CSS into the existing HTML.
     *
     * @param string $css the CSS to inline, must be UTF-8-encoded
     *
     * @return self fluent interface
     *
     * @throws SyntaxErrorException
     */
   
public function inlineCss($css = '')
    {
       
$this->clearAllCaches();
       
$this->purgeVisitedNodes();

       
$this->normalizeStyleAttributesOfAllNodes();

       
$combinedCss = $css;
       
// 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)
       
if ($this->isStyleBlocksParsingEnabled) {
           
$combinedCss .= $this->getCssFromAllStyleNodes();
        }

       
$cssWithoutComments = $this->removeCssComments($combinedCss);
        list(
$cssWithoutCommentsCharsetOrImport, $cssImportRules)
            =
$this->extractImportAndCharsetRules($cssWithoutComments);

       
$excludedNodes = $this->getNodesToExclude();
       
$cssRules = $this->parseCssRules($cssWithoutCommentsCharsetOrImport);
       
$cssSelectorConverter = $this->getCssSelectorConverter();
        foreach (
$cssRules['inlinable'] as $cssRule) {
            try {
               
$nodesMatchingCssSelectors = $this->xPath->query($cssSelectorConverter->toXPath($cssRule['selector']));
            } catch (
SyntaxErrorException $e) {
                if (
$this->debug) {
                    throw
$e;
                }
                continue;
            }

           
/** @var \DOMElement $node */
           
foreach ($nodesMatchingCssSelectors as $node) {
                if (\
in_array($node, $excludedNodes, true)) {
                    continue;
                }
               
$this->copyInlinableCssToStyleAttribute($node, $cssRule);
            }
        }

        if (
$this->isInlineStyleAttributesParsingEnabled) {
           
$this->fillStyleAttributesWithMergedStyles();
        }

       
$this->removeImportantAnnotationFromAllInlineStyles();

       
$this->determineMatchingUninlinableCssRules($cssRules['uninlinable']);
       
$this->copyUninlinableCssToStyleNode($cssImportRules);

        return
$this;
    }

   
/**
     * 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;
    }

   
/**
     * 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]);
        }
    }

   
/**
     * Sets the debug mode.
     *
     * @param bool $debug set to true to enable debug mode
     *
     * @return void
     */
   
public function setDebug($debug)
    {
       
$this->debug = $debug;
    }

   
/**
     * Gets the array of selectors present in the CSS provided to `inlineCss()` for which the declarations could not be
     * applied as inline styles, but which may affect elements in the HTML.  The relevant CSS will have been placed in a
     * `<style>` element.  The selectors may include those used within `@media` rules or those involving dynamic
     * pseudo-classes (such as `:hover`) or pseudo-elements (such as `::after`).
     *
     * @return string[]
     *
     * @throws \BadMethodCallException if `inlineCss` has not been called first
     */
   
public function getMatchingUninlinableSelectors()
    {
        if (
$this->matchingUninlinableCssRules === null) {
            throw new \
BadMethodCallException('inlineCss must be called first', 1568385221);
        }

        return \
array_column($this->matchingUninlinableCssRules, 'selector');
    }

   
/**
     * Clears all caches.
     *
     * @return void
     */
   
private function clearAllCaches()
    {
       
$this->caches = [
           
self::CACHE_KEY_CSS => [],
           
self::CACHE_KEY_SELECTOR => [],
           
self::CACHE_KEY_CSS_DECLARATIONS_BLOCK => [],
           
self::CACHE_KEY_COMBINED_STYLES => [],
        ];
    }

   
/**
     * Purges the visited nodes.
     *
     * @return void
     */
   
private function purgeVisitedNodes()
    {
       
$this->visitedNodes = [];
       
$this->styleAttributesForNodes = [];
    }

   
/**
     * Parses the document and normalizes 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 stores a reference of nodes with existing inline styles so we don't overwrite them.
     *
     * @return void
     */
   
private function normalizeStyleAttributesOfAllNodes()
    {
       
/** @var \DOMElement $node */
       
foreach ($this->getAllNodesWithStyleAttribute() as $node) {
            if (
$this->isInlineStyleAttributesParsingEnabled) {
               
$this->normalizeStyleAttributes($node);
            }
           
// Remove style attribute in every case, so we can add them back (if inline style attributes
            // parsing is enabled) to the end of the style list, thus keeping the right priority of CSS rules;
            // else original inline style rules may remain at the beginning of the final inline style definition
            // of a node, which may give not the desired results
           
$node->removeAttribute('style');
        }
    }

   
/**
     * Returns a list with all DOM nodes that have a style attribute.
     *
     * @return \DOMNodeList
     */
   
private function getAllNodesWithStyleAttribute()
    {
        return
$this->xPath->query('//*[@style]');
    }

   
/**
     * 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-zA-Z][\\w\\-]*+(?=:)/S',
            static 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);
    }

   
/**
     * 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 = [];
        foreach (\
preg_split('/;(?!base64|charset)/', $cssDeclarationsBlock) as $declaration) {
           
$matches = [];
            if (!\
preg_match('/^([A-Za-z\\-]+)\\s*:\\s*(.+)$/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;
    }

   
/**
     * Returns CSS content.
     *
     * @return string
     */
   
private function getCssFromAllStyleNodes()
    {
       
$styleNodes = $this->xPath->query('//style');
        if (
$styleNodes === false) {
            return
'';
        }

       
$css = '';
       
/** @var \DOMNode $styleNode */
       
foreach ($styleNodes as $styleNode) {
           
$css .= "\n\n" . $styleNode->nodeValue;
           
$styleNode->parentNode->removeChild($styleNode);
        }

        return
$css;
    }

   
/**
     * Removes comments from the supplied CSS.
     *
     * @param string $css
     *
     * @return string CSS with the comments removed
     */
   
private function removeCssComments($css)
    {
        return \
preg_replace('%/\\*[^*]*+(?:\\*(?!/)[^*]*+)*+\\*/%', '', $css);
    }

   
/**
     * Extracts `@import` and `@charset` rules from the supplied CSS.  These rules must not be preceded by any other
     * rules, or they will be ignored.  (From the CSS 2.1 specification: "CSS 2.1 user agents must ignore any '@import'
     * rule that occurs inside a block or after any non-ignored statement other than an @charset or an @import rule."
     * Note also that `@charset` is case sensitive whereas `@import` is not.)
     *
     * @param string $css CSS with comments removed
     *
     * @return string[] The first element is the CSS with the valid `@import` and `@charset` rules removed.  The second
     * element contains a concatenation of the valid `@import` rules, each followed by whatever whitespace followed it
     * in the original CSS (so that either unminified or minified formatting is preserved); if there were no `@import`
     * rules, it will be an empty string.  The (valid) `@charset` rules are discarded.
     */
   
private function extractImportAndCharsetRules($css)
    {
       
$possiblyModifiedCss = $css;
       
$importRules = '';

        while (
            \
preg_match(
               
'/^\\s*+(@((?i)import(?-i)|charset)\\s[^;]++;\\s*+)/',
               
$possiblyModifiedCss,
               
$matches
           
)
        ) {
            list(
$fullMatch, $atRuleAndFollowingWhitespace, $atRuleName) = $matches;

            if (\
strtolower($atRuleName) === 'import') {
               
$importRules .= $atRuleAndFollowingWhitespace;
            }

           
$possiblyModifiedCss = \substr($possiblyModifiedCss, \strlen($fullMatch));
        }

        return [
$possiblyModifiedCss, $importRules];
    }

   
/**
     * Find the nodes that are not to be emogrified.
     *
     * @return \DOMElement[]
     *
     * @throws SyntaxErrorException
     */
   
private function getNodesToExclude()
    {
       
$excludedNodes = [];
        foreach (\
array_keys($this->excludedSelectors) as $selectorToExclude) {
            try {
               
$matchingNodes = $this->xPath->query($this->getCssSelectorConverter()->toXPath($selectorToExclude));
            } catch (
SyntaxErrorException $e) {
                if (
$this->debug) {
                    throw
$e;
                }
                continue;
            }
            foreach (
$matchingNodes as $node) {
               
$excludedNodes[] = $node;
            }
        }

        return
$excludedNodes;
    }

   
/**
     * @return CssSelectorConverter
     */
   
private function getCssSelectorConverter()
    {
        if (
$this->cssSelectorConverter === null) {
           
$this->cssSelectorConverter = new CssSelectorConverter();
        }

        return
$this->cssSelectorConverter;
    }

   
/**
     * Extracts and parses the individual rules from a CSS string.
     *
     * @param string $css a string of raw CSS code with comments removed
     *
     * @return string[][][] A 2-entry array with the key "inlinable" containing rules which can be inlined as `style`
     *         attributes and the key "uninlinable" containing rules which cannot.  Each value is an array of string
     *         sub-arrays with the keys
     *         "media" (the media query string, e.g. "@media screen and (max-width: 480px)",
     *         or an empty string if not from a `@media` rule),
     *         "selector" (the CSS selector, e.g., "*" or "header h1"),
     *         "hasUnmatchablePseudo" (true if that selector contains pseudo-elements or dynamic pseudo-classes
     *         such that the declarations cannot be applied inline),
     *         "declarationsBlock" (the semicolon-separated CSS declarations for that selector,
     *         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])) {
            return
$this->caches[self::CACHE_KEY_CSS][$cssKey];
        }

       
$matches = $this->getCssRuleMatches($css);

       
$cssRules = [
           
'inlinable' => [],
           
'uninlinable' => [],
        ];
       
/** @var string[][] $matches */
        /** @var string[] $cssRule */
       
foreach ($matches as $key => $cssRule) {
           
$cssDeclaration = \trim($cssRule['declarations']);
            if (
$cssDeclaration === '') {
                continue;
            }

            foreach (\
explode(',', $cssRule['selectors']) as $selector) {
               
// don't process pseudo-elements and behavioral (dynamic) pseudo-classes;
                // only allow structural pseudo-classes
               
$hasPseudoElement = \strpos($selector, '::') !== false;
               
$hasUnsupportedPseudoClass = (bool)\preg_match(
                   
'/:(?!' . self::PSEUDO_CLASS_MATCHER . ')[\\w\\-]/i',
                   
$selector
               
);
               
$hasUnmatchablePseudo = $hasPseudoElement || $hasUnsupportedPseudoClass;

               
$parsedCssRule = [
                   
'media' => $cssRule['media'],
                   
'selector' => \trim($selector),
                   
'hasUnmatchablePseudo' => $hasUnmatchablePseudo,
                   
'declarationsBlock' => $cssDeclaration,
                   
// keep track of where it appears in the file, since order is important
                   
'line' => $key,
                ];
               
$ruleType = ($cssRule['media'] === '' && !$hasUnmatchablePseudo) ? 'inlinable' : 'uninlinable';
               
$cssRules[$ruleType][] = $parsedCssRule;
            }
        }

        \
usort($cssRules['inlinable'], [$this, 'sortBySelectorPrecedence']);

       
$this->caches[self::CACHE_KEY_CSS][$cssKey] = $cssRules;

        return
$cssRules;
    }

   
/**
     * @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])) {
            return
$this->caches[self::CACHE_KEY_SELECTOR][$selectorKey];
        }

       
$precedence = 0;
        foreach (
$this->selectorPrecedenceMatchers as $matcher => $value) {
            if (\
trim($selector) === '') {
                break;
            }
           
$number = 0;
           
$selector = \preg_replace('/' . $matcher . '\\w+/', '', $selector, -1, $number);
           
$precedence += ($value * $number);
        }
       
$this->caches[self::CACHE_KEY_SELECTOR][$selectorKey] = $precedence;

        return
$precedence;
    }

   
/**
     * Parses a string of CSS into the media query, selectors and declarations for each ruleset in order.
     *
     * @param string $css CSS with comments removed
     *
     * @return string[][] Array of string sub-arrays with the keys
     *         "media" (the media query string, e.g. "@media screen and (max-width: 480px)",
     *         or an empty string if not from an `@media` rule),
     *         "selectors" (the CSS selector(s), e.g., "*" or "h1, h2"),
     *         "declarations" (the semicolon-separated CSS declarations for that/those selector(s),
     *         e.g., "color: red; height: 4px;"),
     */
   
private function getCssRuleMatches($css)
    {
       
$splitCss = $this->splitCssAndMediaQuery($css);

       
$ruleMatches = [];
        foreach (
$splitCss as $cssPart) {
           
// process each part for selectors and definitions
           
\preg_match_all('/(?:^|[\\s^{}]*)([^{]+){([^}]*)}/mi', $cssPart['css'], $matches, PREG_SET_ORDER);

           
/** @var string[][] $matches */
           
foreach ($matches as $cssRule) {
               
$ruleMatches[] = [
                   
'media' => $cssPart['media'],
                   
'selectors' => $cssRule[1],
                   
'declarations' => $cssRule[2],
                ];
            }
        }

        return
$ruleMatches;
    }

   
/**
     * Splits input CSS code into an array of parts for different media queries, in order.
     * Each part is an array where:
     *
     * - key "css" will contain clean CSS code (for @media rules this will be the group rule body within "{...}")
     * - key "media" will contain "@media " followed by the media query list, for all allowed media queries,
     *   or an empty string for CSS not within a media query
     *
     * Example:
     *
     * The CSS code
     *
     *   "@import "file.css"; h1 { color:red; } @media { h1 {}} @media tv { h1 {}}"
     *
     * will be parsed into the following array:
     *
     *   0 => [
     *     "css" => "h1 { color:red; }",
     *     "media" => ""
     *   ],
     *   1 => [
     *     "css" => " h1 {}",
     *     "media" => "@media "
     *   ]
     *
     * @param string $css
     *
     * @return string[][]
     */
   
private function splitCssAndMediaQuery($css)
    {
       
$mediaTypesExpression = '';
        if (!empty(
$this->allowedMediaTypes)) {
           
$mediaTypesExpression = '|' . \implode('|', \array_keys($this->allowedMediaTypes));
        }

       
$mediaRuleBodyMatcher = '[^{]*+{(?:[^{}]*+{.*})?\\s*+}\\s*+';

       
$cssSplitForAllowedMediaTypes = \preg_split(
           
'#(@media\\s++(?:only\\s++)?+(?:(?=[{(])' . $mediaTypesExpression . ')' . $mediaRuleBodyMatcher
           
. ')#misU',
           
$css,
            -
1,
           
PREG_SPLIT_DELIM_CAPTURE
       
);

       
// filter the CSS outside/between allowed @media rules
       
$cssCleaningMatchers = [
           
'import/charset directives' => '/\\s*+@(?:import|charset)\\s[^;]++;/i',
           
'remaining media enclosures' => '/\\s*+@media\\s' . $mediaRuleBodyMatcher . '/isU',
        ];

       
$splitCss = [];
        foreach (
$cssSplitForAllowedMediaTypes as $index => $cssPart) {
           
$isMediaRule = $index % 2 !== 0;
            if (
$isMediaRule) {
                \
preg_match('/^([^{]*+){(.*)}[^}]*+$/s', $cssPart, $matches);
               
$splitCss[] = [
                   
'css' => $matches[2],
                   
'media' => $matches[1],
                ];
            } else {
               
$cleanedCss = \trim(\preg_replace($cssCleaningMatchers, '', $cssPart));
                if (
$cleanedCss !== '') {
                   
$splitCss[] = [
                       
'css' => $cleanedCss,
                       
'media' => '',
                    ];
                }
            }
        }
        return
$splitCss;
    }

   
/**
     * Copies $cssRule into the style attribute of $node.
     *
     * Note: This method does not check whether $cssRule matches $node.
     *
     * @param \DOMElement $node
     * @param string[][] $cssRule
     *
     * @return void
     */
   
private function copyInlinableCssToStyleAttribute(\DOMElement $node, array $cssRule)
    {
       
$newStyleDeclarations = $this->parseCssDeclarationsBlock($cssRule['declarationsBlock']);
        if (
$newStyleDeclarations === []) {
            return;
        }

       
// 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 = [];
        }
       
$node->setAttribute(
           
'style',
           
$this->generateStyleStringFromDeclarationsArrays($oldStyleDeclarations, $newStyleDeclarations)
        );
    }

   
/**
     * 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)
    {
       
$cacheKey = \serialize([$oldStyles, $newStyles]);
        if (isset(
$this->caches[self::CACHE_KEY_COMBINED_STYLES][$cacheKey])) {
            return
$this->caches[self::CACHE_KEY_COMBINED_STYLES][$cacheKey];
        }

       
// Unset the overridden styles to preserve order, important if shorthand and individual properties are mixed
       
foreach ($oldStyles as $attributeName => $attributeValue) {
            if (!isset(
$newStyles[$attributeName])) {
                continue;
            }

           
$newAttributeValue = $newStyles[$attributeName];
            if (
               
$this->attributeValueIsImportant($attributeValue)
                && !
$this->attributeValueIsImportant($newAttributeValue)
            ) {
                unset(
$newStyles[$attributeName]);
            } else {
                unset(
$oldStyles[$attributeName]);
            }
        }

       
$combinedStyles = \array_merge($oldStyles, $newStyles);

       
$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;
    }

   
/**
     * Checks whether $attributeValue is marked as !important.
     *
     * @param string $attributeValue
     *
     * @return bool
     */
   
private function attributeValueIsImportant($attributeValue)
    {
        return \
strtolower(\substr(\trim($attributeValue), -10)) === '!important';
    }

   
/**
     * 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
               
)
            );
        }
    }

   
/**
     * Searches for all nodes with a style attribute and removes the "!important" annotations out of
     * the inline style declarations, eventually by rearranging declarations.
     *
     * @return void
     */
   
private function removeImportantAnnotationFromAllInlineStyles()
    {
        foreach (
$this->getAllNodesWithStyleAttribute() as $node) {
           
$this->removeImportantAnnotationFromNodeInlineStyle($node);
        }
    }

   
/**
     * Removes the "!important" annotations out of the inline style declarations,
     * eventually by rearranging declarations.
     * Rearranging needed when !important shorthand properties are followed by some of their
     * not !important expanded-version properties.
     * For example "font: 12px serif !important; font-size: 13px;" must be reordered
     * to "font-size: 13px; font: 12px serif;" in order to remain correct.
     *
     * @param \DOMElement $node
     *
     * @return void
     */
   
private function removeImportantAnnotationFromNodeInlineStyle(\DOMElement $node)
    {
       
$inlineStyleDeclarations = $this->parseCssDeclarationsBlock($node->getAttribute('style'));
       
$regularStyleDeclarations = [];
       
$importantStyleDeclarations = [];
        foreach (
$inlineStyleDeclarations as $property => $value) {
            if (
$this->attributeValueIsImportant($value)) {
               
$importantStyleDeclarations[$property] = \trim(\str_replace('!important', '', $value));
            } else {
               
$regularStyleDeclarations[$property] = $value;
            }
        }
       
$inlineStyleDeclarationsInNewOrder = \array_merge(
           
$regularStyleDeclarations,
           
$importantStyleDeclarations
       
);
       
$node->setAttribute(
           
'style',
           
$this->generateStyleStringFromSingleDeclarationsArray($inlineStyleDeclarationsInNewOrder)
        );
    }

   
/**
     * Generates a CSS style string suitable to be used inline from the $styleDeclarations property => value array.
     *
     * @param string[] $styleDeclarations
     *
     * @return string
     */
   
private function generateStyleStringFromSingleDeclarationsArray(array $styleDeclarations)
    {
        return
$this->generateStyleStringFromDeclarationsArrays([], $styleDeclarations);
    }

   
/**
     * Determines which of `$cssRules` actually apply to `$this->domDocument`, and sets them in
     * `$this->matchingUninlinableCssRules`.
     *
     * @param string[][] $cssRules the "uninlinable" array of CSS rules returned by `parseCssRules`
     *
     * @return void
     */
   
private function determineMatchingUninlinableCssRules(array $cssRules)
    {
       
$this->matchingUninlinableCssRules = \array_filter($cssRules, [$this, 'existsMatchForSelectorInCssRule']);
    }

   
/**
     * Checks whether there is at least one matching element for the CSS selector contained in the `selector` element
     * of the provided CSS rule.
     *
     * Any dynamic pseudo-classes will be assumed to apply. If the selector matches a pseudo-element,
     * it will test for a match with its originating element.
     *
     * @param string[] $cssRule
     *
     * @return bool
     *
     * @throws SyntaxErrorException
     */
   
private function existsMatchForSelectorInCssRule(array $cssRule)
    {
       
$selector = $cssRule['selector'];
        if (
$cssRule['hasUnmatchablePseudo']) {
           
$selector = $this->removeUnmatchablePseudoComponents($selector);
        }
        return
$this->existsMatchForCssSelector($selector);
    }

   
/**
     * Checks whether there is at least one matching element for $cssSelector.
     * When not in debug mode, it returns true also for invalid selectors (because they may be valid,
     * just not implemented/recognized yet by Emogrifier).
     *
     * @param string $cssSelector
     *
     * @return bool
     *
     * @throws SyntaxErrorException
     */
   
private function existsMatchForCssSelector($cssSelector)
    {
        try {
           
$nodesMatchingSelector = $this->xPath->query($this->getCssSelectorConverter()->toXPath($cssSelector));
        } catch (
SyntaxErrorException $e) {
            if (
$this->debug) {
                throw
$e;
            }
            return
true;
        }

        return
$nodesMatchingSelector !== false && $nodesMatchingSelector->length !== 0;
    }

   
/**
     * Removes pseudo-elements and dynamic pseudo-classes from a CSS selector, replacing them with "*" if necessary.
     * If such a pseudo-component is within the argument of `:not`, the entire `:not` component is removed or replaced.
     *
     * @param string $selector
     *
     * @return string Selector which will match the relevant DOM elements if the pseudo-classes are assumed to apply,
     *                or in the case of pseudo-elements will match their originating element.
     */
   
private function removeUnmatchablePseudoComponents($selector)
    {
       
// The regex allows nested brackets via `(?2)`.
        // A space is temporarily prepended because the callback can't determine if the match was at the very start.
       
$selectorWithoutNots = \ltrim(\preg_replace_callback(
           
'/(\\s?+):not(\\([^()]*+(?:(?2)[^()]*+)*+\\))/i',
            [
$this, 'replaceUnmatchableNotComponent'],
           
' ' . $selector
       
));

       
$pseudoComponentMatcher = ':(?!' . self::PSEUDO_CLASS_MATCHER . '):?+[\\w\\-]++(?:\\([^\\)]*+\\))?+';
        return \
preg_replace(
            [
'/(\\s|^)' . $pseudoComponentMatcher . '/i', '/' . $pseudoComponentMatcher . '/i'],
            [
'$1*', ''],
           
$selectorWithoutNots
       
);
    }

   
/**
     * Helps `removeUnmatchablePseudoComponents()` replace or remove a selector `:not(...)` component if its argument
     * contains pseudo-elements or dynamic pseudo-classes.
     *
     * @param string[] $matches array of elements matched by the regular expression
     *
     * @return string the full match if there were no unmatchable pseudo components within; otherwise, any preceding
     *         whitespace followed by "*", or an empty string if there was no preceding whitespace
     */
   
private function replaceUnmatchableNotComponent(array $matches)
    {
        list(
$notComponentWithAnyPrecedingWhitespace, $anyPrecedingWhitespace, $notArgumentInBrackets) = $matches;

       
$hasUnmatchablePseudo = \preg_match(
           
'/:(?!' . self::PSEUDO_CLASS_MATCHER . ')[\\w\\-:]/i',
           
$notArgumentInBrackets
       
);

        if (
$hasUnmatchablePseudo) {
            return
$anyPrecedingWhitespace !== '' ? $anyPrecedingWhitespace . '*' : '';
        }
        return
$notComponentWithAnyPrecedingWhitespace;
    }

   
/**
     * Applies `$this->matchingUninlinableCssRules` to `$this->domDocument` by placing them as CSS in a `<style>`
     * element.
     *
     * @param string $cssImportRules This may contain any `@import` rules that should precede the CSS placed in the
     *        `<style>` element.  If there are no unlinlinable CSS rules to copy there, a `<style>` element will be
     *        created containing just `$cssImportRules`.  `$cssImportRules` may be an empty string; if it is, and there
     *        are no unlinlinable CSS rules, an empty `<style>` element will not be created.
     *
     * @return void
     */
   
private function copyUninlinableCssToStyleNode($cssImportRules)
    {
       
$css = $cssImportRules;

       
// avoid including unneeded class dependency if there are no rules
       
if ($this->matchingUninlinableCssRules !== []) {
           
$cssConcatenator = new CssConcatenator();
            foreach (
$this->matchingUninlinableCssRules as $cssRule) {
               
$cssConcatenator->append([$cssRule['selector']], $cssRule['declarationsBlock'], $cssRule['media']);
            }
           
$css .= $cssConcatenator->getCss();
        }

       
// avoid adding empty style element
       
if ($css !== '') {
           
$this->addStyleElementToDocument($css);
        }
    }

   
/**
     * Adds a style element with $css to $this->domDocument.
     *
     * This method is protected to allow overriding.
     *
     * @see https://github.com/MyIntervals/emogrifier/issues/103
     *
     * @param string $css
     *
     * @return void
     */
   
protected function addStyleElementToDocument($css)
    {
       
$styleElement = $this->domDocument->createElement('style', $css);
       
$styleAttribute = $this->domDocument->createAttribute('type');
       
$styleAttribute->value = 'text/css';
       
$styleElement->appendChild($styleAttribute);

       
$headElement = $this->getHeadElement();
       
$headElement->appendChild($styleElement);
    }

   
/**
     * Returns the HEAD element.
     *
     * This method assumes that there always is a HEAD element.
     *
     * @return \DOMElement
     */
   
private function getHeadElement()
    {
        return
$this->domDocument->getElementsByTagName('head')->item(0);
    }
}