class NodeExtension

class NodeExtension extends AbstractExtension {
    public const ELEMENT_NAME_IN_LOWER_CASE = 1;
    public const ATTRIBUTE_NAME_IN_LOWER_CASE = 2;
    public const ATTRIBUTE_VALUE_IN_LOWER_CASE = 4;
    public function __construct(int $flags = 0) {
    }
    
    /**
     * @return $this
     */
    public function setFlag(int $flag, bool $on) : static {
        if ($on && !$this->hasFlag($flag)) {
            $this->flags += $flag;
        }
        if (!$on && $this->hasFlag($flag)) {
            $this->flags -= $flag;
        }
        return $this;
    }
    public function hasFlag(int $flag) : bool {
        return (bool) ($this->flags & $flag);
    }
    public function getNodeTranslators() : array {
        return [
            'Selector' => $this->translateSelector(...),
            'CombinedSelector' => $this->translateCombinedSelector(...),
            'Negation' => $this->translateNegation(...),
            'Matching' => $this->translateMatching(...),
            'SpecificityAdjustment' => $this->translateSpecificityAdjustment(...),
            'Function' => $this->translateFunction(...),
            'Pseudo' => $this->translatePseudo(...),
            'Attribute' => $this->translateAttribute(...),
            'Class' => $this->translateClass(...),
            'Hash' => $this->translateHash(...),
            'Element' => $this->translateElement(...),
        ];
    }
    public function translateSelector(Node\SelectorNode $node, Translator $translator) : XPathExpr {
        return $translator->nodeToXPath($node->getTree());
    }
    public function translateCombinedSelector(Node\CombinedSelectorNode $node, Translator $translator) : XPathExpr {
        return $translator->addCombination($node->getCombinator(), $node->getSelector(), $node->getSubSelector());
    }
    public function translateNegation(Node\NegationNode $node, Translator $translator) : XPathExpr {
        $xpath = $translator->nodeToXPath($node->getSelector());
        $subXpath = $translator->nodeToXPath($node->getSubSelector());
        $subXpath->addNameTest();
        if ($subXpath->getCondition()) {
            return $xpath->addCondition(\sprintf('not(%s)', $subXpath->getCondition()));
        }
        return $xpath->addCondition('0');
    }
    public function translateMatching(Node\MatchingNode $node, Translator $translator) : XPathExpr {
        $xpath = $translator->nodeToXPath($node->selector);
        foreach ($node->arguments as $argument) {
            $expr = $translator->nodeToXPath($argument);
            $expr->addNameTest();
            if ($condition = $expr->getCondition()) {
                $xpath->addCondition($condition, 'or');
            }
        }
        return $xpath;
    }
    public function translateSpecificityAdjustment(Node\SpecificityAdjustmentNode $node, Translator $translator) : XPathExpr {
        $xpath = $translator->nodeToXPath($node->selector);
        foreach ($node->arguments as $argument) {
            $expr = $translator->nodeToXPath($argument);
            $expr->addNameTest();
            if ($condition = $expr->getCondition()) {
                $xpath->addCondition($condition, 'or');
            }
        }
        return $xpath;
    }
    public function translateFunction(Node\FunctionNode $node, Translator $translator) : XPathExpr {
        $xpath = $translator->nodeToXPath($node->getSelector());
        return $translator->addFunction($xpath, $node);
    }
    public function translatePseudo(Node\PseudoNode $node, Translator $translator) : XPathExpr {
        $xpath = $translator->nodeToXPath($node->getSelector());
        return $translator->addPseudoClass($xpath, $node->getIdentifier());
    }
    public function translateAttribute(Node\AttributeNode $node, Translator $translator) : XPathExpr {
        $name = $node->getAttribute();
        $safe = $this->isSafeName($name);
        if ($this->hasFlag(self::ATTRIBUTE_NAME_IN_LOWER_CASE)) {
            $name = strtolower($name);
        }
        if ($node->getNamespace()) {
            $name = \sprintf('%s:%s', $node->getNamespace(), $name);
            $safe = $safe && $this->isSafeName($node->getNamespace());
        }
        $attribute = $safe ? '@' . $name : \sprintf('attribute::*[name() = %s]', Translator::getXpathLiteral($name));
        $value = $node->getValue();
        $xpath = $translator->nodeToXPath($node->getSelector());
        if ($this->hasFlag(self::ATTRIBUTE_VALUE_IN_LOWER_CASE)) {
            $value = strtolower($value);
        }
        return $translator->addAttributeMatching($xpath, $node->getOperator(), $attribute, $value);
    }
    public function translateClass(Node\ClassNode $node, Translator $translator) : XPathExpr {
        $xpath = $translator->nodeToXPath($node->getSelector());
        return $translator->addAttributeMatching($xpath, '~=', '@class', $node->getName());
    }
    public function translateHash(Node\HashNode $node, Translator $translator) : XPathExpr {
        $xpath = $translator->nodeToXPath($node->getSelector());
        return $translator->addAttributeMatching($xpath, '=', '@id', $node->getId());
    }
    public function translateElement(Node\ElementNode $node) : XPathExpr {
        $element = $node->getElement();
        if ($element && $this->hasFlag(self::ELEMENT_NAME_IN_LOWER_CASE)) {
            $element = strtolower($element);
        }
        if ($element) {
            $safe = $this->isSafeName($element);
        }
        else {
            $element = '*';
            $safe = true;
        }
        if ($node->getNamespace()) {
            $element = \sprintf('%s:%s', $node->getNamespace(), $element);
            $safe = $safe && $this->isSafeName($node->getNamespace());
        }
        $xpath = new XPathExpr('', $element);
        if (!$safe) {
            $xpath->addNameTest();
        }
        return $xpath;
    }
    public function getName() : string {
        return 'node';
    }
    private function isSafeName(string $name) : bool {
        return 0 < preg_match('~^[a-zA-Z_][a-zA-Z0-9_.-]*$~', $name);
    }

}