class InvalidRegexPatternRule

class InvalidRegexPatternRule implements Rule {
    public function getNodeType() : string {
        return StaticCall::class;
    }
    public function processNode(Node $node, Scope $scope) : array {
        $patterns = $this->extractPatterns($node, $scope);
        $errors = [];
        foreach ($patterns as $pattern) {
            $errorMessage = $this->validatePattern($pattern);
            if ($errorMessage === null) {
                continue;
            }
            $errors[] = RuleErrorBuilder::message(sprintf('Regex pattern is invalid: %s', $errorMessage))->identifier('regexp.pattern')
                ->build();
        }
        return $errors;
    }
    
    /**
     * @return string[]
     */
    private function extractPatterns(StaticCall $node, Scope $scope) : array {
        if (!$node->class instanceof FullyQualified) {
            return [];
        }
        $isRegex = $node->class
            ->toString() === Regex::class;
        $isPreg = $node->class
            ->toString() === Preg::class;
        if (!$isRegex && !$isPreg) {
            return [];
        }
        if (!$node->name instanceof Node\Identifier || !Preg::isMatch('{^(match|isMatch|grep|replace|split)}', $node->name->name)) {
            return [];
        }
        $functionName = $node->name->name;
        if (!isset($node->getArgs()[0])) {
            return [];
        }
        $patternNode = $node->getArgs()[0]->value;
        $patternType = $scope->getType($patternNode);
        $patternStrings = [];
        foreach ($patternType->getConstantStrings() as $constantStringType) {
            if ($functionName === 'replaceCallbackArray') {
                continue;
            }
            $patternStrings[] = $constantStringType->getValue();
        }
        foreach ($patternType->getConstantArrays() as $constantArrayType) {
            if (in_array($functionName, [
                'replace',
                'replaceCallback',
            ], true)) {
                foreach ($constantArrayType->getValueTypes() as $arrayKeyType) {
                    foreach ($arrayKeyType->getConstantStrings() as $constantString) {
                        $patternStrings[] = $constantString->getValue();
                    }
                }
            }
            if ($functionName !== 'replaceCallbackArray') {
                continue;
            }
            foreach ($constantArrayType->getKeyTypes() as $arrayKeyType) {
                foreach ($arrayKeyType->getConstantStrings() as $constantString) {
                    $patternStrings[] = $constantString->getValue();
                }
            }
        }
        return $patternStrings;
    }
    private function validatePattern(string $pattern) : ?string {
        try {
            $msg = null;
            $prev = set_error_handler(function (int $severity, string $message, string $file) use (&$msg) : bool {
                $msg = preg_replace("#^preg_match(_all)?\\(.*?\\): #", '', $message);
                return true;
            });
            if ($pattern === '') {
                return 'Empty string is not a valid regular expression';
            }
            Preg::match($pattern, '');
            if ($msg !== null) {
                return $msg;
            }
        } catch (PcreException $e) {
            if ($e->getCode() === PREG_INTERNAL_ERROR && $msg !== null) {
                return $msg;
            }
            return preg_replace('{.*? failed executing ".*": }', '', $e->getMessage());
        } finally {
            restore_error_handler();
        }
        return null;
    }

}