<?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier <fabien@symfony.com>
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\Routing;

/**
 * RouteCompiler compiles Route instances to CompiledRoute instances.
 *
 * @author Fabien Potencier <fabien@symfony.com>
 * @author Tobias Schultze <http://tobion.de>
 */
class RouteCompiler implements RouteCompilerInterface
{
    /**
     * This string defines the characters that are automatically considered separators in front of
     * optional placeholders (with default and no static text following). Such a single separator
     * can be left out together with the optional placeholder from matching and generating URLs.
     */
    public const SEPARATORS = '/,;.:-_~+*=@|';

    /**
     * The maximum supported length of a PCRE subpattern name
     * http://pcre.org/current/doc/html/pcre2pattern.html#SEC16.
     *
     * @internal
     */
    public const VARIABLE_MAXIMUM_LENGTH = 32;

    /**
     * {@inheritdoc}
     *
     * @throws \InvalidArgumentException if a path variable is named _fragment
     * @throws \LogicException           if a variable is referenced more than once
     * @throws \DomainException          if a variable name starts with a digit or if it is too long to be successfully used as
     *                                   a PCRE subpattern
     */
    public static function compile(Route $route): CompiledRoute
    {
        $hostVariables = [];
        $variables = [];
        $hostRegex = null;
        $hostTokens = [];

        if ('' !== $host = $route->getHost()) {
            $result = self::compilePattern($route, $host, true);

            $hostVariables = $result['variables'];
            $variables = $hostVariables;

            $hostTokens = $result['tokens'];
            $hostRegex = $result['regex'];
        }

        $locale = $route->getDefault('_locale');
        if (null !== $locale && null !== $route->getDefault('_canonical_route') && preg_quote($locale) === $route->getRequirement('_locale')) {
            $requirements = $route->getRequirements();
            unset($requirements['_locale']);
            $route->setRequirements($requirements);
            $route->setPath(str_replace('{_locale}', $locale, $route->getPath()));
        }

        $path = $route->getPath();

        $result = self::compilePattern($route, $path, false);

        $staticPrefix = $result['staticPrefix'];

        $pathVariables = $result['variables'];

        foreach ($pathVariables as $pathParam) {
            if ('_fragment' === $pathParam) {
                throw new \InvalidArgumentException(sprintf('Route pattern "%s" cannot contain "_fragment" as a path parameter.', $route->getPath()));
            }
        }

        $variables = array_merge($variables, $pathVariables);

        $tokens = $result['tokens'];
        $regex = $result['regex'];

        return new CompiledRoute(
            $staticPrefix,
            $regex,
            $tokens,
            $pathVariables,
            $hostRegex,
            $hostTokens,
            $hostVariables,
            array_unique($variables)
        );
    }

    private static function compilePattern(Route $route, string $pattern, bool $isHost): array
    {
        $tokens = [];
        $variables = [];
        $matches = [];
        $pos = 0;
        $defaultSeparator = $isHost ? '.' : '/';
        $useUtf8 = preg_match('//u', $pattern);
        $needsUtf8 = $route->getOption('utf8');

        if (!$needsUtf8 && $useUtf8 && preg_match('/[\x80-\xFF]/', $pattern)) {
            throw new \LogicException(sprintf('Cannot use UTF-8 route patterns without setting the "utf8" option for route "%s".', $route->getPath()));
        }
        if (!$useUtf8 && $needsUtf8) {
            throw new \LogicException(sprintf('Cannot mix UTF-8 requirements with non-UTF-8 pattern "%s".', $pattern));
        }

        // Match all variables enclosed in "{}" and iterate over them. But we only want to match the innermost variable
        // in case of nested "{}", e.g. {foo{bar}}. This in ensured because \w does not match "{" or "}" itself.
        preg_match_all('#\{(!)?(\w+)\}#', $pattern, $matches, \PREG_OFFSET_CAPTURE | \PREG_SET_ORDER);
        foreach ($matches as $match) {
            $important = $match[1][1] >= 0;
            $varName = $match[2][0];
            // get all static text preceding the current variable
            $precedingText = substr($pattern, $pos, $match[0][1] - $pos);
            $pos = $match[0][1] + \strlen($match[0][0]);

            if (!\strlen($precedingText)) {
                $precedingChar = '';
            } elseif ($useUtf8) {
                preg_match('/.$/u', $precedingText, $precedingChar);
                $precedingChar = $precedingChar[0];
            } else {
                $precedingChar = substr($precedingText, -1);
            }
            $isSeparator = '' !== $precedingChar && str_contains(static::SEPARATORS, $precedingChar);

            // A PCRE subpattern name must start with a non-digit. Also a PHP variable cannot start with a digit so the
            // variable would not be usable as a Controller action argument.
            if (preg_match('/^\d/', $varName)) {
                throw new \DomainException(sprintf('Variable name "%s" cannot start with a digit in route pattern "%s". Please use a different name.', $varName, $pattern));
            }
            if (\in_array($varName, $variables)) {
                throw new \LogicException(sprintf('Route pattern "%s" cannot reference variable name "%s" more than once.', $pattern, $varName));
            }

            if (\strlen($varName) > self::VARIABLE_MAXIMUM_LENGTH) {
                throw new \DomainException(sprintf('Variable name "%s" cannot be longer than %d characters in route pattern "%s". Please use a shorter name.', $varName, self::VARIABLE_MAXIMUM_LENGTH, $pattern));
            }

            if ($isSeparator && $precedingText !== $precedingChar) {
                $tokens[] = ['text', substr($precedingText, 0, -\strlen($precedingChar))];
            } elseif (!$isSeparator && '' !== $precedingText) {
                $tokens[] = ['text', $precedingText];
            }

            $regexp = $route->getRequirement($varName);
            if (null === $regexp) {
                $followingPattern = (string) substr($pattern, $pos);
                // Find the next static character after the variable that functions as a separator. By default, this separator and '/'
                // are disallowed for the variable. This default requirement makes sure that optional variables can be matched at all
                // and that the generating-matching-combination of URLs unambiguous, i.e. the params used for generating the URL are
                // the same that will be matched. Example: new Route('/{page}.{_format}', ['_format' => 'html'])
                // If {page} would also match the separating dot, {_format} would never match as {page} will eagerly consume everything.
                // Also even if {_format} was not optional the requirement prevents that {page} matches something that was originally
                // part of {_format} when generating the URL, e.g. _format = 'mobile.html'.
                $nextSeparator = self::findNextSeparator($followingPattern, $useUtf8);
                $regexp = sprintf(
                    '[^%s%s]+',
                    preg_quote($defaultSeparator),
                    $defaultSeparator !== $nextSeparator && '' !== $nextSeparator ? preg_quote($nextSeparator) : ''
                );
                if (('' !== $nextSeparator && !preg_match('#^\{\w+\}#', $followingPattern)) || '' === $followingPattern) {
                    // When we have a separator, which is disallowed for the variable, we can optimize the regex with a possessive
                    // quantifier. This prevents useless backtracking of PCRE and improves performance by 20% for matching those patterns.
                    // Given the above example, there is no point in backtracking into {page} (that forbids the dot) when a dot must follow
                    // after it. This optimization cannot be applied when the next char is no real separator or when the next variable is
                    // directly adjacent, e.g. '/{x}{y}'.
                    $regexp .= '+';
                }
            } else {
                if (!preg_match('//u', $regexp)) {
                    $useUtf8 = false;
                } elseif (!$needsUtf8 && preg_match('/[\x80-\xFF]|(?<!\\\\)\\\\(?:\\\\\\\\)*+(?-i:X|[pP][\{CLMNPSZ]|x\{[A-Fa-f0-9]{3})/', $regexp)) {
                    throw new \LogicException(sprintf('Cannot use UTF-8 route requirements without setting the "utf8" option for variable "%s" in pattern "%s".', $varName, $pattern));
                }
                if (!$useUtf8 && $needsUtf8) {
                    throw new \LogicException(sprintf('Cannot mix UTF-8 requirement with non-UTF-8 charset for variable "%s" in pattern "%s".', $varName, $pattern));
                }
                $regexp = self::transformCapturingGroupsToNonCapturings($regexp);
            }

            if ($important) {
                $token = ['variable', $isSeparator ? $precedingChar : '', $regexp, $varName, false, true];
            } else {
                $token = ['variable', $isSeparator ? $precedingChar : '', $regexp, $varName];
            }

            $tokens[] = $token;
            $variables[] = $varName;
        }

        if ($pos < \strlen($pattern)) {
            $tokens[] = ['text', substr($pattern, $pos)];
        }

        // find the first optional token
        $firstOptional = \PHP_INT_MAX;
        if (!$isHost) {
            for ($i = \count($tokens) - 1; $i >= 0; --$i) {
                $token = $tokens[$i];
                // variable is optional when it is not important and has a default value
                if ('variable' === $token[0] && !($token[5] ?? false) && $route->hasDefault($token[3])) {
                    $firstOptional = $i;
                } else {
                    break;
                }
            }
        }

        // compute the matching regexp
        $regexp = '';
        for ($i = 0, $nbToken = \count($tokens); $i < $nbToken; ++$i) {
            $regexp .= self::computeRegexp($tokens, $i, $firstOptional);
        }
        $regexp = '{^'.$regexp.'$}sD'.($isHost ? 'i' : '');

        // enable Utf8 matching if really required
        if ($needsUtf8) {
            $regexp .= 'u';
            for ($i = 0, $nbToken = \count($tokens); $i < $nbToken; ++$i) {
                if ('variable' === $tokens[$i][0]) {
                    $tokens[$i][4] = true;
                }
            }
        }

        return [
            'staticPrefix' => self::determineStaticPrefix($route, $tokens),
            'regex' => $regexp,
            'tokens' => array_reverse($tokens),
            'variables' => $variables,
        ];
    }

    /**
     * Determines the longest static prefix possible for a route.
     */
    private static function determineStaticPrefix(Route $route, array $tokens): string
    {
        if ('text' !== $tokens[0][0]) {
            return ($route->hasDefault($tokens[0][3]) || '/' === $tokens[0][1]) ? '' : $tokens[0][1];
        }

        $prefix = $tokens[0][1];

        if (isset($tokens[1][1]) && '/' !== $tokens[1][1] && false === $route->hasDefault($tokens[1][3])) {
            $prefix .= $tokens[1][1];
        }

        return $prefix;
    }

    /**
     * Returns the next static character in the Route pattern that will serve as a separator (or the empty string when none available).
     */
    private static function findNextSeparator(string $pattern, bool $useUtf8): string
    {
        if ('' == $pattern) {
            // return empty string if pattern is empty or false (false which can be returned by substr)
            return '';
        }
        // first remove all placeholders from the pattern so we can find the next real static character
        if ('' === $pattern = preg_replace('#\{\w+\}#', '', $pattern)) {
            return '';
        }
        if ($useUtf8) {
            preg_match('/^./u', $pattern, $pattern);
        }

        return str_contains(static::SEPARATORS, $pattern[0]) ? $pattern[0] : '';
    }

    /**
     * Computes the regexp used to match a specific token. It can be static text or a subpattern.
     *
     * @param array $tokens        The route tokens
     * @param int   $index         The index of the current token
     * @param int   $firstOptional The index of the first optional token
     */
    private static function computeRegexp(array $tokens, int $index, int $firstOptional): string
    {
        $token = $tokens[$index];
        if ('text' === $token[0]) {
            // Text tokens
            return preg_quote($token[1]);
        } else {
            // Variable tokens
            if (0 === $index && 0 === $firstOptional) {
                // When the only token is an optional variable token, the separator is required
                return sprintf('%s(?P<%s>%s)?', preg_quote($token[1]), $token[3], $token[2]);
            } else {
                $regexp = sprintf('%s(?P<%s>%s)', preg_quote($token[1]), $token[3], $token[2]);
                if ($index >= $firstOptional) {
                    // Enclose each optional token in a subpattern to make it optional.
                    // "?:" means it is non-capturing, i.e. the portion of the subject string that
                    // matched the optional subpattern is not passed back.
                    $regexp = "(?:$regexp";
                    $nbTokens = \count($tokens);
                    if ($nbTokens - 1 == $index) {
                        // Close the optional subpatterns
                        $regexp .= str_repeat(')?', $nbTokens - $firstOptional - (0 === $firstOptional ? 1 : 0));
                    }
                }

                return $regexp;
            }
        }
    }

    private static function transformCapturingGroupsToNonCapturings(string $regexp): string
    {
        for ($i = 0; $i < \strlen($regexp); ++$i) {
            if ('\\' === $regexp[$i]) {
                ++$i;
                continue;
            }
            if ('(' !== $regexp[$i] || !isset($regexp[$i + 2])) {
                continue;
            }
            if ('*' === $regexp[++$i] || '?' === $regexp[$i]) {
                ++$i;
                continue;
            }
            $regexp = substr_replace($regexp, '?:', $i, 0);
            ++$i;
        }

        return $regexp;
    }
}

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• [F] Alias.php
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Enhancing Payment Security: The Role of Encryption and Tokenization in Digital Transactions

As digital transactions proliferate, ensuring robust payment security is more critical than ever. Two foundational technologies that are pivotal in this effort are encryption and tokenization.
Encryption is a process that transforms data into a secure format, known as ciphertext, which can only be deciphered using a specific decryption key. This means that even if data is intercepted during transmission, it remains unreadable and protected from unauthorized access. Encryption is essential in safeguarding sensitive payment information, such as credit card details and personal data, during online transactions.
Tokenization, on the other hand, involves substituting sensitive data with unique identifiers or "tokens." These tokens serve as placeholders and have no value outside of the specific transaction context. If intercepted, tokens are meaningless and cannot be used to access the original sensitive data. This method significantly reduces the risk of fraud and data breaches, as the actual payment information is not stored or transmitted.
Together, encryption and tokenization form a powerful security framework. Encryption ensures that data is protected during transmission, while tokenization minimizes the risk of exposing sensitive information by replacing it with secure, non-sensitive tokens.
These technologies are integral to modern payment platforms, providing a robust defense against cyber threats. By implementing advanced encryption and tokenization techniques, businesses can enhance the security of digital transactions, ensuring that users' financial and personal information remains safe. This comprehensive approach not only builds user trust but also fortifies the overall security infrastructure of digital payment systems. As cyber threats evolve, the continued advancement of encryption and tokenization will be crucial in maintaining secure and reliable payment processes.

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