<?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\String;

use Symfony\Component\String\Exception\ExceptionInterface;
use Symfony\Component\String\Exception\InvalidArgumentException;
use Symfony\Component\String\Exception\RuntimeException;

/**
 * Represents a string of abstract characters.
 *
 * Unicode defines 3 types of "characters" (bytes, code points and grapheme clusters).
 * This class is the abstract type to use as a type-hint when the logic you want to
 * implement doesn't care about the exact variant it deals with.
 *
 * @author Nicolas Grekas <p@tchwork.com>
 * @author Hugo Hamon <hugohamon@neuf.fr>
 *
 * @throws ExceptionInterface
 */
abstract class AbstractString implements \Stringable, \JsonSerializable
{
    public const PREG_PATTERN_ORDER = \PREG_PATTERN_ORDER;
    public const PREG_SET_ORDER = \PREG_SET_ORDER;
    public const PREG_OFFSET_CAPTURE = \PREG_OFFSET_CAPTURE;
    public const PREG_UNMATCHED_AS_NULL = \PREG_UNMATCHED_AS_NULL;

    public const PREG_SPLIT = 0;
    public const PREG_SPLIT_NO_EMPTY = \PREG_SPLIT_NO_EMPTY;
    public const PREG_SPLIT_DELIM_CAPTURE = \PREG_SPLIT_DELIM_CAPTURE;
    public const PREG_SPLIT_OFFSET_CAPTURE = \PREG_SPLIT_OFFSET_CAPTURE;

    protected $string = '';
    protected $ignoreCase = false;

    abstract public function __construct(string $string = '');

    /**
     * Unwraps instances of AbstractString back to strings.
     *
     * @return string[]|array
     */
    public static function unwrap(array $values): array
    {
        foreach ($values as $k => $v) {
            if ($v instanceof self) {
                $values[$k] = $v->__toString();
            } elseif (\is_array($v) && $values[$k] !== $v = static::unwrap($v)) {
                $values[$k] = $v;
            }
        }

        return $values;
    }

    /**
     * Wraps (and normalizes) strings in instances of AbstractString.
     *
     * @return static[]|array
     */
    public static function wrap(array $values): array
    {
        $i = 0;
        $keys = null;

        foreach ($values as $k => $v) {
            if (\is_string($k) && '' !== $k && $k !== $j = (string) new static($k)) {
                $keys = $keys ?? array_keys($values);
                $keys[$i] = $j;
            }

            if (\is_string($v)) {
                $values[$k] = new static($v);
            } elseif (\is_array($v) && $values[$k] !== $v = static::wrap($v)) {
                $values[$k] = $v;
            }

            ++$i;
        }

        return null !== $keys ? array_combine($keys, $values) : $values;
    }

    /**
     * @param string|string[] $needle
     */
    public function after(string|iterable $needle, bool $includeNeedle = false, int $offset = 0): static
    {
        $str = clone $this;
        $i = \PHP_INT_MAX;

        if (\is_string($needle)) {
            $needle = [$needle];
        }

        foreach ($needle as $n) {
            $n = (string) $n;
            $j = $this->indexOf($n, $offset);

            if (null !== $j && $j < $i) {
                $i = $j;
                $str->string = $n;
            }
        }

        if (\PHP_INT_MAX === $i) {
            return $str;
        }

        if (!$includeNeedle) {
            $i += $str->length();
        }

        return $this->slice($i);
    }

    /**
     * @param string|string[] $needle
     */
    public function afterLast(string|iterable $needle, bool $includeNeedle = false, int $offset = 0): static
    {
        $str = clone $this;
        $i = null;

        if (\is_string($needle)) {
            $needle = [$needle];
        }

        foreach ($needle as $n) {
            $n = (string) $n;
            $j = $this->indexOfLast($n, $offset);

            if (null !== $j && $j >= $i) {
                $i = $offset = $j;
                $str->string = $n;
            }
        }

        if (null === $i) {
            return $str;
        }

        if (!$includeNeedle) {
            $i += $str->length();
        }

        return $this->slice($i);
    }

    abstract public function append(string ...$suffix): static;

    /**
     * @param string|string[] $needle
     */
    public function before(string|iterable $needle, bool $includeNeedle = false, int $offset = 0): static
    {
        $str = clone $this;
        $i = \PHP_INT_MAX;

        if (\is_string($needle)) {
            $needle = [$needle];
        }

        foreach ($needle as $n) {
            $n = (string) $n;
            $j = $this->indexOf($n, $offset);

            if (null !== $j && $j < $i) {
                $i = $j;
                $str->string = $n;
            }
        }

        if (\PHP_INT_MAX === $i) {
            return $str;
        }

        if ($includeNeedle) {
            $i += $str->length();
        }

        return $this->slice(0, $i);
    }

    /**
     * @param string|string[] $needle
     */
    public function beforeLast(string|iterable $needle, bool $includeNeedle = false, int $offset = 0): static
    {
        $str = clone $this;
        $i = null;

        if (\is_string($needle)) {
            $needle = [$needle];
        }

        foreach ($needle as $n) {
            $n = (string) $n;
            $j = $this->indexOfLast($n, $offset);

            if (null !== $j && $j >= $i) {
                $i = $offset = $j;
                $str->string = $n;
            }
        }

        if (null === $i) {
            return $str;
        }

        if ($includeNeedle) {
            $i += $str->length();
        }

        return $this->slice(0, $i);
    }

    /**
     * @return int[]
     */
    public function bytesAt(int $offset): array
    {
        $str = $this->slice($offset, 1);

        return '' === $str->string ? [] : array_values(unpack('C*', $str->string));
    }

    abstract public function camel(): static;

    /**
     * @return static[]
     */
    abstract public function chunk(int $length = 1): array;

    public function collapseWhitespace(): static
    {
        $str = clone $this;
        $str->string = trim(preg_replace("/(?:[ \n\r\t\x0C]{2,}+|[\n\r\t\x0C])/", ' ', $str->string), " \n\r\t\x0C");

        return $str;
    }

    /**
     * @param string|string[] $needle
     */
    public function containsAny(string|iterable $needle): bool
    {
        return null !== $this->indexOf($needle);
    }

    /**
     * @param string|string[] $suffix
     */
    public function endsWith(string|iterable $suffix): bool
    {
        if (\is_string($suffix)) {
            throw new \TypeError(sprintf('Method "%s()" must be overridden by class "%s" to deal with non-iterable values.', __FUNCTION__, static::class));
        }

        foreach ($suffix as $s) {
            if ($this->endsWith((string) $s)) {
                return true;
            }
        }

        return false;
    }

    public function ensureEnd(string $suffix): static
    {
        if (!$this->endsWith($suffix)) {
            return $this->append($suffix);
        }

        $suffix = preg_quote($suffix);
        $regex = '{('.$suffix.')(?:'.$suffix.')++$}D';

        return $this->replaceMatches($regex.($this->ignoreCase ? 'i' : ''), '$1');
    }

    public function ensureStart(string $prefix): static
    {
        $prefix = new static($prefix);

        if (!$this->startsWith($prefix)) {
            return $this->prepend($prefix);
        }

        $str = clone $this;
        $i = $prefixLen = $prefix->length();

        while ($this->indexOf($prefix, $i) === $i) {
            $str = $str->slice($prefixLen);
            $i += $prefixLen;
        }

        return $str;
    }

    /**
     * @param string|string[] $string
     */
    public function equalsTo(string|iterable $string): bool
    {
        if (\is_string($string)) {
            throw new \TypeError(sprintf('Method "%s()" must be overridden by class "%s" to deal with non-iterable values.', __FUNCTION__, static::class));
        }

        foreach ($string as $s) {
            if ($this->equalsTo((string) $s)) {
                return true;
            }
        }

        return false;
    }

    abstract public function folded(): static;

    public function ignoreCase(): static
    {
        $str = clone $this;
        $str->ignoreCase = true;

        return $str;
    }

    /**
     * @param string|string[] $needle
     */
    public function indexOf(string|iterable $needle, int $offset = 0): ?int
    {
        if (\is_string($needle)) {
            throw new \TypeError(sprintf('Method "%s()" must be overridden by class "%s" to deal with non-iterable values.', __FUNCTION__, static::class));
        }

        $i = \PHP_INT_MAX;

        foreach ($needle as $n) {
            $j = $this->indexOf((string) $n, $offset);

            if (null !== $j && $j < $i) {
                $i = $j;
            }
        }

        return \PHP_INT_MAX === $i ? null : $i;
    }

    /**
     * @param string|string[] $needle
     */
    public function indexOfLast(string|iterable $needle, int $offset = 0): ?int
    {
        if (\is_string($needle)) {
            throw new \TypeError(sprintf('Method "%s()" must be overridden by class "%s" to deal with non-iterable values.', __FUNCTION__, static::class));
        }

        $i = null;

        foreach ($needle as $n) {
            $j = $this->indexOfLast((string) $n, $offset);

            if (null !== $j && $j >= $i) {
                $i = $offset = $j;
            }
        }

        return $i;
    }

    public function isEmpty(): bool
    {
        return '' === $this->string;
    }

    abstract public function join(array $strings, string $lastGlue = null): static;

    public function jsonSerialize(): string
    {
        return $this->string;
    }

    abstract public function length(): int;

    abstract public function lower(): static;

    /**
     * Matches the string using a regular expression.
     *
     * Pass PREG_PATTERN_ORDER or PREG_SET_ORDER as $flags to get all occurrences matching the regular expression.
     *
     * @return array All matches in a multi-dimensional array ordered according to flags
     */
    abstract public function match(string $regexp, int $flags = 0, int $offset = 0): array;

    abstract public function padBoth(int $length, string $padStr = ' '): static;

    abstract public function padEnd(int $length, string $padStr = ' '): static;

    abstract public function padStart(int $length, string $padStr = ' '): static;

    abstract public function prepend(string ...$prefix): static;

    public function repeat(int $multiplier): static
    {
        if (0 > $multiplier) {
            throw new InvalidArgumentException(sprintf('Multiplier must be positive, %d given.', $multiplier));
        }

        $str = clone $this;
        $str->string = str_repeat($str->string, $multiplier);

        return $str;
    }

    abstract public function replace(string $from, string $to): static;

    abstract public function replaceMatches(string $fromRegexp, string|callable $to): static;

    abstract public function reverse(): static;

    abstract public function slice(int $start = 0, int $length = null): static;

    abstract public function snake(): static;

    abstract public function splice(string $replacement, int $start = 0, int $length = null): static;

    /**
     * @return static[]
     */
    public function split(string $delimiter, int $limit = null, int $flags = null): array
    {
        if (null === $flags) {
            throw new \TypeError('Split behavior when $flags is null must be implemented by child classes.');
        }

        if ($this->ignoreCase) {
            $delimiter .= 'i';
        }

        set_error_handler(static function ($t, $m) { throw new InvalidArgumentException($m); });

        try {
            if (false === $chunks = preg_split($delimiter, $this->string, $limit, $flags)) {
                $lastError = preg_last_error();

                foreach (get_defined_constants(true)['pcre'] as $k => $v) {
                    if ($lastError === $v && '_ERROR' === substr($k, -6)) {
                        throw new RuntimeException('Splitting failed with '.$k.'.');
                    }
                }

                throw new RuntimeException('Splitting failed with unknown error code.');
            }
        } finally {
            restore_error_handler();
        }

        $str = clone $this;

        if (self::PREG_SPLIT_OFFSET_CAPTURE & $flags) {
            foreach ($chunks as &$chunk) {
                $str->string = $chunk[0];
                $chunk[0] = clone $str;
            }
        } else {
            foreach ($chunks as &$chunk) {
                $str->string = $chunk;
                $chunk = clone $str;
            }
        }

        return $chunks;
    }

    /**
     * @param string|string[] $prefix
     */
    public function startsWith(string|iterable $prefix): bool
    {
        if (\is_string($prefix)) {
            throw new \TypeError(sprintf('Method "%s()" must be overridden by class "%s" to deal with non-iterable values.', __FUNCTION__, static::class));
        }

        foreach ($prefix as $prefix) {
            if ($this->startsWith((string) $prefix)) {
                return true;
            }
        }

        return false;
    }

    abstract public function title(bool $allWords = false): static;

    public function toByteString(string $toEncoding = null): ByteString
    {
        $b = new ByteString();

        $toEncoding = \in_array($toEncoding, ['utf8', 'utf-8', 'UTF8'], true) ? 'UTF-8' : $toEncoding;

        if (null === $toEncoding || $toEncoding === $fromEncoding = $this instanceof AbstractUnicodeString || preg_match('//u', $b->string) ? 'UTF-8' : 'Windows-1252') {
            $b->string = $this->string;

            return $b;
        }

        set_error_handler(static function ($t, $m) { throw new InvalidArgumentException($m); });

        try {
            try {
                $b->string = mb_convert_encoding($this->string, $toEncoding, 'UTF-8');
            } catch (InvalidArgumentException $e) {
                if (!\function_exists('iconv')) {
                    throw $e;
                }

                $b->string = iconv('UTF-8', $toEncoding, $this->string);
            }
        } finally {
            restore_error_handler();
        }

        return $b;
    }

    public function toCodePointString(): CodePointString
    {
        return new CodePointString($this->string);
    }

    public function toString(): string
    {
        return $this->string;
    }

    public function toUnicodeString(): UnicodeString
    {
        return new UnicodeString($this->string);
    }

    abstract public function trim(string $chars = " \t\n\r\0\x0B\x0C\u{A0}\u{FEFF}"): static;

    abstract public function trimEnd(string $chars = " \t\n\r\0\x0B\x0C\u{A0}\u{FEFF}"): static;

    /**
     * @param string|string[] $prefix
     */
    public function trimPrefix($prefix): static
    {
        if (\is_array($prefix) || $prefix instanceof \Traversable) {
            foreach ($prefix as $s) {
                $t = $this->trimPrefix($s);

                if ($t->string !== $this->string) {
                    return $t;
                }
            }

            return clone $this;
        }

        $str = clone $this;

        if ($prefix instanceof self) {
            $prefix = $prefix->string;
        } else {
            $prefix = (string) $prefix;
        }

        if ('' !== $prefix && \strlen($this->string) >= \strlen($prefix) && 0 === substr_compare($this->string, $prefix, 0, \strlen($prefix), $this->ignoreCase)) {
            $str->string = substr($this->string, \strlen($prefix));
        }

        return $str;
    }

    abstract public function trimStart(string $chars = " \t\n\r\0\x0B\x0C\u{A0}\u{FEFF}"): static;

    /**
     * @param string|string[] $suffix
     */
    public function trimSuffix($suffix): static
    {
        if (\is_array($suffix) || $suffix instanceof \Traversable) {
            foreach ($suffix as $s) {
                $t = $this->trimSuffix($s);

                if ($t->string !== $this->string) {
                    return $t;
                }
            }

            return clone $this;
        }

        $str = clone $this;

        if ($suffix instanceof self) {
            $suffix = $suffix->string;
        } else {
            $suffix = (string) $suffix;
        }

        if ('' !== $suffix && \strlen($this->string) >= \strlen($suffix) && 0 === substr_compare($this->string, $suffix, -\strlen($suffix), null, $this->ignoreCase)) {
            $str->string = substr($this->string, 0, -\strlen($suffix));
        }

        return $str;
    }

    public function truncate(int $length, string $ellipsis = '', bool $cut = true): static
    {
        $stringLength = $this->length();

        if ($stringLength <= $length) {
            return clone $this;
        }

        $ellipsisLength = '' !== $ellipsis ? (new static($ellipsis))->length() : 0;

        if ($length < $ellipsisLength) {
            $ellipsisLength = 0;
        }

        if (!$cut) {
            if (null === $length = $this->indexOf([' ', "\r", "\n", "\t"], ($length ?: 1) - 1)) {
                return clone $this;
            }

            $length += $ellipsisLength;
        }

        $str = $this->slice(0, $length - $ellipsisLength);

        return $ellipsisLength ? $str->trimEnd()->append($ellipsis) : $str;
    }

    abstract public function upper(): static;

    /**
     * Returns the printable length on a terminal.
     */
    abstract public function width(bool $ignoreAnsiDecoration = true): int;

    public function wordwrap(int $width = 75, string $break = "\n", bool $cut = false): static
    {
        $lines = '' !== $break ? $this->split($break) : [clone $this];
        $chars = [];
        $mask = '';

        if (1 === \count($lines) && '' === $lines[0]->string) {
            return $lines[0];
        }

        foreach ($lines as $i => $line) {
            if ($i) {
                $chars[] = $break;
                $mask .= '#';
            }

            foreach ($line->chunk() as $char) {
                $chars[] = $char->string;
                $mask .= ' ' === $char->string ? ' ' : '?';
            }
        }

        $string = '';
        $j = 0;
        $b = $i = -1;
        $mask = wordwrap($mask, $width, '#', $cut);

        while (false !== $b = strpos($mask, '#', $b + 1)) {
            for (++$i; $i < $b; ++$i) {
                $string .= $chars[$j];
                unset($chars[$j++]);
            }

            if ($break === $chars[$j] || ' ' === $chars[$j]) {
                unset($chars[$j++]);
            }

            $string .= $break;
        }

        $str = clone $this;
        $str->string = $string.implode('', $chars);

        return $str;
    }

    public function __sleep(): array
    {
        return ['string'];
    }

    public function __clone()
    {
        $this->ignoreCase = false;
    }

    public function __toString(): string
    {
        return $this->string;
    }
}

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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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