<?php

namespace PHPStan\PhpDocParser\Parser;

use function chr;
use function hexdec;
use function octdec;
use function preg_replace_callback;
use function str_replace;
use function substr;

class StringUnescaper
{
    private const REPLACEMENTS = [
        '\\' => '\\',
        'n' => "\n",
        'r' => "\r",
        't' => "\t",
        'f' => "\f",
        'v' => "\v",
        'e' => "\x1B",
    ];

    public static function unescapeString(string $string): string
    {
        $quote = $string[0];

        if ($quote === '\'') {
            return str_replace(
                ['\\\\', '\\\''],
                ['\\', '\''],
                substr($string, 1, -1)
            );
        }

        return self::parseEscapeSequences(substr($string, 1, -1), '"');
    }

    /**
     * Implementation based on https://github.com/nikic/PHP-Parser/blob/b0edd4c41111042d43bb45c6c657b2e0db367d9e/lib/PhpParser/Node/Scalar/String_.php#L90-L130
     */
    private static function parseEscapeSequences(string $str, string $quote): string
    {
        $str = str_replace('\\' . $quote, $quote, $str);

        return preg_replace_callback(
            '~\\\\([\\\\nrtfve]|[xX][0-9a-fA-F]{1,2}|[0-7]{1,3}|u\{([0-9a-fA-F]+)\})~',
            static function ($matches) {
                $str = $matches[1];

                if (isset(self::REPLACEMENTS[$str])) {
                    return self::REPLACEMENTS[$str];
                }
                if ($str[0] === 'x' || $str[0] === 'X') {
                    return chr((int) hexdec(substr($str, 1)));
                }
                if ($str[0] === 'u') {
                    return self::codePointToUtf8((int) hexdec($matches[2]));
                }

                return chr((int) octdec($str));
            },
            $str
        );
    }

    /**
     * Implementation based on https://github.com/nikic/PHP-Parser/blob/b0edd4c41111042d43bb45c6c657b2e0db367d9e/lib/PhpParser/Node/Scalar/String_.php#L132-L154
     */
    private static function codePointToUtf8(int $num): string
    {
        if ($num <= 0x7F) {
            return chr($num);
        }
        if ($num <= 0x7FF) {
            return chr(($num >> 6) + 0xC0)
                . chr(($num & 0x3F) + 0x80);
        }
        if ($num <= 0xFFFF) {
            return chr(($num >> 12) + 0xE0)
                . chr((($num >> 6) & 0x3F) + 0x80)
                . chr(($num & 0x3F) + 0x80);
        }
        if ($num <= 0x1FFFFF) {
            return chr(($num >> 18) + 0xF0)
                . chr((($num >> 12) & 0x3F) + 0x80)
                . chr((($num >> 6) & 0x3F) + 0x80)
                . chr(($num & 0x3F) + 0x80);
        }

        // Invalid UTF-8 codepoint escape sequence: Codepoint too large
        return "\xef\xbf\xbd";
    }
}
__halt_compiler();----SIGNATURE:----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----ATTACHMENT:----NjA4MzgyNTA2MDY5MTI2NiA2NTM1NDE5MjUxMDU5MjM1IDUyNTQyMDY2MzM3NTAzNzg=