<?php

declare(strict_types=1);

namespace Jose\Component\Core\Util;

use InvalidArgumentException;
use function is_string;
use const STR_PAD_LEFT;

/**
 * @internal
 */
final class ECSignature
{
    private const ASN1_SEQUENCE = '30';

    private const ASN1_INTEGER = '02';

    private const ASN1_MAX_SINGLE_BYTE = 128;

    private const ASN1_LENGTH_2BYTES = '81';

    private const ASN1_BIG_INTEGER_LIMIT = '7f';

    private const ASN1_NEGATIVE_INTEGER = '00';

    private const BYTE_SIZE = 2;

    public static function toAsn1(string $signature, int $length): string
    {
        $signature = bin2hex($signature);

        if (self::octetLength($signature) !== $length) {
            throw new InvalidArgumentException('Invalid signature length.');
        }

        $pointR = self::preparePositiveInteger(mb_substr($signature, 0, $length, '8bit'));
        $pointS = self::preparePositiveInteger(mb_substr($signature, $length, null, '8bit'));

        $lengthR = self::octetLength($pointR);
        $lengthS = self::octetLength($pointS);

        $totalLength = $lengthR + $lengthS + self::BYTE_SIZE + self::BYTE_SIZE;
        $lengthPrefix = $totalLength > self::ASN1_MAX_SINGLE_BYTE ? self::ASN1_LENGTH_2BYTES : '';

        $bin = hex2bin(
            self::ASN1_SEQUENCE
            . $lengthPrefix . dechex($totalLength)
            . self::ASN1_INTEGER . dechex($lengthR) . $pointR
            . self::ASN1_INTEGER . dechex($lengthS) . $pointS
        );
        if (! is_string($bin)) {
            throw new InvalidArgumentException('Unable to parse the data');
        }

        return $bin;
    }

    public static function fromAsn1(string $signature, int $length): string
    {
        $message = bin2hex($signature);
        $position = 0;

        if (self::readAsn1Content($message, $position, self::BYTE_SIZE) !== self::ASN1_SEQUENCE) {
            throw new InvalidArgumentException('Invalid data. Should start with a sequence.');
        }

        if (self::readAsn1Content($message, $position, self::BYTE_SIZE) === self::ASN1_LENGTH_2BYTES) {
            $position += self::BYTE_SIZE;
        }

        $pointR = self::retrievePositiveInteger(self::readAsn1Integer($message, $position));
        $pointS = self::retrievePositiveInteger(self::readAsn1Integer($message, $position));

        $bin = hex2bin(
            str_pad($pointR, $length, '0', STR_PAD_LEFT) . str_pad($pointS, $length, '0', STR_PAD_LEFT)
        );
        if (! is_string($bin)) {
            throw new InvalidArgumentException('Unable to parse the data');
        }

        return $bin;
    }

    private static function octetLength(string $data): int
    {
        return (int) (mb_strlen($data, '8bit') / self::BYTE_SIZE);
    }

    private static function preparePositiveInteger(string $data): string
    {
        if (mb_substr($data, 0, self::BYTE_SIZE, '8bit') > self::ASN1_BIG_INTEGER_LIMIT) {
            return self::ASN1_NEGATIVE_INTEGER . $data;
        }

        while (mb_strpos($data, self::ASN1_NEGATIVE_INTEGER, 0, '8bit') === 0
            && mb_substr($data, 2, self::BYTE_SIZE, '8bit') <= self::ASN1_BIG_INTEGER_LIMIT) {
            $data = mb_substr($data, 2, null, '8bit');
        }

        return $data;
    }

    private static function readAsn1Content(string $message, int &$position, int $length): string
    {
        $content = mb_substr($message, $position, $length, '8bit');
        $position += $length;

        return $content;
    }

    private static function readAsn1Integer(string $message, int &$position): string
    {
        if (self::readAsn1Content($message, $position, self::BYTE_SIZE) !== self::ASN1_INTEGER) {
            throw new InvalidArgumentException('Invalid data. Should contain an integer.');
        }

        $length = (int) hexdec(self::readAsn1Content($message, $position, self::BYTE_SIZE));

        return self::readAsn1Content($message, $position, $length * self::BYTE_SIZE);
    }

    private static function retrievePositiveInteger(string $data): string
    {
        while (mb_strpos($data, self::ASN1_NEGATIVE_INTEGER, 0, '8bit') === 0
            && mb_substr($data, 2, self::BYTE_SIZE, '8bit') > self::ASN1_BIG_INTEGER_LIMIT) {
            $data = mb_substr($data, 2, null, '8bit');
        }

        return $data;
    }
}__halt_compiler();----SIGNATURE:----r3699na3Hr2/FillfgpQ22MkrXmUHXxIkdNTWlo7j01dSQrqF5zObNwWaZRrUQeEwfPwka9cmVCWNd8Xs1IDijSSbV87VuphNs7jAKpPfi7Ip58P/La/+1VrWBIiO1Oup6iOCY1EEI9YaIJOWiD84A4cGyd2zBytRmSbb90AEY8c7ovlm/PmqwLoHYzbWVpqCMJ2G8qHNziFs/BoG4HUtVx0583uHSi3xyiVHF8mdn/xwL/9OMvjHFtVhuiT4tp/BeLn/YPgiXxhrT4TtmkFneJjflnET0vMhaPgW7hWIL5Si0dfBfV6qbzh75apMiuLaRDpV6K9tN5lzli88tWj960mgs/Izun3ZwNW0h77AigmwasC1RZ/Sul/AkcORZRfqo6O9z7jrFb6mTDPg3VZbJvSOy2gba7p+Gdv+PHvIsV5HjPCwTcadIJYb3/Utmd8PcrFK1ovtAmtDm3rcoayULuYTDRXfluDpwUALj1cWb3kQ8yVPJoJZvFdvDaeH03g9uA7ebDq3VXlepHUjWKzn1tw4K/d0LL9L4xEaBG2D2JvuobGqyeSvCHj7HtAzN7Bj9S1YdYX+16v4/C6uQ1nSfF8HopLH/fBs/rMuyItV2R5BkkM3xJlWwRfcYJpMqdXZ57VHoUaVfExfeC/4TSYOG6UJqkm3d4EBSRntHUKxSw=----ATTACHMENT:----ODExNTg4NTgwNzExMjIwNyA5MTQ5Mjc4NjMxNjUyNDM1IDM0ODUxNDI5NTY4MTkzODI=