<?php

/**
 * Class Hanzi
 *
 * @created      19.11.2020
 * @author       smiley <smiley@chillerlan.net>
 * @copyright    2020 smiley
 * @license      MIT
 */
namespace WCPOS\Vendor\chillerlan\QRCode\Data;

use WCPOS\Vendor\chillerlan\QRCode\Common\BitBuffer;
use WCPOS\Vendor\chillerlan\QRCode\Common\Mode;
use Throwable;
use function chr, implode, intdiv, is_string, mb_convert_encoding, mb_detect_encoding, mb_internal_encoding, mb_strlen, ord, sprintf, strlen;
/**
 * Hanzi (simplified Chinese) mode, GBT18284-2000: 13-bit double-byte characters from the GB2312/GB18030 character set
 *
 * Please note that this is not part of the QR Code specification and may not be supported by all readers (ZXing-based ones do).
 *
 * @see https://en.wikipedia.org/wiki/GB_2312
 * @see http://www.herongyang.com/GB2312/Introduction-of-GB2312.html
 * @see https://en.wikipedia.org/wiki/GBK_(character_encoding)#Encoding
 * @see https://gist.github.com/codemasher/91da33c44bfb48a81a6c1426bb8e4338
 * @see https://github.com/zxing/zxing/blob/dfb06fa33b17a9e68321be151c22846c7b78048f/core/src/main/java/com/google/zxing/qrcode/decoder/DecodedBitStreamParser.java#L172-L209
 * @see https://www.chinesestandard.net/PDF/English.aspx/GBT18284-2000
 */
final class Hanzi extends QRDataModeAbstract
{
    /**
     * possible values: GB2312, GB18030
     *
     * @var string
     */
    public const ENCODING = 'GB18030';
    /**
     * @todo: other subsets???
     *
     * @var int
     */
    public const GB2312_SUBSET = 0b1;
    /**
     * @inheritDoc
     */
    public const DATAMODE = Mode::HANZI;
    /**
     * @inheritDoc
     */
    protected function getCharCount() : int
    {
        return mb_strlen($this->data, self::ENCODING);
    }
    /**
     * @inheritDoc
     */
    public function getLengthInBits() : int
    {
        return $this->getCharCount() * 13;
    }
    /**
     * @inheritDoc
     * @throws \chillerlan\QRCode\Data\QRCodeDataException
     */
    public static function convertEncoding(string $string) : string
    {
        $detected = mb_detect_encoding($string, [mb_internal_encoding(), 'UTF-8', 'GB2312', 'GB18030', 'CP936', 'EUC-CN', 'HZ'], \true);
        if ($detected === \false) {
            throw new QRCodeDataException('mb_detect_encoding error');
        }
        if ($detected === self::ENCODING) {
            return $string;
        }
        $string = mb_convert_encoding($string, self::ENCODING, $detected);
        if (!is_string($string)) {
            throw new QRCodeDataException('mb_convert_encoding error');
        }
        return $string;
    }
    /**
     * checks if a string qualifies as Hanzi/GB2312
     */
    public static function validateString(string $string) : bool
    {
        try {
            $string = self::convertEncoding($string);
        } catch (Throwable $e) {
            return \false;
        }
        $len = strlen($string);
        if ($len < 2 || $len % 2 !== 0) {
            return \false;
        }
        for ($i = 0; $i < $len; $i += 2) {
            $byte1 = ord($string[$i]);
            $byte2 = ord($string[$i + 1]);
            // byte 1 unused ranges
            if ($byte1 < 0xa1 || $byte1 > 0xa9 && $byte1 < 0xb0 || $byte1 > 0xf7) {
                return \false;
            }
            // byte 2 unused ranges
            if ($byte2 < 0xa1 || $byte2 > 0xfe) {
                return \false;
            }
        }
        return \true;
    }
    /**
     * @inheritDoc
     *
     * @throws \chillerlan\QRCode\Data\QRCodeDataException on an illegal character occurence
     */
    public function write(BitBuffer $bitBuffer, int $versionNumber) : QRDataModeInterface
    {
        $bitBuffer->put(self::DATAMODE, 4)->put($this::GB2312_SUBSET, 4)->put($this->getCharCount(), $this::getLengthBits($versionNumber));
        $len = strlen($this->data);
        for ($i = 0; $i + 1 < $len; $i += 2) {
            $c = (0xff & ord($this->data[$i])) << 8 | 0xff & ord($this->data[$i + 1]);
            if ($c >= 0xa1a1 && $c <= 0xaafe) {
                $c -= 0xa1a1;
            } elseif ($c >= 0xb0a1 && $c <= 0xfafe) {
                $c -= 0xa6a1;
            } else {
                throw new QRCodeDataException(sprintf('illegal char at %d [%d]', $i + 1, $c));
            }
            $bitBuffer->put(($c >> 8 & 0xff) * 0x60 + ($c & 0xff), 13);
        }
        if ($i < $len) {
            throw new QRCodeDataException(sprintf('illegal char at %d', $i + 1));
        }
        return $this;
    }
    /**
     * See specification GBT 18284-2000
     *
     * @throws \chillerlan\QRCode\Data\QRCodeDataException
     */
    public static function decodeSegment(BitBuffer $bitBuffer, int $versionNumber) : string
    {
        // Hanzi mode contains a subset indicator right after mode indicator
        if ($bitBuffer->read(4) !== self::GB2312_SUBSET) {
            throw new QRCodeDataException('ecpected subset indicator for Hanzi mode');
        }
        $length = $bitBuffer->read(self::getLengthBits($versionNumber));
        if ($bitBuffer->available() < $length * 13) {
            throw new QRCodeDataException('not enough bits available');
        }
        // Each character will require 2 bytes. Read the characters as 2-byte pairs and decode as GB2312 afterwards
        $buffer = [];
        $offset = 0;
        while ($length > 0) {
            // Each 13 bits encodes a 2-byte character
            $twoBytes = $bitBuffer->read(13);
            $assembledTwoBytes = intdiv($twoBytes, 0x60) << 8 | $twoBytes % 0x60;
            $assembledTwoBytes += $assembledTwoBytes < 0xa00 ? 0xa1a1 : 0xa6a1;
            // In the 0xB0A1 to 0xFAFE range
            $buffer[$offset] = chr(0xff & $assembledTwoBytes >> 8);
            $buffer[$offset + 1] = chr(0xff & $assembledTwoBytes);
            $offset += 2;
            $length--;
        }
        return mb_convert_encoding(implode('', $buffer), mb_internal_encoding(), self::ENCODING);
    }
}