<?php

/**
 * Class ReedSolomonEncoder
 *
 * @created      07.01.2021
 * @author       smiley <smiley@chillerlan.net>
 * @copyright    2021 smiley
 * @license      MIT
 */
namespace WCPOS\Vendor\chillerlan\QRCode\Data;

use WCPOS\Vendor\chillerlan\QRCode\Common\BitBuffer;
use WCPOS\Vendor\chillerlan\QRCode\Common\EccLevel;
use WCPOS\Vendor\chillerlan\QRCode\Common\GenericGFPoly;
use WCPOS\Vendor\chillerlan\QRCode\Common\GF256;
use WCPOS\Vendor\chillerlan\QRCode\Common\Version;
use function array_fill, array_merge, count, max;
/**
 * Reed-Solomon encoding - ISO/IEC 18004:2000 Section 8.5 ff
 *
 * @see http://www.thonky.com/qr-code-tutorial/error-correction-coding
 */
final class ReedSolomonEncoder
{
    private Version $version;
    private EccLevel $eccLevel;
    private array $interleavedData;
    private int $interleavedDataIndex;
    /**
     * ReedSolomonDecoder constructor
     */
    public function __construct(Version $version, EccLevel $eccLevel)
    {
        $this->version = $version;
        $this->eccLevel = $eccLevel;
    }
    /**
     * ECC encoding and interleaving
     *
     * @throws \chillerlan\QRCode\QRCodeException
     */
    public function interleaveEcBytes(BitBuffer $bitBuffer) : array
    {
        [$numEccCodewords, [[$l1, $b1], [$l2, $b2]]] = $this->version->getRSBlocks($this->eccLevel);
        $rsBlocks = array_fill(0, $l1, [$numEccCodewords + $b1, $b1]);
        if ($l2 > 0) {
            $rsBlocks = array_merge($rsBlocks, array_fill(0, $l2, [$numEccCodewords + $b2, $b2]));
        }
        $bitBufferData = $bitBuffer->getBuffer();
        $dataBytes = [];
        $ecBytes = [];
        $maxDataBytes = 0;
        $maxEcBytes = 0;
        $dataByteOffset = 0;
        foreach ($rsBlocks as $key => [$rsBlockTotal, $dataByteCount]) {
            $dataBytes[$key] = [];
            for ($i = 0; $i < $dataByteCount; $i++) {
                $dataBytes[$key][$i] = $bitBufferData[$i + $dataByteOffset] & 0xff;
            }
            $ecByteCount = $rsBlockTotal - $dataByteCount;
            $ecBytes[$key] = $this->encode($dataBytes[$key], $ecByteCount);
            $maxDataBytes = max($maxDataBytes, $dataByteCount);
            $maxEcBytes = max($maxEcBytes, $ecByteCount);
            $dataByteOffset += $dataByteCount;
        }
        $this->interleavedData = array_fill(0, $this->version->getTotalCodewords(), 0);
        $this->interleavedDataIndex = 0;
        $numRsBlocks = $l1 + $l2;
        $this->interleave($dataBytes, $maxDataBytes, $numRsBlocks);
        $this->interleave($ecBytes, $maxEcBytes, $numRsBlocks);
        return $this->interleavedData;
    }
    /**
     *
     */
    private function encode(array $dataBytes, int $ecByteCount) : array
    {
        $rsPoly = new GenericGFPoly([1]);
        for ($i = 0; $i < $ecByteCount; $i++) {
            $rsPoly = $rsPoly->multiply(new GenericGFPoly([1, GF256::exp($i)]));
        }
        $rsPolyDegree = $rsPoly->getDegree();
        $modCoefficients = (new GenericGFPoly($dataBytes, $rsPolyDegree))->mod($rsPoly)->getCoefficients();
        $ecBytes = array_fill(0, $rsPolyDegree, 0);
        $count = count($modCoefficients) - $rsPolyDegree;
        foreach ($ecBytes as $i => &$val) {
            $modIndex = $i + $count;
            $val = 0;
            if ($modIndex >= 0) {
                $val = $modCoefficients[$modIndex];
            }
        }
        return $ecBytes;
    }
    /**
     *
     */
    private function interleave(array $byteArray, int $maxBytes, int $numRsBlocks) : void
    {
        for ($x = 0; $x < $maxBytes; $x++) {
            for ($y = 0; $y < $numRsBlocks; $y++) {
                if ($x < count($byteArray[$y])) {
                    $this->interleavedData[$this->interleavedDataIndex++] = $byteArray[$y][$x];
                }
            }
        }
    }
}