<?php

declare(strict_types=1);

require_once __DIR__ . '/../../vendor/autoload.php';

use App\Framework\QrCode\ErrorCorrection\ReedSolomonEncoder;

echo "=== Detailed Polynomial Division Test ===\n\n";

// Test with simple known case
$data = [1];
$ecCodewords = 2;

$rs = new ReedSolomonEncoder();
$reflection = new ReflectionClass($rs);

// Get generator
$getGeneratorMethod = $reflection->getMethod('getGeneratorPolynomial');
$getGeneratorMethod->setAccessible(true);
$generator = $getGeneratorMethod->invoke($rs, $ecCodewords);

echo "Data: " . implode(', ', $data) . "\n";
echo "EC codewords: {$ecCodewords}\n";
echo "Generator: " . implode(', ', $generator) . "\n\n";

// Manual trace
$msg = array_merge($data, array_fill(0, $ecCodewords, 0));
echo "Initial message: " . implode(', ', $msg) . "\n\n";

$gfMultiplyMethod = $reflection->getMethod('gfMultiply');
$gfMultiplyMethod->setAccessible(true);

echo "Step-by-step division:\n";
for ($i = 0; $i < count($data); $i++) {
    $coeff = $msg[$i];
    echo "Iteration {$i}: coefficient = {$coeff}\n";
    
    if ($coeff !== 0) {
        echo "  Before: " . implode(', ', $msg) . "\n";
        
        // Current implementation
        $msg[$i] = 0;
        for ($j = 1; $j < count($generator); $j++) {
            $index = $i + $j;
            if ($index < count($msg)) {
                $multiplied = $gfMultiplyMethod->invoke($rs, $generator[$j], $coeff);
                $old = $msg[$index];
                $msg[$index] ^= $multiplied;
                echo "    [{$index}]: {$old} XOR {$multiplied} = {$msg[$index]}\n";
            }
        }
        
        echo "  After:  " . implode(', ', $msg) . "\n\n";
    }
}

$ec = array_slice($msg, count($data));
echo "EC codewords: " . implode(', ', $ec) . "\n\n";

// Compare with actual
$actualEC = $rs->encode($data, $ecCodewords);
echo "Actual EC: " . implode(', ', $actualEC) . "\n\n";

if ($ec === $actualEC) {
    echo "✅ Manual trace matches implementation\n";
} else {
    echo "❌ Manual trace doesn't match\n";
}

// Now test what the correct algorithm should be
echo "\n=== Correct Algorithm (from qrcode.js) ===\n";
// The algorithm from qrcode.js:
// for (var i = 0; i < data.length; i++) {
//   var lead = msg[i];
//   if (lead !== 0) {
//     msg[i] = 0;
//     for (var j = 1; j < gen.length; j++) {
//       msg[i + j] ^= gfMult(gen[j], lead);
//     }
//   }
// }

// This is exactly what we're doing! So the algorithm should be correct.
// The problem must be with the generator polynomial format or the GF multiplication.