<?php

declare(strict_types=1);

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

use App\Framework\QrCode\ErrorCorrection\ReedSolomonEncoder;

echo "=== Reed-Solomon Algorithm Verification ===\n\n";

// Test with simple known data
$testData = [1, 2, 3, 4, 5];
$ecCodewords = 5;

echo "Test data: " . implode(', ', $testData) . "\n";
echo "EC codewords: {$ecCodewords}\n\n";

$reedSolomon = new ReedSolomonEncoder();
$ec = $reedSolomon->encode($testData, $ecCodewords);

echo "EC codewords generated: " . implode(', ', $ec) . "\n\n";

// Verify: For RS codes, the message polynomial evaluated at generator roots should be zero
// But we need the decoder for that. For now, let's verify the algorithm structure.

echo "=== Algorithm Verification ===\n";
echo "Reed-Solomon encoding algorithm:\n";
echo "1. Create message polynomial: m(x) = data + zeros\n";
echo "2. Multiply message by x^t (shift left by t positions)\n";
echo "3. Divide by generator polynomial g(x)\n";
echo "4. EC codewords = remainder\n\n";

// Check if our implementation does this correctly
$reflection = new ReflectionClass($reedSolomon);
$encodeMethod = $reflection->getMethod('encode');
$getGeneratorMethod = $reflection->getMethod('getGeneratorPolynomial');
$getGeneratorMethod->setAccessible(true);

$generator = $getGeneratorMethod->invoke($reedSolomon, $ecCodewords);

echo "Generator polynomial (degree {$ecCodewords}): " . implode(', ', $generator) . "\n";
echo "Coefficient count: " . count($generator) . " (expected: " . ($ecCodewords + 1) . ")\n\n";

// The key issue: In our implementation, we're doing polynomial division
// But we need to verify that the algorithm is correct.

echo "=== Potential Issue ===\n";
echo "The Reed-Solomon encoding in QR codes uses:\n";
echo "  - Message polynomial: m(x) = data codewords\n";
echo "  - Shift: m(x) * x^t (where t = number of EC codewords)\n";
echo "  - Division: (m(x) * x^t) / g(x)\n";
echo "  - EC = remainder\n\n";

echo "Our implementation:\n";
echo "  - Creates message polynomial with zeros: [data, 0, 0, ..., 0]\n";
echo "  - Performs polynomial division\n";
echo "  - Returns last t coefficients as EC codewords\n\n";

echo "This should be correct, but let's verify the polynomial division algorithm.\n";