<?php

declare(strict_types=1);

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

use App\Framework\QrCode\ErrorCorrection\ReedSolomonEncoder;

echo "=== Syndrome Calculation with Generator Roots ===\n\n";

// Reference data and EC codewords
$data = [64, 180, 132, 84, 196, 196, 242, 5, 116, 245, 174, 59, 64, 109, 236, 233];
$ec = [0, 245, 228, 127, 21, 207, 194, 102, 66, 52];

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

// Initialize GF(256)
$gfLog = array_fill(0, 256, 0);
$gfExp = array_fill(0, 512, 0);

$x = 1;
for ($i = 0; $i < 255; $i++) {
    $gfExp[$i] = $x;
    $gfLog[$x] = $i;
    $x <<= 1;
    if ($x & 0x100) {
        $x ^= 0x11d;
    }
}

for ($i = 255; $i < 512; $i++) {
    $gfExp[$i] = $gfExp[$i - 255];
}

function gfMult(array $gfExp, array $gfLog, int $a, int $b): int
{
    if ($a === 0 || $b === 0) return 0;
    return $gfExp[$gfLog[$a] + $gfLog[$b]];
}

// Get generator polynomial
$rs = new ReedSolomonEncoder();
$reflection = new \ReflectionClass($rs);
$getGeneratorMethod = $reflection->getMethod('getGeneratorPolynomial');
$getGeneratorMethod->setAccessible(true);
$generator = $getGeneratorMethod->invoke($rs, 10);

echo "Generator polynomial: " . implode(', ', $generator) . "\n";
echo "Note: This represents g(x) = (x-α^0)(x-α^1)...(x-α^9)\n\n";

// The generator roots are α^0, α^1, ..., α^9
// For a valid codeword, c(α^i) should be 0 for i = 0 to 9

$fullCodeword = array_merge($data, $ec);
echo "Full codeword: " . implode(', ', $fullCodeword) . "\n\n";

// Test: Evaluate codeword polynomial at generator roots
echo "=== Evaluating at Generator Roots ===\n";
echo "For a valid RS codeword, c(α^i) should be 0 for all generator roots.\n\n";

// Standard RS: c(x) = c[0] + c[1]*x + c[2]*x^2 + ... + c[n-1]*x^(n-1)
// But QR codes might use different polynomial representation

// Test 1: Standard polynomial (LSB-first)
echo "Test 1: Standard polynomial c(x) = c[0] + c[1]*x + ...\n";
$syndromes1 = [];
for ($i = 0; $i < 10; $i++) {
    $alphaPower = $gfExp[$i];
    $syndrome = 0;
    $power = 1; // x^0 = 1
    for ($j = 0; $j < count($fullCodeword); $j++) {
        $syndrome ^= gfMult($gfExp, $gfLog, $fullCodeword[$j], $power);
        $power = gfMult($gfExp, $gfLog, $power, $alphaPower);
    }
    $syndromes1[$i] = $syndrome;
    echo "  c(α^{$i}) = {$syndrome}\n";
}
$allZero1 = array_sum($syndromes1) === 0;
echo ($allZero1 ? "✅" : "❌") . " All syndromes are zero\n\n";

// Test 2: Reversed polynomial (MSB-first)
// c(x) = c[0]*x^(n-1) + c[1]*x^(n-2) + ... + c[n-1]
echo "Test 2: Reversed polynomial c(x) = c[0]*x^(n-1) + c[1]*x^(n-2) + ...\n";
$n = count($fullCodeword);
$syndromes2 = [];
for ($i = 0; $i < 10; $i++) {
    $alphaPower = $gfExp[$i];
    $syndrome = 0;
    // Start with x^(n-1) evaluated at α^i
    $power = $gfExp[($i * ($n - 1)) % 255];
    for ($j = 0; $j < $n; $j++) {
        $syndrome ^= gfMult($gfExp, $gfLog, $fullCodeword[$j], $power);
        // Divide by α^i (multiply by α^(255-i))
        $power = gfMult($gfExp, $gfLog, $power, $gfExp[255 - $i]);
    }
    $syndromes2[$i] = $syndrome;
    echo "  c(α^{$i}) = {$syndrome}\n";
}
$allZero2 = array_sum($syndromes2) === 0;
echo ($allZero2 ? "✅" : "❌") . " All syndromes are zero\n\n";

// Test 3: Maybe we need to evaluate at different roots?
// Generator: g(x) = (x-α^0)(x-α^1)...(x-α^9)
// But maybe the roots are α^1, α^2, ..., α^10?
echo "Test 3: Evaluating at α^1 to α^10 (shifted roots)\n";
$syndromes3 = [];
for ($i = 1; $i <= 10; $i++) {
    $alphaPower = $gfExp[$i];
    $syndrome = 0;
    $power = 1;
    for ($j = 0; $j < count($fullCodeword); $j++) {
        $syndrome ^= gfMult($gfExp, $gfLog, $fullCodeword[$j], $power);
        $power = gfMult($gfExp, $gfLog, $power, $alphaPower);
    }
    $syndromes3[$i - 1] = $syndrome;
    echo "  c(α^{$i}) = {$syndrome}\n";
}
$allZero3 = array_sum($syndromes3) === 0;
echo ($allZero3 ? "✅" : "❌") . " All syndromes are zero\n\n";

if ($allZero1 || $allZero2 || $allZero3) {
    echo "✅ Found correct evaluation method!\n";
} else {
    echo "❌ None of the methods work. The problem might be in the generator polynomial.\n";
}