<?php

declare(strict_types=1);

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

use App\Framework\QrCode\ErrorCorrection\ReedSolomonEncoder;
use App\Framework\QrCode\ValueObjects\EncodingMode;
use App\Framework\QrCode\ValueObjects\QrCodeVersion;

echo "=== Encoding Issue Analysis ===\n\n";

$testData = 'HELLO WORLD';
echo "Test data: '{$testData}'\n";
echo "Length: " . strlen($testData) . " bytes\n\n";

// Expected codewords from QR code specification
$expectedCodewords = [64, 180, 132, 84, 196, 196, 242, 5, 116, 245, 174, 59, 64, 109, 236, 233];
echo "Expected codewords (16):\n";
echo implode(', ', $expectedCodewords) . "\n\n";

// Step-by-step encoding
$version = QrCodeVersion::fromNumber(1);
$encodingMode = EncodingMode::BYTE;

// 1. Mode indicator
$modeBits = $encodingMode->getModeBits();
echo "1. Mode indicator: {$modeBits} (4 bits)\n";

// 2. Character count
$charCountBits = $encodingMode->getCharacterCountBits($version);
$countBits = str_pad(decbin(strlen($testData)), $charCountBits, '0', STR_PAD_LEFT);
echo "2. Character count: {$countBits} (8 bits) = " . strlen($testData) . "\n";

// 3. Data bytes
$dataBits = '';
for ($i = 0; $i < strlen($testData); $i++) {
    $byte = ord($testData[$i]);
    $byteBits = str_pad(decbin($byte), 8, '0', STR_PAD_LEFT);
    $dataBits .= $byteBits;
    echo "3.{$i} Data byte '{$testData[$i]}': {$byteBits} = {$byte}\n";
}

// 4. Build bit string
$bits = $modeBits . $countBits . $dataBits;
echo "\nTotal bits: " . strlen($bits) . "\n";

// 5. Get EC info
$ecInfo = ReedSolomonEncoder::getECInfo(1, 'M');
$requiredBits = $ecInfo['dataCodewords'] * 8;
echo "Required bits: {$requiredBits}\n";
echo "Bits needed: " . ($requiredBits - strlen($bits)) . "\n\n";

// 6. Terminator (up to 4 bits)
$terminatorLength = min(4, max(0, $requiredBits - strlen($bits)));
$bits .= str_repeat('0', $terminatorLength);
echo "After terminator ({$terminatorLength} bits): " . strlen($bits) . " bits\n";

// 7. Pad to multiple of 8
$remainder = strlen($bits) % 8;
if ($remainder !== 0) {
    $bits .= str_repeat('0', 8 - $remainder);
}
echo "After padding to 8: " . strlen($bits) . " bits\n";

// 8. Add pad codewords
$padBytes = ['11101100', '00010001'];
$padIndex = 0;
while (strlen($bits) < $requiredBits) {
    $bits .= $padBytes[$padIndex % 2];
    $padIndex++;
}
echo "After pad codewords ({$padIndex} added): " . strlen($bits) . " bits\n\n";

// 9. Convert to codewords
$codewords = [];
for ($i = 0; $i < strlen($bits); $i += 8) {
    $byte = substr($bits, $i, 8);
    $codewords[] = bindec($byte);
}

echo "Generated codewords (16):\n";
echo implode(', ', $codewords) . "\n\n";

// Compare bit by bit
echo "=== Bit-by-Bit Comparison ===\n";
$expectedBits = '';
foreach ($expectedCodewords as $cw) {
    $expectedBits .= str_pad(decbin($cw), 8, '0', STR_PAD_LEFT);
}

echo "Our bits (128):\n";
echo $bits . "\n\n";
echo "Expected bits (128):\n";
echo $expectedBits . "\n\n";

// Find differences
$differences = [];
for ($i = 0; $i < 128; $i++) {
    if ($bits[$i] !== $expectedBits[$i]) {
        $differences[] = $i;
    }
}

if (empty($differences)) {
    echo "✅ All bits match!\n";
} else {
    echo "❌ " . count($differences) . " bits differ at positions: ";
    echo implode(', ', array_slice($differences, 0, 20));
    if (count($differences) > 20) {
        echo " ...";
    }
    echo "\n\n";
    
    // Show first 10 differences in detail
    echo "First differences:\n";
    for ($i = 0; $i < min(10, count($differences)); $i++) {
        $pos = $differences[$i];
        $codeword = (int)($pos / 8);
        $bitInCodeword = $pos % 8;
        echo "  Bit {$pos} (Codeword {$codeword}, bit {$bitInCodeword}): got '{$bits[$pos]}', expected '{$expectedBits[$pos]}'\n";
    }
}