michaelschiemer/tests/debug/test-data-placement-validation.php

<?php

declare(strict_types=1);

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

use App\Framework\QrCode\QrCodeGenerator;
use App\Framework\QrCode\ErrorCorrection\ReedSolomonEncoder;
use App\Framework\QrCode\ValueObjects\ErrorCorrectionLevel;
use App\Framework\QrCode\ValueObjects\QrCodeConfig;
use App\Framework\QrCode\ValueObjects\QrCodeVersion;
use App\Framework\QrCode\ValueObjects\EncodingMode;

echo "=== Data Placement Validation ===\n\n";

$testData = 'HELLO WORLD';
$config = new QrCodeConfig(
    version: QrCodeVersion::fromNumber(1),
    errorCorrectionLevel: ErrorCorrectionLevel::M,
    encodingMode: EncodingMode::BYTE
);

$matrix = QrCodeGenerator::generate($testData, $config);

// Get expected data codewords
$ecInfo = ReedSolomonEncoder::getECInfo(1, 'M');
echo "Data codewords: {$ecInfo['dataCodewords']}\n";
echo "EC codewords: {$ecInfo['ecCodewords']}\n";
echo "Total codewords: {$ecInfo['totalCodewords']}\n\n";

// Verify data can be read back from matrix
echo "=== Reading Data from Matrix ===\n";

// We need to:
// 1. Read format info to get mask pattern
// 2. Read data bits from matrix (in correct order)
// 3. Unmask the data
// 4. Decode to get original data

// Step 1: Read format info
$formatCols = [0, 1, 2, 3, 4, 5, 7, 8, 20, 19, 18, 17, 16, 15, 14];
$formatH = '';
foreach ($formatCols as $col) {
    $formatH .= $matrix->getModuleAt(8, $col)->isDark() ? '1' : '0';
}

$xorMask = '101010000010010';
$unmasked = '';
for ($i = 0; $i < 15; $i++) {
    $unmasked .= (int)$formatH[$i] ^ (int)$xorMask[$i];
}

$maskPattern = bindec(substr($unmasked, 2, 3));
echo "Mask Pattern: {$maskPattern}\n\n";

// Step 2: Read data bits from matrix (in placement order)
// ISO/IEC 18004 Section 7.7.3: Column pairs, right-to-left, zig-zag up/down
$size = $matrix->getSize();
$dataBits = '';
$bitCount = 0;
$maxBits = $ecInfo['totalCodewords'] * 8;

for ($col = $size - 1; $col >= 1; $col -= 2) {
    if ($col === 6) {
        $col--;
    }
    
    $upward = ((int) (($size - 1 - $col) / 2) % 2) === 0;
    
    for ($i = 0; $i < $size; $i++) {
        $row = $upward ? ($size - 1 - $i) : $i;
        
        for ($c = 0; $c < 2; $c++) {
            $currentCol = $col - $c;
            
            // Skip function patterns
            if (
                ($row <= 8 && $currentCol <= 8) ||
                ($row <= 7 && $currentCol >= $size - 8) ||
                ($row >= $size - 8 && $currentCol <= 7) ||
                $row === 6 || $currentCol === 6 ||
                ($row === 8 && (($currentCol >= 0 && $currentCol <= 5) || $currentCol === 7 || $currentCol === 8 || $currentCol >= $size - 8)) ||
                ($currentCol === 8 && (($row >= 0 && $row <= 5) || $row === 7 || $row === 8 || $row >= $size - 7)) ||
                ($row === 13 && $currentCol === 8) // Dark module
            ) {
                continue;
            }
            
            if ($bitCount < $maxBits) {
                $isDark = $matrix->getModuleAt($row, $currentCol)->isDark();
                $dataBits .= $isDark ? '1' : '0';
                $bitCount++;
            }
        }
    }
}

echo "Read {$bitCount} bits from matrix\n";
echo "Expected: {$maxBits} bits\n\n";

// Step 3: Unmask the data
require_once __DIR__ . '/../../src/Framework/QrCode/Masking/MaskPattern.php';
use App\Framework\QrCode\Masking\MaskPattern;

$maskPatternEnum = MaskPattern::from($maskPattern);
$unmaskedBits = '';
$bitIndex = 0;

// Re-read with unmasking
for ($col = $size - 1; $col >= 1; $col -= 2) {
    if ($col === 6) {
        $col--;
    }
    
    $upward = ((int) (($size - 1 - $col) / 2) % 2) === 0;
    
    for ($i = 0; $i < $size; $i++) {
        $row = $upward ? ($size - 1 - $i) : $i;
        
        for ($c = 0; $c < 2; $c++) {
            $currentCol = $col - $c;
            
            // Skip function patterns
            if (
                ($row <= 8 && $currentCol <= 8) ||
                ($row <= 7 && $currentCol >= $size - 8) ||
                ($row >= $size - 8 && $currentCol <= 7) ||
                $row === 6 || $currentCol === 6 ||
                ($row === 8 && (($currentCol >= 0 && $currentCol <= 5) || $currentCol === 7 || $currentCol === 8 || $currentCol >= $size - 8)) ||
                ($currentCol === 8 && (($row >= 0 && $row <= 5) || $row === 7 || $row === 8 || $row >= $size - 7)) ||
                ($row === 13 && $currentCol === 8)
            ) {
                continue;
            }
            
            if ($bitIndex < $maxBits) {
                $isDark = $matrix->getModuleAt($row, $currentCol)->isDark();
                
                // Unmask if mask pattern says to invert
                if ($maskPatternEnum->shouldInvert($row, $currentCol)) {
                    $isDark = !$isDark;
                }
                
                $unmaskedBits .= $isDark ? '1' : '0';
                $bitIndex++;
            }
        }
    }
}

echo "Unmasked bits: {$bitIndex} bits\n\n";

// Step 4: Decode data
// First 4 bits: Mode indicator
$modeBits = substr($unmaskedBits, 0, 4);
echo "Mode indicator (bits 0-3): {$modeBits}\n";

if ($modeBits === '0100') {
    echo "✅ Mode indicator correct (Byte mode)\n";
} else {
    echo "❌ Mode indicator incorrect (expected 0100, got {$modeBits})\n";
}

// Next 8 bits: Character count
$countBits = substr($unmaskedBits, 4, 8);
$count = bindec($countBits);
echo "Character count (bits 4-11): {$countBits} = {$count}\n";
echo "Expected: " . strlen($testData) . "\n";

if ($count === strlen($testData)) {
    echo "✅ Character count correct\n";
} else {
    echo "❌ Character count incorrect\n";
}

// Next: Data bytes
echo "\nData bytes:\n";
$dataStart = 12;
for ($i = 0; $i < min($count, 11); $i++) {
    $byteBits = substr($unmaskedBits, $dataStart + $i * 8, 8);
    $byte = bindec($byteBits);
    $char = chr($byte);
    
    $expected = $testData[$i] ?? '';
    $expectedByte = $expected ? ord($expected) : 0;
    
    echo "  Byte {$i}: {$byteBits} = {$byte} ('{$char}')";
    
    if ($byte === $expectedByte) {
        echo " ✅\n";
    } else {
        echo " ❌ (expected: " . str_pad(decbin($expectedByte), 8, '0', STR_PAD_LEFT) . " = {$expectedByte} ('{$expected}'))\n";
    }
}