<?php
session_start();

$downloadLink = null;
$errorMessage = null;

// Function to convert hex color to PDF color components (0-1 range)
function hexToPdfColor($hex) {
    $hex = ltrim($hex, '#');
    $r = hexdec(substr($hex, 0, 2)) / 255;
    $g = hexdec(substr($hex, 2, 2)) / 255;
    $b = hexdec(substr($hex, 4, 2)) / 255;
    return sprintf('%.3f %.3f %.3f', $r, $g, $b);
}

if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    // Basic check for mutool
    $mutoolPath = trim(shell_exec('which mutool'));
    if (empty($mutoolPath)) {
        $errorMessage = "Error: The required PDF processing tool (mupdf-tools) is not installed on the server. Please contact the administrator.";
    } else {
        if (isset($_FILES['pdfFile']) && $_FILES['pdfFile']['error'] === UPLOAD_ERR_OK) {
            $fileTmpPath = $_FILES['pdfFile']['tmp_name'];
            $fileType = mime_content_type($fileTmpPath);

            if ($fileType === 'application/pdf') {
                $uploadsDir = __DIR__ . '/uploads/';
                $downloadsDir = __DIR__ . '/downloads/';
                
                $uniqueId = uniqid('pdf_', true);
                $originalFileName = $uploadsDir . $uniqueId . '.pdf';
                $decompressedFileName = $uploadsDir . $uniqueId . '-decompressed.pdf';
                $recoloredFileName = $uploadsDir . $uniqueId . '-recolored.pdf';
                $outputFileName = $downloadsDir . $uniqueId . '-final.pdf';

                if (move_uploaded_file($fileTmpPath, $originalFileName)) {
                    $color = $_POST['colorPicker'] ?? '#000000';
                    $pdfColor = hexToPdfColor($color);
                    $newColorCommand = $pdfColor . " rg";
                    $newColorCommandStroke = $pdfColor . " RG";

                    // 1. Decompress the PDF to make content streams editable
                    shell_exec(escapeshellcmd("$mutoolPath clean -d " . escapeshellarg($originalFileName) . " " . escapeshellarg($decompressedFileName)));

                    if (file_exists($decompressedFileName)) {
                        $content = file_get_contents($decompressedFileName);
                        
                        // 2. Replace existing color definitions with the new color
                        // This is a broad approach and might affect non-text elements
                        // Pattern for RGB color (non-stroking)
                        $content = preg_replace('/\d*\.?\d+\s+\d*\.?\d+\s+\d*\.?\d+\s+rg/', $newColorCommand, $content);
                        // Pattern for Grayscale (non-stroking)
                        $content = preg_replace('/\d*\.?\d+\s+g/', $newColorCommand, $content);
                        // Pattern for CMYK (non-stroking)
                        $content = preg_replace('/\d*\.?\d+\s+\d*\.?\d+\s+\d*\.?\d+\s+\d*\.?\d+\s+k/', $newColorCommand, $content);

                        // Also replace stroking colors to be safe
                        $content = preg_replace('/\d*\.?\d+\s+\d*\.?\d+\s+\d*\.?\d+\s+RG/', $newColorCommandStroke, $content);
                        $content = preg_replace('/\d*\.?\d+\s+G/', $newColorCommandStroke, $content);
                        $content = preg_replace('/\d*\.?\d+\s+\d*\.?\d+\s+\d*\.?\d+\s+\d*\.?\d+\s+K/', $newColorCommandStroke, $content);


                        file_put_contents($recoloredFileName, $content);

                        // 3. Re-compress and clean the PDF to fix structure and xref table
                        shell_exec(escapeshellcmd("$mutoolPath clean " . escapeshellarg($recoloredFileName) . " " . escapeshellarg($outputFileName)));

                        if (file_exists($outputFileName)) {
                            $downloadLink = '/downloads/' . basename($outputFileName);
                            $_SESSION['last_download'] = $downloadLink;
                        } else {
                            $errorMessage = "Failed to rebuild the PDF file.";
                        }

                        // 4. Clean up temporary files
                        @unlink($decompressedFileName);
                        @unlink($recoloredFileName);
                        @unlink($originalFileName);

                    } else {
                        $errorMessage = "Failed to decompress the PDF for editing.";
                        @unlink($originalFileName);
                    }
                } else {
                    $errorMessage = "Failed to move uploaded file.";
                }
            } else {
                $errorMessage = "Invalid file type. Please upload a PDF.";
            }
        } else {
            $errorMessage = "File upload failed. Please try again.";
        }
    }
}

// Check for a download link from a previous successful submission
if (isset($_SESSION['last_download'])) {
    $downloadLink = $_SESSION['last_download'];
    unset($_SESSION['last_download']);
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>PDF Text Recolor - Free Online Tool</title>
    <meta name="description" content="Free online tool to change the text color of your PDF files. Upload your file, pick a new color, and download the modified PDF instantly.">
    
    <!-- Open Graph / Facebook & Twitter Card Meta Tags -->
    <?php
        $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? "https://" : "http://";
        $host = $_SERVER['HTTP_HOST'];
        $imageUrl = $protocol . $host . '/assets/pasted-20250928-215140-17dd4a54.png';
        $pageUrl = $protocol . $host . $_SERVER['REQUEST_URI'];
    ?>
    <meta property="og:title" content="PDF Text Recolor - Free Online Tool">
    <meta property="og:description" content="Free, online tool to change the text color of your PDF files. Upload your file, pick a new color, and download.">
    <meta property="og:image" content="<?php echo $imageUrl; ?>">
    <meta property="og:url" content="<?php echo $pageUrl; ?>">
    <meta property="og:type" content="website">
    <meta name="twitter:card" content="summary_large_image">
    <meta name="twitter:title" content="PDF Text Recolor - Free Online Tool">
    <meta name="twitter:description" content="Free, online tool to change the text color of your PDF files. Upload your file, pick a new color, and download.">
    <meta name="twitter:image" content="<?php echo $imageUrl; ?>">

    <link href="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/css/bootstrap.min.css" rel="stylesheet">
    <link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/bootstrap-icons@1.11.3/font/bootstrap-icons.min.css">
    <link rel="preconnect" href="https://fonts.googleapis.com">
    <link rel="preconnect" href="https://fonts.gstatic.com" crossorigin>
    <link href="https://fonts.googleapis.com/css2?family=Inter:wght@400;600;700&display=swap" rel="stylesheet">
    <link rel="stylesheet" href="assets/css/custom.css?v=<?php echo time(); ?>">
</head>
<body>

    <nav class="navbar navbar-expand-lg navbar-light bg-white shadow-sm">
        <div class="container">
            <a class="navbar-brand" href="/">PDF Text Recolor</a>
            <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNav" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
                <span class="navbar-toggler-icon"></span>
            </button>
            <div class="collapse navbar-collapse" id="navbarNav">
                <ul class="navbar-nav ms-auto">
                    <li class="nav-item"><a class="nav-link" href="#how-it-works">How It Works</a></li>
                    <li class="nav-item"><a class="nav-link" href="/privacy.php">Privacy</a></li>
                </ul>
            </div>
        </div>
    </nav>

    <main>
        <section class="hero text-center">
            <div class="container">
                <div class="row justify-content-center">
                    <div class="col-lg-8">
                        <h1 class="display-4 fw-bold">Recolor Text in Your PDFs, Instantly</h1>
                        <p class="lead text-muted mb-5">Free, online tool to change the text color of your PDF files. Upload your file, pick a new color, and download.</p>
                        
                        <div class="card p-4 p-md-5">
                            <?php if ($errorMessage): ?>
                                <div class="alert alert-danger">
                                    <?php echo htmlspecialchars($errorMessage); ?>
                                </div>
                            <?php endif; ?>

                            <?php if ($downloadLink): ?>
                                <div class="alert alert-success text-center">
                                    <h4>Your PDF is ready!</h4>
                                    <p>The text color has been changed. Click the button below to download your file.</p>
                                    <a href="<?php echo htmlspecialchars($downloadLink); ?>" class="btn btn-success btn-lg w-100">
                                        <i class="bi bi-download me-2"></i> Download Your Recicolored PDF
                                    </a>
                                    <hr>
                                    <a href="/" class="btn btn-secondary mt-2">Start Over</a>
                                </div>
                            <?php else: ?>
                                <form id="recolor-form" method="POST" enctype="multipart/form-data">
                                    <div class="mb-3">
                                        <label for="pdfFile" class="form-label fs-5">1. Upload your PDF</label>
                                        <input class="form-control form-control-lg" type="file" id="pdfFile" name="pdfFile" accept=".pdf" required>
                                    </div>
                                    <div class="mb-4">
                                        <label for="colorPicker" class="form-label fs-5">2. Pick a new color</label>
                                        <input type="color" class="form-control form-control-color w-100" id="colorPicker" name="colorPicker" value="#4A90E2" title="Choose your color">
                                    </div>
                                    <button type="submit" class="btn btn-primary btn-lg w-100">Recolor & Download <i class="bi bi-arrow-right-circle ms-2"></i></button>
                                </form>
                            <?php endif; ?>
                        </div>
                    </div>
                </div>
            </div>
        </section>

        <section id="how-it-works" class="py-5">
            <div class="container">
                <h2 class="text-center mb-5">How It Works</h2>
                <div class="row text-center g-4">
                    <div class="col-md-4">
                        <div class="card h-100 p-4">
                            <i class="bi bi-cloud-arrow-up step-icon mb-3"></i>
                            <h3 class="h4">Upload</h3>
                            <p class="text-muted">Select the PDF document you want to modify from your device.</p>
                            <img src="https://picsum.photos/seed/upload-step/400/300" class="img-fluid rounded mt-3" alt="Icon representing uploading a file">
                        </div>
                    </div>
                    <div class="col-md-4">
                        <div class="card h-100 p-4">
                            <i class="bi bi-palette step-icon mb-3"></i>
                            <h3 class="h4">Pick Color</h3>
                            <p class="text-muted">Choose the new color for the text using the simple color picker.</p>
                             <img src="https://picsum.photos/seed/color-step/400/300" class="img-fluid rounded mt-3" alt="Icon representing a color palette">
                        </div>
                    </div>
                    <div class="col-md-4">
                        <div class="card h-100 p-4">
                            <i class="bi bi-file-earmark-arrow-down step-icon mb-3"></i>
                            <h3 class="h4">Download</h3>
                            <p class="text-muted">Your new PDF will be ready for download immediately, with no watermarks.</p>
                            <img src="https://picsum.photos/seed/download-step/400/300" class="img-fluid rounded mt-3" alt="Icon representing downloading a file">
                        </div>
                    </div>
                </div>
            </div>
        </section>
    </main>

    <footer class="footer mt-auto py-4 bg-light">
        <div class="container text-center">
            <p class="text-muted mb-0">&copy; <?php echo date("Y"); ?> PDF Text Recolor. All Rights Reserved. | <a href="/privacy.php" class="text-muted">Privacy Policy</a></p>
        </div>
    </footer>

    <script src="https://cdn.jsdelivr.net/npm/bootstrap@5.3.2/dist/js/bootstrap.bundle.min.js"></script>
    <script src="assets/js/main.js?v=<?php echo time(); ?>"></script>
</body>
</html>