<?php
/**
 * Export Batch URLs to CSV
 * Allows clients to download all URLs from a specific batch as CSV
 */

require_once 'client-session.php';
requireClientLogin();

$client_id = $_SESSION['client_id'];

// Get parameters
$project_id = $_GET['project_id'] ?? '';
$batch_number = (int)($_GET['batch'] ?? 0);

// Validate parameters
if (empty($project_id) || $batch_number < 1) {
    $_SESSION['error'] = 'Invalid export parameters';
    header('Location: projects-list.php');
    exit;
}

try {
    // Get database connection
    $pdo = getClientDBConnection();
    
    // Verify access to project and batch
    $stmt = $pdo->prepare("
        SELECT 
            p.project_name,
            p.project_id,
            b.batch_number,
            b.total_urls,
            b.sent_count,
            b.upload_type,
            b.created_at
        FROM survey_url_batches b
        JOIN projects p ON b.project_id = p.project_id
        WHERE b.project_id = ? 
        AND b.batch_number = ?
        AND p.client_id = ?
    ");
    $stmt->execute([$project_id, $batch_number, $client_id]);
    $batch = $stmt->fetch(PDO::FETCH_ASSOC);
    
    if (!$batch) {
        $_SESSION['error'] = 'Batch not found or access denied';
        header('Location: projects-list.php');
        exit;
    }
    
    // Get all URLs from this batch
    $stmt = $pdo->prepare("
        SELECT 
            unique_identifier,
            rr_proxy_url,
            client_url,
            is_sent,
            sent_to_user_id,
            sent_at,
            created_at
        FROM survey_urls
        WHERE project_id = ? AND batch_number = ?
        ORDER BY id ASC
    ");
    $stmt->execute([$project_id, $batch_number]);
    $urls = $stmt->fetchAll(PDO::FETCH_ASSOC);
    
    if (empty($urls)) {
        $_SESSION['error'] = 'No URLs found in this batch';
        header('Location: view-batch-urls.php?project_id=' . urlencode($project_id) . '&batch=' . $batch_number);
        exit;
    }
    
    // Generate filename
    $filename = sprintf(
        '%s_Batch%d_%s.csv',
        $project_id,
        $batch_number,
        date('Ymd_His')
    );
    
    // Set headers for CSV download
    header('Content-Type: text/csv; charset=utf-8');
    header('Content-Disposition: attachment; filename="' . $filename . '"');
    header('Pragma: no-cache');
    header('Expires: 0');
    
    // Open output stream
    $output = fopen('php://output', 'w');
    
    // Add UTF-8 BOM for Excel compatibility
    fprintf($output, chr(0xEF).chr(0xBB).chr(0xBF));
    
    // Write CSV headers
    fputcsv($output, [
        'Unique ID',
        'Relevant Reflex URL',
        'Client Survey URL',
        'Status',
        'Sent To User ID',
        'Sent Date/Time',
        'Created Date/Time'
    ]);
    
    // Write data rows
    foreach ($urls as $url) {
        fputcsv($output, [
            $url['unique_identifier'],
            $url['rr_proxy_url'],
            $url['client_url'],
            $url['is_sent'] ? 'Sent' : 'Available',
            $url['sent_to_user_id'] ?? '',
            $url['sent_at'] ? date('Y-m-d H:i:s', strtotime($url['sent_at'])) : '',
            date('Y-m-d H:i:s', strtotime($url['created_at']))
        ]);
    }
    
    // Add summary row
    fputcsv($output, []); // Empty row
    fputcsv($output, ['SUMMARY']);
    fputcsv($output, ['Project ID', $batch['project_id']]);
    fputcsv($output, ['Project Name', $batch['project_name']]);
    fputcsv($output, ['Batch Number', $batch_number]);
    fputcsv($output, ['Total URLs', $batch['total_urls']]);
    fputcsv($output, ['Sent URLs', $batch['sent_count']]);
    fputcsv($output, ['Available URLs', $batch['total_urls'] - $batch['sent_count']]);
    fputcsv($output, ['Upload Type', ucfirst($batch['upload_type'])]);
    fputcsv($output, ['Batch Created', date('Y-m-d H:i:s', strtotime($batch['created_at']))]);
    fputcsv($output, ['Export Date', date('Y-m-d H:i:s')]);
    
    // Close output stream
    fclose($output);
    
    // Log export activity
    error_log(sprintf(
        "Client %d exported %d URLs from project %s batch %d",
        $client_id,
        count($urls),
        $project_id,
        $batch_number
    ));
    
    exit;
    
} catch (Exception $e) {
    error_log("Export Error: " . $e->getMessage());
    
    $_SESSION['error'] = 'Error exporting URLs: ' . $e->getMessage();
    header('Location: view-batch-urls.php?project_id=' . urlencode($project_id) . '&batch=' . $batch_number);
    exit;
}
?>