<?php
session_start();
require_once 'includes/db-config.php';
require_once 'includes/auth-check.php';

if (!isset($_SESSION['client_id'])) {
    header('Location: login.php');
    exit;
}

$client_id = $_SESSION['client_id'];
$project_id = $_GET['project_id'] ?? '';
$batch_number = (int)($_GET['batch'] ?? 0);

if (empty($project_id) || $batch_number < 1) {
    exit;
}

try {
    $shopPdo = getShopDBConnection();
    
    // Verify access
    $stmt = $shopPdo->prepare("
        SELECT p.project_name, b.batch_number
        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) {
        exit;
    }
    
    // Get all URLs
    $stmt = $shopPdo->prepare("
        SELECT 
            unique_identifier,
            rr_proxy_url,
            client_url,
            is_sent,
            sent_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);
    
    // Set headers for CSV download
    header('Content-Type: text/csv; charset=utf-8');
    header('Content-Disposition: attachment; filename="' . $project_id . '_Batch' . $batch_number . '_' . date('Ymd') . '.csv"');
    
    // Open output stream
    $output = fopen('php://output', 'w');
    
    // Add UTF-8 BOM for Excel
    fprintf($output, chr(0xEF).chr(0xBB).chr(0xBF));
    
    // Write headers
    fputcsv($output, [
        'Unique ID',
        'Relevant Reflex URL',
        'Client Survey URL',
        'Status',
        'Sent Date'
    ]);
    
    // Write data
    foreach ($urls as $url) {
        fputcsv($output, [
            $url['unique_identifier'],
            $url['rr_proxy_url'],
            $url['client_url'],
            $url['is_sent'] ? 'Sent' : 'Available',
            $url['sent_at'] ? date('Y-m-d H:i:s', strtotime($url['sent_at'])) : ''
        ]);
    }
    
    fclose($output);
    exit;
    
} catch (Exception $e) {
    error_log("Export error: " . $e->getMessage());
    exit;
}