<?php
require_once 'inc/config.php';

header('Content-Type: application/xml; charset=utf-8');

$today = date('Y-m-d');
$si    = isset($_GET['si'])   ? $mysqli->real_escape_string($_GET['si'])   : null;
$year  = isset($_GET['year']) ? $mysqli->real_escape_string($_GET['year']) : null;

echo '<?xml version="1.0" encoding="UTF-8"?>', "\n";
echo '<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">', "\n";

if ($si && $year) {
    // Prepare once
    $sql = "
        SELECT archivesid, year, refnumber, volume, issue, part, file, modification
        FROM archives
        WHERE year = ? AND specialissue = ? AND status = 'enabled'
    ";
    if (! $stmt = $mysqli->prepare($sql)) {
        die('An error occurred. Please try again later.');
    }

    $stmt->bind_param('ss', $year, $si);
    $stmt->execute();
    $stmt->bind_result($archivesid, $rowYear, $refnumber, $volume, $issue, $part, $file, $modification);

    while ($stmt->fetch()) {
        $lastmod = ($modification && !empty($modification) && $modification !== '0000-00-00 00:00:00') ? date('Y-m-d', strtotime($modification)) : $today;

        // Build the set of URLs for *this* row
        $templates = array();

        if ($si === 'Y') {
            // Special-issue URLs
            $templates[] = $baseurl . "special-issue/{$rowYear}.v{$volume}.i{$issue}";
            $templates[] = $baseurl . "special-issue/{$rowYear}.v{$volume}.i{$issue}.{$archivesid}";
        } else {
            // Regular-archive URLs
            $templates[] = $baseurl . "archives/{$rowYear}.v{$volume}.i{$issue}.{$part}";
            $templates[] = $baseurl . "archives/{$rowYear}.v{$volume}.i{$issue}.{$part}.{$archivesid}";
        }

        // File-specific URL (common)
        $templates[] = $baseurl . "archives/{$rowYear}/vol{$volume}issue{$issue}/Part{$part}/{$file}";

        // Emit each URL entry
        foreach ($templates as $loc) {
            echo "  <url>\n"
               . "    <loc>" . htmlspecialchars($loc, ENT_XML1, 'UTF-8') . "</loc>\n"
               . "    <lastmod>{$lastmod}</lastmod>\n"
               . "    <changefreq>monthly</changefreq>\n"
               . "    <priority>0.8</priority>\n"
               . "  </url>\n";
        }
    }

    $stmt->close();
}

echo '</urlset>';