<?php
declare(strict_types=1);

require_once __DIR__ . '/includes/db.php';

header('Content-Type: text/calendar; charset=utf-8');
header('Content-Disposition: inline; filename="calendar.ics"');

$pdo = db();
$stmt = $pdo->query("SELECT * FROM calendar_events WHERE visibility='public' AND start_datetime >= NOW() ORDER BY start_datetime ASC LIMIT 200");
$rows = $stmt->fetchAll();

function ics_escape(string $s): string {
    $s = str_replace(["\\", ";", ",", "
", ""], ["\\\\", "\\;", "\\,", "\\n", ""], $s);
    return $s;
}

echo "BEGIN:VCALENDAR\r\n";
echo "VERSION:2.0\r\n";
echo "PRODID:-//Tri-State Santa//Schedule//EN\r\n";
echo "CALSCALE:GREGORIAN\r\n";
echo "METHOD:PUBLISH\r\n";

foreach ($rows as $r) {
    $uid = "event-" . (int)$r['id'] . "@tristate-santa";
    $dtStart = (new DateTime($r['start_datetime']))->format('Ymd\THis');
    $dtEnd = (new DateTime($r['end_datetime']))->format('Ymd\THis');
    $title = ics_escape((string)$r['title']);
    $desc = ics_escape((string)($r['description'] ?? ''));
    $loc = ics_escape(trim(($r['city'] ?? '') . (empty($r['state']) ? '' : ', ' . $r['state'])));

    echo "BEGIN:VEVENT\r\n";
    echo "UID:$uid\r\n";
    echo "DTSTAMP:" . gmdate('Ymd\THis\Z') . "\r\n";
    echo "DTSTART:$dtStart\r\n";
    echo "DTEND:$dtEnd\r\n";
    echo "SUMMARY:$title\r\n";
    if ($desc !== '') echo "DESCRIPTION:$desc\r\n";
    if ($loc !== '') echo "LOCATION:$loc\r\n";
    echo "END:VEVENT\r\n";
}

echo "END:VCALENDAR\r\n";