<?php
/**
 * JARVIS Calendar Sync — iCloud CalDAV + Google/ICS feeds
 * Fetches events, parses them, syncs into appointments table.
 * Runs via cron (/usr/local/lsws/lsphp85/bin/lsphp /path/to/calendar_sync.php)
 * or via HTTP: GET /api/calendar/sync
 */

$isCLI = php_sapi_name() === 'cli' || php_sapi_name() === 'litespeed';
if (!class_exists('JarvisDB')) {
    require_once __DIR__ . '/../config.php';
    require_once __DIR__ . '/../lib/db.php';
}

// ── ICS Parser ───────────────────────────────────────────────────────────────
function parseICS(string $ics): array {
    $events = [];
    // Unfold lines (RFC 5545: lines folded with CRLF + whitespace)
    $ics = preg_replace('/\r\n[ \t]/', '', $ics);
    $ics = preg_replace('/\n[ \t]/', '', $ics);

    preg_match_all('/BEGIN:VEVENT(.+?)END:VEVENT/s', $ics, $blocks);
    foreach ($blocks[1] as $block) {
        $e = [];
        // Parse each property line
        foreach (explode("\n", $block) as $line) {
            $line = trim($line);
            if (!$line) continue;
            // Split on first colon not inside quotes
            $pos = strpos($line, ':');
            if ($pos === false) continue;
            $prop = strtoupper(trim(substr($line, 0, $pos)));
            $val  = trim(substr($line, $pos + 1));
            // Extract param-stripped property name (e.g. DTSTART;TZID=... → DTSTART)
            $propBase = explode(';', $prop)[0];
            // Extract TZID param if present
            $tzid = null;
            if (preg_match('/TZID=([^;:]+)/i', $prop, $tzm)) $tzid = $tzm[1];
            $e[$propBase] = ['val' => $val, 'tzid' => $tzid, 'raw_prop' => $prop];
        }
        if (empty($e['SUMMARY']) || empty($e['UID'])) continue;

        $uid     = $e['UID']['val'];
        $summary = calDecode($e['SUMMARY']['val']);
        $desc    = isset($e['DESCRIPTION']) ? calDecode($e['DESCRIPTION']['val']) : '';
        $loc     = isset($e['LOCATION'])    ? calDecode($e['LOCATION']['val'])    : '';

        $startRaw = $e['DTSTART']['val'] ?? null;
        $endRaw   = $e['DTEND']['val']   ?? ($e['DURATION']['val'] ?? null);
        if (!$startRaw) continue;

        $startDt  = parseCalDate($startRaw, $e['DTSTART']['tzid'] ?? null);
        $endDt    = $endRaw ? parseCalDate($endRaw, $e['DTEND']['tzid'] ?? null) : null;
        $allDay   = (strlen($startRaw) === 8); // YYYYMMDD format = all-day

        if (!$startDt) continue;

        // Skip events more than 1 year in the past
        if (strtotime($startDt) < time() - 365 * 86400) continue;

        $events[] = compact('uid','summary','desc','loc','startDt','endDt','allDay');
    }
    return $events;
}

function parseCalDate(string $raw, ?string $tzid): ?string {
    $raw = preg_replace('/[^0-9T Z]/i', '', $raw);
    // All-day: YYYYMMDD
    if (preg_match('/^(\d{4})(\d{2})(\d{2})$/', $raw, $m))
        return "{$m[1]}-{$m[2]}-{$m[3]} 00:00:00";
    // Datetime: YYYYMMDDTHHMMSS[Z]
    if (preg_match('/^(\d{4})(\d{2})(\d{2})T(\d{2})(\d{2})(\d{2})/', $raw, $m)) {
        $ts = gmmktime((int)$m[4],(int)$m[5],(int)$m[6],(int)$m[2],(int)$m[3],(int)$m[1]);
        // Convert to local (server) timezone
        return date('Y-m-d H:i:s', $ts - date('Z'));
    }
    return null;
}

function calDecode(string $s): string {
    // Decode quoted-printable and backslash escapes
    $s = str_replace(['\\n','\\N','\\,','\;'], ["\n"," ",",",";"], $s);
    return trim($s);
}

// ── CalDAV Client ─────────────────────────────────────────────────────────────
function caldavRequest(string $method, string $url, string $user, string $pass,
                       string $body = '', array $extraHeaders = []): array {
    $ch = curl_init($url);
    $headers = array_merge([
        'Content-Type: text/xml; charset=utf-8',
        'Prefer: return-minimal',
    ], $extraHeaders);
    curl_setopt_array($ch, [
        CURLOPT_RETURNTRANSFER => true,
        CURLOPT_CUSTOMREQUEST  => $method,
        CURLOPT_USERPWD        => "$user:$pass",
        CURLOPT_HTTPHEADER     => $headers,
        CURLOPT_POSTFIELDS     => $body,
        CURLOPT_TIMEOUT        => 20,
        CURLOPT_CONNECTTIMEOUT => 8,
        CURLOPT_SSL_VERIFYPEER => true,
        CURLOPT_FOLLOWLOCATION => true,
        CURLOPT_MAXREDIRS      => 5,
    ]);
    $resp = curl_exec($ch);
    $code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
    $err  = curl_error($ch);
    curl_close($ch);
    return ['code' => $code, 'body' => $resp ?: '', 'error' => $err];
}

function xmlVal(string $xml, string $tag): ?string {
    if (preg_match('~<(?:[^:]+:)?' . preg_quote($tag, '~') . '[^>]*>(.*?)</(?:[^:]+:)?' . preg_quote($tag, '~') . '>~s', $xml, $m))
        return trim(html_entity_decode(strip_tags($m[1])));
    return null;
}

function fetchICloudCalendars(string $user, string $pass): array {
    $results = [];
    // Step 1: Discover principal
    $propfind = '<?xml version="1.0"?><d:propfind xmlns:d="DAV:"><d:prop><d:current-user-principal/></d:prop></d:propfind>';
    $r = caldavRequest('PROPFIND', 'https://caldav.icloud.com/', $user, $pass, $propfind, ['Depth: 0']);
    $principal = xmlVal($r['body'], 'current-user-principal');
    if (!$principal) $principal = xmlVal($r['body'], 'href');
    if (!$principal) return ['error' => 'Cannot discover principal: HTTP ' . $r['code']];

    // Make absolute URL
    if (!str_starts_with($principal, 'http')) $principal = 'https://caldav.icloud.com' . $principal;

    // Step 2: Get calendar home
    $propfind2 = '<?xml version="1.0"?><d:propfind xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav"><d:prop><c:calendar-home-set/></d:prop></d:propfind>';
    $r2 = caldavRequest('PROPFIND', $principal, $user, $pass, $propfind2, ['Depth: 0']);
    $calHome = xmlVal($r2['body'], 'calendar-home-set');
    if (!$calHome) $calHome = xmlVal($r2['body'], 'href');
    if (!$calHome) return ['error' => 'Cannot find calendar home'];

    if (!str_starts_with($calHome, 'http')) $calHome = 'https://caldav.icloud.com' . $calHome;

    // Step 3: List calendars
    $propfind3 = '<?xml version="1.0"?><d:propfind xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav"><d:prop><d:displayname/><c:supported-calendar-component-set/></d:prop></d:propfind>';
    $r3 = caldavRequest('PROPFIND', $calHome, $user, $pass, $propfind3, ['Depth: 1']);

    // Parse calendar URLs from multistatus response
    preg_match_all('~<d:response>(.*?)</d:response>~s', $r3['body'], $responses);
    foreach ($responses[1] as $resp) {
        $href = xmlVal($resp, 'href');
        $name = xmlVal($resp, 'displayname');
        // Only include actual calendars (not the home itself)
        if ($href && $href !== parse_url($calHome, PHP_URL_PATH) && strpos($resp, 'VEVENT') !== false) {
            $calUrl = str_starts_with($href, 'http') ? $href : 'https://caldav.icloud.com' . $href;
            $results[] = ['url' => $calUrl, 'name' => $name ?: 'iCloud Calendar'];
        }
    }
    return ['calendars' => $results, 'home' => $calHome];
}

function fetchCalDAVEvents(string $calUrl, string $user, string $pass): array {
    // Fetch events from 1 year ago to 2 years ahead
    $from = gmdate('Ymd\THis\Z', strtotime('-1 year'));
    $to   = gmdate('Ymd\THis\Z', strtotime('+2 years'));
    $report = <<<XML
<?xml version="1.0" encoding="utf-8" ?>
<c:calendar-query xmlns:d="DAV:" xmlns:c="urn:ietf:params:xml:ns:caldav">
  <d:prop><d:getetag/><c:calendar-data/></d:prop>
  <c:filter>
    <c:comp-filter name="VCALENDAR">
      <c:comp-filter name="VEVENT">
        <c:time-range start="$from" end="$to"/>
      </c:comp-filter>
    </c:comp-filter>
  </c:filter>
</c:calendar-query>
XML;
    $r = caldavRequest('REPORT', $calUrl, $user, $pass, $report, ['Depth: 1', 'Content-Type: text/xml']);
    if ($r['code'] !== 207) return ['error' => 'CalDAV REPORT failed: HTTP ' . $r['code']];

    // Extract calendar-data from response
    $allICS = '';
    preg_match_all('~<(?:[^:]+:)?calendar-data[^>]*>(.*?)</(?:[^:]+:)?calendar-data>~s', $r['body'], $m);
    foreach ($m[1] as $icsBlock) {
        $allICS .= html_entity_decode($icsBlock) . "\n";
    }
    return ['events' => parseICS("BEGIN:VCALENDAR\n" . $allICS . "\nEND:VCALENDAR")];
}

// ── Sync events to DB ─────────────────────────────────────────────────────────
function syncEvents(array $events, string $source, string $feedName): array {
    $inserted = $updated = $skipped = 0;
    foreach ($events as $ev) {
        $uid = md5($source . ':' . $ev['uid']); // deterministic per source
        $existing = JarvisDB::single('SELECT id, start_at, title FROM appointments WHERE external_uid=? AND external_source=?', [$uid, $source]);
        $cat = 'personal';
        if (preg_match('/\b(work|meeting|office|client|project|call|conference|interview|standup|sprint)\b/i', $ev['summary'])) $cat = 'work';
        if (preg_match('/\b(doctor|medical|dentist|pharmacy|hospital|clinic|appointment)\b/i', $ev['summary'])) $cat = 'medical';

        if ($existing) {
            // Update if start time changed
            if ($existing['start_at'] !== $ev['startDt']) {
                JarvisDB::execute(
                    'UPDATE appointments SET title=?, description=?, location=?, start_at=?, end_at=?, all_day=?, category=?, last_synced=NOW() WHERE id=?',
                    [$ev['summary'], $ev['desc'], $ev['loc'], $ev['startDt'], $ev['endDt'], $ev['allDay'] ? 1 : 0, $cat, $existing['id']]
                );
                $updated++;
            } else {
                $skipped++;
            }
        } else {
            JarvisDB::execute(
                'INSERT INTO appointments (title, description, location, category, start_at, end_at, all_day, external_uid, external_source, last_synced)
                 VALUES (?,?,?,?,?,?,?,?,?,NOW())',
                [$ev['summary'], $ev['desc'], $ev['loc'], $cat, $ev['startDt'], $ev['endDt'], $ev['allDay'] ? 1 : 0, $uid, $source]
            );
            $inserted++;
        }
    }
    // Remove events that no longer exist in the feed (deleted from calendar)
    $syncedUids = array_map(fn($ev) => md5($source . ':' . $ev['uid']), $events);
    if ($syncedUids) {
        $placeholders = implode(',', array_fill(0, count($syncedUids), '?'));
        JarvisDB::execute(
            "DELETE FROM appointments WHERE external_source=? AND external_uid NOT IN ($placeholders) AND external_uid IS NOT NULL",
            array_merge([$source], $syncedUids)
        );
    }
    return compact('inserted', 'updated', 'skipped');
}

// ── Main sync runner ──────────────────────────────────────────────────────────
function runSync(): array {
    $results = [];

    // ── iCloud CalDAV ──────────────────────────────────────────────────────
    if (defined('ICLOUD_USER') && ICLOUD_USER && defined('ICLOUD_PASS') && ICLOUD_PASS) {
        $calInfo = fetchICloudCalendars(ICLOUD_USER, ICLOUD_PASS);
        if (isset($calInfo['error'])) {
            $results['icloud'] = 'Error: ' . $calInfo['error'];
        } else {
            $totalEvents = [];
            foreach ($calInfo['calendars'] as $cal) {
                $evData = fetchCalDAVEvents($cal['url'], ICLOUD_USER, ICLOUD_PASS);
                if (!empty($evData['events'])) $totalEvents = array_merge($totalEvents, $evData['events']);
            }
            $r = syncEvents($totalEvents, 'icloud', 'iCloud');
            JarvisDB::execute("UPDATE calendar_feeds SET last_sync=NOW(), last_count=? WHERE source='icloud'", [count($totalEvents)]);
            $results['icloud'] = "OK: {$r['inserted']} new, {$r['updated']} updated, {$r['skipped']} unchanged (" . count($totalEvents) . " events total)";
        }
    }

    // ── Google Calendar ICS ────────────────────────────────────────────────
    $feeds = JarvisDB::query("SELECT * FROM calendar_feeds WHERE source IN ('google','ics') AND active=1") ?? [];
    foreach ($feeds as $feed) {
        if (!$feed['ics_url']) continue;
        $ch = curl_init($feed['ics_url']);
        curl_setopt_array($ch, [CURLOPT_RETURNTRANSFER=>true, CURLOPT_TIMEOUT=>20, CURLOPT_FOLLOWLOCATION=>true, CURLOPT_SSL_VERIFYPEER=>true]);
        if ($feed['username']) curl_setopt($ch, CURLOPT_USERPWD, $feed['username'] . ':' . $feed['password']);
        $ics  = curl_exec($ch);
        $code = curl_getinfo($ch, CURLINFO_HTTP_CODE);
        curl_close($ch);
        if ($code !== 200 || !$ics) {
            $results[$feed['name']] = "Error fetching ICS (HTTP $code)";
            continue;
        }
        $events = parseICS($ics);
        $r = syncEvents($events, $feed['source'] . '_' . $feed['id'], $feed['name']);
        JarvisDB::execute('UPDATE calendar_feeds SET last_sync=NOW(), last_count=? WHERE id=?', [count($events), $feed['id']]);
        $results[$feed['name']] = "OK: {$r['inserted']} new, {$r['updated']} updated (" . count($events) . " events)";
    }

    return $results;
}

// ── Entry point ───────────────────────────────────────────────────────────────
if ($isCLI) {
    echo date('Y-m-d H:i:s') . " Calendar sync started\n";
    $r = runSync();
    foreach ($r as $src => $msg) echo "  $src: $msg\n";
    echo date('Y-m-d H:i:s') . " Done\n";
} else {
    // HTTP endpoint
    $r = runSync();
    echo json_encode(['status' => 'ok', 'results' => $r, 'timestamp' => date('c')]);
}