<?php
declare(strict_types=1);
require_once __DIR__ . '/../../src/bootstrap.php';

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

if (($_SERVER['REQUEST_METHOD'] ?? 'GET') !== 'POST') {
    http_response_code(405);
    echo json_encode(['error' => 'method_not_allowed']);
    exit;
}

$raw = file_get_contents('php://input') ?: '';
$req = json_decode($raw, true);
if (!is_array($req)) {
    http_response_code(400);
    echo json_encode(['error' => 'invalid_json']);
    exit;
}

$heartbeat = $req['heartbeat'] ?? [];
if (!is_array($heartbeat)) {
    $heartbeat = [];
}

$type = (string)($heartbeat['type'] ?? 'generic');
$srvEpoch = time();
$srvTz = date('O');

$resp = [
    'heartbeat' => [
        'type' => $type,
        'server_date' => $srvEpoch,
        'server_tz' => $srvTz,
    ],
];

if ($type === 'ntp') {
    $clientDate = (int)($heartbeat['date'] ?? 0);
    $clientTz = (string)($heartbeat['tz'] ?? '');
    $resp['heartbeat']['client_date'] = $clientDate;
    $resp['heartbeat']['client_tz'] = $clientTz;
    $resp['heartbeat']['correction_seconds'] = $clientDate > 0 ? ($srvEpoch - $clientDate) : null;
    $resp['heartbeat']['enabled'] = true;
}

if ($type === 'ip') {
    $resp['heartbeat']['external_ip'] = $_SERVER['HTTP_X_FORWARDED_FOR'] ?? ($_SERVER['REMOTE_ADDR'] ?? '');
}

echo json_encode($resp, JSON_UNESCAPED_SLASHES | JSON_UNESCAPED_UNICODE);