<?php $app = require '../../app/inc.php';

use App\Timetable\TimeMapper;

$timeMapper = new TimeMapper($app->database->conn);

/**
 * Long polling
 */
session_write_close();
ignore_user_abort(false);
set_time_limit(30);

// if ajax request has send a timestamp, then $last_ajax_call = timestamp, else $last_ajax_call = null
$last_ajax_call = isset($_GET['timestamp']) ? (int)$_GET['timestamp'] : NULL;

// main loop
while(TRUE)
{
    $time = $timeMapper->getLatest();

    if ($time)
    {
        $last_change_in_timetable = $time->date->getTimestamp();

        if ($time && $last_ajax_call == NULL || $last_change_in_timetable > $last_ajax_call)
        {
            exit(json_encode(["data" => json_encode($timeMapper->getAll()), "timestamp" => $last_change_in_timetable]));
        }
    }

    // PHP caches file data, like requesting the size of a file, by default. clearstatcache() clears that cache
    clearstatcache();
    // wait for 1 sec (not very sexy as this blocks the PHP/Apache process, but that's how it goes)
    sleep(1);
    continue;
}