web/public/api/v1/race/sync.php

<?php $app = require '../../../../app/inc.php';
/**
 * We originally wanted to use SSE for this, but the hosting provider
 * did not support that so we resorted to simple polling instead
 * 
 * This page compiles a set of data and sends it if the provided hash of 
 * the data is not equal.
 */

use App\Teamtable\TeamMapper;
use App\Timetable\TimeMapper;

$team_mapper = new TeamMapper($app->database->conn);
$time_mapper = new TimeMapper($app->database->conn);

$prev_hash = (int)filter_input(INPUT_GET, 'h');

$data = [];
$times = $time_mapper->getAll();

foreach ($times as $time)
{
    $team = $team_mapper->get($time->team_id);

    $row = [
        "name"   => $team->name,
        "date"   => $time->date->getTimestamp()
    ];

    array_push($data, $row);
}

$hash = crc32(serialize($data));

if ($prev_hash !== $hash)
{
    $app->api([
            "hash" => $hash,
            "data" => $data
        ]);
}
// return nothing
http_response_code(204);