mcst/src/routes.php

<?php

use Psr\Http\Message\ResponseInterface as Response;
use Psr\Http\Message\ServerRequestInterface as Request;
use Slim\Views\Twig;

// index GET route - this page should welcome the user and direct them to the available actions
$app->get('/', function (Request $request, Response $response, $args) {
  $config = $this->get('config');

  $view = Twig::fromRequest($request);
  return $view->render($response, 'index.twig', [
    'server_dir' => $config->get('server_directory'),
  ]);
})->setName('index');

// create GET route - this page allows a user to create a new server instance
$app->get('/create', function (Request $request, Response $response, $args) {
  $view = Twig::fromRequest($request);
  return $view->render($response, 'create.twig');
})->setName('create');

// create POST route - processes the new server creation
$app->post('/create', function (Request $request, Response $response, $args) {
  // set up the POST parameters and grab our config
  $params = (array)$request->getParsedBody();
  $config = $this->get('config');

  // create our server directory
  $serverDir = join('/', array($config->get('server_directory'), $params['serverName']));
  mkdir($serverDir);

  // grab the server JAR file
  $serverJarUrl = "https://piston-data.mojang.com/v1/objects/f69c284232d7c7580bd89a5a4931c3581eae1378/server.jar";
  $serverJarName = "server_" . $params['serverVersion'] . ".jar";
  $serverJarPath = join('/', array($serverDir, $serverJarName));
  file_put_contents($serverJarPath, file_get_contents($serverJarUrl));

  // create the start.sh shell script
  $scriptFilePath = join('/', array($serverDir, 'start.sh'));
  $scriptFile = fopen($scriptFilePath, 'w');
  $scriptContent = "#!/bin/sh\n\ncd " . $serverDir . "\njava -Xmx2048M -Xms2048M -jar server_1.19.2.jar nogui";
  fwrite($scriptFile, $scriptContent);
  fclose($scriptFile);
  chmod($scriptFilePath, 0755);

  return $response
    ->withHeader('Location', '/')
    ->withStatus(302);
});