<?php

function generate_uuid_v4(): string {
  $bytes = openssl_random_pseudo_bytes(16);
  $bytes[6] = chr(ord($bytes[6]) & 0x0f | 0x40); // set version to 0100
  $bytes[8] = chr(ord($bytes[8]) & 0x3f | 0x80); // set bits 6-7 to 10
  return vsprintf('%s%s-%s-%s-%s-%s%s%s', str_split(bin2hex($bytes), 4));
}

if (file_exists("config.php")) {
  include "config.php";
}

if (empty($state_file)) {
  $state_file = "state.json";
}

if (empty($error_reporting)) {
  $error_reporting = false;
}

if (empty($lobby_timeout_seconds)) {
  $lobby_timeout_seconds = 30;
}

if ($error_reporting) {
  error_reporting(E_ALL);
  ini_set('display_errors', 1);
}

$dirname = dirname($state_file);
if (!is_dir($dirname)) {
  mkdir($dirname, 0777, true);
}

$state_fp = fopen($state_file, "c+");
flock($state_fp, LOCK_EX);

$contents = stream_get_contents($state_fp);
$state = json_decode($contents, true);
if (empty($state)) {
  $state = ["lobbies" => []];
}

$cutoff_timestamp = time() - $lobby_timeout_seconds;
foreach (array_keys($state["lobbies"]) as $id) {
  if ($state["lobbies"][$id]["updated_at"] < $cutoff_timestamp) {
    unset($state["lobbies"][$id]);
  }
}

if (isset($_GET["list"])) {
  $list = [];
  foreach ($state["lobbies"] as $id => $lobby) {
    $list[$id] = [
      "id" => $lobby["id"],
      "host" => $lobby["host"],
      "port" => $lobby["port"],
      "name" => $lobby["name"],
      "creator" => $lobby["creator"],
      "version" => $lobby["version"],
      "created_at" => $lobby["created_at"],
    ];
  }
  header("Content-Type: application/json");
  echo json_encode(["lobbies" => $list]);
}
elseif (isset($_GET["new"])) {
  require "enet_probe.php";
  $host = $_SERVER['REMOTE_ADDR'];
  if (!empty($_GET["host"])) {
    $host = $_GET["host"];
  }
  $port = 50403;
  if (!empty($_GET["port"]) && is_numeric($_GET["port"])) {
    $port = intval($_GET["port"]);
  }
  $reachable = enet_probe($host, $port);
  header("Content-Type: application/json");
  if ($reachable) {
    $id = generate_uuid_v4();
    $secret = generate_uuid_v4();
    $version = $_GET["version"] ?? "";
    $creator = $_GET["creator"] ?? "";
    $name = "{$creator}'s lobby";
    if (!empty($_GET["name"])) {
      $name = $_GET["name"];
    }
    $lobby = [
      "id" => $id,
      "secret" => $secret,
      "host" => $host,
      "port" => $port,
      "name" => $name,
      "version" => $version,
      "creator" => $creator,
      "updated_at" => time(),
      "created_at" => time(),
    ];
    $state["lobbies"][$id] = $lobby;
    echo json_encode($lobby);
  }
  else {
    http_response_code(424);
    echo json_encode(["error" => "NOT_REACHABLE", "host" => $host, "port" => $port]);
  }
}
elseif (isset($_GET["update"])) {
  $id = $_GET["id"];
  $secret = $_GET["secret"];
  $lobby = $state["lobbies"][$id];
  header("Content-Type: application/json");
  if (!in_array($id, array_keys($state["lobbies"])) || empty($lobby)) {
    http_response_code(404);
    echo json_encode(["error" => "NOT_FOUND", "id" => $id]);
  }
  elseif ($lobby["secret"] != $secret) {
    http_response_code(403);
    echo json_encode(["error" => "NOT_AUTHORIZED", "id" => $id]);
  }
  else {
    $name = $_GET["name"] ?? "";
    if (!empty($name)) {
      $lobby["name"] = $name;
    }
    $lobby["updated_at"] = time();
    $state["lobbies"][$id] = $lobby;
    echo json_encode(["result" => "updated"]);
  }
}
elseif (isset($_GET["close"])) {
  $id = $_GET["id"];
  $secret = $_GET["secret"];
  $lobby = $state["lobbies"][$id];
  header("Content-Type: application/json");
  if (!in_array($id, array_keys($state["lobbies"])) || empty($lobby)) {
    http_response_code(404);
    echo json_encode(["error" => "NOT_FOUND", "id" => $id]);
  }
  elseif ($lobby["secret"] != $secret) {
    http_response_code(403);
    echo json_encode(["error" => "NOT_AUTHORIZED", "id" => $id]);
  }
  else {
    unset($state["lobbies"][$id]);
    echo json_encode(["result" => "closed"]);
  }
}
else {
  header("Content-Type: application/json");
  echo json_encode(["status" => "OK"]);
}

ftruncate($state_fp, 0);
rewind($state_fp);
fwrite($state_fp, json_encode($state, JSON_PRETTY_PRINT));
fflush($state_fp);
flock($state_fp, LOCK_UN);
fclose($state_fp);