<?php
function validateUser($db, $username, $password) {
  $query = "SELECT username FROM tbladmin WHERE username=? AND password=SHA2(?, 256);";

  $result = myDBQuery($db, $query, $username, $password);

  return count($result);
}

function startSession() {
  session_start();
  session_regenerate_id(true);
  $_SESSION["username"] = $_POST["username"];
  $_SESSION["datetime"] = date("Y-m-d H:i:s");
  $_SESSION["online"] = true;
}

function endSession() {
  session_unset();

  if (ini_get("session.use_cookies")) {
    $data = session_get_cookie_params();

    $path = $data["path"];
    $domain = $data["domain"];
    $secure = $data["secure"];
    $httponly = $data["httponly"];

    setcookie(session_name(), "", time() - 3600, $path, $domain, $secure, $httponly);
  }

  session_destroy();
}

function checkSession() {
  session_start();
  $online = false;

  if (isset($_SESSION["online"])) {
    $online = true;
    session_regenerate_id(true);
  } else {
    endSession();
  }

  return $online;
}

function isAdmin() {
  return $_SESSION['online'];
}