function request(url) {
  var xhr = new XMLHttpRequest();
  xhr.open("POST", url, true);
  xhr.setRequestHeader("Content-Type", "application/json");
  return xhr;
}

function check(id) {
  var checkbox = document.getElementById("task-"+id);
  if (checkbox.checked) {
    var xhr = request("/do");
    xhr.onreadystatechange = function() {
      if (xhr.readyState === 4) {
        // TODO handle success / errors
        console.log(xhr.responseText);
      }
    }
    xhr.send(JSON.stringify({api_key: API_KEY, id: id}));
  } else {
    var xhr = request("/undo");
    xhr.onreadystatechange = function() {
      if (xhr.readyState === 4) {
        // TODO handle success / errors
        console.log(xhr.responseText);
      }
    }
    xhr.send(JSON.stringify({api_key: API_KEY, id: id}));
  }
}

function new() {
  var text = document.getElementById("new-task");
  console.log(text); // TEMPORARY
  var xhr = request("/new");
  xhr.onreadystatechange = function() {
    if (xhr.readyState === 4) {
      // TODO handle success / errors
      console.log(xhr.responseText);
    }
  }
  xhr.send(JSON.stringify({api_key: API_KEY, text: text.value}));

  return false; // prevent form submission
}