/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* global MPShowMessage, MPIsEnabled, MPToggleLights */

"use strict";

// decode a 16-bit string in which only one byte of each
// 16-bit unit is occupied, to UTF-8. This is necessary to
// comply with `btoa` API constraints.
function fromBinary(encoded) {
  const binary = atob(decodeURIComponent(encoded));
  const bytes = new Uint8Array(binary.length);
  for (let i = 0; i < bytes.length; i++) {
    bytes[i] = binary.charCodeAt(i);
  }
  return String.fromCharCode(...new Uint16Array(bytes.buffer));
}

function decodeMessageFromUrl() {
  const url = new URL(document.location.href);

  if (url.searchParams.has("json")) {
    const encodedMessage = url.searchParams.get("json");

    return fromBinary(encodedMessage);
  }
  return null;
}

// Light switch things
document.addEventListener("DOMContentLoaded", () => {
  document
    .querySelector("#light-switch")
    .addEventListener("click", MPToggleLights);
});

const message = decodeMessageFromUrl();

if (message) {
  // If message preview is enabled, show the message.
  if (MPIsEnabled()) {
    MPShowMessage(message);
  }
}