'use strict';

const heightLimit = window.outerHeight * 2;
let height = getCurrentHeight();
setupResizeListener();

///

function setupResizeListener() {
  const resizeObserver = new ResizeObserver(handleHeightChange);
  resizeObserver.observe(document.body);
}

function handleHeightChange(entries) {
  const updatedHeight = getCurrentHeight();
  if (height === updatedHeight || updatedHeight > heightLimit) {
    return;
  }

  const RESIZE_CODE = 'resize:';
  window.parent.postMessage(RESIZE_CODE + JSON.stringify({height}), '*');
  height = updatedHeight;
}

function getCurrentHeight() {
  return document.querySelector('body > main').scrollHeight;
}