ai-labs-team/casium-devtools

import { fromMatches } from './util';

/**
 * Inject a Script into the inspected window containing an Instrumenter
 * configured to use the `postMessage` client.
 */
const doc = (document.head || document.documentElement);
const clientScript = document.createElement('script');
clientScript.src = browser.extension.getURL('injected-script.js');
doc && doc.appendChild(clientScript);

if (!doc) {
  console.warn('[Casium Dev Tools] Could not instrument application: document object not found');
}

const isAllowedPortSender = fromMatches([
  'CasiumDevToolsPanel',
  'CasiumDevToolsBackgroundScript'
]);

const isAllowedPostMessageSender = fromMatches(['CasiumDevToolsInstrumenter']);

const port = browser.runtime.connect(undefined, { name: 'CasiumDevToolsPageScript' });

/**
 * Relay messages from the Background Script to the Client via
 * `window.postMessage`.
 */
port.onMessage.addListener(msg => {
  isAllowedPortSender(msg) && window.postMessage(msg, '*');
});

/**
 * Relay messages from the Client via `port.postMessage`
 */
window.addEventListener('message', ({ data }) => {
  isAllowedPostMessageSender(data) && port.postMessage(data);
});