cyclejs/cycle-core

let portToLauncher: chrome.runtime.Port | null = null;

// Setup BACKGROUND<=>LAUNCHER (wrapping a panel) communication
chrome.runtime.onConnect.addListener(function(port) {
  // inspectedTabs[port.sender.id] = port;
  portToLauncher = port;
  const devToolsListener = function(rawMessage: any, sender: chrome.runtime.Port) {
    // const message = JSON.parse(rawMessage);
    // alert('BACKGROUND on this port message: ' + rawMessage)
    // OPTIONAL: communicate to the USER PAGE through an injected script
  };
  // alert('BACKGROUND connecting to a launcher port');
  port.onMessage.addListener(devToolsListener);

  port.onDisconnect.addListener(function() {
    port.onMessage.removeListener(devToolsListener);
  });
});

interface BackgroundMessage {
  type: 'panelData' | 'tabLoading';
  data?: Object;
  tabId?: number;
}

// From the CONTENT SCRIPT
chrome.runtime.onMessage.addListener(function (message, sender) {
  // alert('BACKGROUND got general message ' + JSON.stringify(message))
  if (portToLauncher) {
    // To the LAUNCHER port
    portToLauncher.postMessage({type: 'panelData', data: message} as BackgroundMessage);
  }
});

// Necessary to avoid the background detecting a reload triggered from the
// launcher and then causing the launcher to reload, and repeating this process
// in an infinite cycle, we need to keep track of even/odd instances of reload.
let reloaded = 0; // number of times reloaded

chrome.tabs.onUpdated.addListener(function (tabId, changeInfo, tab) {
  // alert('BACKGROUND a tab was updated');
  if (portToLauncher && changeInfo.status === 'loading') {
    if (reloaded % 2 === 0) {
      portToLauncher.postMessage({ type: 'tabLoading', tabId } as BackgroundMessage);
    }
    reloaded += 1;
  }
});