background.js

const authenticateURL = "https://kinto.dev.mozaws.net/v1/fxa-oauth/login?redirect=https://natim.github.io/get_fxa_token/%23";
const redirectIntermediate = "https://natim.github.io/get_fxa_token/#";

function tabCallback(tabId, changeInfo, updatedTab) {
  if (changeInfo.status === 'complete' && updatedTab.url.indexOf(redirectIntermediate) === 0) {
    chrome.tabs.remove(tabId);
    const bearer = updatedTab.url.split(redirectIntermediate)[1];
    chrome.storage.local.set({bearer: bearer}, function() {
      if (chrome.runtime.lastError) {
        console.error(chrome.runtime.lastError);
        chrome.runtime.sendMessage({ action: 'error', error: chrome.runtime.lastError });
      } else {
        chrome.runtime.sendMessage({ action: 'authenticated', bearer: bearer });
      }
    });
  }
}

function handleMaybeInt(maybeString) {
  const maybeInt = parseInt(maybeString, 10);
  if (Number.isNaN(maybeInt)) {
    return null;
  }
  return maybeInt;
}

function handlePassphraseCleaning() {
  chrome.storage.local.get(["lastModified", "lockAfterSeconds", "temporaryPassphrase"], function(data) {
    const currentTime = Date.now();
    const lastModified = handleMaybeInt(data.lastModified);
    const lockAfterSeconds = handleMaybeInt(data.lockAfterSeconds);

    if (data.temporaryPassphrase && lastModified) {
      console.log("lastModified", lastModified,
                  "lockAfterSeconds", lockAfterSeconds,
                  "time spent", (currentTime - lastModified) / 1000);
      if (!lockAfterSeconds || currentTime - lastModified > lockAfterSeconds * 1000) {
        console.log("cleaning the passphrase in the background.");
        chrome.storage.local.set({
          lastModified: null,
          temporaryPassphrase: null
        });
      } else {
        console.log("Looking for passphrase cleaning");
        /* Try again when the passphrase is supposed to expire */
        const waitForMilliseconds = (lockAfterSeconds * 1000) - (currentTime - lastModified) + 1;
        setTimeout(handlePassphraseCleaning, waitForMilliseconds);
      }
    } else if (data.temporaryPassphrase && lockAfterSeconds) {
      /* If we don't have a lastModified yet, it's because it just started */
      setTimeout(handlePassphraseCleaning, lockAfterSeconds * 1000);
    }
  });
}

function handleAuthentication() {
  chrome.tabs.create({ 'url': authenticateURL }, function () {
    chrome.tabs.onUpdated.addListener(tabCallback);
  });
}

chrome.runtime.onMessage.addListener(function (eventData) {
  switch (eventData.action) {
    case 'passphraseCleaner':
      handlePassphraseCleaning();
      break;
    case 'authenticate':
      handleAuthentication();
      break;
  }
});