background.js

{
	"manifest_version": 2,

	"name": "Facebook Container for Opera",
	"description": "Facebook Container is an add-on you can install on Opera but ported from Firefox to prevent Facebook from tracking your activity on other websites, so you can continue to use Facebook while protecting your privacy.” article",
	"version": "1.0",
	"background": {
		"scripts": ["background.js"]
	},

	"permissions": ["tabs"],
	"browser_action": {
		"default_icon": "icon.png",
		"default_title": "Go to Dev.Opera!"
	}
}

// Param values from https://developer.mozilla.org/Add-ons/WebExtensions/API/contextualIdentities/create
const FACEBOOK_CONTAINER_NAME = "Facebook";
const FACEBOOK_CONTAINER_COLOR = "blue";
const FACEBOOK_CONTAINER_ICON = "briefcase";
const FACEBOOK_DOMAINS = ["facebook.com", "www.facebook.com", "fb.com"];

const MAC_ADDON_ID = "@testpilot-containers";

let facebookCookieStoreId = null;

const facebookHostREs = [];

async function isFacebookAlreadyAssignedInMAC () {
  let macAddonInfo;
  // If the MAC add-on isn't installed, return false
  try {
    macAddonInfo = await browser.management.get(MAC_ADDON_ID);
  } catch (e) {
    return false;
  }
  let anyFBDomainsAssigned = false;
  for (let facebookDomain of FACEBOOK_DOMAINS) {
    const facebookCookieUrl = `https://${facebookDomain}/`;
    const assignment = await browser.runtime.sendMessage(MAC_ADDON_ID, {
      method: "getAssignment",
      url: facebookCookieUrl
    });
    if (assignment) {
      anyFBDomainsAssigned = true;
    }
  }
  return anyFBDomainsAssigned;
}

(async function init() {
  const facebookAlreadyAssigned = await isFacebookAlreadyAssignedInMAC();
  if (facebookAlreadyAssigned) {
    return;
  }

  // Clear all facebook cookies
  for (let facebookDomain of FACEBOOK_DOMAINS) {
    facebookHostREs.push(new RegExp(`^(.*)?${facebookDomain}$`));
    const facebookCookieUrl = `https://${facebookDomain}/`;

    browser.cookies.getAll({domain: facebookDomain}).then(cookies => {
      for (let cookie of cookies) {
        browser.cookies.remove({name: cookie.name, url: facebookCookieUrl});
      }
    });
  }

  // Use existing Facebook container, or create one
  browser.contextualIdentities.query({name: FACEBOOK_CONTAINER_NAME}).then(contexts => {
    if (contexts.length > 0) {
      facebookCookieStoreId = contexts[0].cookieStoreId;
    } else {
      browser.contextualIdentities.create({
        name: FACEBOOK_CONTAINER_NAME,
        color: FACEBOOK_CONTAINER_COLOR,
        icon: FACEBOOK_CONTAINER_ICON}
      ).then(context => {
        facebookCookieStoreId = context.cookieStoreId;
      });
    }
  });

  // Listen to requests and open Facebook into its Container,
  // open other sites into the default tab context
  async function containFacebook(options) {
    const requestUrl = new URL(options.url);
    let isFacebook = false;
    for (let facebookHostRE of facebookHostREs) {
      if (facebookHostRE.test(requestUrl.host)) {
        isFacebook = true;
        break;
      }
    }
    const tab = await browser.tabs.get(options.tabId);
    const tabCookieStoreId = tab.cookieStoreId;
    if (isFacebook) {
      if (tabCookieStoreId !== facebookCookieStoreId && !tab.incognito) {
        // See https://github.com/mozilla/contain-facebook/issues/23
        // Sometimes this add-on is installed but doesn't get a facebookCookieStoreId ?
        if (facebookCookieStoreId) {
          browser.tabs.create({url: requestUrl.toString(), cookieStoreId: facebookCookieStoreId});
          browser.tabs.remove(options.tabId);
          return {cancel: true};
        }
      }
    } else {
      if (tabCookieStoreId === facebookCookieStoreId) {
        browser.tabs.create({url: requestUrl.toString()});
        browser.tabs.remove(options.tabId);
        return {cancel: true};
      }
    }
  }

  // Add the request listener
  browser.webRequest.onBeforeRequest.addListener(containFacebook, {urls: ["<all_urls>"], types: ["main_frame"]}, ["blocking"]);
})();