Issue 6699 - Support the "circumvention" filter list as default subscription

lib/subscriptionInit.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 69 matching lines @@
 
     if (subscription instanceof SpecialSubscription &&
         subscription.filters.length > 0)
       return false;
   }
 
   return true;
 }
 
 /**
- * Finds the element for the default ad blocking filter subscription based
+ * @typedef {object} DefaultSubscriptions
+ * @property {?Element} ads
+ * @property {?Element} circumvention
+ */
+/**
+ * Finds the elements for the default ad blocking filter subscriptions based
  * on the user's locale.
  *
  * @param {HTMLCollection} subscriptions
- * @return {Element}
+ * @return {DefaultSubscriptions}
  */
-function chooseFilterSubscription(subscriptions)
+function chooseFilterSubscriptions(subscriptions)
 {
-  let selectedItem = null;
+  let selectedItem = {};
   let selectedPrefix = null;
   let matchCount = 0;
   for (let subscription of subscriptions)
   {
-    if (!selectedItem)
-      selectedItem = subscription;
-
     let prefixes = subscription.getAttribute("prefixes");
     let prefix = prefixes && prefixes.split(",").find(
       lang => new RegExp("^" + lang + "\\b").test(Utils.appLocale)
     );
 
     let subscriptionType = subscription.getAttribute("type");
 
-    if (prefix && subscriptionType == "ads")
+    if (subscriptionType in ["ads", "circumvention"] &&
+        !selectedItem[subscriptionType])
+      selectedItem[subscriptionType] = subscription;
+
+    if (prefix)
     {
-      if (!selectedPrefix || selectedPrefix.length < prefix.length)
+      // The "ads" subscription is the one driving the selection.
+      if (subscriptionType == "ads")
       {
-        selectedItem = subscription;
-        selectedPrefix = prefix;
-        matchCount = 1;
+        if (!selectedPrefix || selectedPrefix.length < prefix.length)
+        {
+          selectedItem[subscriptionType] = subscription;
+          selectedPrefix = prefix;
+          matchCount = 1;
+        }
+        else if (selectedPrefix && selectedPrefix.length == prefix.length)
+        {
+          matchCount++;
+
+          // If multiple items have a matching prefix of the same length:
+          // Select one of the items randomly, probability should be the same
+          // for all items. So we replace the previous match here with
+          // probability 1/N (N being the number of matches).
+          if (Math.random() * matchCount < 1)
+          {
+            selectedItem[subscriptionType] = subscription;
+            selectedPrefix = prefix;
+          }
+        }
       }
-      else if (selectedPrefix && selectedPrefix.length == prefix.length)
+      else if (subscriptionType == "circumvention")
       {
-        matchCount++;
-
-        // If multiple items have a matching prefix of the same length:
-        // Select one of the items randomly, probability should be the same
-        // for all items. So we replace the previous match here with
-        // probability 1/N (N being the number of matches).
-        if (Math.random() * matchCount < 1)
-        {
-          selectedItem = subscription;
-          selectedPrefix = prefix;
-        }
+        selectedItem[subscriptionType] = subscription;
       }
     }
   }
   return selectedItem;
 }
 
 function supportsNotificationsWithButtons()
 {
   // Microsoft Edge (as of EdgeHTML 16) doesn't have the notifications API.
   // Opera gives an asynchronous error when buttons are provided (we cannot
@@ skipping 55 matching lines @@
   // Add default ad blocking subscription (e.g. EasyList)
   if (shouldAddDefaultSubscription())
   {
     return fetch("subscriptions.xml")
       .then(response => response.text())
       .then(text =>
       {
         let doc = new DOMParser().parseFromString(text, "application/xml");
         let nodes = doc.getElementsByTagName("subscription");
 
-        let node = chooseFilterSubscription(nodes);
-        if (node)
+        let subs = chooseFilterSubscriptions(nodes);

[Manish Jethani, 2018/06/14 05:07:34]

Just a thought: Maybe a good idea to rename `subs` to `defaultSubscriptions`?
Not sure.

[hub, 2018/06/14 19:59:57]

Done.

+        if (subs)
         {
-          let url = node.getAttribute("url");
-          if (url)
+          for (let name in subs)
           {
-            let subscription = Subscription.fromURL(url);
-            subscription.disabled = false;
-            subscription.title = node.getAttribute("title");
-            subscription.homepage = node.getAttribute("homepage");
-            subscriptions.push(subscription);
+            let node = subs[name];
+            if (!node)
+              continue;
+
+            let url = node.getAttribute("url");
+            if (url)
+            {
+              let subscription = Subscription.fromURL(url);
+              subscription.disabled = false;
+              subscription.title = node.getAttribute("title");
+              subscription.homepage = node.getAttribute("homepage");
+              subscription.type = node.getAttribute("type");
+              subscriptions.push(subscription);
+            }
           }
         }
 
         return subscriptions;
       });
   }
 
   return subscriptions;
 }
 
@@ skipping 69 matching lines @@
  * Sets a callback that is called with an array of subscriptions to be added
  * during initialization. The callback must return an array of subscriptions
  * that will effectively be added.
  *
  * @param {function} callback
  */
 exports.setSubscriptionsCallback = callback =>
 {
   subscriptionsCallback = callback;
 };
+
+// Exports for tests only
+exports.chooseFilterSubscriptions = chooseFilterSubscriptions;