From b445f4f4cd470d4a7246b7c2e8cfbe2d14e3647e Mon Sep 17 00:00:00 2001
From: Dave Vandyke <kzar@kzar.co.uk>
Date: Tue, 24 Oct 2023 16:16:14 +0100
Subject: [PATCH] Improve google-ima shim script (#3899)

We made use of the google-ima shim script from uBlock in the
DuckDuckGo Privacy Essentials extension recently, but found a few
issues with website breakage. After debugging and fixing those[1], I
thought it would be worth sharing the improvements back again. Issues
we ran into:

- The AdDisplayContainer[2] constructor usually creates some DOM
  elements inside the given container. They are all nested within a
  DIV and some websites break when at least that top DIV element isn't
  created.
- While not documented (that I could see), the event listeners can be
  added using an array of event types. Some websites make use of that
  and then hang forever when the expected events aren't fired. This
  caused videos not to play on some websites.
- The Ad.prototype.getUniversalAdIds()[3] method should return an
  array of UniversalAdIdInfo Objects, instead of an Array of
  strings. When an array of strings are returned, some websites then
  break when the UniversalAdIdInfo's methods are missing.
- The UniversalAdIdInfo.prototype.getAdIdValue()[4] method had a typo
  in the name ("getAsIdValue") and was effectively missing. That
  caused some websites to break when the missing method was called.
- The google.ima.OmidVerificationVendor[5] Object was missing, which
  broke some websites that attempted to access it.

1 - https://github.com/duckduckgo/tracker-surrogates/commit/52f2999523ae0aeacaeb57937b2f790b886d12c1
2 - https://developers.google.com/interactive-media-ads/docs/sdks/html5/client-side/reference/js/google.ima.AdDisplayContainer
3 - https://developers.google.com/interactive-media-ads/docs/sdks/html5/client-side/reference/js/google.ima.Ad#getUniversalAdIds
4 - https://developers.google.com/interactive-media-ads/docs/sdks/html5/client-side/reference/js/google.ima.UniversalAdIdInfo#getAdIdValue
5 - https://developers.google.com/interactive-media-ads/docs/sdks/html5/client-side/reference/js/google.ima#.OmidVerificationVendor
---
 src/web_accessible_resources/google-ima.js | 51 +++++++++++++++-------
 1 file changed, 35 insertions(+), 16 deletions(-)

diff --git a/src/web_accessible_resources/google-ima.js b/src/web_accessible_resources/google-ima.js
index ad1277289..53fc78d0b 100644
--- a/src/web_accessible_resources/google-ima.js
+++ b/src/web_accessible_resources/google-ima.js
@@ -233,6 +233,12 @@ if (!window.google || !window.google.ima || !window.google.ima.VERSION) {
   const ima = {};
 
   class AdDisplayContainer {
+    constructor(containerElement) {
+      const divElement = document.createElement("div");
+      divElement.style.setProperty("display", "none", "important");
+      divElement.style.setProperty("visibility", "collapse", "important");
+      containerElement.appendChild(divElement);
+    }
     destroy() {}
     initialize() {}
   }
@@ -335,17 +341,30 @@ if (!window.google || !window.google.ima || !window.google.ima.VERSION) {
       }
     }
 
-    addEventListener(t, c) {
-      if (!this.listeners.has(t)) {
-        this.listeners.set(t, new Set());
+    addEventListener(types, c) {
+      if (!Array.isArray(types)) {
+        types = [types];
+      }
+
+      for (const t of types) {
+        if (!this.listeners.has(t)) {
+          this.listeners.set(t, new Set());
+        }
+        this.listeners.get(t).add(c);
       }
-      this.listeners.get(t).add(c);
     }
 
-    removeEventListener(t, c) {
-      const typeSet = this.listeners.get(t);
-      if (!typeSet) { return; }
-      typeSet.delete(c);
+    removeEventListener(types, c) {
+      if (!Array.isArray(types)) {
+        types = [types];
+      }
+
+      for (const t of types) {
+        const typeSet = this.listeners.get(t);
+        if (typeSet) {
+          typeSet.delete(c);
+        }
+      }
     }
   }
 
@@ -553,7 +572,7 @@ if (!window.google || !window.google.ima || !window.google.ima.VERSION) {
       return "unknown";
     }
     getUniversalAdIds() {
-      return [""];
+      return [new UniversalAdIdInfo()];
     }
     getUniversalAdIdValue() {
       return "unknown";
@@ -765,7 +784,7 @@ if (!window.google || !window.google.ima || !window.google.ima.VERSION) {
     getAdIdRegistry() {
       return "";
     }
-    getAdIsValue() {
+    getAdIdValue() {
       return "";
     }
   }
@@ -793,12 +812,12 @@ if (!window.google || !window.google.ima || !window.google.ima.VERSION) {
       FULL: "full",
       LIMITED: "limited",
     },
-    OmidVerificationVendor: new Proxy({}, {
-        get(target, prop) {
-            if ( typeof prop === 'number' ) { return ''; }
-            return 0;
-        }
-    }),
+    OmidVerificationVendor: {
+      1: "OTHER",
+      2: "GOOGLE",
+      GOOGLE: 2,
+      OTHER: 1
+    },
     settings: new ImaSdkSettings(),
     UiElements: {
       AD_ATTRIBUTION: "adAttribution",