From 9c3a494a2826e24a60898ae47766a7a41c4cce2d Mon Sep 17 00:00:00 2001
From: "J. Koppen" <j.koppen@bluebillywig.com>
Date: Tue, 4 Oct 2022 21:05:19 +0200
Subject: [PATCH] fix: Respect existing app usage of Cast SDK (#4523)

Closes #4521
---
 AUTHORS                 |  1 +
 CONTRIBUTORS            |  1 +
 lib/cast/cast_sender.js | 53 ++++++++++++++++++++++++++++++-----------
 3 files changed, 41 insertions(+), 14 deletions(-)

diff --git a/AUTHORS b/AUTHORS
index cfc62d4f2e..7594b07afd 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -82,3 +82,4 @@ ViacomCBS <*@viacomcbs.com>
 Vincent Valot <valot.vince@gmail.com>
 Wayne Morgan <wayne.morgan.dev@gmail.com>
 Raymond Cheng <raycheng100@gmail.com>
+Blue Billywig <*@bluebillywig.com>
diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 47fe23ff05..9c4da40aee 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -122,3 +122,4 @@ Vincent Valot <valot.vince@gmail.com>
 Wayne Morgan <wayne.morgan.dev@gmail.com>
 Yohann Connell <robinconnell@google.com>
 Raymond Cheng <raycheng100@gmail.com>
+Janroel Koppen <j.koppen@bluebillywig.com>
diff --git a/lib/cast/cast_sender.js b/lib/cast/cast_sender.js
index 95e9aec6c5..f1b5e2f96a 100644
--- a/lib/cast/cast_sender.js
+++ b/lib/cast/cast_sender.js
@@ -192,21 +192,14 @@ shaka.cast.CastSender = class {
       // If the API becomes available before this instance dies, init will be
       // called again.
 
-      // A note about this value: In our testing environment, we load both
-      // uncompiled and compiled code.  This global callback in uncompiled mode
-      // can be overwritten by the same in compiled mode.  The two versions will
-      // each have their own instances_ map.  Therefore the callback must have a
-      // name, as opposed to being anonymous.  This way, the CastSender tests
-      // can invoke the named static method instead of using a global that could
-      // be overwritten.
-      if (!window.__onGCastApiAvailable) {
-        window.__onGCastApiAvailable = shaka.cast.CastSender.onSdkLoaded_;
-      }
-      if (window.__onGCastApiAvailable != shaka.cast.CastSender.onSdkLoaded_) {
-        shaka.log.alwaysWarn('A global Cast SDK hook is already installed! ' +
-          'Shaka Player will be unable to receive a notification when the ' +
-          'Cast SDK is ready.');
+      // Check if our callback is already installed.
+      if (window.__onGCastApiAvailable !== CastSender.onGCastApiAvailable_) {
+        // Save pre-existing __onGCastApiAvailable in order to restore later.
+        CastSender.__onGCastApiAvailable_ =
+          window.__onGCastApiAvailable || null;
+        window.__onGCastApiAvailable = CastSender.onGCastApiAvailable_;
       }
+
       return;
     }
 
@@ -757,6 +750,9 @@ shaka.cast.CastSender.hasReceivers_ = false;
 /** @private {chrome.cast.Session} */
 shaka.cast.CastSender.session_ = null;
 
+/** @private {?function(boolean)} */
+shaka.cast.CastSender.__onGCastApiAvailable_ = null;
+
 /**
  * A set of all living CastSender instances.  The constructor and destroy
  * methods will add and remove instances from this set.
@@ -784,3 +780,32 @@ shaka.cast.CastSender.onSdkLoaded_ = (loaded) => {
     }
   }
 };
+
+/**
+ * @param {boolean} available
+ * @private
+ */
+shaka.cast.CastSender.onGCastApiAvailable_ = (available) => {
+  // Restore callback from saved.
+  if (shaka.cast.CastSender.__onGCastApiAvailable_) {
+    window.__onGCastApiAvailable =
+      shaka.cast.CastSender.__onGCastApiAvailable_;
+  } else {
+    delete window.__onGCastApiAvailable;
+  }
+  shaka.cast.CastSender.__onGCastApiAvailable_ = null;
+
+  // A note about this value: In our testing environment, we load both
+  // uncompiled and compiled code.  This global callback in uncompiled mode
+  // can be overwritten by the same in compiled mode.  The two versions will
+  // each have their own instances_ map.  Therefore the callback must have a
+  // name, as opposed to being anonymous.  This way, the CastSender tests
+  // can invoke the named static method instead of using a global that could
+  // be overwritten.
+  shaka.cast.CastSender.onSdkLoaded_(available);
+
+  // call restored callback (if any)
+  if (typeof window.__onGCastApiAvailable === 'function') {
+    window.__onGCastApiAvailable(available);
+  }
+};