From 01e977f922ea29cd2994f96c18e4b3f033b1802d Mon Sep 17 00:00:00 2001
From: Wojtek Kosior <koszko@koszko.org>
Date: Mon, 27 Dec 2021 16:55:28 +0100
Subject: facilitate egistering dynamic content scripts with mappings data

---
 common/broadcast.js      |  6 ++---
 common/indexeddb.js      |  4 ++++
 common/message_server.js | 61 +++++++++++++++++++++++++++++++++++++++++-------
 3 files changed, 60 insertions(+), 11 deletions(-)

(limited to 'common')

diff --git a/common/broadcast.js b/common/broadcast.js
index b69f352..b7743a6 100644
--- a/common/broadcast.js
+++ b/common/broadcast.js
@@ -43,12 +43,12 @@
 
 #IMPORT common/connection_types.js AS CONNECTION_TYPE
 
-#FROM common/browser.js IMPORT browser
+#FROM common/message_server.js IMPORT connect_to_background
 
 function sender_connection()
 {
     return {
-	port: browser.runtime.connect({name: CONNECTION_TYPE.BROADCAST_SEND})
+	port: connect_to_background(CONNECTION_TYPE.BROADCAST_SEND)
     };
 }
 #EXPORT sender_connection
@@ -94,7 +94,7 @@ function flush(sender_conn)
 function listener_connection(cb)
 {
     const conn = {
-	port: browser.runtime.connect({name: CONNECTION_TYPE.BROADCAST_LISTEN})
+	port: connect_to_background(CONNECTION_TYPE.BROADCAST_LISTEN)
     };
 
     conn.port.onMessage.addListener(cb);
diff --git a/common/indexeddb.js b/common/indexeddb.js
index c97c115..096391a 100644
--- a/common/indexeddb.js
+++ b/common/indexeddb.js
@@ -45,7 +45,11 @@
 #IMPORT common/broadcast.js
 
 let initial_data = (
+#IF UNIT_TEST
+    {}
+#ELSE
 #INCLUDE_VERBATIM default_settings.json
+#ENDIF
 );
 
 /* Update when changes are made to database schema. Must have 3 elements */
diff --git a/common/message_server.js b/common/message_server.js
index fd609c7..657e140 100644
--- a/common/message_server.js
+++ b/common/message_server.js
@@ -43,23 +43,68 @@
 
 #FROM common/browser.js IMPORT browser
 
-var listeners = {};
+let listeners = {};
+let listening = false;
 
-/* magic should be one of the constants from /common/connection_types.js */
+function raw_listen(port)
+{
+    if (listeners[port.name] === undefined)
+	return;
+
+    listeners[port.name](port);
+}
 
+/* magic should be one of the constants from /common/connection_types.js */
 function listen_for_connection(magic, cb)
 {
+    if (!listening) {
+	listening = true;
+	browser.runtime.onConnect.addListener(raw_listen);
+    }
     listeners[magic] = cb;
 }
+#EXPORT listen_for_connection
 
-function raw_listen(port)
+/*
+ * Messaging background page from itself might result in messages being silently
+ * discarded. Here we implement an interface (somewhat) compatible with the one
+ * provided by the browser, but which allows for background page to communicate
+ * with itself.
+ */
+function EvTarget()
 {
-    if (listeners[port.name] === undefined)
-	return;
+    this.listeners = new Set();
+    this.addListener    = cb => this.listeners.add(cb);
+    this.removeListener = cb => this.listeners.delete(cb);
+    this.dispatch       = msg => this.listeners.forEach(l => l(msg));
+}
 
-    listeners[port.name](port);
+function Port(magic)
+{
+    this.name = magic;
+    this.onDisconnect = new EvTarget();
+    this.onMessage    = new EvTarget();
+    this.postMessage  = msg => this.other.onMessage.dispatch(msg);
+    this.disconnect   = () => this.other.onDisconnect.dispatch(this.other);
 }
 
-browser.runtime.onConnect.addListener(raw_listen);
+let bg_page_url;
+function connect_to_background(magic)
+{
+    if (bg_page_url === undefined)
+	bg_page_url = browser.runtime.getURL("_generated_background_page.html");
+    if (typeof document === "undefined" || document.URL !== bg_page_url)
+	return browser.runtime.connect({name: magic});
 
-#EXPORT listen_for_connection
+    if (!(magic in listeners))
+	throw `no listener for '${magic}'`
+
+    const ports = [new Port(magic), new Port(magic)];
+    ports[0].other = ports[1];
+    ports[1].other = ports[0];
+
+    listeners[magic](ports[0]);
+    return ports[1];
+}
+
+#EXPORT connect_to_background
-- 
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