Adds the ability to play youtube videos.

It still needs a bit of work, but playing and pausing are operational.

add-on/background.js

@@ -1,10 +1,112 @@
 console.log("Hello from Universal Music addon!")
+const tabMessages = new Map();
+var numTabMessages = 0;
 /*
 On startup, connect to the "ping_pong" app.
 */
 var port = browser.runtime.connectNative("universalmusic");
 
+var tabPort = null;
+
+function setupTab(port)
+{
+    console.info("Tab " + port.sender.tab.url + " loaded.");
+    tabPort = port;
+    tabPort.onDisconnect.addListener(e => {
+        tabPort = null;
+        if (e.error)
+        {
+            console.error("Tab error: ", e.error)
+        }
+        else
+        {
+            console.info("Tab " + e.sender.tab.url + " disconnected.");
+        }
+        browser.tabs.remove(e.sender.tab.id);
+    });
+    tabPort.onMessage.addListener(message => {
+        if (typeof message == "object" && message.type == "response")
+        {
+            tabMessages.set(message.num, message.data);
+        }
+    });
+    return true;
+}
+
+function queryTab(message)
+{
+    let num = numTabMessages++;
+    let promise = new Promise((resolve, reject) => {
+        tabPort.postMessage({
+            num: num,
+            data: message
+        });
+        (function awaitResponse() {
+            if (tabMessages.has(num))
+            {
+                response = tabMessages.get(num);
+                tabMessages.delete(num);
+                return resolve(response);
+            }
+            else
+            {
+                setTimeout(awaitResponse, 30);
+            }
+        })();
+    });
+    tabMessages.set(numTabMessages, promise);
+    numTabMessages++;
+    return promise;
+}
+
 var listeners = [function (message, returnValue) {
+    if (typeof message == "object" && "type" in message)
+    {
+        let type = message.type;
+        lastPeriod = type.lastIndexOf(".");
+        if (lastPeriod != -1)
+        {
+            type = type.substring(lastPeriod + 1);
+        }
+        switch (type)
+        {
+        case "CommandSong":
+            returnValue = () => browser.tabs.create({url: message.song}).then(setupTab);
+            if (tabPort)
+            {
+                console.log("Replacing tab");
+                /*
+                 * Closes the existing tab first
+                 */
+                returnValue = browser.tabs.remove(e.sender.tab.id).then(returnValue);
+            }
+            else
+            {
+                console.log("Opening tab");
+                returnValue = returnValue();
+            }
+            break;
+        case "QueryStatus":
+            if (!tabPort)
+            {
+                returnValue = 4;
+                break;
+            }
+        case "QueryTime":
+        case "QueryLength":
+        case "CommandSetPlayback":
+        case "CommandSeek":
+            returnValue = queryTab(message);
+            break;
+        case "CommandQuit":
+            returnValue = quit();
+            break;
+        }
+    }
+    else if (message == "quit")
+    {
+        returnValue = quit();
+    }
     if (returnValue == null)
     {
         returnValue = "pong";
@@ -12,6 +114,17 @@ var listeners = [function (message, returnValue) {
     return returnValue;
 }];
 
+function quit()
+{
+    console.log("Quitting browser");
+    return browser.tabs.query({}).then(tabs => {
+        for (let tab of tabs)
+        {
+            browser.tabs.remove(tab.id);
+        }
+    });
+}
+
 function sleep(ms) {
     return new Promise(resolve => setTimeout(resolve, ms));
 }
@@ -20,11 +133,25 @@ function handleMessage(message)
 {
     return new Promise((resolve, reject) => {
         var returnValue = null;
-        for (index in listeners)
+        try
         {
-            returnValue = listeners[index](message, returnValue);
+            for (index in listeners)
+            {
+                returnValue = listeners[index](message, returnValue);
+            }
+            if (returnValue instanceof Promise)
+            {
+                returnValue.then(resolve).catch(reject);
+            }
+            else
+            {
+                resolve(returnValue);
+            }
+        }
+        catch (e)
+        {
+            reject(e);
         }
-        resolve(returnValue);
     })
 }
 
@@ -32,14 +159,26 @@ function handleMessage(message)
  * Listen for messages from the app.
  */
 port.onMessage.addListener((message) => {
-    console.log("Received: ", message);
+    console.log("Received from interface: ", message);
 
     handleMessage(message.message).then((response) => {
         returnValue = {
             "messageNum": message.messageNum,
-            "message": response
+            "message": {
+                "type": "edu.regis.universeplayer.browserCommands.CommandReturn",
+                "returnValue": response,
+                "confirmation": {
+                    type: "edu.regis.universeplayer.browserCommands.CommandConfirmation",
+                    message: "Done",
+                    errorCode: null
+                }
+            }
         }
         console.log("Sending ", returnValue)
         port.postMessage(returnValue);
+    }).catch(error => {
+
     });
 });
+
+browser.runtime.onConnect.addListener(setupTab);