cordova-angular: use new pause event API

Uses the new 'pauseLock.release()' API to suspend the app only after
the socket.io server closes.
Keeps track of every socket to close the underlying connection in the
pause event.
Adds a error event listener to not crash when the OS forcibly closes
an unclosed socket when the application suspends.

Author: jaimecbernardo

cordova-angularjs/src/server/main.js

@@ -51,12 +51,35 @@ io.on('connection', (newSocket) => {
         console.log('Socket.io: error: ' + err);
     });
 
-    newSocket.on('disconnect', () => {
-        console.log('Socket.io: disconnected');
+    newSocket.on('close', () => {
+        console.log('Socket.io: close ');
+    });
+
+    newSocket.on('disconnecting', (reason) => {
+        console.log('Socket.io: disconnecting. Reason: ' + reason);
+    });
+
+    newSocket.on('disconnect', (reason) => {
+        console.log('Socket.io: disconnected. Reason: ' + reason);
         newSocket.removeAllListeners();
     });
 });
 
+// Keep a set of all connected sockets to destroy destroy when trying to close the server.
+let connectedSockets = new Set();
+server.on('connection', (conn) => {
+    connectedSockets.add(conn);
+    conn.on('close', () => {
+        console.log('Socket.io: close ');
+        connectedSockets.delete(conn);
+    });
+});
+
+// Catch errors from the OS when the server is not closed before app suspension.
+server.on('error', (err) => {
+    console.log('Server error: ' + JSON.stringify(err));
+});
+
 function server_start() {
     if (!server.listening) {
         server.listen(8081, () => {
@@ -68,14 +91,23 @@ function server_start() {
 if (isMobile) {
     const cordova = require('cordova-bridge');
 
-    cordova.app.on('pause', () => {
-        console.log('NodeJS received a pause event.');
-        server.close();
+    cordova.app.on('pause', (lock) => {
+        io.close( () => {
+            console.log("Node: I have closed the server.")
+            lock.release();
+        });
+        // The server will only close after all underlying connections have been destroyed.
+        var socketsToDestroy = connectedSockets.values();
+        connectedSockets.forEach( (sock) => {
+            sock.destroy();
+        });
+        cordova.channel.post('angular-log', "pause event received.");
     });
 
     cordova.app.on('resume', () => {
         console.log('NodeJS received a resume event.');
         server_start();
+        cordova.channel.post('angular-log', "resume event received.");
     });
 
     let listenersBackup = {};