From 9ccb1b138ea28784c6193656f48889576ac675fa Mon Sep 17 00:00:00 2001
From: Khush Jammu <khushjammu@gmail.com>
Date: Thu, 4 Jun 2020 15:41:28 +0800
Subject: [PATCH] overhaul disconnect handling

---
 public/js/chat.js | 46 +++++++++++++++++++++++++++++-----------------
 server.js         |  5 +++++
 2 files changed, 34 insertions(+), 17 deletions(-)

diff --git a/public/js/chat.js b/public/js/chat.js
index 0c528af..b3b8224 100644
--- a/public/js/chat.js
+++ b/public/js/chat.js
@@ -106,11 +106,10 @@ var VideoChat = {
     VideoChat.localVideo.style.border = `3px solid ${VideoChat.borderColor}`;
 
     // Add listeners to the websocket
+    VideoChat.socket.on("leave", VideoChat.onLeave);
     VideoChat.socket.on("full", chatRoomFull);
     VideoChat.socket.on("offer", VideoChat.onOffer);
     VideoChat.socket.on("initiateCall", VideoChat.call);
-
-    // Set up listeners on the socket
     VideoChat.socket.on("candidate", VideoChat.onCandidate);
     VideoChat.socket.on("answer", VideoChat.onAnswer);
     VideoChat.socket.on("requestToggleCaptions", () => toggleSendCaptions());
@@ -119,6 +118,7 @@ var VideoChat = {
     );
   },
 
+  // Initiate a call with newly joined peer
   call: function (uuid, room) {
     logIt(`call >>> Initiating call with ${uuid}...`);
     VideoChat.socket.on(
@@ -130,6 +130,24 @@ var VideoChat = {
     VideoChat.socket.emit("token", roomHash, uuid);
   },
 
+  // Handle a peer leaving the room
+  onLeave: function(uuid) {
+    logIt("disconnected - UUID " + uuid);
+    // Remove video element
+    VideoChat.remoteVideoWrapper.removeChild(
+      document.querySelectorAll(`[uuid="${uuid}"]`)[0]
+    );
+
+    // Delete connection & metadata
+    VideoChat.connected.delete(uuid);
+    VideoChat.peerConnections.delete(uuid);
+    dataChannel.delete(uuid);
+
+    if (VideoChat.peerConnections.size === 0) {
+      displayWaitingCaption();
+    }
+  },
+
   establishConnection: function (correctUuid, callback) {
     return function (token, uuid) {
       if (correctUuid != uuid) {
@@ -202,23 +220,12 @@ var VideoChat = {
             logIt("connected");
             break;
           case "disconnected":
-            // First possibility: we disconnected from the peer
-            if (VideoChat.socket.connected === false) {
+            // Remove UUID if connection to server is intact
+            if (VideoChat.socket.connected) {
+              VideoChat.onLeave(uuid);
+            } else {
               location.reload();
             }
-
-            // Second possibility: the peer disconnected from us
-            logIt("disconnected - UUID " + uuid);
-            VideoChat.remoteVideoWrapper.removeChild(
-              document.querySelectorAll(`[uuid="${uuid}"]`)[0]
-            );
-            VideoChat.connected.delete(uuid);
-            VideoChat.peerConnections.delete(uuid);
-            dataChannel.delete(uuid);
-
-            if (VideoChat.peerConnections.size === 0) {
-              displayWaitingCaption();
-            }
             break;
           case "failed":
             logIt("failed");
@@ -1001,6 +1008,11 @@ function displayWaitingCaption() {
   rePositionCaptions();
 }
 
+window.onbeforeunload = function () {
+  VideoChat.socket.emit("leave", roomHash);
+  return null;
+};
+
 function startUp() {
   //  Try and detect in-app browsers and redirect
   var ua = navigator.userAgent || navigator.vendor || window.opera;
diff --git a/server.js b/server.js
index a82b726..84c4d00 100644
--- a/server.js
+++ b/server.js
@@ -93,6 +93,11 @@ io.on("connection", function (socket) {
     }
   });
 
+  socket.on("leave", function (room) {
+    logIt("A client has left the room", room);
+    socket.broadcast.to(room).emit("leave", socket.id);
+  });
+
   // When receiving the token message, use the Twilio REST API to request an
   // token to get ephemeral credentials to use the TURN server.
   socket.on("token", function (room, uuid) {