moved latency calculation server-side

made host per channel exclusive
added auto-reconnection

server/index.js

@@ -17,6 +17,7 @@ const wss = new WebSocket.Server({
 function noop() {}
 
 function heartbeat() {
+  this.latency = Math.round((new Date().getTime() - this.pingStart) / 2);
   this.isAlive = true;
 }
 
@@ -25,11 +26,32 @@ wss.on("connection", function connection(ws, req) {
     .split("/")
     .pop()
     .toLocaleLowerCase();
+  if (ws.channel.match(/-host$/i)) {
+    ws.isHost = true;
+    ws.channel = ws.channel.substr(0, ws.channel.length - 5);
+    // check for another host on this channel
+    if (
+      Array.from(wss.clients).some(
+        client =>
+          client !== ws &&
+          client.readyState === WebSocket.OPEN &&
+          client.channel === ws.channel &&
+          client.isHost
+      )
+    ) {
+      console.log(ws.channel, "duplicate host");
+      ws.close(1000, `The channel "${ws.channel}" already has a host`);
+      return;
+    }
+  }
   ws.isAlive = true;
+  ws.pingStart = new Date().getTime();
+  ws.ping(noop);
   ws.on("pong", heartbeat);
   ws.on("message", function incoming(data) {
-    if (!data.match(/^\["ping/i)) {
-      console.log(ws.channel, wss.clients.size, data);
+    const isPing = data.match(/^\["ping/i);
+    if (!isPing) {
+      console.log(new Date(), wss.clients.size, ws.channel, data);
     }
     wss.clients.forEach(function each(client) {
       if (
@@ -37,8 +59,13 @@ wss.on("connection", function connection(ws, req) {
         client.readyState === WebSocket.OPEN &&
         client.channel === ws.channel
       ) {
+        // inject latency between both clients if ping message
+        if (isPing && client.latency && ws.latency) {
+          client.send(data.replace(/latency/, client.latency + ws.latency));
+        } else {
           client.send(data);
         }
+      }
     });
   });
 });
@@ -47,6 +74,7 @@ const interval = setInterval(function ping() {
   wss.clients.forEach(function each(ws) {
     if (ws.isAlive === false) return ws.terminate();
     ws.isAlive = false;
+    ws.pingStart = new Date().getTime();
     ws.ping(noop);
   });
 }, 30000);

src/components/Menu.vue

@@ -3,7 +3,10 @@
     <Screenshot ref="screenshot"></Screenshot>
     <span
       class="session"
-      :class="{ spectator: session.isSpectator }"
+      :class="{
+        spectator: session.isSpectator,
+        reconnecting: session.isReconnecting
+      }"
       v-if="session.sessionId"
       @click="leaveSession"
       :title="
@@ -342,6 +345,16 @@ export default {
     &.spectator {
       color: $townsfolk;
     }
+    &.reconnecting {
+      animation: blink 1s infinite;
+    }
+  }
+}
+
+@keyframes blink {
+  50% {
+    opacity: 0.5;
+    color: gray;
   }
 }
 

src/store/modules/session.js

@@ -20,6 +20,7 @@ const handleVote = (state, [index, vote]) => {
 const state = () => ({
   sessionId: "",
   isSpectator: false,
+  isReconnecting: false,
   playerCount: 0,
   ping: 0,
   playerId: "",
@@ -38,6 +39,7 @@ const mutations = {
   setSessionId: set("sessionId"),
   setPlayerId: set("playerId"),
   setSpectator: set("isSpectator"),
+  setReconnecting: set("isReconnecting"),
   setPlayerCount: set("playerCount"),
   setPing: set("ping"),
   setVotingSpeed: set("votingSpeed"),

src/store/socket.js

@@ -10,6 +10,7 @@ class LiveSession {
     this._store = store;
     this._pingInterval = 30 * 1000; // 30 seconds between pings
     this._pingTimer = null;
+    this._reconnectTimer = null;
     this._players = {}; // map of players connected to a session
     this._pings = {}; // map of player IDs to ping
     // reconnect to previous session
@@ -25,14 +26,26 @@ class LiveSession {
    */
   _open(channel) {
     this.disconnect();
-    this._socket = new WebSocket(this._wss + channel);
+    this._socket = new WebSocket(
+      this._wss + channel + (this._isSpectator ? "" : "-host")
+    );
     this._socket.addEventListener("message", this._handleMessage.bind(this));
     this._socket.onopen = this._onOpen.bind(this);
-    this._socket.onclose = () => {
+    this._socket.onclose = err => {
       this._socket = null;
-      this._store.commit("session/setSessionId", "");
       clearInterval(this._pingTimer);
       this._pingTimer = null;
+      if (err.code !== 1000) {
+        // connection interrupted, reconnect after 3 seconds
+        this._store.commit("session/setReconnecting", true);
+        this._reconnectTimer = setTimeout(
+          () => this.connect(channel),
+          3 * 1000
+        );
+      } else {
+        this._store.commit("session/setSessionId", "");
+        if (err.reason) alert(err.reason);
+      }
     };
   }
 
@@ -69,7 +82,7 @@ class LiveSession {
     this._send("ping", [
       this._isSpectator,
       this._store.state.session.playerId,
-      new Date().getTime()
+      "latency"
     ]);
     this._handlePing();
     clearTimeout(this._pingTimer);
@@ -168,9 +181,11 @@ class LiveSession {
     this._pings = {};
     this._store.commit("session/setPlayerCount", 0);
     this._store.commit("session/setPing", 0);
+    this._store.commit("session/setReconnecting", false);
+    clearTimeout(this._reconnectTimer);
     if (this._socket) {
       this._send("bye", this._store.state.session.playerId);
-      this._socket.close();
+      this._socket.close(1000);
       this._socket = null;
     }
   }
@@ -378,7 +393,7 @@ class LiveSession {
    * @param timestamp
    * @private
    */
-  _handlePing([isSpectator, playerId, timestamp] = []) {
+  _handlePing([isSpectator, playerId, latency] = []) {
     const now = new Date().getTime();
     // remove players that haven't sent a ping in twice the timespan
     for (let player in this._players) {
@@ -404,10 +419,12 @@ class LiveSession {
         alert("Another storyteller joined the session!");
       } else if (this._isSpectator && !isSpectator) {
         // ping to ST
-        this._store.commit("session/setPing", now - timestamp);
-      } else {
+        if (parseInt(latency, 10)) {
+          this._store.commit("session/setPing", parseInt(latency, 10));
+        }
+      } else if(parseInt(latency, 10)) {
         // ping to Players
-        this._pings[playerId] = now - timestamp;
+        this._pings[playerId] = parseInt(latency, 10);
         const pings = Object.values(this._pings);
         this._store.commit(
           "session/setPing",