Implemented session management in game route

src/helpers/useSession.js

@@ -0,0 +1,92 @@
+import { useEffect, useState } from "react";
+import Peer from "peerjs";
+
+function useSession(onConnectionOpen) {
+  const [peerId, setPeerId] = useState(null);
+  const [peer, setPeer] = useState(null);
+  const [connections, setConnections] = useState({});
+  function addConnection(connection) {
+    setConnections(prevConnnections => ({
+      ...prevConnnections,
+      [connection.peer]: connection
+    }));
+  }
+
+  useEffect(() => {
+    setPeer(new Peer());
+  }, []);
+
+  useEffect(() => {
+    function handleOpen(id) {
+      setPeerId(id);
+    }
+
+    function handleConnection(connection) {
+      connection.on("open", () => {
+        connection.send(
+          JSON.stringify({
+            id: "sync",
+            data: Object.keys(connections)
+          })
+        );
+
+        addConnection(connection);
+
+        if (onConnectionOpen) {
+          onConnectionOpen();
+        }
+      });
+
+      function removeConnection() {
+        setConnections(prevConnections => {
+          const { [connection.peer]: old, ...rest } = prevConnections;
+          return rest;
+        });
+      }
+
+      connection.on("close", removeConnection);
+      connection.on("error", removeConnection);
+    }
+
+    if (!peer) {
+      return;
+    }
+
+    peer.on("open", handleOpen);
+    peer.on("connection", handleConnection);
+    return () => {
+      peer.removeListener("open", handleOpen);
+      peer.removeListener("connection", handleConnection);
+    };
+  }, [peer, peerId, connections]);
+
+  function sync(connectionIds) {
+    for (let connectionId of connectionIds) {
+      if (connectionId in connections) {
+        continue;
+      }
+      const connection = peer.connect(connectionId);
+      addConnection(connection);
+    }
+  }
+
+  function connectTo(connectionId) {
+    if (connectionId in connections) {
+      return;
+    }
+    const connection = peer.connect(connectionId);
+    connection.on("open", () => {
+      connection.on("data", json => {
+        const data = JSON.parse(json);
+        if (data.id === "sync") {
+          sync(data.data);
+        }
+      });
+    });
+    addConnection(connection);
+  }
+
+  return [peer, peerId, connections, connectTo];
+}
+
+export default useSession;

src/routes/Game.js

@@ -1,10 +1,18 @@
-import React, { useContext } from "react";
+import React, { useContext, useEffect } from "react";
 import { A } from "hookrouter";
 
 import GameContext from "../contexts/GameContext";
+import useSession from "../helpers/useSession";
 
 function Game() {
   const [gameId, setGameId] = useContext(GameContext);
+  const [peer, peerId, connections, connectTo] = useSession();
+
+  useEffect(() => {
+    if (gameId !== null && peerId !== null) {
+      connectTo(gameId);
+    }
+  }, [gameId, peerId]);
 
   return (
     <div>

src/routes/Join.js

@@ -24,7 +24,7 @@ function Join() {
           my={4}
           id="id"
           name="id"
-          value={gameId}
+          value={gameId || ""}
           onChange={handleChange}
         />
         <Button>Go ʕ•ᴥ•ʔ</Button>

src/useSession.js

@@ -1,56 +0,0 @@
-import { useEffect, useState } from "react";
-import Peer from "peerjs";
-
-function useSession(imgRef) {
-  const [peerId, setPeerId] = useState(null);
-  const [peer, setPeer] = useState(null);
-  const [connections, setConnections] = useState({});
-
-  useEffect(() => {
-    setPeer(new Peer());
-  }, []);
-
-  useEffect(() => {
-    function handleOpen(id) {
-      setPeerId(id);
-    }
-
-    function handleConnection(connection) {
-      setConnections(prevConnnections => ({
-        ...prevConnnections,
-        [connection.peer]: connection
-      }));
-
-      connection.on("open", () => {
-        if (imgRef.current) {
-          connection.send(imgRef.current);
-        }
-      });
-
-      function removeConnection() {
-        setConnections(prevConnections => {
-          const { [connection.peer]: old, ...rest } = prevConnections;
-          return rest;
-        });
-      }
-
-      connection.on("close", removeConnection);
-      connection.on("error", removeConnection);
-    }
-
-    if (!peer) {
-      return;
-    }
-
-    peer.on("open", handleOpen);
-    peer.on("connection", handleConnection);
-    return () => {
-      peer.removeListener("open", handleOpen);
-      peer.removeListener("connection", handleConnection);
-    };
-  }, [peer, peerId, connections, imgRef]);
-
-  return [peer, peerId, connections];
-}
-
-export default useSession;