buzzer-game/main.go

package main

import (
	"log"
	"net/http"
	"sync"

	"github.com/gorilla/websocket"
)

type webSocketHandler struct {
	upgrader websocket.Upgrader
}

// GLOBALS
var connections int = 0
var wg sync.WaitGroup

func (wsh webSocketHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	//upgrade http connection to websocket
	connection, err := wsh.upgrader.Upgrade(w, r, nil)
	if err != nil {
		log.Printf("Error while upgrading connection to websocket: %s", err)
		return
	}
	connections++
	log.Printf("New websocket connection. There are now %v\n", connections)
	wg.Add(1)
	go func() {
		defer connection.Close()
		for {
			msgType, message, err := connection.ReadMessage()
			if err != nil {
				log.Printf("Error trying to read message from client: %s", err)
				return
			}
			if msgType == websocket.BinaryMessage {
				err = connection.WriteMessage(websocket.TextMessage, []byte("this server does not support binary messages"))
				if err != nil {
					log.Printf("Error trying to send message to client: %s", err)
				}
				return
			}
			log.Printf("received message from client: %s", message)
			err = connection.WriteMessage(websocket.TextMessage, []byte("Message received!"))
		}
	}()
}

func main() {
	webSocketHandler := webSocketHandler{
		upgrader: websocket.Upgrader{},
	}
	var port string = "8080"
	http.Handle("/", webSocketHandler)
	wg.Add(1)
	log.Printf("listening on port %s...\n", port)
	log.Fatal(http.ListenAndServe("localhost:8080", nil))
	wg.Wait()
}