code: refactor code to use enums, and reorder funcs

code/hub.go

@@ -7,8 +7,44 @@ import (
 	"github.com/gorilla/websocket"
 )
 
+var usernames = make(map[*websocket.Conn]string)
+
+func handleIncomingMessage(sender *websocket.Conn, msg string) {
+	if _, ok := usernames[sender]; !ok {
+		username := strings.TrimSpace(msg)
+		if username == "" || username == "server" {
+			sender.WriteJSON(newError("You have an illegal nickname"))
+			return
+		}
+		sendUserList(sender)
+
+		usernames[sender] = username
+		m := newMessage(msgJoin, "server", username)
+		m.dispatch()
+		return
+	}
+
+	sendChatMessage(sender, msg)
+}
+
+func handleDisconnection(sender *websocket.Conn) {
+	m := newMessage(msgLeave, "server", usernames[sender])
+	m.dispatch()
+	delete(usernames, sender)
+}
+
+type messageType string
+
+const (
+	msgChat     messageType = "message"
+	msgJoin     messageType = "join"
+	msgLeave    messageType = "leave"
+	msgErr      messageType = "error"
+	msgUserList messageType = "users"
+)
+
 type message struct {
-	Type    string      `json:"type"`
+	Type    messageType `json:"type"`
 	Sender  string      `json:"sender"`
 	Content interface{} `json:"content"`
 	Date    time.Time   `json:"date"`
@@ -17,7 +53,7 @@ type message struct {
 
 func newError(content string) message {
 	return message{
-		Type:    "error",
+		Type:    msgErr,
 		Sender:  "",
 		Content: content,
 		Date:    time.Now().UTC(),
@@ -25,7 +61,7 @@ func newError(content string) message {
 	}
 }
 
-func newMessage(msgType string, sender string, content string) message {
+func newMessage(msgType messageType, sender string, content string) message {
 	return message{
 		Type:    msgType,
 		Sender:  sender,
@@ -41,8 +77,6 @@ func (m message) dispatch() {
 	}
 }
 
-var usernames = make(map[*websocket.Conn]string)
-
 func sendUserList(who *websocket.Conn) {
 	list := []string{}
 	for _, username := range usernames {
@@ -50,7 +84,7 @@ func sendUserList(who *websocket.Conn) {
 	}
 
 	m := message{
-		Type:    "users",
+		Type:    msgUserList,
 		Sender:  "",
 		Content: list,
 		Date:    time.Now().UTC(),
@@ -61,30 +95,6 @@ func sendUserList(who *websocket.Conn) {
 }
 
 func sendChatMessage(sender *websocket.Conn, msg string) {
-	m := newMessage("message", usernames[sender], msg)
+	m := newMessage(msgChat, usernames[sender], msg)
-	m.dispatch()
-}
-
-func handleDisconnection(sender *websocket.Conn) {
-	m := newMessage("leave", "server", usernames[sender])
 	m.dispatch()
-	delete(usernames, sender)
-}
-
-func handleIncomingMessage(sender *websocket.Conn, msg string) {
-	if _, ok := usernames[sender]; !ok {
-		username := strings.TrimSpace(msg)
-		if username == "" || username == "server" {
-			sender.WriteJSON(newError("You have an illegal nickname"))
-			return
-		}
-		sendUserList(sender)
-
-		usernames[sender] = username
-		m := newMessage("join", "server", username)
-		m.dispatch()
-		return
-	}
-
-	sendChatMessage(sender, msg)
 }

code/main.go

@@ -7,12 +7,10 @@ import (
 	"github.com/gorilla/websocket"
 )
 
-var (
+var upgrader = websocket.Upgrader{
-	upgrader = websocket.Upgrader{
 	ReadBufferSize:  1024,
 	WriteBufferSize: 1024,
 }
-)
 
 func websocketConnection(w http.ResponseWriter, r *http.Request) {
 	ws, err := upgrader.Upgrade(w, r, nil)