code: add go.mod and send user list on join

code/hub.go

@@ -8,14 +8,16 @@ import (
 )
 
 type message struct {
-	Sender  string    `json:"sender"`
-	Content string    `json:"content"`
-	Date    time.Time `json:"date"`
-	Success bool      `json:"success"`
+	Type    string      `json:"type"`
+	Sender  string      `json:"sender"`
+	Content interface{} `json:"content"`
+	Date    time.Time   `json:"date"`
+	Success bool        `json:"success"`
 }
 
 func newError(content string) message {
 	return message{
+		Type:    "error",
 		Sender:  "",
 		Content: content,
 		Date:    time.Now().UTC(),
@@ -25,6 +27,7 @@ func newError(content string) message {
 
 func newMessage(sender string, content string) message {
 	return message{
+		Type:    "message",
 		Sender:  sender,
 		Content: content,
 		Date:    time.Now().UTC(),
@@ -40,6 +43,23 @@ func (m message) dispatch() {
 
 var usernames = make(map[*websocket.Conn]string)
 
+func sendUserList(who *websocket.Conn) {
+	list := []string{}
+	for _, username := range usernames {
+		list = append(list, username)
+	}
+
+	m := message{
+		Type:    "users",
+		Sender:  "",
+		Content: list,
+		Date:    time.Now().UTC(),
+		Success: true,
+	}
+
+	_ = who.WriteJSON(m)
+}
+
 func sendChatMessage(sender *websocket.Conn, msg string) {
 	m := newMessage(usernames[sender], msg)
 	m.dispatch()
@@ -61,6 +81,7 @@ func handleIncomingMessage(sender *websocket.Conn, msg string) {
 
 		usernames[sender] = username
 
+		sendUserList(sender)
 		m := newMessage("server", username+" has joined the chat")
 		m.dispatch()
 		return

go.mod

@@ -0,0 +1,5 @@
+module gitea.teamortix.com/hamza/go-websockets-talk
+
+go 1.12
+
+require github.com/gorilla/websocket v1.4.1

go.sum

@@ -0,0 +1,2 @@
+github.com/gorilla/websocket v1.4.1 h1:q7AeDBpnBk8AogcD4DSag/Ukw/KV+YhzLj2bP5HvKCM=
+github.com/gorilla/websocket v1.4.1/go.mod h1:YR8l580nyteQvAITg2hZ9XVh4b55+EU/adAjf1fMHhE=