Merge pull request #5 from Ronmi/issue

Doing long polling in Bot.Listen to ensure message order

api.go

@@ -126,12 +126,13 @@ func getMe(token string) (User, error) {
 	return User{}, AuthError{botInfo.Description}
 }
 
-func getUpdates(token string, offset int, updates chan<- Update) error {
+func getUpdates(token string, offset int, timeout int) (updates []Update, err error) {
 	params := url.Values{}
 	params.Set("offset", strconv.Itoa(offset))
+	params.Set("timeout", strconv.Itoa(timeout))
 	updatesJSON, err := sendCommand("getUpdates", token, params)
 	if err != nil {
-		return err
+		return
 	}
 
 	var updatesRecieved struct {
@@ -142,16 +143,14 @@ func getUpdates(token string, offset int, updates chan<- Update) error {
 
 	err = json.Unmarshal(updatesJSON, &updatesRecieved)
 	if err != nil {
-		return err
+		return
 	}
 
 	if !updatesRecieved.Ok {
-		return FetchError{updatesRecieved.Description}
+		err = FetchError{updatesRecieved.Description}
-	}
+		return
-
-	for _, update := range updatesRecieved.Result {
-		updates <- update
 	}
 
-	return nil
+	updates = updatesRecieved.Result
+	return
 }

bot.go

@@ -32,27 +32,18 @@ func NewBot(token string) (*Bot, error) {
 
 // Listen periodically looks for updates and delivers new messages
 // to subscription channel.
-func (b Bot) Listen(subscription chan<- Message, interval time.Duration) {
+func (b Bot) Listen(subscription chan<- Message, timeout time.Duration) {
-	updates := make(chan Update)
-	pulse := time.NewTicker(interval)
-	latestUpdate := 0
-
-	go func() {
-		for _ = range pulse.C {
-			go getUpdates(b.Token,
-				latestUpdate+1,
-				updates)
-		}
-	}()
 
 	go func() {
-		for update := range updates {
+		latestUpdate := 0
-			if update.ID > latestUpdate {
+		for {
+			if updates, err := getUpdates(b.Token, latestUpdate+1, int(timeout / time.Second)); err == nil {
+				for _, update := range updates {
 					latestUpdate = update.ID
-			}
-
 					subscription <- update.Payload
 				}
+			}
+		}
 	}()
 }