Added HandleUpdate method for serverless deploy

(cherry picked from commit d4b2e3c213)

bot.go

@@ -451,18 +451,23 @@ func (bot *BotAPI) ListenForWebhook(pattern string) UpdatesChannel {
 	ch := make(chan Update, bot.Buffer)
 
 	http.HandleFunc(pattern, func(w http.ResponseWriter, r *http.Request) {
-		bytes, _ := ioutil.ReadAll(r.Body)
+		ch <- bot.HandleUpdate(w, r)
-		r.Body.Close()
-
-		var update Update
-		json.Unmarshal(bytes, &update)
-
-		ch <- update
 	})
 
 	return ch
 }
 
+// HandleUpdate parses and returns update received via webhook
+func (bot *BotAPI) HandleUpdate(res http.ResponseWriter, req *http.Request) Update {
+	bytes, _ := ioutil.ReadAll(req.Body)
+	req.Body.Close()
+
+	var update Update
+	json.Unmarshal(bytes, &update)
+
+	return update
+}
+
 // WriteToHTTPResponse writes the request to the HTTP ResponseWriter.
 //
 // It doesn't support uploading files.

bot_test.go

@@ -599,6 +599,35 @@ func ExampleNewWebhook() {
 	}
 }
 
+func ExampleWebhookHandler() {
+	bot, err := NewBotAPI("MyAwesomeBotToken")
+	if err != nil {
+		panic(err)
+	}
+
+	bot.Debug = true
+
+	log.Printf("Authorized on account %s", bot.Self.UserName)
+
+	_, err = bot.Request(NewWebhookWithCert("https://www.google.com:8443/"+bot.Token, "cert.pem"))
+	if err != nil {
+		panic(err)
+	}
+	info, err := bot.GetWebhookInfo()
+	if err != nil {
+		panic(err)
+	}
+	if info.LastErrorDate != 0 {
+		log.Printf("[Telegram callback failed]%s", info.LastErrorMessage)
+	}
+
+	http.HandleFunc("/"+bot.Token, func(w http.ResponseWriter, r *http.Request) {
+		log.Printf("%+v\n", bot.HandleUpdate(w, r))
+	})
+
+	go http.ListenAndServeTLS("0.0.0.0:8443", "cert.pem", "key.pem", nil)
+}
+
 func ExampleInlineConfig() {
 	bot, err := NewBotAPI("MyAwesomeBotToken") // create new bot
 	if err != nil {