Env documentation, log, last hope handler

Signed-off-by: Terekhin Alexandr <alex@bearns.me>

go.mod

@@ -1,3 +1,5 @@
 module bearns.me/didinst/tg-bot-example
 
 go 1.15
+
+require gopkg.in/tucnak/telebot.v2 v2.3.5

main.go

@@ -9,10 +9,10 @@ import (
 
 func main() {
 	var (
-        port      = os.Getenv("PORT")
-        publicURL = os.Getenv("PUBLIC_URL")
-        token     = os.Getenv("TOKEN")
-        apiURL	= os.Getenv("API_URL")
+		port      = os.Getenv("PORT")       // Bot app listening port, same as port in API_URL
+		publicURL = os.Getenv("PUBLIC_URL") // http://<telegram-api-server>:<port>
+		token     = os.Getenv("TOKEN")      // Token from @BotFather
+		apiURL    = os.Getenv("API_URL")    // http://<bot-app-host>:<bot-app-port>/<random-name-path>
 	)
 
 	webhook := &tb.Webhook{
@@ -31,13 +31,18 @@ func main() {
 		log.Fatal(err)
 	}
 
+	b.Handle("/hello", func(m *tb.Message) {
+		log.Print(m)
+		_, err := b.Send(m.Sender, "Hello World!")
 		if err != nil {
-		log.Fatal(err)
-		return
+			log.Print(err)
 		}
+	})
 
-	b.Handle("/hello", func(m *tb.Message) {
-		b.Send(m.Sender, "Hello World!")
+	b.Handle(tb.OnText, func(m *tb.Message) {
+		log.Print(m)
+		// all the text messages that weren't
+		// captured by existing handlers
 	})
 
 	b.Start()