Fixed lack of checks for nil.

cmd/test/main.go

@@ -13,12 +13,14 @@ var startScreenButton = tx.NewButton().
 	ScreenChange("start")
 
 var beh = tx.NewBehaviour().
+
 	// The function will be called every time
 	// the bot is started.
 	OnStartFunc(func(c *tx.Context) {
 		c.V["counter"] = new(int)
 		c.ChangeScreen("start")
 	}).WithKeyboards(
+
 	// Increment/decrement keyboard.
 	tx.NewKeyboard("inc/dec").Row(
 		tx.NewButton().WithText("+").ActionFunc(func(c *tx.Context) {
@@ -34,6 +36,7 @@ var beh = tx.NewBehaviour().
 	).Row(
 		startScreenButton,
 	),
+
 	// The navigational keyboard.
 	tx.NewKeyboard("nav").Row(
 		tx.NewButton().WithText("Inc/Dec").ScreenChange("inc/dec"),
@@ -41,40 +44,70 @@ var beh = tx.NewBehaviour().
 		tx.NewButton().WithText("Upper case").ScreenChange("upper-case"),
 		tx.NewButton().WithText("Lower case").ScreenChange("lower-case"),
 	),
+
+	tx.NewKeyboard("istart").Row(
+		tx.NewButton().WithText("GoT Github page").
+			WithUrl("https://github.com/mojosa-software/got"),
+	),
+
 	// The keyboard to return to the start screen.
 	tx.NewKeyboard("nav-start").Row(
 		startScreenButton,
 	),
 ).WithScreens(
 	tx.NewScreen("start").
-		WithText("The bot started!").
-		Keyboard("nav"),
+		WithText(
+			"The bot started!"+
+				" The bot is supposed to provide basic"+
+				" understand of how the API works, so just"+
+				" horse around a bit to guess everything out"+
+				" by yourself!",
+		).Keyboard("nav").
+		IKeyboard("istart"),
+
 	tx.NewScreen("inc/dec").
 		WithText(
 			"The screen shows how"+
 				"user separated data works"+
-				"by saving the counter for each of them",
+				"by saving the counter for each of users"+
+				"separately.",
 		).
 		Keyboard("inc/dec").
 		// The function will be called when reaching the screen.
 		ActionFunc(func(c *tx.Context) {
 			counter := c.V["counter"].(*int)
-			c.Sendf("Current counter value equals %d", *counter)
+			c.Sendf("Current counter value = %d", *counter)
 		}),
+
 	tx.NewScreen("upper-case").
 		WithText("Type text and the bot will send you the upper case version to you").
 		Keyboard("nav-start").
-		ActionFunc(func(c *tx.Context) {
-			for {
-				s, err := c.ReadTextMessage()
-				if err == tx.NotAvailableErr {
-					break
-				}
-				c.Sendf("%s", strings.ToUpper(s))
-			}
-		}),
+		ActionFunc(mutateMessage(strings.ToUpper)),
+
+	tx.NewScreen("lower-case").
+		WithText("Type text and the bot will send you the lower case version").
+		Keyboard("nav-start").
+		ActionFunc(mutateMessage(strings.ToLower)),
 )
 
+func mutateMessage(fn func(string) string) tx.ActionFunc {
+	return func(c *tx.Context) {
+		for {
+			msg, err := c.ReadTextMessage()
+			if err == tx.NotAvailableErr {
+				break
+			} else if err != nil {
+				panic(err)
+			}
+
+			err = c.Sendf("%s", fn(msg))
+			if err != nil {
+				panic(err)
+			}
+		}
+	}
+}
+
 func main() {
 	token := os.Getenv("BOT_TOKEN")
 

src/tx/context.go

@@ -44,10 +44,7 @@ func (c *Context) handleUpdateChan(updates chan *Update) {
 				continue
 			}
 
-			if !ok {
-			}
-
-			if ok {
+			if ok && btn.Action != nil {
 				c.run(btn.Action)
 			}
 		} else if u.CallbackQuery != nil {

src/tx/keyboard.go

@@ -38,12 +38,16 @@ func NewKeyboard(id KeyboardId) *Keyboard {
 
 // Adds a new button row to the current keyboard.
 func (kbd *Keyboard) Row(btns ...*Button) *Keyboard {
+	// For empty row. We do not need that.
+	if len(btns) < 1 {
+		return kbd
+	}
 	kbd.Rows = append(kbd.Rows, btns)
 	return kbd
 }
 
 // Convert the Keyboard to the Telegram API type.
-func (kbd *Keyboard) toTelegram() apix.ReplyKeyboardMarkup {
+func (kbd *Keyboard) ToTelegram() apix.ReplyKeyboardMarkup {
 	rows := [][]apix.KeyboardButton{}
 	for _, row := range kbd.Rows {
 		buttons := []apix.KeyboardButton{}
@@ -56,7 +60,7 @@ func (kbd *Keyboard) toTelegram() apix.ReplyKeyboardMarkup {
 	return apix.NewReplyKeyboard(rows...)
 }
 
-func (kbd *Keyboard) toTelegramInline() apix.InlineKeyboardMarkup {
+func (kbd *Keyboard) ToTelegramInline() apix.InlineKeyboardMarkup {
 	rows := [][]apix.InlineKeyboardButton{}
 	for _, row := range kbd.Rows {
 		buttons := []apix.InlineKeyboardButton{}

src/tx/screen.go

@@ -80,7 +80,7 @@ func (s *Screen) Render(c *Context) error {
 		if !ok {
 			return KeyboardNotExistErr
 		}
-		msg.ReplyMarkup = kbd.toTelegramInline()
+		msg.ReplyMarkup = kbd.ToTelegramInline()
 	}
 
 	_, err := c.B.Send(msg)
@@ -101,7 +101,7 @@ func (s *Screen) Render(c *Context) error {
 			if !ok {
 				return KeyboardNotExistErr
 			}
-			tkbd = kbd.toTelegram()
+			tkbd = kbd.ToTelegram()
 		}
 
 		msg.ReplyMarkup = tkbd