Re-implemented the customizing by the Widget interface.

cmd/test/main.go

@@ -16,11 +16,31 @@ type UserData struct {
 	Counter int
 }
 
+type MutateMessageWidget struct {
+	Mutate func(string) string
+}
+
+func NewMutateMessageWidget(fn func(string) string) *MutateMessageWidget {
+	ret := &MutateMessageWidget{}
+	ret.Mutate = fn
+	return ret
+}
+
+func (w *MutateMessageWidget) Serve(c *tg.Context, updates chan *tg.Update) {
+	for u := range updates {
+		if u.Message == nil {
+			continue
+		}
+		text := u.Message.Text
+		c.Sendf("%s", w.Mutate(text))
+	}
+}
+
 var (
 	startScreenButton = tg.NewButton("🏠 To the start screen").
 				ScreenChange("start")
 
-	incDecKeyboard = tg.NewInline().Row(
+	incDecKeyboard = tg.NewReply().Row(
 		tg.NewButton("+").ActionFunc(func(c *tg.Context) {
 			d := c.Session.Value.(*UserData)
 			d.Counter++
@@ -38,12 +58,12 @@ var (
 	navKeyboard = tg.NewReply().
 			WithOneTime(true).
 			Row(
-			tg.NewButton("Inc/Dec").ScreenChange("inc/dec"),
+			tg.NewButton("Inc/Dec").ScreenChange("start/inc-dec"),
 		).Row(
-		tg.NewButton("Upper case").ScreenChange("upper-case"),
-		tg.NewButton("Lower case").ScreenChange("lower-case"),
+		tg.NewButton("Upper case").ScreenChange("start/upper-case"),
+		tg.NewButton("Lower case").ScreenChange("start/lower-case"),
 	).Row(
-		tg.NewButton("Send location").ScreenChange("send-location"),
+		tg.NewButton("Send location").ScreenChange("start/send-location"),
 	)
 
 	sendLocationKeyboard = tg.NewReply().
@@ -64,7 +84,7 @@ var (
 							l.Heading,
 						)
 					} else {
-						_, err = c.Sendf("Somehow wrong location was sent")
+						_, err = c.Sendf("Somehow location was not sent")
 					}
 					if err != nil {
 						c.Sendf("%q", err)
@@ -89,62 +109,69 @@ var beh = tg.NewBehaviour().
 	WithPreStartFunc(func(c *tg.Context){
 		c.Sendf("Please, use the /start command to start the bot")
 	}).WithScreens(
-	tg.NewScreen("start").
-		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!",
-		).WithReply(navKeyboard).
-		// The inline keyboard with link to GitHub page.
-		WithInline(
+		tg.NewScreen("start", tg.NewPage(
+				"The bot started!",
+			).WithInline(
 				tg.NewInline().Row(
 					tg.NewButton("GoT Github page").
 						WithUrl("https://github.com/mojosa-software/got"),
 				),
+			).WithReply(
+				navKeyboard,
 			),
-
-	tg.NewScreen("inc/dec").
-		WithText(
+		),
+		tg.NewScreen("start/inc-dec", tg.NewPage(
 				"The screen shows how "+
 					"user separated data works "+
 					"by saving the counter for each of users "+
 					"separately. ",
-		).
-		WithReply(&tg.ReplyKeyboard{Keyboard: incDecKeyboard.Keyboard}).
-		// The function will be called when reaching the screen.
-		ActionFunc(func(c *tg.Context) {
+			).WithReply(
+				incDecKeyboard,
+			).ActionFunc(func(c *tg.Context) {
+				// The function will be calleb before serving page.
 				d := c.Session.Value.(*UserData)
 				c.Sendf("Current counter value = %d", d.Counter)
 			}),
+		),
 
-	tg.NewScreen("upper-case").
-		WithText("Type text and the bot will send you the upper case version to you").
-		WithReply(navToStartKeyboard).
-		ActionFunc(mutateMessage(strings.ToUpper)),
+		tg.NewScreen("start/upper-case", tg.NewPage(
+				"Type text and the bot will send you the upper case version to you",
+			).WithReply(
+				navToStartKeyboard,
+			).WithSub(
+				NewMutateMessageWidget(strings.ToUpper),
+			),
+		),
 
-	tg.NewScreen("lower-case").
-		WithText("Type text and the bot will send you the lower case version").
-		WithReply(navToStartKeyboard).
-		ActionFunc(mutateMessage(strings.ToLower)),
+		tg.NewScreen("start/lower-case", tg.NewPage(
+				"Type text and the bot will send you the lower case version",
+			).WithReply(
+				navToStartKeyboard,
+			).WithSub(
+				NewMutateMessageWidget(strings.ToLower),
+			),
+		),
 
-	tg.NewScreen("send-location").
-		WithText("Send your location and I will tell where you are!").
-		WithReply(sendLocationKeyboard).
-		WithInline(
+		tg.NewScreen("start/send-location", tg.NewPage(
+				"Send your location and I will tell where you are!",
+			).WithReply(
+				sendLocationKeyboard,
+			).WithInline(
 				tg.NewInline().Row(
-				tg.NewButton("Check").
-					WithData("check").
-					ActionFunc(func(a *tg.Context) {
-						d := a.Session.Value.(*UserData)
-						a.Sendf("Counter = %d", d.Counter)
+					tg.NewButton(
+						"Check",
+					).WithData(
+						"check",
+					).ActionFunc(func(c *tg.Context) {
+							d := c.Session.Value.(*UserData)
+							c.Sendf("Counter = %d", d.Counter)
 					}),
 				),
 			),
+		),
 ).WithCommands(
 	tg.NewCommand("start").
-		Desc("start the bot").
+		Desc("start or restart the bot or move to the start screen").
 		ActionFunc(func(c *tg.Context){
 			c.ChangeScreen("start")
 		}),
@@ -156,12 +183,12 @@ var beh = tg.NewBehaviour().
 	tg.NewCommand("read").
 		Desc("reads a string and sends it back").
 		ActionFunc(func(c *tg.Context) {
-			c.Sendf("Type some text:")
+			/*c.Sendf("Type some text:")
 			msg, err := c.ReadTextMessage()
 			if err != nil {
 				return
 			}
-			c.Sendf("You typed %q", msg)
+			c.Sendf("You typed %q", msg)*/
 		}),
 	tg.NewCommand("image").
 		Desc("sends a sample image").
@@ -177,24 +204,6 @@ var beh = tg.NewBehaviour().
 		}),
 )
 
-func mutateMessage(fn func(string) string) tg.ActionFunc {
-	return func(c *tg.Context) {
-		for {
-			msg, err := c.ReadTextMessage()
-			if err == tg.NotAvailableErr {
-				break
-			} else if err != nil {
-				panic(err)
-			}
-
-			_, err = c.Sendf("%s", fn(msg))
-			if err != nil {
-				panic(err)
-			}
-		}
-	}
-}
-
 var gBeh = tg.NewGroupBehaviour().
 	InitFunc(func(c *tg.GC) {
 	}).

tg/bot.go

@@ -187,7 +187,6 @@ func (bot *Bot) handlePrivate(updates chan *Update) {
 				ctx := &context{
 					Bot:     bot,
 					Session: session,
-					updates: make(chan *Update),
 				}
 				chn := make(chan *Update)
 				chans[sid] = chn
@@ -201,7 +200,6 @@ func (bot *Bot) handlePrivate(updates chan *Update) {
 			ctx := &context{
 				Bot:     bot,
 				Session: lsession,
-				updates: make(chan *Update),
 			}
 			chn := make(chan *Update)
 			chans[sid] = chn

tg/keyboard.go

@@ -6,9 +6,13 @@ import (
 
 // The general keyboard type used both in Reply and Inline.
 type Keyboard struct {
+	// The action is called if there is no
+	// defined action for the button.
+	Action *action
 	Rows []ButtonRow
 }
 
+// The type represents reply keyboards.
 type ReplyKeyboard struct {
 	Keyboard
 	// If true will be removed after one press.
@@ -17,16 +21,18 @@ type ReplyKeyboard struct {
 	Remove bool
 }
 
-// The keyboard to be emdedded into the messages.
+// The type represents keyboard to be emdedded into the messages.
 type InlineKeyboard struct {
 	Keyboard
 }
 
+// Returns new empty inline keyboard.
 func NewInline() *InlineKeyboard {
 	ret := &InlineKeyboard{}
 	return ret
 }
 
+// Returns new empty reply keyboard.
 func NewReply() *ReplyKeyboard {
 	ret := &ReplyKeyboard {}
 	return ret
@@ -41,6 +47,18 @@ func (kbd *InlineKeyboard) Row(btns ...*Button) *InlineKeyboard {
 	kbd.Rows = append(kbd.Rows, btns)
 	return kbd
 }
+
+// Set default action for the buttons in keyboard.
+func (kbd *InlineKeyboard) WithAction(a Action) *InlineKeyboard {
+	kbd.Action = newAction(a)
+	return kbd
+}
+
+// Alias to WithAction to simpler define actions.
+func (kbd *InlineKeyboard) ActionFunc(fn ActionFunc) *InlineKeyboard {
+	return kbd.WithAction(fn)
+}
+
 // Adds a new button row to the current keyboard.
 func (kbd *ReplyKeyboard) Row(btns ...*Button) *ReplyKeyboard {
 	// For empty row. We do not need that.
@@ -51,6 +69,17 @@ func (kbd *ReplyKeyboard) Row(btns ...*Button) *ReplyKeyboard {
 	return kbd
 }
 
+// Set default action for the keyboard.
+func (kbd *ReplyKeyboard) WithAction(a Action) *ReplyKeyboard {
+	kbd.Action = newAction(a)
+	return kbd
+}
+
+// Alias to WithAction for simpler callback declarations.
+func (kbd *ReplyKeyboard) ActionFunc(fn ActionFunc) *ReplyKeyboard {
+	return kbd.WithAction(fn)
+}
+
 // Convert the Keyboard to the Telegram API type of reply keyboard.
 func (kbd *ReplyKeyboard) ToApi() any {
 	// Shades everything.
@@ -74,6 +103,7 @@ func (kbd *ReplyKeyboard) ToApi() any {
 	return tgbotapi.NewReplyKeyboard(rows...)
 }
 
+// Convert the inline keyboard to markup for the tgbotapi.
 func (kbd *InlineKeyboard) ToApi() tgbotapi.InlineKeyboardMarkup {
 	rows := [][]tgbotapi.InlineKeyboardButton{}
 	for _, row := range kbd.Rows {
@@ -87,18 +117,22 @@ func (kbd *InlineKeyboard) ToApi() tgbotapi.InlineKeyboardMarkup {
 	return tgbotapi.NewInlineKeyboardMarkup(rows...)
 }
 
+// Set if we should remove current keyboard on the user side
+// when sending the keyboard.
 func (kbd *ReplyKeyboard) WithRemove(remove bool) *ReplyKeyboard {
 	kbd.Remove = remove
 	return kbd
 }
 
+// Set if the keyboard should be hidden after
+// one of buttons is pressede.
 func (kbd *ReplyKeyboard) WithOneTime(oneTime bool) *ReplyKeyboard {
 	kbd.OneTime = oneTime
 	return kbd
 }
 
 // Returns the map of buttons. Used to define the Action.
-func (kbd Keyboard) buttonMap() ButtonMap {
+func (kbd Keyboard) ButtonMap() ButtonMap {
 	ret := make(ButtonMap)
 	for _, vi := range kbd.Rows {
 		for _, vj := range vi {
@@ -108,3 +142,4 @@ func (kbd Keyboard) buttonMap() ButtonMap {
 
 	return ret
 }
+

tg/private.go

@@ -3,17 +3,15 @@ package tg
 import (
 	"fmt"
 
-	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api/v5"
+	//tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api/v5"
 )
 
 type context struct {
 	Session *Session
+	// To reach the bot abilities inside callbacks.
 	Bot     *Bot
-	updates chan *Update
-	// Is true if currently reading the Update.
-	readingUpdate bool
-
-	curScreen, prevScreen *Screen
+	widgetUpdates chan *Update
+	CurScreen, PrevScreen *Screen
 }
 
 // The type represents way to interact with user in
@@ -29,102 +27,46 @@ func (c *context) handleUpdateChan(updates chan *Update) {
 		c.run(beh.Init, nil)
 	}
 	for u := range updates {
-		var act Action
-		screen := c.curScreen
 		// The part is added to implement custom update handling.
-		if u.Message != nil {
-			if !session.Started {
+		if !session.started {
 			if u.Message.IsCommand() &&
 					u.Message.Command() == "start" {
 				// Special treatment for the "/start"
 				// command.
-					session.Started = true
+				session.started = true
 				cmdName := CommandName("start")
 				cmd, ok := beh.Commands[cmdName]
 				if ok {
-						act = cmd.Action
+					if cmd.Action != nil {
+						c.run(cmd.Action, u)
+					}
 				} else {
 					// Some usage.
 				}
 			} else {
 				// Prestart handling.
-					act = preStart
+				c.run(preStart, u)
 			}
-			} else if u.Message.IsCommand() {
+
+			continue
+		}
+
+		if u.Message != nil && u.Message.IsCommand() {
 			// Command handling.
 			cmdName := CommandName(u.Message.Command())
 			cmd, ok := beh.Commands[cmdName]
 			if ok {
-					act = cmd.Action
+				if cmd.Action != nil {
+					c.run(cmd.Action, u)
+				}
 			} else {
 				// Some usage.
 			}
-			} else {
-				// Simple messages handling.
-				kbd := screen.Reply
-				if kbd == nil {
-					if c.readingUpdate {
-						c.updates <- u
-					}
-					continue
-				}
-				btns := kbd.buttonMap()
-				text := u.Message.Text
-				btn, ok := btns[text]
-				if !ok {
-					if u.Message.Location != nil {
-						for _, b := range btns {
-							if b.SendLocation {
-								btn = b
-								ok = true
-							}
-						}
-					} else if c.readingUpdate {
-						// Skipping the update sending it to
-						// the reading goroutine.
-						c.updates <- u
-						continue
-					}
-				}
-
-				if ok {
-					act = btn.Action
-				}
-			}
-		} else if u.CallbackQuery != nil && session.Started {
-			cb := tgbotapi.NewCallback(
-				u.CallbackQuery.ID,
-				u.CallbackQuery.Data,
-			)
-			data := u.CallbackQuery.Data
-
-			_, err := c.Bot.Api.Request(cb)
-			if err != nil {
-				panic(err)
-			}
-			kbd := screen.Inline
-			if kbd == nil {
-				if c.readingUpdate {
-					c.updates <- u
-				}
 			continue
 		} 
 		
-			btns := kbd.buttonMap()
-			btn, ok := btns[data]
-			if !ok && c.readingUpdate {
-				c.updates <- u
-				continue
-			}
-			if !ok {
-				c.Sendf("%q", btns)
-				continue
-			}
-			act = btn.Action
-		}
-		if act != nil {
-			c.run(act, u)
-		}
+		// The standard thing - send messages to widgets.
+		c.widgetUpdates <- u
 	}
 }
 
@@ -135,29 +77,8 @@ func (c *context) run(a Action, u *Update) {
 	})
 }
 
-// Returns the next update ignoring current screen.
-func (c *context) ReadUpdate() (*Update, error) {
-	c.readingUpdate = true
-	u := <-c.updates
-	c.readingUpdate = false
-	if u == nil {
-		return nil, NotAvailableErr
-	}
-
-	return u, nil
-}
-
-// Returns the next text message that the user sends.
-func (c *context) ReadTextMessage() (string, error) {
-	u, err := c.ReadUpdate()
-	if err != nil {
-		return "", err
-	}
-	if u.Message == nil {
-		return "", WrongUpdateType{}
-	}
-
-	return u.Message.Text, nil
+func (c *context) Render(v Renderable) ([]*Message, error) {
+	return c.Bot.Render(c.Session.Id, v)
 }
 
 // Sends to the Sendable object.
@@ -217,19 +138,36 @@ func (c *Context) ChangeScreen(screenId ScreenId) error {
 	// Stop the reading by sending the nil,
 	// since we change the screen and
 	// current goroutine needs to be stopped.
-	if c.readingUpdate {
-		c.updates <- nil
-	}
+	// if c.readingUpdate {
+		// c.Updates <- nil
+	// }
 
 	// Getting the screen and changing to
-	// then executing its action.
+	// then executing its widget.
 	screen := c.Bot.behaviour.Screens[screenId]
-	c.prevScreen = c.curScreen
-	c.curScreen = screen
-	c.Bot.Render(c.Session.Id, screen)
-	if screen.Action != nil {
-		c.run(screen.Action, c.Update)
+	c.PrevScreen = c.CurScreen
+	c.CurScreen = screen
+
+	// Making the new channel for the widget.
+	if c.widgetUpdates != nil {
+		close(c.widgetUpdates)
 	}
+	c.widgetUpdates = make(chan *Update)
+	if screen.Widget != nil {
+		// Running the widget if the screen has one.
+		go screen.Widget.Serve(c, c.widgetUpdates)
+	} else {
+		// Skipping updates if there is no
+		// widget to handle them.
+		go func() {
+			for _ = range c.widgetUpdates {}
+		}()
+	}
+
+	//c.Bot.Render(c.Session.Id, screen)
+	//if screen.Action != nil {
+		//c.run(screen.Action, c.Update)
+	//}
 
 	return nil
 }

tg/screen.go

@@ -1,9 +1,5 @@
 package tg
 
-import (
-	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api/v5"
-)
-
 // Unique identifier for the screen.
 type ScreenId string
 
@@ -11,100 +7,19 @@ type ScreenId string
 // Mostly what buttons to show.
 type Screen struct {
 	Id ScreenId
-	// The text to be displayed when the screen is
-	// reached.
-	Text string
-	// The keyboard to be sent in the message part.
-	Inline *InlineKeyboard
-	// Keyboard to be displayed on the screen.
-	Reply *ReplyKeyboard
-	// Action called on the reaching the screen.
-	Action *action
+	// The widget to run when reaching the screen.
+	Widget Widget
+
 }
 
 // Map structure for the screens.
 type ScreenMap map[ScreenId]*Screen
 
-// Returns the new screen with specified Text and Keyboard.
-func NewScreen(id ScreenId) *Screen {
+// Returns the new screen with specified name and widget.
+func NewScreen(id ScreenId, widget Widget) *Screen {
 	return &Screen{
 		Id: id,
+		Widget: widget,
 	}
 }
 
-// Returns the screen with specified text printing on appearing.
-func (s *Screen) WithText(text string) *Screen {
-	s.Text = text
-	return s
-}
-
-func (s *Screen) WithInline(ikbd *InlineKeyboard) *Screen {
-	s.Inline= ikbd
-	return s
-}
-
-func (s *Screen) WithReply(kbd *ReplyKeyboard) *Screen {
-	s.Reply = kbd
-	return s
-}
-
-func (s *Screen) WithAction(a Action) *Screen {
-	s.Action = newAction(a)
-	return s
-}
-
-func (s *Screen) ActionFunc(a ActionFunc) *Screen {
-	return s.WithAction(a)
-}
-
-func (s *Screen) Render(
-	sid SessionId, bot *Bot,
-) ([]*SendConfig, error) {
-	cid := sid.ToApi()
-	reply := s.Reply
-	inline := s.Inline
-	ret := []*SendConfig{}
-	var txt string
-	// Screen text and inline keyboard.
-	if s.Text != "" {
-		txt = s.Text
-	} else if inline != nil {
-		// Default to send the keyboard.
-		txt = ">"
-	}
-	if txt != "" {
-		msgConfig := tgbotapi.NewMessage(cid, txt)
-		if inline != nil {
-			msgConfig.ReplyMarkup = inline.ToApi()
-		} else if reply != nil {
-			msgConfig.ReplyMarkup = reply.ToApi()
-			ret = append(ret, &SendConfig{Message: &msgConfig})
-			return ret, nil
-		} else {
-			msgConfig.ReplyMarkup = NewReply().
-				WithRemove(true).
-				ToApi()
-			ret = append(ret, &SendConfig{Message: &msgConfig})
-			return ret, nil
-		}
-		ret = append(ret, &SendConfig{Message: &msgConfig})
-	}
-
-	// Screen text and reply keyboard.
-	if reply != nil {
-		msgConfig := tgbotapi.NewMessage(cid, ">")
-		msgConfig.ReplyMarkup = reply.ToApi()
-		ret = append(ret, &SendConfig{
-			Message: &msgConfig,
-		})
-	} else {
-		// Removing keyboard if there is none.
-		msgConfig := tgbotapi.NewMessage(cid, ">")
-		msgConfig.ReplyMarkup = NewReply().
-			WithRemove(true).
-			ToApi()
-			ret = append(ret, &SendConfig{Message: &msgConfig})
-	}
-
-	return ret, nil
-}

tg/session.go

@@ -16,7 +16,7 @@ type Session struct {
 	Id SessionId
 	// True if the session started.
 	// (got the '/start' command.
-	Started bool
+	started bool
 	// Custom value for each user.
 	Value any
 }

tg/widget.go

@@ -0,0 +1,212 @@
+package tg
+
+import (
+	tgbotapi "github.com/go-telegram-bot-api/telegram-bot-api/v5"
+)
+
+// Implementing the interface provides
+// ability to build your own widgets,
+// aka components.
+type Widget interface {
+	// When the update channel is closed
+	// widget MUST end its work.
+	// Mostly made by looping over the
+	// updates range.
+	Serve(*Context, chan *Update)
+}
+
+// The basic widget to provide keyboard functionality
+// without implementing much.
+type Page struct {
+	Text string
+	SubWidget Widget
+	Inline *InlineKeyboard
+	Reply *ReplyKeyboard
+	Action Action
+}
+
+// Return new page with the specified text.
+func NewPage(text string) *Page {
+	ret := &Page{}
+	ret.Text = text
+	return ret
+}
+
+// Set the inline keyboard.
+func (p *Page) WithInline(inline *InlineKeyboard) *Page {
+	p.Inline = inline
+	return p
+}
+
+// Set the reply keyboard.
+func (p *Page) WithReply(reply *ReplyKeyboard) *Page {
+	p.Reply = reply
+	return p
+}
+
+// Set the action to be run before serving.
+func (p *Page) WithAction(a Action) *Page {
+	p.Action = a
+	return p
+}
+
+// Alias to with action to simpler define actions.
+func (p *Page) ActionFunc(fn ActionFunc) *Page {
+	return p.WithAction(fn)
+}
+
+// Set the sub widget that will get the skipped
+// updates.
+func (p *Page) WithSub(sub Widget) *Page {
+	p.SubWidget = sub
+	return p
+}
+
+func (p *Page) Serve(
+	c *Context, updates chan *Update,
+) {
+	msgs, err := c.Render(p)
+	if err != nil {
+		panic(err)
+	}
+
+	// The inline message is always returned
+	// and the reply one is useless in our case.
+	inlineMsg := msgs[0]
+
+	if p.Action != nil {
+		c.run(p.Action, c.Update)
+	}
+	var subUpdates chan *Update
+	if p.SubWidget != nil {
+		subUpdates = make(chan *Update)
+		go p.SubWidget.Serve(c, subUpdates)
+		defer close(subUpdates)
+	}
+	for u := range updates {
+		var act Action
+		if u.Message != nil {
+			text := u.Message.Text
+			kbd := p.Reply
+			if kbd == nil {
+				if subUpdates != nil {
+					subUpdates <- u
+				}
+				continue
+			}
+			btns := kbd.ButtonMap()
+			btn, ok := btns[text]
+			if !ok {
+				if u.Message.Location != nil {
+					for _, b := range btns {
+						if b.SendLocation {
+							btn = b
+							ok = true
+						}
+					}
+				} else if subUpdates != nil {
+					subUpdates <- u
+				}
+			}
+			if btn != nil {
+				act = btn.Action
+			} else if kbd.Action != nil {
+				act = kbd.Action
+			}
+		} else if u.CallbackQuery != nil {
+			if u.CallbackQuery.Message.MessageID != inlineMsg.MessageID {
+				if subUpdates != nil {
+					subUpdates <- u
+				}
+				continue
+			}
+			cb := tgbotapi.NewCallback(
+				u.CallbackQuery.ID,
+				u.CallbackQuery.Data,
+			)
+			data := u.CallbackQuery.Data
+
+			_, err := c.Bot.Api.Request(cb)
+			if err != nil {
+				panic(err)
+			}
+			kbd := p.Inline
+			if kbd == nil {
+				if subUpdates != nil {
+					subUpdates <- u
+				}
+				continue
+			}
+
+			btns := kbd.ButtonMap()
+			btn, ok := btns[data]
+			if !ok {
+				if subUpdates != nil {
+					subUpdates <- u
+				}
+				continue
+			}
+			if btn != nil {
+				act = btn.Action
+			} else if kbd.Action != nil {
+				act = kbd.Action
+			}
+		}
+		if act != nil {
+			c.run(act, u)
+		} 
+	}
+}
+
+func (s *Page) Render(
+	sid SessionId, bot *Bot,
+) ([]*SendConfig, error) {
+	cid := sid.ToApi()
+	reply := s.Reply
+	inline := s.Inline
+	ret := []*SendConfig{}
+	var txt string
+	// Screen text and inline keyboard.
+	if s.Text != "" {
+		txt = s.Text
+	} else if inline != nil {
+		// Default to send the keyboard.
+		txt = ">"
+	}
+	if txt != "" {
+		msgConfig := tgbotapi.NewMessage(cid, txt)
+		if inline != nil {
+			msgConfig.ReplyMarkup = inline.ToApi()
+		} else if reply != nil {
+			msgConfig.ReplyMarkup = reply.ToApi()
+			ret = append(ret, &SendConfig{Message: &msgConfig})
+			return ret, nil
+		} else {
+			msgConfig.ReplyMarkup = NewReply().
+				WithRemove(true).
+				ToApi()
+			ret = append(ret, &SendConfig{Message: &msgConfig})
+			return ret, nil
+		}
+		ret = append(ret, &SendConfig{Message: &msgConfig})
+	}
+
+	// Screen text and reply keyboard.
+	if reply != nil {
+		msgConfig := tgbotapi.NewMessage(cid, ">")
+		msgConfig.ReplyMarkup = reply.ToApi()
+		ret = append(ret, &SendConfig{
+			Message: &msgConfig,
+		})
+	} else {
+		// Removing keyboard if there is none.
+		msgConfig := tgbotapi.NewMessage(cid, ">")
+		msgConfig.ReplyMarkup = NewReply().
+			WithRemove(true).
+			ToApi()
+			ret = append(ret, &SendConfig{Message: &msgConfig})
+	}
+
+	return ret, nil
+}
+