package tg

type WidgetSpecial int
const (
	widgetEmpty WidgetSpecial = iota
	widgetBack
)


func (w WidgetSpecial) Render(_ Context) UI {
	return nil
}

var (
	Back = Widget(widgetBack)
)

/*// Unique identifier for the screen.
type Path int
const (
	PathEmpty Path = 0
	// Going to the path returns
	// a context to the previous screen.
	PathBack Path = -1
)

// Returns true if the path is empty.
func (p Path) IsEmpty() bool {
	return p == 0
}

// Screen statement of the bot.
// Mostly what buttons to show.
type Screen struct {
	// The widget to run when reaching the screen.
	Widget Widget
}

// The first node with the "/" path.
type RootNode struct {
	Screen *Screen
	Subs []*Node
}

// The node is a simple way to represent
// tree-like structured applications.
type Node struct {
	Path Path
	Screen *Screen
	Subs []*Node
}*/

// Return new root node with the specified widget in the screen.
/*func NewRootNode(widget Widget, subs ...*Node) *RootNode {
	ret := &RootNode{}
	ret.Screen = NewScreen(widget)
	ret.Subs = subs
	return ret
}

func NewNode(relPath Path, widget Widget, subs ...*Node) *Node {
	ret := &Node{}
	ret.Path = relPath
	ret.Screen = NewScreen(widget)
	ret.Subs = subs
	return ret
}

func (n *RootNode) ScreenMap() ScreenMap {
	m := make(ScreenMap)
	var root Path = "/"
	m[root] = n.Screen
	for _, sub := range n.Subs {
		buf := sub.ScreenMap(root)
		for k, v := range buf {
			_, ok := m[k]
			if ok {
				panic("duplicate paths in node definition")
			}
			m[k] = v
		}
	}
	return m
}

func (n *Node) ScreenMap(root Path) ScreenMap {
	m := make(ScreenMap)
	pth := (root + n.Path).Clean()
	m[pth] = n.Screen
	for _, sub := range n.Subs {
		buf := sub.ScreenMap(pth + "/")
		for k, v := range buf {
			_, ok := m[k]
			if ok {
				panic("duplicate paths in node definition")
			}
			m[k] = v
		}
	}
	return m
}*/


// Returns the new screen with specified name and widget.
/*func NewScreen(widget Widget) *Screen {
	return &Screen{
		Widget: widget,
	}
}*/