implement unit and artifact switch action

Simplify the Choice Widget and make it a TextBox variant.

Drive-by fixes:
  * ui.Collection: prioritize newer widgets during active widget selection
  * game.FullAction: fix incorrect cost function.
                     Full actions cost all available actions. Also
                     fix the cost check

2 files changed, 27 insertions, 40 deletions

diff --git a/go/ui/choice.go b/go/ui/choice.go
index 28878604..04b8f725 100644
--- a/go/ui/choice.go
+++ b/go/ui/choice.go
@@ -9,66 +9,50 @@ import (
 )
 
 type Choice struct {
-	X, Y                int
-	Width, choiceHeight int
-	choices             []string
-	onClick             func(*Choice, int, int)
-	buttons             []Button
+	TextBox
+	choices []interface{}
+	onClick func(*Choice, int, int)
 }
 
 func choiceButtonOnClickDummy(b *SimpleButton) {}
 
-func NewChoice(x, y int, width, choiceHeight int, choices []string,
-	onClick func(*Choice, int, int),
-) *Choice {
-	c := &Choice{x, y, width, choiceHeight, choices, onClick, []Button{}}
-
-	for i, choice := range c.choices {
-		b := NewSimpleButton(c.X, c.Y+i*c.choiceHeight, c.Width, c.choiceHeight, choice,
-			choiceButtonOnClickDummy)
+func NewChoice(x, y int, choices []interface{}, onClick func(*Choice, int, int)) *Choice {
+	c := &Choice{
+		TextBox: *(NewAutoTextBox(x, y, "")),
+		choices: choices,
+		onClick: onClick,
+	}
 
-		c.buttons = append(c.buttons, b)
+	c.renderImpl = func() *ebiten.Image {
+		c.setText()
+		return c.render()
 	}
 	return c
 }
 
-func (c *Choice) Draw(screen *ebiten.Image) {
-	for _, b := range c.buttons {
-		b.Draw(screen)
+func (c *Choice) setText() {
+	c.Width, c.Height = -1, -1
+	t := ""
+	for _, choice := range c.choices {
+		t = fmt.Sprintf("%s%v\n", t, choice)
 	}
+
+	c.text = t[:len(t)-1]
 }
 
 func (c *Choice) GetChoosen(x, y int) int {
-	return (y - c.Y) / c.choiceHeight
+	i := (y - c.Y) / (c.Height / len(c.choices))
+	return i
 }
 
 func (c *Choice) Click(x, y int) {
 	c.onClick(c, x, y)
 }
 
-func (c *Choice) Contains(x, y int) bool {
-	height := len(c.choices) * c.choiceHeight
-	return x >= c.X && x <= c.X+c.Width && y >= c.Y && y <= c.Y+height
-}
-
-func (c *Choice) FindObjectAt(x, y int) interface{} { return nil }
-func (c *Choice) Render() *ebiten.Image             { return nil }
-
-func NewObjectChoice(x, y int, objs []interface{}, onClick func(*Choice, int, int)) *Choice {
-	// TODO: use dynamic with width and height
-	width := 200
-	choiceHeight := 40
-	labels := make([]string, 0, len(objs))
-	for _, obj := range objs {
-		labels = append(labels, fmt.Sprintf("%v", obj))
-	}
-	return NewChoice(x, y, width, choiceHeight, labels, onClick)
-}
-
 func NewActionChoice(x, y int, actions []game.Action, onClick func(*Choice, int, int)) *Choice {
-	return NewObjectChoice(x, y, utils.TypedSliceToInterfaceSlice(actions), onClick)
+	return NewChoice(x, y, utils.TypedSliceToInterfaceSlice(actions), onClick)
 }
 
 func NewPermChoice(x, y int, perms []game.Permanent, onClick func(*Choice, int, int)) *Choice {
-	return NewObjectChoice(x, y, utils.TypedSliceToInterfaceSlice(perms), onClick)
+	return NewChoice(x, y, utils.TypedSliceToInterfaceSlice(perms), onClick)
 }
diff --git a/go/ui/collection.go b/go/ui/collection.go
index d75e3267..027d0d99 100644
--- a/go/ui/collection.go
+++ b/go/ui/collection.go
@@ -69,7 +69,10 @@ func (c *Collection) Update() error {
 	x, y := ebiten.CursorPosition()
 
 	var activeWidget Widget
-	for _, w := range c.widgets {
+	// Iterate the widget in reverse order to ensure that upper widgets are
+	// considered first
+	for i := len(c.widgets) - 1; i >= 0; i-- {
+		w := c.widgets[i]
 		if !w.Contains(x, y) {
 			continue
 		}