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

1 files changed, 60 insertions, 22 deletions

diff --git a/go/game/action.go b/go/game/action.go
index 77e9743f..1e25cd67 100644
--- a/go/game/action.go
+++ b/go/game/action.go
@@ -161,13 +161,7 @@ func NewMoveAction(u *Unit) *MoveAction {
 		u.move(s, tile)
 	}
 
-	a.costFunc = func(*State) bool {
-		if u.AvailMoveActions < 1 {
-			return false
-		}
-		u.AvailMoveActions--
-		return true
-	}
+	a.costFunc = genMoveActionCost(u)
 
 	return a
 }
@@ -182,6 +176,36 @@ func (a *MoveAction) String() string {
 	return fmt.Sprintf("%s -> %v", u.FmtWController(), t.Position)
 }
 
+func genBaseActionCost(u *Unit, attack, move int) ActionCostFunc {
+	return func(*State) bool {
+		if u.AvailAttackActions < attack || u.AvailMoveActions < move {
+			return false
+		}
+		u.AvailAttackActions -= attack
+		u.AvailMoveActions -= move
+		return true
+	}
+}
+
+func genAttackActionCost(u *Unit) ActionCostFunc {
+	return genBaseActionCost(u, 1, 0)
+}
+
+func genMoveActionCost(u *Unit) ActionCostFunc {
+	return genBaseActionCost(u, 0, 1)
+}
+
+func genFullActionCost(u *Unit) ActionCostFunc {
+	return func(*State) bool {
+		if u.AvailAttackActions < 1 || u.AvailMoveActions < 1 {
+			return false
+		}
+		u.AvailAttackActions = 0
+		u.AvailMoveActions = 0
+		return true
+	}
+}
+
 type AttackAction struct {
 	ActionBase
 }
@@ -200,13 +224,7 @@ func NewAttackAction(u *Unit) *AttackAction {
 		s.Fight(u, a.Target().sel[0].(Permanent))
 	}
 
-	a.costFunc = func(*State) bool {
-		if u.AvailAttackActions < 1 {
-			return false
-		}
-		u.AvailAttackActions--
-		return true
-	}
+	a.costFunc = genAttackActionCost(u)
 
 	return a
 }
@@ -221,6 +239,33 @@ func (a *AttackAction) String() string {
 	return fmt.Sprintf("%s x %v", u.FmtWController(), target.Tile().Position)
 }
 
+type ArtifactSwitchAction struct {
+	ActionBase
+	Artifact Permanent
+}
+
+func newArtifactSwitchAction(u *Unit, artifact Permanent) *ArtifactSwitchAction {
+	a := &ArtifactSwitchAction{
+		ActionBase{
+			source: u,
+			Card:   u.Card(),
+		},
+		artifact,
+	}
+
+	a.resolveFunc = func(s *State) {
+		s.switchPermanents(a.Source().(*Unit), a.Artifact)
+	}
+
+	a.costFunc = genMoveActionCost(u)
+
+	return a
+}
+
+func (a *ArtifactSwitchAction) String() string {
+	return fmt.Sprintf("%s <-> %v", a.Source().(*Unit).FmtWController(), a.Artifact)
+}
+
 type FullAction struct {
 	ActionBase
 	desc string
@@ -242,14 +287,7 @@ func NewFullAction(u *Unit, proto ActionFuncPrototype, desc string) *FullAction
 		rf(s)
 	}
 
-	a.costFunc = func(*State) bool {
-		if u.AvailAttackActions < 1 && u.AvailMoveActions < 1 {
-			return false
-		}
-		u.AvailAttackActions--
-		u.AvailMoveActions--
-		return true
-	}
+	a.costFunc = genFullActionCost(u)
 	return a
 }