Refactor fuel state

Author: morozov

pkg/audio/sound.go

@@ -78,7 +78,7 @@ func (s *SoundSystem) Update(gs *state.GameState) {
 	}
 
 	s.updateEngine(gs.Speed)
-	s.updateLowFuel(gs.Controls.LowFuel)
+	s.updateLowFuel(gs.Controls.FuelState == state.FuelStateLow)
 	s.updateRefuel(gs)
 	s.updateFire(gs)
 	s.updateExplosion(gs)
@@ -142,10 +142,10 @@ func (s *SoundSystem) updateLowFuel(low bool) {
 }
 
 // updateRefuel plays the refueling beep once per frame while actively receiving fuel.
-// Suppressed when the tank is full (FuelFull is set) — no fuel is being added.
+// Suppressed when the tank is full — no fuel is being added.
 // The beep (~14.6 ms) finishes well before the next frame, so there is no overlap.
 func (s *SoundSystem) updateRefuel(gs *state.GameState) {
-	if gs.GameplayMode == domain.GameplayRefuel && !gs.Controls.FuelFull {
+	if gs.GameplayMode == domain.GameplayRefuel && gs.Controls.FuelState != state.FuelStateFull {
 		rewindAndPlay(s.refuel)
 	}
 }
@@ -176,9 +176,8 @@ func (s *SoundSystem) updateBonusLife(gs *state.GameState) {
 
 // updateFuelFull plays the tank-full beep when the fuel cap is hit.
 func (s *SoundSystem) updateFuelFull(gs *state.GameState) {
-	if gs.Controls.FuelFull {
+	if gs.Controls.FuelState == state.FuelStateFull {
 		rewindAndPlay(s.fuelFull)
-		gs.Controls.FuelFull = false
 	}
 }
 

pkg/logic/collision.go

@@ -258,7 +258,7 @@ func checkFirstHit(s striker, targets []target, r *CollisionResult) (hitResult,
 }
 
 // checkFuelOverlap returns true and the object index when the plane overlaps a
-// fuel depot. Fuel is not a valid striker target (playerPlane.canHit returns
+// fuel depot. FuelState is not a valid striker target (playerPlane.canHit returns
 // false for ObjectFuel), so it must be checked separately.
 func checkFuelOverlap(plane playerPlane, vp *state.Viewport) bool {
 	px, py, pw, ph := plane.bounds()

pkg/logic/death_test.go

@@ -249,7 +249,7 @@ func TestResetPerLife_FuelRestored(t *testing.T) {
 	ResetPerLife(s, noopTerrain)
 
 	if s.Fuel != fuelRefuelCap {
-		t.Errorf("Fuel = %d, want %d", s.Fuel, fuelRefuelCap)
+		t.Errorf("FuelState = %d, want %d", s.Fuel, fuelRefuelCap)
 	}
 }
 

pkg/logic/fuel.go

@@ -1,6 +1,8 @@
 package logic
 
-// Fuel system constants.
+import "github.com/morozov/river-raid-ebiten/pkg/state"
+
+// FuelState system constants.
 const (
 	fuelConsumeTickMask = 1   // consume on even frames
 	fuelConsumeAmount   = 1   // fuel consumed per eligible frame
@@ -9,41 +11,30 @@ const (
 	fuelRefuelCap       = 252 // "tank full" cap during refueling
 )
 
-// FuelResult describes what happened during fuel processing.
-type FuelResult int
-
-// Fuel results.
-const (
-	FuelResultNormal FuelResult = iota
-	FuelResultLowFuel
-	FuelResultNoFuel
-	FuelResultFullFuel
-)
-
 // UpdateFuel processes fuel consumption and refueling for one frame.
 // tick is the current frame counter. refueling is true if the plane is over a depot.
 // Returns the new fuel level and any triggered events.
-func UpdateFuel(fuel, tick int, refueling bool) (int, FuelResult) {
+func UpdateFuel(fuel, tick int, refueling bool) (int, state.FuelState) {
 	if refueling {
 		fuel += fuelIntakeAmount
 
 		if fuel >= fuelRefuelCap {
 			if fuel > fuelRefuelCap {
 				fuel = fuelRefuelCap
 			}
-			return fuel, FuelResultFullFuel
+			return fuel, state.FuelStateFull
 		}
 	} else if tick&fuelConsumeTickMask == 0 {
 		fuel -= fuelConsumeAmount
 	}
 
 	if fuel <= 0 {
-		return 0, FuelResultNoFuel
+		return 0, state.FuelStateEmpty
 	}
 
 	if fuel < fuelLowThreshold {
-		return fuel, FuelResultLowFuel
+		return fuel, state.FuelStateLow
 	}
 
-	return fuel, FuelResultNormal
+	return fuel, state.FuelStateNormal
 }

pkg/logic/fuel_test.go

@@ -1,6 +1,10 @@
 package logic
 
-import "testing"
+import (
+	"testing"
+
+	"github.com/morozov/river-raid-ebiten/pkg/state"
+)
 
 func TestUpdateFuel_ConsumesOnEvenTick(t *testing.T) {
 	t.Parallel()
@@ -42,37 +46,37 @@ func TestUpdateFuel_EmptyTriggersDeath(t *testing.T) {
 		t.Errorf("fuel = %d, want 0", fuel)
 	}
 
-	if result != FuelResultNoFuel {
-		t.Error("expected FuelResultNoFuel")
+	if result != state.FuelStateEmpty {
+		t.Error("expected FuelStateEmpty")
 	}
 }
 
 func TestUpdateFuel_LowFuelWarning(t *testing.T) {
 	t.Parallel()
 
 	_, result := UpdateFuel(63, 1, false)
-	if result != FuelResultLowFuel {
-		t.Error("expected FuelResultLowFuel at 63")
+	if result != state.FuelStateLow {
+		t.Error("expected FuelStateLow at 63")
 	}
 
 	_, result = UpdateFuel(64, 1, false)
-	if result != FuelResultNormal {
-		t.Error("expected no FuelResultNormal at 64")
+	if result != state.FuelStateNormal {
+		t.Error("expected FuelStateNormal at 64")
 	}
 }
 
 func TestUpdateFuel_FuelFullOnCapTransition(t *testing.T) {
 	t.Parallel()
 
-	// Fuel just below cap → transitions to cap: FuelFull should be set.
+	// FuelState just below cap → transitions to cap: FuelFull should be set.
 	_, result := UpdateFuel(250, 0, true)
-	if result != FuelResultFullFuel {
-		t.Error("expected FuelResultFullFuel when fuel reaches cap")
+	if result != state.FuelStateFull {
+		t.Error("expected FuelStateFull when fuel reaches cap")
 	}
 
 	// Not refueling with enough fuel.
 	_, result = UpdateFuel(250, 0, false)
-	if result != FuelResultNormal {
-		t.Error("expected no FuelResultNormal when not refueling")
+	if result != state.FuelStateNormal {
+		t.Error("expected FuelStateNormal when not refueling")
 	}
 }

pkg/logic/gameplay.go

@@ -131,11 +131,8 @@ func step(s *state.GameState, in input.Interface, terrain TerrainRenderer) {
 	advanceAndRender(s, int(s.Speed), terrain)
 
 	// step 10: Handle fuel consumption.
-	var fuelResult FuelResult
-	s.Fuel, fuelResult = UpdateFuel(s.Fuel, int(s.Tick), s.GameplayMode == domain.GameplayRefuel)
-	s.Controls.LowFuel = fuelResult == FuelResultLowFuel
-	s.Controls.FuelFull = fuelResult == FuelResultFullFuel
-	if fuelResult == FuelResultNoFuel {
+	s.Fuel, s.Controls.FuelState = UpdateFuel(s.Fuel, int(s.Tick), s.GameplayMode == domain.GameplayRefuel)
+	if s.Controls.FuelState == state.FuelStateEmpty {
 		triggerDeath(s)
 		return
 	}

pkg/state/fuel.go

@@ -0,0 +1,12 @@
+package state
+
+// FuelState represents the current fuel condition.
+type FuelState int
+
+// FuelState states.
+const (
+	FuelStateNormal FuelState = iota
+	FuelStateLow
+	FuelStateEmpty
+	FuelStateFull
+)

pkg/state/state.go

@@ -9,9 +9,8 @@ import (
 // ControlFlags holds the expanded state of the original control byte.
 type ControlFlags struct {
 	Speed     domain.Speed
+	FuelState FuelState
 	FireSound bool
-	LowFuel   bool
-	FuelFull  bool
 	BonusLife bool
 	Exploding bool
 }