commit 5c694cec8a75c46c4ecfe58f39db353d5c668f46
Author: Nhân <hi@imnhan.com>
Date:   Sun Sep 17 13:47:15 2023 +0700

    implement hungry + feed state

diff --git a/main.go b/main.go
index aefab9e..024d63f 100644
--- a/main.go
+++ b/main.go
@@ -48,23 +48,24 @@ type Anim struct {
 
 type Position struct{ x, y int }
 
+var DurationTillHungry time.Duration
+
 type Game struct {
-	CurrentAnim            *Anim
-	CurrentFrame           int
-	Ticks                  int
-	IsDragging             bool
-	PreviousMousePos       Vector
-	WinStartPos            Vector
-	MouseStartPos          Vector
-	Size                   int
-	LastFed                time.Time
-	NanosecondsUntilHungry time.Duration
-	WalkChance             int
-	StopChance             int
-	X                      int
-	Y                      int
-	MaxX                   int
-	MaxY                   int
+	CurrentAnim      *Anim
+	CurrentFrame     int
+	Ticks            int
+	IsDragging       bool
+	PreviousMousePos Vector
+	WinStartPos      Vector
+	MouseStartPos    Vector
+	Size             int
+	LastFed          time.Time
+	WalkChance       int
+	StopChance       int
+	X                int
+	Y                int
+	MaxX             int
+	MaxY             int
 }
 
 type Vector struct{ x, y int }
@@ -101,7 +102,7 @@ func (g *Game) Update() error {
 
 	isHungry := false
 
-	if time.Now().Sub(g.LastFed) >= g.NanosecondsUntilHungry {
+	if time.Now().Sub(g.LastFed) >= DurationTillHungry {
 		// The only allowed interaction when hungry is right-click to feed.
 		isHungry = true
 		g.IsDragging = false
@@ -265,7 +266,7 @@ func main() {
 	var game Game
 	game.CurrentAnim = Idle
 	game.LastFed = time.Now()
-	game.NanosecondsUntilHungry = time.Duration(secondsUntilHungryFlag) * 1_000_000_000
+	DurationTillHungry = time.Duration(secondsUntilHungryFlag) * 1_000_000_000
 	game.Size = sizeFlag
 	game.WalkChance = walkChanceFlag
 	game.StopChance = stopChanceFlag
diff --git a/states.go b/states.go
index fa690e8..36e6bce 100644
--- a/states.go
+++ b/states.go
@@ -1,6 +1,8 @@
 package main
 
 import (
+	"time"
+
 	"github.com/hajimehoshi/ebiten/v2"
 	"github.com/hajimehoshi/ebiten/v2/inpututil"
 )
@@ -11,11 +13,14 @@ type StateMachine struct {
 	animFrameCount int // number of frames in current anim
 	frameIdx       int // frame index in current animation
 	ticks          int // ticks since last animation frame change
+
+	lastFed time.Time
 }
 
 func NewStateMachine() *StateMachine {
 	sm := StateMachine{}
 	sm.SetState(&StateIdle{})
+	sm.lastFed = time.Now()
 	return &sm
 }
 
@@ -33,7 +38,14 @@ func (sm *StateMachine) SetState(s State) {
 	sm.state.Enter(sm)
 }
 func (sm *StateMachine) Update() error {
-	sm.state.Update(sm)
+	now := time.Now()
+
+	if now.Sub(sm.lastFed) >= DurationTillHungry {
+		sm.SetState(&StateHungry{})
+		sm.lastFed = now
+	} else {
+		sm.state.Update(sm)
+	}
 
 	// Advance to next animation frame
 	sm.ticks += 1
@@ -66,8 +78,6 @@ type State interface {
 	EndAnimHook(sm *StateMachine)
 }
 
-type StateHungry struct{}
-type StateFeed struct{}
 type StateWalkL struct{}
 type StateWalkR struct{}
 
@@ -121,3 +131,22 @@ func (s *StateRClick) Update(sm *StateMachine) {}
 func (s *StateRClick) EndAnimHook(sm *StateMachine) {
 	sm.SetState(&StateIdle{})
 }
+
+type StateHungry struct{}
+
+func (s *StateHungry) Enter(sm *StateMachine) { sm.SetAnim(Hungry) }
+func (s *StateHungry) Update(sm *StateMachine) {
+	if inpututil.IsMouseButtonJustPressed(ebiten.MouseButtonRight) {
+		sm.SetState(&StateFeed{})
+		return
+	}
+}
+func (s *StateHungry) EndAnimHook(sm *StateMachine) {}
+
+type StateFeed struct{}
+
+func (s *StateFeed) Enter(sm *StateMachine)  { sm.SetAnim(Feeding) }
+func (s *StateFeed) Update(sm *StateMachine) {}
+func (s *StateFeed) EndAnimHook(sm *StateMachine) {
+	sm.SetState(&StateIdle{})
+}