package client

import "github.com/hajimehoshi/ebiten/v2"

type GameState interface {
	Enter() error
	Update() (GameState, error)
	Draw(*ebiten.Image)
	Exit() error
}

type StateManager struct {
	currentState GameState
}

func (m *StateManager) ChangeState(state GameState) error {
	if m.currentState != nil {
		if err := m.currentState.Exit(); err != nil {
			return err
		}
	}
	if err := state.Enter(); err != nil {
		return err
	}
	m.currentState = state
	return nil
}

func (m *StateManager) Update() error {
	if m.currentState == nil {
		return nil
	}

	newState, err := m.currentState.Update()
	if err != nil {
		return err
	}
	if newState != nil {
		if err := m.ChangeState(newState); err != nil {
			return err
		}
	}

	return nil
}

func (m *StateManager) Draw(screen *ebiten.Image) {
	if m.currentState != nil {
		m.currentState.Draw(screen)
	}
}