[C#/Unity] 이벤트

class Button
{
    public event EventHandler Click;

    public void OnClick()
    {
        // null 체크 후 호출 (기존 방식)
        if (Click != null)
        {
            Click();
        }

        // null 조건 연산자 사용 (권장)
        Click?.Invoke();
    }
}

public class Player : MonoBehaviour
{
    public int hp = 100;

    // 인스펙터에서 보이게 하려면 public 또는 [SerializeField]
    public UnityEvent OnDead;

    public void TakeDamage(int damage)
    {
        hp -= damage;

        if (hp <= 0)
        {
            OnDead?.Invoke();
        }
    }
}

public class OnHpChangedEvent : UnityEvent<int> { }

public class Player : MonoBehaviour
{
    public int hp = 100;

    public OnHpChangedEvent OnHpChanged;
    public UnityEvent OnDead;

    public void TakeDamage(int damage)
    {
        hp -= damage;
        OnHpChanged?.Invoke(hp);  // 현재 HP를 넘김

        if (hp <= 0)
        {
            OnDead?.Invoke();
        }
    }
}

public class UIManager : MonoBehaviour
{
    [SerializeField] private Player player;

    private void OnEnable()
    {
        player.OnHpChanged.AddListener(UpdateHpBar);  
        player.OnDead.AddListener(ShowGameOver);
    }

    private void OnDisable()
    {
        player.OnHpChanged.RemoveListener(UpdateHpBar);  
        player.OnDead.RemoveListener(ShowGameOver);
    }

    private void UpdateHpBar(int currentHp)
    {
        Debug.Log($"HP 바 갱신: {currentHp}");
    }

    private void ShowGameOver()
    {
        Debug.Log("게임 오버 UI 표시");
    }
}