using System.Collections.Generic;
using UnityEngine;

public class AreaClearanceManager : MonoBehaviour
{
    public static AreaClearanceManager Instance { get; private set; }

    [SerializeField] private LevelExit levelExit;
    private readonly HashSet<EnemyController> activeEnemies = new HashSet<EnemyController>();
    private bool areaCleared = false;

    public int RemainingEnemies => activeEnemies.Count;
    public bool IsAreaCleared => areaCleared;

    private void Awake()
    {
        if (Instance != null && Instance != this)
        {
            Destroy(gameObject);
        }
        else
        {
            Instance = this;
        }
    }

    private void Start()
    {
        if (levelExit != null)
        {
            levelExit.gameObject.SetActive(false);
        }
    }

    public void RegisterEnemy(EnemyController enemy)
    {
        if (enemy == null) return;

        if (!activeEnemies.Contains(enemy))
        {
            activeEnemies.Add(enemy);
            UpdateUI();
        }
    }

    public void UnregisterEnemy(EnemyController enemy)
    {
        if (enemy == null) return;

        if (activeEnemies.Contains(enemy))
        {
            activeEnemies.Remove(enemy);
            UpdateUI();

            if (activeEnemies.Count == 0 && !areaCleared)
            {
                UnlockArea();
            }
        }
    }

    private void UnlockArea()
    {
        areaCleared = true;
        if (levelExit != null)
        {
            levelExit.gameObject.SetActive(true);
        }

        if (UIController.Instance != null)
        {
            UIController.Instance.ShowNotification("Area Cleared! Proceed to Exit.");
        }
    }

    private void UpdateUI()
    {
        if (UIController.Instance != null)
        {
            UIController.Instance.UpdateZombiesRemaining(activeEnemies.Count);
        }
    }
}