using System;
using System.Collections.Generic;
using UnityEngine;

public class GameplayManager : MonoBehaviour
{
    public static GameplayManager Instance = null;

    [Header("Assign levels in order (Level 1 at index 0)")]
    public List<Level> levels;

    private int currentLevelIndex = -1;
    private Level currentLevel;
    [SerializeField] private List<GameObject> levelStartTriggers;
    private void Awake()
    {
        if (Instance == null)
            Instance = this;
        else if (Instance != this)
        {
            DestroyImmediate(gameObject);
            return;
        }

        DontDestroyOnLoad(gameObject);

        // Ensure all levels are disabled initially
        foreach (var lvl in levels)
        {
            if (lvl != null) lvl.gameObject.SetActive(false);
        }
        var upcomingLevel = levels[0];
        ObjectiveManager.Instance.SetList(upcomingLevel.config.objectives);
        EnableOnlyTrigger(0);
    }

    private void EnableOnlyTrigger(int index)
    {
        if (levelStartTriggers == null) return;
        for (int i = 0; i < levelStartTriggers.Count; i++)
            if (levelStartTriggers[i] != null)
                levelStartTriggers[i].SetActive(i == index);
    }
    
    public void StartLevel(int index)
    {
        if (index < 0 || index >= levels.Count)
        {
            Debug.LogError($"GameplayManager: Invalid level index {index}");
            return;
        }

        // End previous level if any
        if (currentLevel != null)
        {
            currentLevel.OnLevelEnd();
            currentLevel.gameObject.SetActive(false);
        }

        currentLevelIndex = index;
        currentLevel = levels[currentLevelIndex];

        currentLevel.gameObject.SetActive(true);
        currentLevel.OnLevelStart();
        Debug.Log($"GameplayManager: Started Level {currentLevelIndex + 1}");
    }

    public void CompleteCurrentLevel()
    {
        if (currentLevel == null) return;

        Debug.Log($"GameplayManager: Level {currentLevelIndex + 1} completed.");

        currentLevel.OnLevelEnd();
        currentLevel.gameObject.SetActive(false);
        currentLevel = null;
        
        // If you want to auto-progress:
        int next = currentLevelIndex + 1;
        // var upcomingLevel = levels[currentLevelIndex];
        // ObjectiveManager.Instance.SetList(upcomingLevel.config.objectives);
        if (next < levels.Count)
        {
            var upcomingLevel = levels[next];
            ObjectiveManager.Instance.SetList(
                upcomingLevel.config.objectives,
                upcomingLevel.config.startObjectiveIndex
            );
        }
        EnableOnlyTrigger(next);
        // if (next < levels.Count)
        // {
        //     StartLevel(next);
        // }
        // else
        // {
        //     Debug.Log("GameplayManager: All levels completed!");
        // }
    }

    
    
    private void LoadUpNextLevel()
    {
        int next = currentLevelIndex + 1;
        var upcomingLevel = levels[currentLevelIndex];
        ObjectiveManager.Instance.SetList(upcomingLevel.config.objectives);
    }
    // Optional: callable by a trigger to start Level 1 specifically
    public void StartLevelOne()
    {
        StartLevel(0);
    }
}