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

public class SceneLoader : MonoBehaviour
{
    public static SceneLoader Instance { get; private set; }
    private void Awake()
    {
        if (Instance == null) Instance = this;
    }

    [Header("Scenes")]
    [SerializeField] private string debugScene;
    [SerializeField] private GameObject disableTest;
    [SerializeField] private List<string> loadedScenes;

    [Header("ReadOnly")]
    [SerializeField, ReadOnly] private bool loading;

    private void UnloadAllScenes()
    {
        foreach (var scene in loadedScenes)
        {
            StartCoroutine(UnloadSceneAsync(scene));
        }
    }
    public void LoadScene(string sceneName, Action onLoad)
    {
        disableTest.SetActive(false);
        if (loading)
        {
            Debug.LogWarning("Scene can't start loading if the other scene not loaded yet.");
            return;
        }

        UnloadAllScenes();
        StartCoroutine(LoadSceneAsync(sceneName, onLoad));
    }

    public void LoadScene(string sceneName) => LoadScene(sceneName, null);

    private IEnumerator LoadSceneAsync(string sceneName, Action onLoad)
    {
        yield return null;

        AsyncOperation operation = SceneManager.LoadSceneAsync(sceneName, LoadSceneMode.Additive);
        loading = true;

        Debug.Log("Scene loading...");
        while (!operation.isDone) 
        {
            yield return null;
        }

        yield return null;

        loading = false;
        loadedScenes.Add(sceneName);
        onLoad?.Invoke();
        Debug.Log("Scene loaded.");
    }

    private IEnumerator UnloadSceneAsync(string sceneName)
    {
        yield return null;

        AsyncOperation operation = SceneManager.UnloadSceneAsync(sceneName);

        while (!operation.isDone)
        {
            yield return null;
        }

        loadedScenes.Remove(sceneName);
    }

    private void Start()
    {
        if (debugScene != "")
        {
            LoadScene(debugScene);
        }
    }

}