using UnityEngine;
using System;
using UnityEngine.SceneManagement;
#if UNITY_EDITOR
using UnityEditor;
#endif

/// <summary>
/// Simple pause manager. Call Pause(true) to pause or Pause(false) to resume.
/// - overlayRoot: GameObject that will be enabled when paused and disabled when resumed.
/// - Pressing Escape toggles pause while the manager exists.
/// </summary>
public class PauseManager : MonoBehaviour
{
    public static PauseManager Instance { get; private set; }

    [Header("Overlay")]
    public GameObject overlayRoot; // object to enable/disable on pause

    public bool IsPaused { get; private set; } = false;

    // 添加暂停状态改变事件
    public event Action<bool> OnPauseStateChanged;

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

    void Start()
    {
        if (overlayRoot != null)
            overlayRoot.SetActive(false);
    }

    void Update()
    {
        // Delete = immediate quit (stop play in editor or quit app)
        if (Input.GetKeyDown(KeyCode.Delete))
        {
#if UNITY_EDITOR
            EditorApplication.isPlaying = false;
#else
            Application.Quit();
#endif
            return;
        }

        if (Input.GetKeyDown(KeyCode.Escape))
        {
            TogglePause();
        }

        // 当处于暂停状态且按下 Backspace 时返回主界面
        if (IsPaused && Input.GetKeyDown(KeyCode.Backspace))
        {
            // 恢复时间流并触发事件，然后加载主场景
            Pause(false);
            // 确保场景名称与项目中的主场景匹配
            SceneManager.LoadScene("Main_main");
        }
    }

    /// <summary>
    /// Pause or resume the game. Call Pause(true) to pause.
    /// This implementation enables/disables overlayRoot and sets Time.timeScale.
    /// </summary>
    public void Pause(bool pause)
    {
        if (pause)
        {
            if (IsPaused) return;
            if (overlayRoot != null) overlayRoot.SetActive(true);
            Time.timeScale = 0f;
            IsPaused = true;
            OnPauseStateChanged?.Invoke(true);
        }
        else
        {
            if (!IsPaused) return;
            if (overlayRoot != null) overlayRoot.SetActive(false);
            Time.timeScale = 1f;
            IsPaused = false;
            OnPauseStateChanged?.Invoke(false);
        }
    }

    public void TogglePause()
    {
        Pause(!IsPaused);
    }
}