using System.Collections;
using System.IO;
using Michsky.UI.Reach;
using UI.Settings;
using UnityEngine;
using UnityEngine.SceneManagement;

namespace UI.Title
{
    public class TitleMenuController : MonoBehaviour
    {
        [SerializeField] private bool debugLogs = true;

        [Header("Scene")]
        [SerializeField] private int nextSceneBuildIndex = 2;

        [Header("Buttons")]
        [SerializeField] private ButtonManager startOrRestartButton;
        [SerializeField] private ButtonManager continueButton;
        [SerializeField] private ButtonManager settingsButton;
        [SerializeField] private ButtonManager quitButton;

        [Header("Settings Panel")]
        [SerializeField] private SettingsController settingsController;

        [Header("Labels")]
        [SerializeField] private string loadingText = "正在加载";
        [SerializeField] private string startText = "开始游戏";
        [SerializeField] private string restartText = "重新开始";
        [SerializeField] private string continueText = "继续游戏";

        private AsyncOperation loadOperation;
        private bool isWired;
        private bool hasSave;

        private void Awake()
        {
            Cursor.lockState = CursorLockMode.None;
            Cursor.visible = true;

            if (settingsController == null)
            {
                settingsController = FindObjectOfType<SettingsController>(true);
            }

            if (debugLogs) Debug.Log($"[TitleMenu] Awake. settingsController={(settingsController!=null)} nextSceneBuildIndex={nextSceneBuildIndex}");
            RefreshSaveState();
            WireOnce();
            UpdateButtons();
        }

        private void Start()
        {
            BeginPreload();
        }

        private void OnEnable()
        {
            Cursor.lockState = CursorLockMode.None;
            Cursor.visible = true;

            RefreshSaveState();
            UpdateButtons();
        }

        public void BeginPreload()
        {
            if (loadOperation != null) { return; }

            if (nextSceneBuildIndex < 0 || nextSceneBuildIndex >= SceneManager.sceneCountInBuildSettings)
            {
                if (debugLogs) Debug.Log($"[TitleMenu] Invalid nextSceneBuildIndex={nextSceneBuildIndex}");
                return;
            }

            if (debugLogs) Debug.Log($"[TitleMenu] BeginPreload buildIndex={nextSceneBuildIndex}");
            StartCoroutine(PreloadRoutine());
        }

        private IEnumerator PreloadRoutine()
        {
            loadOperation = SceneManager.LoadSceneAsync(nextSceneBuildIndex);
            if (loadOperation == null) { yield break; }

            loadOperation.allowSceneActivation = false;

            while (loadOperation.progress < 0.9f)
            {
                UpdateButtons();
                yield return null;
            }

            if (debugLogs) Debug.Log("[TitleMenu] Preload ready (progress>=0.9).");
            UpdateButtons();
        }

        private bool IsPreloadReady()
        {
            return loadOperation != null && loadOperation.progress >= 0.9f;
        }

        private void WireOnce()
        {
            if (isWired) { return; }

            if (startOrRestartButton != null) { startOrRestartButton.onClick.AddListener(OnStartOrRestartClicked); }
            if (continueButton != null) { continueButton.onClick.AddListener(OnContinueClicked); }
            if (settingsButton != null) { settingsButton.onClick.AddListener(OnSettingsClicked); }
            if (quitButton != null) { quitButton.onClick.AddListener(OnQuitClicked); }

            isWired = true;
        }

        private void RefreshSaveState()
        {
            string savePath = Path.Combine(Application.persistentDataPath, "savegame.json");
            hasSave = File.Exists(savePath);
        }

        private void UpdateButtons()
        {
            bool preloadReady = IsPreloadReady();

            if (startOrRestartButton != null)
            {
                if (!preloadReady)
                {
                    startOrRestartButton.SetText(loadingText);
                    startOrRestartButton.Interactable(false);
                }
                else
                {
                    startOrRestartButton.SetText(hasSave ? restartText : startText);
                    startOrRestartButton.Interactable(true);
                }
            }

            if (continueButton != null)
            {
                continueButton.gameObject.SetActive(hasSave);

                if (hasSave)
                {
                    if (!preloadReady)
                    {
                        continueButton.SetText(loadingText);
                        continueButton.Interactable(false);
                    }
                    else
                    {
                        continueButton.SetText(continueText);
                        continueButton.Interactable(true);
                    }
                }
            }
        }

        private void OnStartOrRestartClicked()
        {
            if (!IsPreloadReady()) { return; }

            if (hasSave)
            {
                string savePath = Path.Combine(Application.persistentDataPath, "savegame.json");
                if (File.Exists(savePath)) { File.Delete(savePath); }
                hasSave = false;
            }

            ActivateLoadedScene();
        }

        private void OnContinueClicked()
        {
            if (!hasSave) { return; }
            if (!IsPreloadReady()) { return; }
            ActivateLoadedScene();
        }

        private void ActivateLoadedScene()
        {
            if (loadOperation == null) { return; }
            loadOperation.allowSceneActivation = true;
        }

        private void OnSettingsClicked()
        {
            if (debugLogs) Debug.Log($"[TitleMenu] Settings clicked. settingsController={(settingsController!=null)}");
            if (settingsController != null)
            {
                settingsController.OpenAtIndex(0);
            }
        }

        private void OnQuitClicked()
        {
            Application.Quit();
        }
    }
}