using System;
using System.Collections;
using System.Collections.Generic;
using AK.Wwise;
using Ichni.Menu;
using Ichni.Menu.UI;
using Ichni.Story;
using Ichni.Story.UI;
using Ichni.UI;
using Sirenix.OdinInspector;
using SLSUtilities.WwiseAssistance;
using UniRx;
using UnityEngine;
using UnityEngine.SceneManagement;
using UnityEngine.Serialization;

namespace Ichni
{
    public partial class MenuManager : MonoBehaviour
    {
        public static MenuManager instance;
        
        public StartUIPage startUIPage;
        public LoginPage loginPage;
        public ChapterSelectionUIPage chapterSelectionUIPage;
        public StoryUIPage storyUIPage;
        public SelectionBoxUIPage selectionBoxUIPage;
        // dialogUIPage 已随旧对话系统移除；阶段 3 将接入新的 VN 对话页面引用
        public SongSelectionUIPage songSelectionUIPage;
        public TransitionUIPage transitionUIPage;
        public SettingsUIPage settingsUIPage;

        public List<string> languageList;
        public List<string> displayLanguageList;
    }
    
    public partial class MenuManager
    {
        AsyncOperation asyncOperation;
        public bool isEnteringGame;

        /// <summary>
        /// 当前 MenuScene 是否已经完成 GameScene 预加载且尚未处于切场中。
        /// TutorialFlowController 在写入“已处理”剧情变量前使用此状态进行最后一次启动前检查。
        /// </summary>
        public bool CanBeginGame => !isEnteringGame && asyncOperation != null;
        
        private void Awake()
        {
            instance = this;
        }

        private void Start()
        {
            isEnteringGame = false;
            
            InformationTransistor information = InformationTransistor.instance;
            MenuReturnDestination returnDestination = information != null
                ? information.menuReturnDestination
                : MenuReturnDestination.None;

            if (returnDestination == MenuReturnDestination.SongSelection &&
                information != null && information.chapter != null &&
                information.song != null && information.difficulty != null)
            {
                startUIPage.mainCanvasGroup.gameObject.SetActive(false);
                ChapterSelectionManager.instance.currentChapter = 
                    information.chapter;
                AudioManager.SetSwitch(ChapterSelectionManager.instance.currentChapter.chapterSwitch);
                MenuInformationRecorder.instance.songSelectionRecords[
                    ChapterSelectionManager.instance.currentChapter] =
                    new SongSelectionRecord(information.song, information.difficulty);
                songSelectionUIPage.FadeIn();
            }
            else if (returnDestination == MenuReturnDestination.Story &&
                     information != null && information.chapter != null)
            {
                startUIPage.mainCanvasGroup.gameObject.SetActive(false);
                ChapterSelectionManager.instance.currentChapter = information.chapter;
                AudioManager.SetSwitch(ChapterSelectionManager.instance.currentChapter.chapterSwitch);

                // MenuScene 会在教程游玩后重新创建，必须显式重建章节故事树，
                // 不能依赖旧场景中残留的 Block 实例。
                StoryManager.instance?.OpenChapter(ChapterSelectionManager.instance.currentChapter.chapterIndex);
                storyUIPage.FadeIn();
            }

            // 返回目标是一次性运行态信息。无论是否能恢复页面，都不能让它在下次重进菜单时重复生效。
            information?.ClearMenuReturnDestination();
            
            Application.targetFrameRate = SettingsManager.instance.gameSettings.targetFrame;
            asyncOperation = SceneManager.LoadSceneAsync("GameScene");
            asyncOperation.allowSceneActivation = false;
        }
    }
    
    public partial class MenuManager
    {
        public void EnterGame()
        {
            EnterGame(MenuReturnDestination.SongSelection);
        }

        /// <summary>
        /// 激活已预加载的 GameScene，并写入唯一的菜单返回目标。
        /// 普通选曲使用 <see cref="MenuReturnDestination.SongSelection"/>，教程使用
        /// <see cref="MenuReturnDestination.Story"/>。
        /// </summary>
        public void EnterGame(MenuReturnDestination returnDestination)
        {
            InformationTransistor.instance?.SetMenuReturnDestination(returnDestination);
            EnterGameScene();
        }

        /// <summary>
        /// 为 TutorialBlock 等非选曲入口准备上下文并播放通用转场。
        /// 运行成功后会返回 true；返回 false 时不会修改剧情变量或存档，调用方应保留原状。
        /// </summary>
        public bool TryBeginGame(ChapterSelectionUnit chapter, SongItemData song,
            DifficultyData difficulty, MenuReturnDestination returnDestination, UIPageBase sourcePage)
        {
            if (!CanBeginGame)
            {
                Debug.LogWarning("[MenuManager] GameScene 未完成预加载或菜单已在切换，忽略启动请求。");
                return false;
            }

            if (InformationTransistor.instance == null ||
                !InformationTransistor.instance.PrepareGameLaunch(chapter, song, difficulty, returnDestination))
            {
                return false;
            }

            isEnteringGame = true;
            sourcePage?.FadeOut();
            transitionUIPage?.FadeIn();
            AudioManager.Post(AK.EVENTS.ENTERTOGAME);

            Observable.Timer(TimeSpan.FromSeconds(0.6f)).Subscribe(_ => EnterGameScene());
            return true;
        }
        
        public void EnterGameScene()
        {
            if (asyncOperation == null)
            {
                Debug.LogError("[MenuManager] GameScene 尚未完成预加载，无法进入游戏。");
                isEnteringGame = false;
                return;
            }

            MenuInputManager.instance?.gameInput?.Menu.Disable();
            asyncOperation.allowSceneActivation = true;
        }
    }
}