ichni_Official/Assets/Scripts/UI/SongSelection/SongSelectionUIPage.cs

using DG.Tweening;
using Ichni.RhythmGame;
using Ichni.Story;
using Ichni.UI;
using SLSUtilities.WwiseAssistance;
using UnityEngine;
using UnityEngine.Events;
using UnityEngine.UI;
using UnityEngine.UI.Extensions;

namespace Ichni.Menu
{
    public partial class SongSelectionUIPage : UIPageBase
    {
        public Button backButton;

        [Tooltip("从选曲页进入当前章节剧情树的按钮。会优先定位当前选中歌曲对应的 SongBlock；未找到时显示剧情开头。")]
        public Button enterStoryButton;
        
        public Gradient2 backgroundFrames;
        public float framePositionOffset = -1;
        
        public SongListControllerUI songListController;
        public PlaySongUI playSongUI;
        public SongInfoUI songInfoUI;
        public DifficultySelectionContainer difficultySelectionContainer;
        //public int currentSelectedDifficultyIndex;

        protected override void Awake()
        {
            base.Awake();

            fadeOutAction = () =>
            {
                songListController.ClearSongTabs();
                MenuInputManager.OnMoveUp -= songListController.GoToFormerTab;
                MenuInputManager.OnMoveDown -= songListController.GoToNextTab;
            };

            fadeInStartAction = () =>
            {
                songListController.InitializeList();
            };

            fadeInFinishAction = () =>
            {
                MenuInputManager.OnMoveUp += songListController.GoToFormerTab;
                MenuInputManager.OnMoveDown += songListController.GoToNextTab;
            };
            
            backButton.onClick.AddListener(ReturnToChapterSelection);

            if (enterStoryButton != null)
                enterStoryButton.onClick.AddListener(OpenStoryForSelectedSong);
            
            songInfoUI.SetUp();
        }

        private void OnDestroy()
        {
            backButton.onClick.RemoveListener(ReturnToChapterSelection);

            if (enterStoryButton != null)
                enterStoryButton.onClick.RemoveListener(OpenStoryForSelectedSong);
        }

        /// <summary>
        /// 选曲页的全局返回语义固定为回到章节选择页。
        /// 即使本次页面最初由 Story SongBlock 打开，也不再把 Back 视为“返回剧情树”；
        /// 玩家需要使用专门的 <see cref="enterStoryButton"/> 进入剧情。
        /// </summary>
        private void ReturnToChapterSelection()
        {
            FadeOut();
            SongSelectionManager.instance.StopPreviewSong();

            // Story SongBlock 入口上下文只服务于一次“进入游戏后返回剧情”的流程。
            // 玩家主动离开选曲页时必须清除它，避免之后普通选曲误继承旧的目标歌曲与返回目的地。
            InformationTransistor.instance?.storySongEntryContext?.Clear();
            MenuManager.instance.chapterSelectionUIPage.FadeIn();
        }

        /// <summary>
        /// 从选曲页打开当前章节的剧情树。若当前歌曲在 StoryData 中存在对应 SongBlock，
        /// StoryManager 会把视口定位到该 Block；未选中歌曲或没有对应 Block 时则显示剧情开头。
        /// </summary>
        private void OpenStoryForSelectedSong()
        {
            ChapterSelectionUnit chapter = ChapterSelectionManager.instance?.currentChapter;
            StoryManager.instance?.TryOpenStoryForSong(chapter, selectedSong);
        }

        private void Start()
        {
            Sequence framesSeq = DOTween.Sequence();
            framesSeq.Append(DOTween.To(() => framePositionOffset, x => framePositionOffset = x, 1f, 1f)
                    .SetEase(Ease.Linear)
                    .OnUpdate(() => backgroundFrames.Offset = framePositionOffset));
            framesSeq.AppendInterval(4f);
            framesSeq.SetLoops(-1, LoopType.Restart);
            framesSeq.Play();
        }
    }

    public partial class SongSelectionUIPage
    {
        public SongItemData selectedSong;
        public DifficultyData selectedDifficulty;
        public SongStatusSave selectedSave;
    }
}