using Ichni;
using Ichni.Menu;
using TMPro;
using UnityEngine;
using UnityEngine.UI;

namespace Ichni.Story.UI
{
    /// <summary>
    /// 剧情树中的歌曲 Block 视图。
    /// 它只保存 <see cref="StoryBlockDefinition.songName"/> 这一个稳定歌曲标识；歌曲名称、作曲者与插画
    /// 均从当前章节的 <see cref="SongItemData"/> 读取，避免 StoryData 与选曲资料出现两份可漂移的数据。
    /// 点击后切换到选曲并自动选中对应歌曲的流程将在后续阶段接入。
    /// </summary>
    public class SongBlockView : StoryBlockView
    {
        [Header("Song Block")]
        [Tooltip("Mask 下的 16:9 插画 Image。Sprite 由当前章节的 SongItemData.illustration 提供。")]
        public Image illustrationImage;

        [Tooltip("illustrationImage 对应的 RectTransform。仅修改其 anchoredPosition.y 以完成纵向裁切。")]
        public RectTransform illustrationRect;

        public TMP_Text songNameText;
        public TMP_Text composerText;

        [Tooltip("歌曲或剧情 Block 不可进入时显示的遮罩节点。")]
        public GameObject lockOverlay;

        private ChapterSelectionUnit _chapter;
        private SongItemData _song;
        private bool _canEnterSong;

        public override void Initialize(StoryBlockDefinition def, Vector2 position, StoryBlockState blockState)
        {
            base.Initialize(def, position, blockState);

            if (TryResolveSong(out _chapter, out _song))
            {
                illustrationImage.sprite = _song.illustration;
                songNameText.text = _song.displaySongName;
                composerText.text = _song.composer;
            }
            else
            {
                // 配置错误时保留稳定 ID 以便定位问题，同时锁定 Block，避免从剧情页绕过内容授权。
                illustrationImage.sprite = null;
                songNameText.text = def.songName;
                composerText.text = string.Empty;
            }

            // 数据存储的是最终 local Y，而非叠加在 Prefab 默认位置上的偏移量。
            // Clamp 仍保留作为运行时防线：即使旧资产或外部工具写入越界值，也不会在 Mask 边缘露出空白。
            Vector2 illustrationPosition = illustrationRect.anchoredPosition;
            illustrationPosition.y = Mathf.Clamp(def.illustrationLocalY, -74.25f, 74.25f);
            illustrationRect.anchoredPosition = illustrationPosition;

            ApplyState(blockState);
        }

        /// <summary>
        /// StoryBlock 的剧情状态和歌曲的内容解锁状态必须同时满足，才能真正点击进入歌曲。
        /// <see cref="UnlockSaveModule.CanEnterSong"/> 复用选曲页面的统一授权判断，防止 Story SongBlock 成为绕过入口。
        /// </summary>
        public override void ApplyState(StoryBlockState newState)
        {
            base.ApplyState(newState);

            bool storyAllowsInteraction = state != StoryBlockState.Locked && state != StoryBlockState.Forbidden;
            _canEnterSong = _chapter != null && _song != null &&
                            GameSaveManager.instance != null &&
                            GameSaveManager.instance.UnlockSaveModule != null &&
                            GameSaveManager.instance.UnlockSaveModule.CanEnterSong(_chapter, _song);

            bool canInteract = storyAllowsInteraction && _canEnterSong;
            button.interactable = canInteract;
            lockOverlay.SetActive(!canInteract);
        }

        /// <summary>
        /// 根据正在构建的剧情章节索引定位歌曲，而不是盲目信任 currentChapter。
        /// 这样即使未来从其它页面直接打开 StoryData，也不会把同名歌曲解析到上一次残留的章节中。
        /// </summary>
        private bool TryResolveSong(out ChapterSelectionUnit chapter, out SongItemData song)
        {
            chapter = null;
            song = null;

            string chapterIndex = StoryManager.instance?.treeController?.ActiveChapterIndex;
            ChapterSelectionManager chapterManager = ChapterSelectionManager.instance;
            if (string.IsNullOrEmpty(chapterIndex) || chapterManager == null)
            {
                Debug.LogWarning($"[SongBlockView] 无法解析歌曲 Block '{blockId}'：当前章节或 ChapterSelectionManager 不可用。");
                return false;
            }

            foreach (ChapterSelectionUnit candidate in chapterManager.chapters)
            {
                if (candidate != null && candidate.chapterIndex == chapterIndex)
                {
                    chapter = candidate;
                    break;
                }
            }

            if (chapter == null)
            {
                Debug.LogWarning($"[SongBlockView] 无法解析歌曲 Block '{blockId}'：找不到章节 '{chapterIndex}' 的 ChapterSelectionUnit。");
                return false;
            }

            foreach (SongItemData candidate in chapter.songs)
            {
                if (candidate != null && candidate.songName == definition.songName)
                {
                    song = candidate;
                    return true;
                }
            }

            Debug.LogWarning($"[SongBlockView] 无法解析歌曲 Block '{blockId}'：章节 '{chapterIndex}' 中不存在歌曲 ID '{definition.songName}'。");
            return false;
        }

        protected override void OnClicked()
        {
            if (!_canEnterSong)
            {
                return;
            }

            // 占位：后续接入曲目选择流程
            Debug.Log($"[SongBlockView] 点击音乐块 '{blockId}' (song='{definition.songName}')。占位实现，曲目选择将在后续阶段接入。");
        }
    }
}