using UnityEngine;
using UnityEngine.UI;
using TMPro;
using UnityEngine.SceneManagement;
using System.Collections.Generic;

public class SongSelectUI : MonoBehaviour
{
    public SongList songList;              // 存储歌曲列表的 ScriptableObject
    public GameObject songButtonPrefab;    // 歌曲按钮的 Prefab (Button)
    public Transform contentPanel;         // 滚动视图的 Content 面板

    [SerializeField] Button button_Main;
    [SerializeField] string ui_Main_Scene_Name = "UI_UI";

    void Start()
    {
        if (songList == null || songButtonPrefab == null || contentPanel == null)
        {
            Debug.LogError("请在 Inspector 中分配所有字段！");
            return;
        }

        button_Main.onClick.AddListener(
        () => SceneManager.LoadScene(ui_Main_Scene_NAME(), LoadSceneMode.Single));
        // Do not populate the song list at start. DLC buttons will request songs when clicked.
    }

    // 显示所有歌曲 (kept for manual use)
    public void DisplaySongs()
    {
        ClearSongList();

        foreach (SongData song in songList.songs)
        {
            InstantiateSongButton(song);
        }
    }

    // Instantiate from a provided list (used by dlcButton to show DLC songs)
    public void DisplaySongsFromList(List<SongData> list)
    {
        ClearSongList();

        if (list == null) return;
        foreach (var song in list)
            InstantiateSongButton(song);
    }

    private void ClearSongList()
    {
        if (contentPanel == null) return;
        for (int i = contentPanel.childCount - 1; i >= 0; i--)
        {
#if UNITY_EDITOR
            if (!Application.isPlaying) DestroyImmediate(contentPanel.GetChild(i).gameObject);
            else Destroy(contentPanel.GetChild(i).gameObject);
#else
            Destroy(contentPanel.GetChild(i).gameObject);
#endif
        }
    }

    private void InstantiateSongButton(SongData song)
    {
        if (songButtonPrefab == null || contentPanel == null) return;

        GameObject songButtonObj = Instantiate(songButtonPrefab, contentPanel);
        songButtonObj.transform.SetParent(contentPanel, false);

        SongButton songButton = songButtonObj.GetComponent<SongButton>();
        if (songButton != null)
        {
            songButton.SetButtonData(song.songName, song.personalRecord, song.difficultyID, song.illustration, song.songID);
        }

        Image songImage = songButtonObj.GetComponentInChildren<Image>();
        TMP_Text[] texts = songButtonObj.GetComponentsInChildren<TMP_Text>();

        if (songImage != null && song.illustration != null)
        {
            songImage.sprite = song.illustration;
            songImage.enabled = true;
        }

        if (texts.Length >= 4)
        {
            texts[0].text = song.songName;
            texts[1].text = "Record : " + song.personalRecord;
            texts[3].text = "" + song.difficultyID;
            texts[2].text = "SongID : " + song.songID.ToString();
        }

        Button button = songButtonObj.GetComponent<Button>();
        if (button != null && songButton != null)
            button.onClick.AddListener(() => songButton.OnSongButtonClick());
    }

    // helper to avoid hardcoding scene name string in delegate - keeps serializer-friendly field
    private string ui_Main_Scene_NAME() => ui_Main_Scene_Name;
}