using UnityEngine;
using UnityEngine.UI;
using UnityEngine.EventSystems;
using System.Collections.Generic;
using System.Collections;
using System.IO;

public class dlcButton : MonoBehaviour, IPointerEnterHandler, IPointerExitHandler
{
    [Header("Inspector")]
    public Image dlc_profileImgae;
    public Text dlcName;
    public Text dlcID;
    public Text dlcProducer;
    public Text dlcPubliushDate;
    public Text dlcSongsAmount;
    public Image dlc_nowSelectedImageBoarder;
    [Header("Inspector")]
    public GameObject dlcDetailParent;
    public Text dlcDescription;

    [Header("Inspector")]
    public dlcData dlcDataSO;

    [Header("Inspector")]
    public List<SongData> dlcContent = new List<SongData>();

    [Header("Inspector")]
    public string editorSearchFolder = "Assets/Resources/dlc_dlcIndex";
    public string runtimeResourcesFolder = "Resources/dlc_dlcIndex";

    private Button _btn;
    public bool Resolved { get; private set; }

    // Shared cache to avoid repeated Resources.LoadAll scans
    private static Dictionary<int, dlcData> cachedById = new Dictionary<int, dlcData>();
    private static List<dlcData> cachedAll = new List<dlcData>();
    private static bool cacheBuilt = false;
    private static bool cacheBuilding = false;
    private static string cachedFolder = string.Empty;


    // Selection management (shared across all dlcButton instances)
    private static List<dlcButton> allButtons = new List<dlcButton>();
    private static int selectedIndex = -1;
    private const string PlayerPrefsKey = "dlc_selected_index";

    private int instanceIndex = -1;
    private Coroutine hoverCoroutine;

    public void OnPointerEnter(PointerEventData eventData)
    {
        if (hoverCoroutine != null) StopCoroutine(hoverCoroutine);
        hoverCoroutine = StartCoroutine(HandleHover());
    }

    public void OnPointerExit(PointerEventData eventData)
    {
        if (hoverCoroutine != null) StopCoroutine(hoverCoroutine);
        if (dlcDetailParent != null) dlcDetailParent.SetActive(false);
    }

    private IEnumerator HandleHover()
    {
        yield return new WaitForSecondsRealtime(0.5f);
        
        // 尝试从场景中查找 dlcDetailParent (如果自身引用的为空)
        if (dlcDetailParent == null)
        {
            var details = GameObject.FindObjectsByType<dlcButton>(FindObjectsInactive.Include, FindObjectsSortMode.None);
            foreach (var b in details)
            {
                if (b != this && b.dlcDetailParent != null)
                {
                    dlcDetailParent = b.dlcDetailParent;
                    dlcDescription = b.dlcDescription;
                    break;
                }
            }
        }

        if (dlcDetailParent != null)
        {
            dlcDetailParent.SetActive(true);
            // 更新简介信息
            if (dlcDescription != null)
            {
                if (dlcDataSO != null)
                {
                    dlcDescription.text = string.IsNullOrEmpty(dlcDataSO.dlcDescription) ? "暂无DLC简介信息。" : dlcDataSO.dlcDescription;
                }
                else
                {
                    dlcDescription.text = "暂无DLC简介信息。";
                }
            }
        }
    }

    void Awake()
    {
        _btn = GetComponent<Button>();
        if (_btn != null)
        {
            _btn.onClick.RemoveAllListeners();
            _btn.onClick.AddListener(OnButtonClicked_ShowSongs);
        }

        // register this button for centralized selection handling
        RegisterInstance();

        // ensure border initial state
        if (dlc_nowSelectedImageBoarder != null)
        {
            var c = dlc_nowSelectedImageBoarder.color;
            c.a = 0f;
            dlc_nowSelectedImageBoarder.color = c;
            dlc_nowSelectedImageBoarder.gameObject.SetActive(false);
        }

        Debug.Log($"dlcButton.Awake: registered '{gameObject.name}' as index {instanceIndex}");
    }

    private void RegisterInstance()
    {
        if (!allButtons.Contains(this))
        {
            instanceIndex = allButtons.Count;
            allButtons.Add(this);

            // If no selectedIndex loaded yet, load from PlayerPrefs default 0
            if (selectedIndex == -1)
            {
                selectedIndex = PlayerPrefs.GetInt(PlayerPrefsKey, 0);
            }

            // If this instance matches the persisted selection, apply selection
            if (instanceIndex == selectedIndex)
            {
                // ensure other buttons are deselected
                ApplySelectionToAll(instanceIndex);
            }
            else
            {
                // ensure unselected visual
                SetSelectedVisual(false, immediate: true);
            }
        }
    }

    private void UnregisterInstance()
    {
        if (allButtons.Contains(this))
        {
            int idx = allButtons.IndexOf(this);
            allButtons.Remove(this);

            // if removed index was before selectedIndex, adjust saved index
            if (idx >= 0 && idx < instanceIndex)
            {
                // nothing: instanceIndex only used at registration time
            }
        }
    }

    void OnDestroy()
    {
        UnregisterInstance();
    }

    // Ensure only one button is selected and persist the index
    public void Select()
    {
        ApplySelectionToAll(instanceIndex);
        selectedIndex = instanceIndex;
        PlayerPrefs.SetInt(PlayerPrefsKey, selectedIndex);
        PlayerPrefs.Save();
        Debug.Log($"dlcButton.Select: '{gameObject.name}' selected (index {instanceIndex}) and saved to PlayerPrefs");
    }

    private static void ApplySelectionToAll(int selectIdx)
    {
        for (int i = 0; i < allButtons.Count; i++)
        {
            var btn = allButtons[i];
            if (btn == null) continue;
            bool shouldSelect = (i == selectIdx);
            btn.SetSelectedVisual(shouldSelect);
        }
    }

    // fades the border in or out; if immediate, set without coroutine
    private Coroutine borderFadeCoroutine = null;
    private Coroutine showSongsRetryCoroutine = null;
    private void SetSelectedVisual(bool selected, bool immediate = false)
    {
        if (dlc_nowSelectedImageBoarder == null) return;

        if (borderFadeCoroutine != null)
        {
            StopCoroutine(borderFadeCoroutine);
            borderFadeCoroutine = null;
        }

        if (immediate)
        {
            dlc_nowSelectedImageBoarder.gameObject.SetActive(selected);
            var c = dlc_nowSelectedImageBoarder.color;
            c.a = selected ? 1f : 0f;
            dlc_nowSelectedImageBoarder.color = c;
        }
        else
        {
            dlc_nowSelectedImageBoarder.gameObject.SetActive(true);
            borderFadeCoroutine = StartCoroutine(FadeBorder(dlc_nowSelectedImageBoarder, selected ? 1f : 0f, 0.25f));
        }
    }

    private IEnumerator<YieldInstruction> FadeBorder(Image img, float targetAlpha, float duration)
    {
        if (img == null) yield break;
        float startAlpha = img.color.a;
        float t = 0f;
        // if fading out, ensure we start from current alpha
        while (t < duration)
        {
            t += Time.unscaledDeltaTime;
            float a = Mathf.Lerp(startAlpha, targetAlpha, Mathf.Clamp01(t / duration));
            var c = img.color;
            c.a = a;
            img.color = c;
            yield return null;
        }
        var final = img.color;
        final.a = targetAlpha;
        img.color = final;
        if (Mathf.Approximately(targetAlpha, 0f))
        {
            img.gameObject.SetActive(false);
        }
        borderFadeCoroutine = null;
    }

    void Start()
    {
        // Do not auto-resolve here anymore. Resolution will be triggered externally after instantiation of all buttons.
    }

    public void OnButtonClicked_ShowSongs()
    {
        // set current DLC key for SongSelectUI to allow per-DLC song selection restore
        string dlcKey = null;
        if (dlcDataSO != null)
        {
            dlcKey = "dlc_" + dlcDataSO.dlcID;
        }
        else if (dlcID != null && int.TryParse(dlcID.text, out int parsedId))
        {
            dlcKey = "dlc_" + parsedId;
        }
        else
        {
            dlcKey = "dlc_instance_" + instanceIndex;
        }

        // assign to SongSelectUI static key
        try { SongSelectUI.CurrentDlcKey = dlcKey; } catch { }

        // mark selection first
        Select();

        if (TryDisplaySongsNow())
        {
            return;
        }

        if (showSongsRetryCoroutine != null)
        {
            StopCoroutine(showSongsRetryCoroutine);
        }
        showSongsRetryCoroutine = StartCoroutine(RetryDisplaySongsWhenUIReady());
    }

    private SongSelectUI FindSongSelectUI()
    {
        var ui = Object.FindAnyObjectByType<SongSelectUI>();
        if (ui != null)
        {
            return ui;
        }

        var all = Object.FindObjectsByType<SongSelectUI>(FindObjectsInactive.Include, FindObjectsSortMode.None);
        if (all != null && all.Length > 0)
        {
            return all[0];
        }

        return null;
    }

    private bool TryDisplaySongsNow()
    {
        var ui = FindSongSelectUI();
        if (ui == null)
        {
            return false;
        }

        ui.DisplaySongsFromList(dlcContent);
        return true;
    }

    private IEnumerator RetryDisplaySongsWhenUIReady()
    {
        const int maxRetryFrames = 8;
        for (int i = 0; i < maxRetryFrames; i++)
        {
            yield return null;
            if (TryDisplaySongsNow())
            {
                showSongsRetryCoroutine = null;
                yield break;
            }
        }

        showSongsRetryCoroutine = null;
        Debug.LogWarning("dlcButton: SongSelectUI not found in scene to display songs");
    }

    // Try to find a dlcData SO by id and apply its songList to dlcContent
    public void LoadDlcDataById(int id)
    {
        Debug.Log($"dlcButton.LoadDlcDataById: searching for id={id} (editorFolder='{editorSearchFolder}', runtimeFolder='{runtimeResourcesFolder}') on '{gameObject.name}'");
#if UNITY_EDITOR
        // Editor search: search recursively for asset files under editorSearchFolder
        if (!string.IsNullOrEmpty(editorSearchFolder) && Directory.Exists(editorSearchFolder))
        {
            try
            {
                var files = Directory.GetFiles(editorSearchFolder, "*.asset", SearchOption.AllDirectories);
                Debug.Log($"dlcButton.LoadDlcDataById: found {files.Length} asset files under {editorSearchFolder}");
                foreach (var path in files)
                {
                    string fileName = Path.GetFileNameWithoutExtension(path);
                    if (fileName.StartsWith(id.ToString()))
                    {
                        string assetPath = path.Replace("\\", "/");
                        Debug.Log($"dlcButton.LoadDlcDataById: candidate assetPath={assetPath}");
                        var so = UnityEditor.AssetDatabase.LoadAssetAtPath<dlcData>(assetPath);
                        if (so != null)
                        {
                            Debug.Log($"dlcButton.LoadDlcDataById: loaded dlcData SO '{so.name}' for id={id}");
                            dlcDataSO = so;
                            ApplyDlcData(so);
                            return;
                        }
                    }
                }
            }
            catch (System.Exception e)
            {
                Debug.LogWarning("dlcButton LoadDlcDataById (Editor) failed: " + e.Message);
            }
        }
        else
        {
            Debug.Log($"dlcButton.LoadDlcDataById: editorSearchFolder '{editorSearchFolder}' does not exist or not set");
        }
#endif
        // Runtime: search Resources (load all dlcData then filter by name prefix)
        try
        {
            var arr = Resources.LoadAll<dlcData>(runtimeResourcesFolder);
            Debug.Log($"dlcButton.LoadDlcDataById: Resources.LoadAll('{runtimeResourcesFolder}') returned {(arr != null ? arr.Length : 0)} items");
            if (arr != null)
            {
                foreach (var so in arr)
                {
                    if (so == null) continue;
                    if (so.name.StartsWith(id.ToString()))
                    {
                        Debug.Log($"dlcButton.LoadDlcDataById: found runtime dlcData '{so.name}' for id={id}");
                        dlcDataSO = so;
                        ApplyDlcData(so);
                        return;
                    }
                }
            }
        }
        catch (System.Exception e)
        {
            Debug.LogWarning($"dlcButton.LoadDlcDataById: Resources search failed: {e.Message}");
        }

        // fallback: search all Resources
        var all = Resources.LoadAll<dlcData>("");
        Debug.Log("dlcButton.LoadDlcDataById: Resources.LoadAll(\"\") returned " + (all != null ? all.Length : 0) + " items");
        if (all != null)
        {
            foreach (var so in all)
            {
                if (so == null) continue;
                if (so.name.StartsWith(id.ToString()))
                {
                    Debug.Log($"dlcButton.LoadDlcDataById: found fallback dlcData '{so.name}' for id={id}");
                    dlcDataSO = so;
                    ApplyDlcData(so);
                    return;
                }
            }
        }

        // if no dlcData found, keep dlcContent empty but attempt old behavior: search SongData by id prefix
        Debug.Log($"dlcButton.LoadDlcDataById: no dlcData found for id={id}, falling back to song prefix search");
        LoadContentBySongIdPrefix(id);
    }

    // Populate dlcContent from dlcData SO and update UI texts/images
    private void ApplyDlcData(dlcData so)
    {
        if (so == null) return;
        dlcContent = new List<SongData>();
        if (so.songList != null)
        {
            foreach (var s in so.songList)
                if (s != null) dlcContent.Add(s);
        }

        if (dlcSongsAmount != null)
        {
            dlcSongsAmount.text = dlcContent.Count.ToString();
        }

        if (dlcName != null) dlcName.text = so.dlcName ?? dlcName.text;
        if (dlcProducer != null) dlcProducer.text = so.dlcProducer ?? dlcProducer.text;
        if (dlcDescription != null) dlcDescription.text = so.dlcDescription ?? dlcDescription.text;
        if (dlcPubliushDate != null) dlcPubliushDate.text = so.dlcPublishDate ?? dlcPubliushDate.text;
        if (dlc_profileImgae != null)
        {
            dlc_profileImgae.sprite = so.dlc_image;
            dlc_profileImgae.enabled = so.dlc_image != null;
        }

        Debug.Log($"dlcButton.ApplyDlcData: applied dlcData '{so.name}' with {dlcContent.Count} songs to button '{gameObject.name}'");
    }

    // Legacy: if no dlcData SO, search SongData assets by id prefix and fill dlcContent
    public void LoadContentBySongIdPrefix(int id)
    {
        dlcContent.Clear();
#if UNITY_EDITOR
        if (!string.IsNullOrEmpty(editorSearchFolder) && Directory.Exists(editorSearchFolder))
        {
            try
            {
                var files = Directory.GetFiles(editorSearchFolder, "*.asset", SearchOption.AllDirectories);
                foreach (var path in files)
                {
                    var fileName = Path.GetFileNameWithoutExtension(path);
                    if (fileName.StartsWith(id.ToString()))
                    {
                        var assetPath = path.Replace("\\", "/");
                        var so = UnityEditor.AssetDatabase.LoadAssetAtPath<SongData>(assetPath);
                        if (so != null) dlcContent.Add(so);
                    }
                }
            }
            catch (System.Exception e)
            {
                Debug.LogWarning("dlcButton LoadContentBySongIdPrefix (Editor) failed: " + e.Message);
            }
        }
#endif
        if (!string.IsNullOrEmpty(runtimeResourcesFolder))
        {
            var arr = Resources.LoadAll<SongData>(runtimeResourcesFolder);
            if (arr != null)
            {
                foreach (var so in arr)
                {
                    if (so == null) continue;
                    if (so.name.StartsWith(id.ToString())) dlcContent.Add(so);
                }
            }
        }

        if (dlcContent.Count == 0)
        {
            var arr2 = Resources.LoadAll<SongData>("");
            if (arr2 != null)
            {
                foreach (var so in arr2)
                {
                    if (so == null) continue;
                    if (so.name.StartsWith(id.ToString())) dlcContent.Add(so);
                }
            }
        }

        Debug.Log($"dlcButton: Loaded {dlcContent.Count} SongData entries for DLC id={id} (fallback search)");
    }

    // Resolve dlcData after all buttons have been instantiated
    public void ResolveDlcData()
    {
        if (Resolved)
        {
            return;
        }
        StartCoroutine(ResolveDlcDataAsync());
    }

    public IEnumerator ResolveDlcDataAsync()
    {
        if (Resolved)
        {
            yield break;
        }

        Debug.Log($"dlcButton.ResolveDlcData called on '{gameObject.name}'");

        if (dlcDataSO != null)
        {
            Debug.Log($"dlcButton: dlcDataSO already assigned on '{gameObject.name}' -> {dlcDataSO.name}");
            ApplyDlcData(dlcDataSO);
            Resolved = true;
            yield break;
        }

        int id;
        if (!TryGetResolveId(out id))
        {
            Debug.LogWarning($"dlcButton.ResolveDlcData: no dlcID text and no name to parse for '{gameObject.name}'");
            Resolved = true;
            yield break;
        }

        yield return BuildCacheIfNeeded(runtimeResourcesFolder);

        if (TryResolveFromCache(id))
        {
            Resolved = true;
            yield break;
        }

        LoadContentBySongIdPrefix(id);
        Resolved = true;
    }

    private bool TryGetResolveId(out int id)
    {
        id = 0;
        if (dlcID != null && int.TryParse(dlcID.text, out id))
        {
            return true;
        }

        string goName = gameObject.name;
        if (!string.IsNullOrEmpty(goName))
        {
            var parts = goName.Split('_');
            if (parts.Length > 0 && int.TryParse(parts[0], out id))
            {
                return true;
            }
        }
        return false;
    }

    private bool TryResolveFromCache(int id)
    {
        if (!cacheBuilt)
        {
            return false;
        }

        dlcData so;
        if (cachedById.TryGetValue(id, out so) && so != null)
        {
            dlcDataSO = so;
            ApplyDlcData(so);
            return true;
        }

        string prefix = id.ToString();
        for (int i = 0; i < cachedAll.Count; i++)
        {
            var item = cachedAll[i];
            if (item == null) continue;
            if (item.name.StartsWith(prefix))
            {
                dlcDataSO = item;
                ApplyDlcData(item);
                return true;
            }
        }

        return false;
    }

    private static string NormalizeResourcesPath(string path)
    {
        if (string.IsNullOrEmpty(path))
        {
            return string.Empty;
        }
        string p = path.Replace("\\", "/");
        int idx = p.IndexOf("Resources/", System.StringComparison.OrdinalIgnoreCase);
        if (idx >= 0)
        {
            p = p.Substring(idx + "Resources/".Length);
        }
        return p.Trim('/');
    }

    private static IEnumerator BuildCacheIfNeeded(string runtimeFolder)
    {
        if (cacheBuilt)
        {
            yield break;
        }
        if (cacheBuilding)
        {
            while (!cacheBuilt)
            {
                yield return null;
            }
            yield break;
        }

        cacheBuilding = true;
        cachedById.Clear();
        cachedAll.Clear();
        cachedFolder = NormalizeResourcesPath(runtimeFolder);

        // allow one frame before heavy load
        yield return null;

        dlcData[] arr = null;
        if (!string.IsNullOrEmpty(cachedFolder))
        {
            arr = Resources.LoadAll<dlcData>(cachedFolder);
        }
        if (arr == null || arr.Length == 0)
        {
            arr = Resources.LoadAll<dlcData>("");
        }

        if (arr != null)
        {
            for (int i = 0; i < arr.Length; i++)
            {
                var so = arr[i];
                if (so == null) continue;
                cachedAll.Add(so);
                if (!cachedById.ContainsKey(so.dlcID))
                {
                    cachedById.Add(so.dlcID, so);
                }
            }
        }

        cacheBuilt = true;
        cacheBuilding = false;
    }
}