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

public class SongSelectManager : MonoBehaviour
{
    [SerializeField] private Button          tabAllBtn;
    [SerializeField] private Button          tabOwnedBtn;
    [SerializeField] private RectTransform   cardContainer;
    [SerializeField] private SongDetailPanel detailPanel;
    [SerializeField] private DownloadManager downloadManager;
    [SerializeField] private GameObject      loadingOverlay;
    [SerializeField] private GameObject      errorOverlay;
    [SerializeField] private TMP_Text        errorText;
    [SerializeField] private TMP_FontAsset   cardFont;

    private static readonly Color TabActive   = Color.white;
    private static readonly Color TabInactive = new Color(0.6f, 0.6f, 0.6f);

    private static string CachePath =>
        Path.Combine(Application.persistentDataPath, "songs_cache.json");

    private List<SongInfo> allSongs     = new List<SongInfo>();
    private bool           showingOwned = false;

    private void Start()
    {
        tabAllBtn  .onClick.AddListener(() => SwitchTab(false));
        tabOwnedBtn.onClick.AddListener(() => SwitchTab(true));
        detailPanel.gameObject.SetActive(false);
        SetTabVisual(false);
        FetchSongs();
    }

    private void SwitchTab(bool owned)
    {
        showingOwned = owned;
        SetTabVisual(owned);
        RefreshCards();
    }

    private void SetTabVisual(bool owned)
    {
        ApplyTabColor(tabAllBtn,   owned ? TabInactive : TabActive);
        ApplyTabColor(tabOwnedBtn, owned ? TabActive   : TabInactive);
    }

    private static void ApplyTabColor(Button btn, Color c)
    {
        var colors        = btn.colors;
        colors.normalColor = c;
        btn.colors        = colors;
    }

    private void FetchSongs()
    {
        loadingOverlay.SetActive(true);
        errorOverlay  .SetActive(false);

        downloadManager.FetchSongsList(
            onSuccess: list =>
            {
                allSongs = list.songs;
                SaveCache(list);
                SongLibrary.Instance.ValidateWithFileSystem(downloadManager, list.songs);
                loadingOverlay.SetActive(false);
                RefreshCards();
            },
            onError: _ =>
            {
                SongsList cached = LoadCache();
                loadingOverlay.SetActive(false);
                if (cached != null)
                {
                    allSongs = cached.songs;
                    RefreshCards();
                }
                else
                {
                    errorOverlay.SetActive(true);
                    errorText.text = "Failed to connect to server\nPlease check your internet connection";
                }
            });
    }

    public void RefreshCards()
    {
        for (int i = cardContainer.childCount - 1; i >= 0; i--)
            Destroy(cardContainer.GetChild(i).gameObject);

        List<SongInfo> songs = showingOwned
            ? allSongs.FindAll(s => SongLibrary.Instance.IsSongDownloaded(s.id))
            : allSongs;

        foreach (SongInfo song in songs)
            SpawnCard(song);
    }

    private void SpawnCard(SongInfo song)
    {
        bool downloaded = SongLibrary.Instance.IsSongDownloaded(song.id);

        var card = new GameObject(song.title);
        card.transform.SetParent(cardContainer, false);

        var le = card.AddComponent<LayoutElement>();
        le.preferredHeight = 13f;
        le.flexibleWidth   = 1f;

        var bg = card.AddComponent<Image>();
        bg.color = new Color(1f, 1f, 1f, 0.06f);

        var btn = card.AddComponent<Button>();
        btn.targetGraphic = bg;
        var bc = btn.colors;
        bc.normalColor      = new Color(1f, 1f, 1f, 0.06f);
        bc.highlightedColor = new Color(0.4f, 0.75f, 1f, 0.25f);
        bc.pressedColor     = new Color(0.3f, 0.60f, 0.9f, 0.45f);
        bc.fadeDuration     = 0.1f;
        btn.colors = bc;

        // Title
        var titleGO = new GameObject("Title");
        titleGO.transform.SetParent(card.transform, false);
        var tr = titleGO.AddComponent<RectTransform>();
        tr.anchorMin = new Vector2(0f, 0.5f);
        tr.anchorMax = new Vector2(1f, 1f);
        tr.offsetMin = new Vector2(5f, 0f);
        tr.offsetMax = new Vector2(downloaded ? -18f : -3f, -1f);
        var tTmp = titleGO.AddComponent<TextMeshProUGUI>();
        if (cardFont != null) tTmp.font = cardFont;
        tTmp.text         = song.title;
        tTmp.fontSize     = 5f;
        tTmp.color        = Color.white;
        tTmp.alignment    = TextAlignmentOptions.MidlineLeft;
        tTmp.overflowMode = TextOverflowModes.Ellipsis;

        // Artist
        var artistGO = new GameObject("Artist");
        artistGO.transform.SetParent(card.transform, false);
        var ar = artistGO.AddComponent<RectTransform>();
        ar.anchorMin = new Vector2(0f, 0f);
        ar.anchorMax = new Vector2(1f, 0.5f);
        ar.offsetMin = new Vector2(5f, 1f);
        ar.offsetMax = new Vector2(-3f, 0f);
        var aTmp = artistGO.AddComponent<TextMeshProUGUI>();
        if (cardFont != null) aTmp.font = cardFont;
        aTmp.text      = song.artist;
        aTmp.fontSize  = 4f;
        aTmp.color     = new Color(1f, 1f, 1f, 0.6f);
        aTmp.alignment = TextAlignmentOptions.MidlineLeft;

        // Downloaded badge
        if (downloaded)
        {
            var badge = new GameObject("Badge");
            badge.transform.SetParent(card.transform, false);
            var br = badge.AddComponent<RectTransform>();
            br.anchorMin        = new Vector2(1f, 0.5f);
            br.anchorMax        = new Vector2(1f, 0.5f);
            br.pivot            = new Vector2(1f, 0.5f);
            br.anchoredPosition = new Vector2(-3f, 0f);
            br.sizeDelta        = new Vector2(14f, 5.5f);
            badge.AddComponent<Image>().color = new Color(0.2f, 0.78f, 0.4f, 0.85f);

            var bl = new GameObject("Text");
            bl.transform.SetParent(badge.transform, false);
            var blr = bl.AddComponent<RectTransform>();
            blr.anchorMin = Vector2.zero;
            blr.anchorMax = Vector2.one;
            blr.offsetMin = blr.offsetMax = Vector2.zero;
            var blTmp = bl.AddComponent<TextMeshProUGUI>();
            blTmp.text      = "OWNED";
            blTmp.fontSize  = 3.5f;
            blTmp.color     = Color.white;
            blTmp.alignment = TextAlignmentOptions.Center;
        }

        SongInfo captured = song;
        btn.onClick.AddListener(() => OnCardClicked(captured));
    }

    private void OnCardClicked(SongInfo song)
    {
        detailPanel.gameObject.SetActive(true);
        detailPanel.Show(song, downloadManager, this);
    }

    private static void SaveCache(SongsList list)
    {
        try { File.WriteAllText(CachePath, JsonUtility.ToJson(list, true)); }
        catch { }
    }

    private static SongsList LoadCache()
    {
        if (!File.Exists(CachePath)) return null;
        try { return JsonUtility.FromJson<SongsList>(File.ReadAllText(CachePath)); }
        catch { return null; }
    }
}