using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using TMPro;
using GeoSus.Client;

/// <summary>
/// Attach to any manager GameObject in create.unity or join loading.unity.
/// On Start(), removes all placeholder Art elements from the Canvas and builds
/// a proper mobile-portrait lobby screen entirely in code.
/// </summary>
public class LobbyDisplayUI : MonoBehaviour
{
    // ── Static hub so GameManager_UI can push state updates ──────────────────
    private static readonly HashSet<LobbyDisplayUI> _all = new HashSet<LobbyDisplayUI>();
    public static void RefreshAll(LobbyState state)
    {
        foreach (var ui in _all) ui._pending = state;
    }

    // ── Built UI references ───────────────────────────────────────────────────
    private TMP_Text   _codeText;
    private TMP_Text   _countText;
    private Transform  _listContent;
    private TMP_Text   _statusText;
    private GameObject _startFooter;
    private GameObject _waitFooter;

    private readonly List<GameObject> _rows = new List<GameObject>();
    private LobbyState _pending;

    // ── Colour palette ────────────────────────────────────────────────────────
    static Color H(string hex) { ColorUtility.TryParseHtmlString(hex, out var c); return c; }
    static readonly Color C_BG      = H("#0D0F1A");
    static readonly Color C_HDR     = H("#141927");
    static readonly Color C_SUBBG   = H("#0F1221");
    static readonly Color C_ROW_A   = H("#1A2035");
    static readonly Color C_ROW_B   = H("#161C2E");
    static readonly Color C_DIVIDER = H("#252A3F");
    static readonly Color C_ACCENT  = H("#3399FF");
    static readonly Color C_GOLD    = H("#FFB800");
    static readonly Color C_GREEN   = H("#2DB84B");
    static readonly Color C_RED     = H("#C43232");
    static readonly Color C_MUTED   = new Color(0.47f, 0.53f, 0.67f);
    static readonly Color C_WHITE   = Color.white;
    static readonly Color C_SOFT    = new Color(0.73f, 0.80f, 0.88f);

    void OnEnable()  => _all.Add(this);
    void OnDisable() => _all.Remove(this);

    // ── Lifecycle ─────────────────────────────────────────────────────────────
    void Start()
    {
        var canvasGO = GameObject.Find("Canvas");
        if (canvasGO == null)
        {
            Debug.LogError("[LobbyDisplayUI] No Canvas found in scene!");
            return;
        }

        // Remove all placeholder Art children immediately (before we build)
        var kill = new List<GameObject>();
        foreach (Transform child in canvasGO.transform)
            kill.Add(child.gameObject);
        foreach (var go in kill)
            DestroyImmediate(go);

        Build(canvasGO.transform);
    }

    void Update()
    {
        var gm = GameManager.Instance;
        if (gm?.gameClient?.CurrentLobbyState != null)
            _pending = gm.gameClient.CurrentLobbyState;

        if (_pending != null && _listContent != null)
        {
            Refresh(_pending);
            _pending = null;
        }
    }

    // ── Full UI construction ──────────────────────────────────────────────────
    void Build(Transform canvasRoot)
    {
        const float HDR_H   = 250f;
        const float SUB_H   = 88f;
        const float FOOT_H  = 180f;
        const float BTN_W   = 200f;

        // Fullscreen dark overlay
        var root = RT("Root", canvasRoot);
        Stretch(root);
        Img(root, C_BG);

        // ─── Header bar ───────────────────────────────────────────────────────
        var header = RT("Header", root);
        PinTop(header, HDR_H);
        Img(header, C_HDR);

        // Back (✕) button — left side of header
        var backBtn = RT("BackBtn", header);
        backBtn.anchorMin = new Vector2(0f, 0f);
        backBtn.anchorMax = new Vector2(0f, 1f);
        backBtn.pivot     = new Vector2(0f, 0.5f);
        backBtn.offsetMin = new Vector2(18f, 22f);
        backBtn.offsetMax = new Vector2(BTN_W + 18f, -22f);
        Img(backBtn, C_RED);
        Btn(backBtn, C_RED, () => GameManager.Instance?.LeaveLobbyButton());
        TxtChild(backBtn, "✕", 72, C_WHITE, TextAlignmentOptions.Center, bold: true);

        // "LOBBY CODE" micro label — upper-center of header
        var codeLbl = RT("CodeLbl", header);
        codeLbl.anchorMin = new Vector2(0.14f, 0.52f);
        codeLbl.anchorMax = new Vector2(0.86f, 0.97f);
        codeLbl.offsetMin = codeLbl.offsetMax = Vector2.zero;
        TmpDirect(codeLbl, "LOBBY CODE", 28, C_MUTED, TextAlignmentOptions.Center, bold: true);

        // Large code value — lower-center of header
        var codeValRT = RT("CodeVal", header);
        codeValRT.anchorMin = new Vector2(0.14f, 0.05f);
        codeValRT.anchorMax = new Vector2(0.86f, 0.52f);
        codeValRT.offsetMin = codeValRT.offsetMax = Vector2.zero;
        _codeText = TmpDirect(codeValRT, "------", 76, C_ACCENT, TextAlignmentOptions.Center, bold: true);

        // Copy (⎘) button — right side of header
        var copyBtn = RT("CopyBtn", header);
        copyBtn.anchorMin = new Vector2(1f, 0f);
        copyBtn.anchorMax = new Vector2(1f, 1f);
        copyBtn.pivot     = new Vector2(1f, 0.5f);
        copyBtn.offsetMin = new Vector2(-(BTN_W + 18f), 22f);
        copyBtn.offsetMax = new Vector2(-18f, -22f);
        Img(copyBtn, C_ACCENT);
        Btn(copyBtn, C_ACCENT, () =>
        {
            if (_codeText != null) GUIUtility.systemCopyBuffer = _codeText.text;
        });
        TxtChild(copyBtn, "⎘", 60, C_WHITE, TextAlignmentOptions.Center);

        // ─── Player count subtitle bar ─────────────────────────────────────────
        var subBar = RT("CountBar", root);
        PinBelowTop(subBar, HDR_H, SUB_H);
        Img(subBar, C_SUBBG);
        _countText = TxtChild(subBar, "0 players in lobby", 34, C_MUTED, TextAlignmentOptions.Center);

        // ─── Scrollable player list ────────────────────────────────────────────
        var scrollArea = RT("PlayerScroll", root);
        Fill(scrollArea, HDR_H + SUB_H, FOOT_H);
        BuildScroll(scrollArea);

        // ─── Footer: START GAME (host) or waiting text (others) ───────────────
        _startFooter = new GameObject("StartFooter");
        var sfRT = _startFooter.AddComponent<RectTransform>();
        sfRT.SetParent(root, false);
        sfRT.localScale = Vector3.one;
        PinBottom(sfRT, FOOT_H);
        Img(sfRT, C_SUBBG);

        var startBtnRT = RT("StartBtn", sfRT);
        Fill(startBtnRT, 20f, 20f, 24f, 24f);
        Img(startBtnRT, C_GREEN);
        Btn(startBtnRT, C_GREEN, () => GameManager.Instance?.StartGameButton());
        TxtChild(startBtnRT, "▶  START GAME", 54, C_WHITE, TextAlignmentOptions.Center, bold: true);
        _startFooter.SetActive(false);

        _waitFooter = new GameObject("WaitFooter");
        var wfRT = _waitFooter.AddComponent<RectTransform>();
        wfRT.SetParent(root, false);
        wfRT.localScale = Vector3.one;
        PinBottom(wfRT, FOOT_H);
        Img(wfRT, C_SUBBG);
        _statusText = TxtChild(wfRT, "⌛  Waiting for host to start...", 38, C_MUTED,
                               TextAlignmentOptions.Center, italic: true);
        _waitFooter.SetActive(true);
    }

    void BuildScroll(RectTransform rt)
    {
        var sr = rt.gameObject.AddComponent<ScrollRect>();

        var viewport = RT("Viewport", rt);
        Stretch(viewport);
        viewport.gameObject.AddComponent<RectMask2D>();

        var content = RT("Content", viewport);
        content.anchorMin        = new Vector2(0f, 1f);
        content.anchorMax        = new Vector2(1f, 1f);
        content.pivot            = new Vector2(0.5f, 1f);
        content.sizeDelta        = new Vector2(0f, 0f);
        content.anchoredPosition = Vector2.zero;

        var vlg = content.gameObject.AddComponent<VerticalLayoutGroup>();
        vlg.childControlWidth      = true;
        vlg.childControlHeight     = false;
        vlg.childForceExpandWidth  = true;
        vlg.childForceExpandHeight = false;
        vlg.spacing                = 2f;
        vlg.padding                = new RectOffset(0, 0, 0, 0);

        var csf = content.gameObject.AddComponent<ContentSizeFitter>();
        csf.verticalFit = ContentSizeFitter.FitMode.PreferredSize;

        sr.viewport          = viewport;
        sr.content           = content;
        sr.horizontal        = false;
        sr.vertical          = true;
        sr.scrollSensitivity = 80f;
        sr.movementType      = ScrollRect.MovementType.Elastic;
        sr.elasticity        = 0.1f;

        _listContent = content;
    }

    // ── State refresh ─────────────────────────────────────────────────────────
    void Refresh(LobbyState state)
    {
        if (_codeText  != null) _codeText.text  = state.JoinCode ?? "------";

        int n = state.Players.Count;
        if (_countText != null)
            _countText.text = $"{n}  player{(n == 1 ? "" : "s")} in lobby";

        var gm      = GameManager.Instance;
        bool isHost = gm?.gameClient?.IsOwner ?? false;
        string myId = gm?.gameClient?.ClientUuid ?? "";

        if (_startFooter != null) _startFooter.SetActive(isHost);
        if (_waitFooter  != null) _waitFooter.SetActive(!isHost);

        if (_statusText != null)
            _statusText.text = state.Phase == GamePhase.Loading
                ? "⏳  Downloading map data..."
                : "⌛  Waiting for host to start...";

        if (_listContent == null) return;

        foreach (var row in _rows) Destroy(row);
        _rows.Clear();

        for (int i = 0; i < state.Players.Count; i++)
        {
            var p   = state.Players[i];
            bool me = p.ClientUuid == myId;
            var row = BuildRow(p.DisplayName ?? "???", me, p.IsOwner,
                               i % 2 == 0 ? C_ROW_A : C_ROW_B);
            row.transform.SetParent(_listContent, false);
            _rows.Add(row);
        }
    }

    GameObject BuildRow(string playerName, bool isMe, bool isHostPlayer, Color bg)
    {
        const float ROW_H = 130f;
        var go = new GameObject("PlayerRow");
        var rt = go.AddComponent<RectTransform>();
        rt.sizeDelta = new Vector2(0f, ROW_H);

        var le = go.AddComponent<LayoutElement>();
        le.minHeight       = ROW_H;
        le.preferredHeight = ROW_H;

        Img(rt, bg);

        // Bottom divider line
        var divRT = RT("Div", rt);
        divRT.anchorMin = new Vector2(0f, 0f);
        divRT.anchorMax = new Vector2(1f, 0f);
        divRT.pivot     = new Vector2(0.5f, 0f);
        divRT.offsetMin = new Vector2(20f, 0f);
        divRT.offsetMax = new Vector2(-20f, 2f);
        Img(divRT, C_DIVIDER);

        float nameLeft = 24f;

        // Crown emoji for lobby host
        if (isHostPlayer)
        {
            var crownRT = RT("Crown", rt);
            crownRT.anchorMin        = new Vector2(0f, 0.5f);
            crownRT.anchorMax        = new Vector2(0f, 0.5f);
            crownRT.pivot            = new Vector2(0f, 0.5f);
            crownRT.sizeDelta        = new Vector2(90f, 90f);
            crownRT.anchoredPosition = new Vector2(18f, 0f);
            TmpDirect(crownRT, "👑", 52, C_GOLD, TextAlignmentOptions.Center);
            nameLeft = 118f;
        }

        // Player name
        float nameMaxX = isMe ? 0.68f : 1f;
        var nameRT = RT("Name", rt);
        nameRT.anchorMin = new Vector2(0f, 0f);
        nameRT.anchorMax = new Vector2(nameMaxX, 1f);
        nameRT.offsetMin = new Vector2(nameLeft, 6f);
        nameRT.offsetMax = new Vector2(-10f, -6f);
        var nt = nameRT.gameObject.AddComponent<TextMeshProUGUI>();
        nt.text         = playerName;
        nt.fontSize     = 48;
        nt.color        = isMe ? C_WHITE : C_SOFT;
        nt.alignment    = TextAlignmentOptions.MidlineLeft;
        nt.fontStyle    = isMe ? FontStyles.Bold : FontStyles.Normal;
        nt.overflowMode = TextOverflowModes.Ellipsis;

        // "YOU" badge
        if (isMe)
        {
            var badgeRT = RT("YouBadge", rt);
            badgeRT.anchorMin = new Vector2(0.68f, 0.22f);
            badgeRT.anchorMax = new Vector2(1f, 0.78f);
            badgeRT.offsetMin = new Vector2(0f, 0f);
            badgeRT.offsetMax = new Vector2(-20f, 0f);
            Img(badgeRT, C_ACCENT);
            TxtChild(badgeRT, "YOU", 30, C_WHITE, TextAlignmentOptions.Center, bold: true);
        }

        return go;
    }

    // ── Layout helpers ────────────────────────────────────────────────────────
    RectTransform RT(string name, Transform parent)
    {
        var go = new GameObject(name);
        var rt = go.AddComponent<RectTransform>();
        rt.SetParent(parent, false);
        rt.localScale = Vector3.one;
        return rt;
    }

    void Stretch(RectTransform rt)
    {
        rt.anchorMin = Vector2.zero;
        rt.anchorMax = Vector2.one;
        rt.offsetMin = Vector2.zero;
        rt.offsetMax = Vector2.zero;
    }

    void Fill(RectTransform rt, float top, float bottom, float left = 0f, float right = 0f)
    {
        rt.anchorMin = Vector2.zero;
        rt.anchorMax = Vector2.one;
        rt.offsetMin = new Vector2(left, bottom);
        rt.offsetMax = new Vector2(-right, -top);
    }

    void PinTop(RectTransform rt, float h)
    {
        rt.anchorMin = new Vector2(0f, 1f);
        rt.anchorMax = new Vector2(1f, 1f);
        rt.pivot     = new Vector2(0.5f, 1f);
        rt.offsetMin = new Vector2(0f, -h);
        rt.offsetMax = Vector2.zero;
    }

    void PinBelowTop(RectTransform rt, float fromTop, float h)
    {
        rt.anchorMin = new Vector2(0f, 1f);
        rt.anchorMax = new Vector2(1f, 1f);
        rt.pivot     = new Vector2(0.5f, 1f);
        rt.offsetMin = new Vector2(0f, -(fromTop + h));
        rt.offsetMax = new Vector2(0f, -fromTop);
    }

    void PinBottom(RectTransform rt, float h)
    {
        rt.anchorMin = Vector2.zero;
        rt.anchorMax = new Vector2(1f, 0f);
        rt.pivot     = new Vector2(0.5f, 0f);
        rt.offsetMin = Vector2.zero;
        rt.offsetMax = new Vector2(0f, h);
    }

    // ── Graphic helpers ───────────────────────────────────────────────────────

    /// Adds an Image directly to rt.
    Image Img(RectTransform rt, Color c)
    {
        var img = rt.gameObject.AddComponent<Image>();
        img.color = c;
        return img;
    }

    /// Adds TMP directly to rt — only use when rt has NO Image component.
    TMP_Text TmpDirect(RectTransform rt, string text, float size, Color color,
                       TextAlignmentOptions align, bool bold = false, bool italic = false)
    {
        var tmp = rt.gameObject.AddComponent<TextMeshProUGUI>();
        tmp.text      = text;
        tmp.fontSize  = size;
        tmp.color     = color;
        tmp.alignment = align;
        if (bold)   tmp.fontStyle |= FontStyles.Bold;
        if (italic) tmp.fontStyle |= FontStyles.Italic;
        return tmp;
    }

    /// Creates a stretch-fill child GO with TMP — safe when parent already has Image.
    TMP_Text TxtChild(RectTransform parent, string text, float size, Color color,
                      TextAlignmentOptions align, bool bold = false, bool italic = false)
    {
        var childRT = RT("Txt", parent);
        Stretch(childRT);
        return TmpDirect(childRT, text, size, color, align, bold, italic);
    }

    void Btn(RectTransform rt, Color normal, System.Action onClick)
    {
        var btn = rt.gameObject.AddComponent<Button>();
        btn.targetGraphic = rt.gameObject.GetComponent<Image>();
        btn.onClick.AddListener(() => onClick());
        var cols = btn.colors;
        cols.normalColor      = normal;
        cols.highlightedColor = Color.Lerp(normal, Color.white, 0.3f);
        cols.pressedColor     = Color.Lerp(normal, Color.black, 0.3f);
        cols.selectedColor    = normal;
        btn.colors = cols;
    }
}