// Assets/_Project/Scripts/UI/HUDController.cs
using System.Collections;
using System.Collections.Generic;
using Unity.Netcode;
using UnityEngine;
using UnityEngine.InputSystem;
using UnityEngine.SceneManagement;
using UnityEngine.UIElements;
using TD.Core;
using TD.Gameplay;
using TD.Towers;
using TD.UI.Minimap;

namespace TD.UI
{
    /// <summary>
    /// Drives the in-match HUD. Requires a UIDocument on the same GameObject.
    /// Wires gold display, tower command grid, tooltip, rejection messages,
    /// and minimap RenderTexture to their UI Toolkit counterparts.
    /// </summary>
    [RequireComponent(typeof(UIDocument))]
    public class HUDController : MonoBehaviour
    {
        // ----- Inspector --------------------------------------------------

        [Header("Scene References")]
        [Tooltip("The local client's TowerPlacementController.")]
        [SerializeField] private TowerPlacementController placementController;

        [Tooltip("The TowerPlacementManager NetworkObject in the scene.")]
        [SerializeField] private TowerPlacementManager placementManager;

        [Tooltip("The local client's CameraController. Used by the minimap for click-to-jump " +
                 "and drag-to-pan.")]
        [SerializeField] private CameraController cameraController;

        [Header("Settings")]
        [SerializeField] private float rejectionMessageDuration = 2.5f;

        // ----- Cached UI element references -------------------------------

        private Label goldLabel;
        private Label waveLabel;
        private Label livesLabel;
        private Label portraitName;
        private Label levelLabel;
        private VisualElement statLines;
        private VisualElement commandGrid;
        private VisualElement actionFrame;   // hidden via display:none when no actions are available
        private VisualElement buildProgressContainer;   // info-panel sub-view, shown for BuildSiteVisual selections
        private VisualElement buildProgressFill;        // width driven each frame from progress
        private Label         buildProgressPercent;
        private Label ttTitle;
        private Label ttDesc;
        private Label ttStats;
        private Label ttCost;
        private Label rejectionLabel;
        private VisualElement portraitFrame;

        // Enemy-info sub-panel — built programmatically and inserted into stat-lines
        // whenever an Enemy is selected. Cached so we can update HP each frame
        // without rebuilding the elements.
        private VisualElement enemyHealthBar;
        private VisualElement enemyHealthFill;
        private Label         enemyHealthText;

        // Match-end overlay — built once on Start and toggled on Phase changes.
        private VisualElement matchEndOverlay;
        private Label         matchEndTitle;

        // ----- State ------------------------------------------------------

        private Coroutine rejectionFadeCoroutine;
        private bool placementManagerReady;   // true once TowerPlacementManager.Instance is non-null
        private bool uiInitialized;
        private bool selectionSubscribed;   // true once we've successfully hooked SelectionState.OnSelectionChanged
        private bool matchStateSubscribed;  // true once OnPhaseChanged is hooked
        private MinimapView minimapView;
        private IPanel myPanel;   // tracked separately so OnDestroy only clears the static if it still points at us

        // ----- Hotkeys ----------------------------------------------------
        //
        // Per-slot hotkey layout matching the WC3 / Wintermaul Reforged convention.
        // Slot index 0..14 corresponds to row-major position in the 5×3 action grid.
        // To rebind, edit this array. (Per-tower hotkeys could live on TowerDefinition
        // later; for now the position-based layout is enough and predictable.)
        private static readonly Key[] HotkeyLayout =
        {
            Key.Q, Key.W, Key.E, Key.R, Key.T,
            Key.A, Key.S, Key.D, Key.F, Key.G,
            Key.Z, Key.X, Key.C, Key.V, Key.B,
        };

        // Active hotkey bindings — rebuilt on every selection change inside
        // PopulateGridForSelection. HandleHotkeys reads this every Update.
        private readonly List<HotkeyBinding> hotkeyBindings = new List<HotkeyBinding>();

        private readonly struct HotkeyBinding
        {
            public readonly Key Key;
            public readonly VisualElement Button;   // for enabledSelf gating
            public readonly System.Action Action;
            public HotkeyBinding(Key k, VisualElement b, System.Action a)
            { Key = k; Button = b; Action = a; }
        }

        // ----- Static hit-test probe --------------------------------------

        // Set when InitializeUI succeeds; cleared on OnDestroy. Non-UI systems (camera,
        // input handlers) can query IsPointerOverInteractiveHud without taking a direct
        // reference to HUDController.
        private static IPanel s_hudPanel;

        /// <summary>
        /// True if <paramref name="screenMousePos"/> falls over an interactive (non-ignore)
        /// HUD element. Non-UI systems that consume mouse input (camera scroll-zoom, edge-pan)
        /// should gate their handling on this so a cursor over the minimap, command grid, or
        /// any other interactive HUD region doesn't drive both the HUD and the world at once.
        /// </summary>
        /// <remarks>
        /// Convention: <paramref name="screenMousePos"/> uses Unity Input System screen coords
        /// (origin bottom-left, y up). Returns false before the HUD has initialized; safe to
        /// call from any system at any time.
        /// </remarks>
        public static bool IsPointerOverInteractiveHud(Vector2 screenMousePos)
        {
            if (s_hudPanel == null) return false;

            // Coord convention rabbit hole:
            //   - Screen mouse position: origin bottom-left, y up (Unity Input System).
            //   - UI Toolkit panel coords: origin top-left, y down.
            //
            // RuntimePanelUtils.ScreenToPanel converts the SCALE (e.g., reference resolution
            // vs. actual resolution) but does NOT flip Y. We flip manually using the visual
            // tree's height so the result works regardless of PanelSettings scale mode.
            //
            // Subtle: visualTree.worldBound height may be 0 for one frame on the very first
            // layout pass. The caller (CameraController) checks the result against "is over
            // interactive HUD"; a one-frame false positive (camera zooms when it shouldn't)
            // is harmless and self-corrects the next frame.
            Vector2 scaled = RuntimePanelUtils.ScreenToPanel(s_hudPanel, screenMousePos);
            float panelHeight = s_hudPanel.visualTree.worldBound.height;
            Vector2 panelPos = new Vector2(scaled.x, panelHeight - scaled.y);

            // panel.Pick returns null when the topmost element under the point has
            // PickingMode.Ignore (or there's no element there at all). Non-null means an
            // interactive HUD element is under the cursor.
            return s_hudPanel.Pick(panelPos) != null;
        }

        // ----- Lifecycle --------------------------------------------------

        private void Start()
        {
            // UIDocument creates its panel in OnEnable, which runs after all
            // Awake() calls. Accessing rootVisualElement in Awake() is too early.
            // Start() is safe because all OnEnable() calls have completed by then.
            InitializeUI();
            TryReadyPlacementManager();

            // Subscription fallback: if OnEnable couldn't subscribe (SelectionState.Awake
            // hadn't run yet), Start() is guaranteed to be after all Awake calls in the
            // scene. Retry here. Without this fallback, the HUD silently misses every
            // selection event for the rest of the session.
            TrySubscribeSelection();

            // Seed portrait/grid in case the builder already auto-selected before Start.
            HandleSelectionChanged(SelectionState.Instance?.SelectedObject);

            TrySubscribeMatchState();
        }

        private void TrySubscribeMatchState()
        {
            if (matchStateSubscribed) return;
            if (MatchState.Instance == null) return;
            MatchState.Instance.OnPhaseChanged += HandlePhaseChanged;
            matchStateSubscribed = true;
        }

        private void InitializeUI()
        {
            var doc = GetComponent<UIDocument>();
            if (doc == null)
            {
                Debug.LogError("[HUDController] No UIDocument component found.");
                return;
            }

            var root = doc.rootVisualElement;
            if (root == null)
            {
                Debug.LogError("[HUDController] rootVisualElement is null. " +
                               "Check that Panel Settings and Source Asset are assigned.");
                return;
            }

            // Cache element references — log a warning for any that are missing
            // so UXML/USS mismatches surface immediately.
            goldLabel              = Require<Label>(root, "gold-label");
            waveLabel              = Require<Label>(root, "wave-label");
            livesLabel             = Require<Label>(root, "lives-label");
            portraitName           = Require<Label>(root, "portrait-name");
            levelLabel             = Require<Label>(root, "level-label");
            statLines              = Require<VisualElement>(root, "stat-lines");
            commandGrid            = Require<VisualElement>(root, "command-grid");
            actionFrame            = Require<VisualElement>(root, "action-frame");
            buildProgressContainer = Require<VisualElement>(root, "build-progress");
            buildProgressFill      = Require<VisualElement>(root, "build-progress-fill");
            buildProgressPercent   = Require<Label>(root, "build-progress-percent");
            ttTitle                = Require<Label>(root, "tt-title");
            ttDesc                 = Require<Label>(root, "tt-desc");
            ttStats                = Require<Label>(root, "tt-stats");
            ttCost                 = Require<Label>(root, "tt-cost");
            rejectionLabel         = Require<Label>(root, "rejection-label");

            // Map area and its transparent ancestors must not consume pointer
            // events so clicks reach the 3D scene underneath. The bottom-ui is now
            // a transparent strip too — the *individual frames* are the opaque
            // interactive surfaces, so the empty margins on either side click
            // through to the world.
            SetPickIgnore(root, "hud-root");
            SetPickIgnore(root, "main-area");
            SetPickIgnore(root, "map-area");
            SetPickIgnore(root, "bottom-ui");
            if (rejectionLabel != null)
                rejectionLabel.pickingMode = PickingMode.Ignore;

            // Minimap. The MinimapView owns the two sub-elements (terrain + entity overlay)
            // and drives them; we just hand it the host container and the camera controller.
            // Bake is deferred until LevelLoader is ready — view tries each frame in Tick().
            var minimapContainer = root.Q<VisualElement>("minimap");
            if (minimapContainer != null)
            {
                if (cameraController == null)
                    Debug.LogWarning("[HUDController] cameraController not assigned. " +
                                     "Click-to-jump and drag-to-pan on the minimap will be disabled.");
                minimapView = new MinimapView(minimapContainer, cameraController);
            }

            // Portrait click → center camera on current selection (WC3 convention).
            portraitFrame = root.Q<VisualElement>("portrait-frame");
            if (portraitFrame != null)
                portraitFrame.RegisterCallback<ClickEvent>(OnPortraitClicked);

            // Build the match-end overlay (Victory / Defeat + Retry). Hidden until
            // MatchState.OnPhaseChanged fires Victory or Defeat.
            BuildMatchEndOverlay(root);

            // Publish the panel so non-UI systems can query "is pointer over the HUD".
            // Stored on `myPanel` too so OnDestroy only clears the static if it still
            // points at this instance (defensive against re-creation overlap).
            myPanel = root.panel;
            s_hudPanel = myPanel;

            uiInitialized = true;
        }

        private void OnEnable()
        {
            TowerPlacementController.OnRejectionMessageReady += ShowRejectionMessage;
            // Try to subscribe now; if SelectionState.Awake hasn't run yet (Unity does
            // not guarantee Awake/OnEnable ordering across objects), Start will retry.
            TrySubscribeSelection();
        }

        private void OnDisable()
        {
            TowerPlacementController.OnRejectionMessageReady -= ShowRejectionMessage;
            if (selectionSubscribed && SelectionState.Instance != null)
            {
                SelectionState.Instance.OnSelectionChanged -= HandleSelectionChanged;
                selectionSubscribed = false;
            }
            if (matchStateSubscribed && MatchState.Instance != null)
            {
                MatchState.Instance.OnPhaseChanged -= HandlePhaseChanged;
                matchStateSubscribed = false;
            }
        }

        private void TrySubscribeSelection()
        {
            if (selectionSubscribed) return;
            if (SelectionState.Instance == null) return;
            SelectionState.Instance.OnSelectionChanged += HandleSelectionChanged;
            selectionSubscribed = true;
        }

        private void Update()
        {
            if (!uiInitialized) return;

            if (!placementManagerReady)
                TryReadyPlacementManager();

            if (!matchStateSubscribed)
                TrySubscribeMatchState();

            RefreshGoldDisplay();
            RefreshMatchStateDisplays();
            UpdateBuildProgressIfShown();
            UpdateEnemyInfoIfShown();
            HandleHotkeys();
            minimapView?.Tick();
        }

        /// <summary>
        /// While a BuildSiteVisual is selected, refresh the progress bar's fill
        /// width and the percent label. Runs every frame so the bar tracks server
        /// time as construction advances. Cheap enough not to throttle (one width
        /// assignment, one string allocation per frame while selected).
        /// </summary>
        private void UpdateBuildProgressIfShown()
        {
            if (buildProgressContainer == null) return;

            var sel = SelectionState.Instance?.SelectedObject;
            // Use Unity's overloaded equality via cast — a destroyed BuildSiteVisual
            // still passes `is` but blows up on member access. Match the same
            // backstop pattern SelectionVisualizer uses.
            if (sel is BuildSiteVisual bsv && (UnityEngine.Object)bsv != null)
            {
                float progress = bsv.ComputeProgressNormalized();

                if (buildProgressFill != null)
                {
                    // Width is a percent of the parent bar background; multiplying
                    // by 100 keeps the StyleLength in percent units.
                    buildProgressFill.style.width =
                        new StyleLength(new Length(progress * 100f, LengthUnit.Percent));
                }
                if (buildProgressPercent != null)
                {
                    buildProgressPercent.text = $"{Mathf.RoundToInt(progress * 100f)}%";
                }
            }
        }

        /// <summary>
        /// Reads raw keyboard state via the New Input System and fires the matching
        /// action for any bound hotkey pressed this frame. Mirrors the disabled-button
        /// behaviour: a SetEnabled(false) button is skipped (so Upgrade/Sell don't
        /// trigger from the keyboard while their backing systems are still stubbed).
        /// </summary>
        private void HandleHotkeys()
        {
            var kb = Keyboard.current;
            if (kb == null) return;

            // Iterate by index — foreach over a struct list would copy each entry.
            for (int i = 0; i < hotkeyBindings.Count; i++)
            {
                var binding = hotkeyBindings[i];
                if (!kb[binding.Key].wasPressedThisFrame) continue;
                if (binding.Button == null || !binding.Button.enabledSelf) continue;
                binding.Action?.Invoke();
            }
        }

        private void OnDestroy()
        {
            minimapView?.Dispose();
            minimapView = null;

            if (s_hudPanel != null && s_hudPanel == myPanel)
                s_hudPanel = null;
            myPanel = null;
        }

        // ----- Gold display -----------------------------------------------

        private void RefreshGoldDisplay()
        {
            if (goldLabel == null) return;
            var gm = PlayerGoldManager.Local;
            goldLabel.text = gm != null ? $"{gm.CurrentGold:N0} g" : "-- g";
        }

        // ----- Match-state display ----------------------------------------

        // Polled each frame from Update. MatchState exposes Lives and CurrentWave
        // as plain int properties backed by NetworkVariables; polling avoids
        // having to add OnLivesChanged / OnCurrentWaveChanged events to MatchState
        // for every consumer that wants to display them. The cost is one int read
        // and a string allocation per frame — negligible at HUD scale.
        private void RefreshMatchStateDisplays()
        {
            var ms = MatchState.Instance;

            if (livesLabel != null)
                livesLabel.text = ms != null ? $"lives: {ms.Lives}" : "lives: --";

            if (waveLabel != null)
            {
                int total = WaveManager.Instance?.TotalWaves ?? 0;
                waveLabel.text = ms != null && ms.CurrentWave > 0 && total > 0
                    ? $"Wave {ms.CurrentWave} / {total}"
                    : "Wave --";
            }
        }

        // ----- Command grid -----------------------------------------------

        private const int GRID_COLS = 5;
        private const int GRID_ROWS = 3;
        private const int GRID_MAX  = GRID_COLS * GRID_ROWS;

        // First-time check that TowerPlacementManager exists. Once ready, populates the
        // grid for the current selection. Subsequent populates flow through
        // HandleSelectionChanged → PopulateGridForSelection.
        private void TryReadyPlacementManager()
        {
            if (placementManager == null)
                placementManager = TowerPlacementManager.Instance;

            if (placementManager == null) return;   // not spawned yet — retry next frame

            placementManagerReady = true;
            PopulateGridForSelection(SelectionState.Instance?.SelectedObject);
        }

        /// <summary>
        /// Rebuilds the command grid based on the current selection AND toggles the
        /// action frame visibility. Builder → tower-build buttons in the early slots.
        /// Tower → Upgrade in slot 0, Sell in the last slot. Anything else (Enemy,
        /// null) → action frame hidden entirely (display:none).
        /// </summary>
        private void PopulateGridForSelection(ISelectable selection)
        {
            if (commandGrid == null) return;
            if (!placementManagerReady) return;     // deferred to TryReadyPlacementManager

            // Selection changed — invalidate the previous frame's hotkey bindings
            // before creating new ones. Without this, stale buttons from a previous
            // selection would keep responding to their hotkey.
            hotkeyBindings.Clear();

            // Decide whether any actions exist for this selection. The action frame
            // is hidden entirely when there are none — matches the WC3-style UX.
            bool hasActions = selection is Builder
                           || selection is TowerInstance
                           || selection is BuildSiteVisual;
            if (actionFrame != null)
                actionFrame.style.display = hasActions ? DisplayStyle.Flex : DisplayStyle.None;

            commandGrid.Clear();
            if (!hasActions) return;     // grid stays empty; frame is hidden anyway

            // Build the 15-cell action layout for the active selection kind.
            var cells = new VisualElement[GRID_MAX];

            if (selection is Builder)
            {
                int i = 0;
                foreach (var (def, typeId) in placementManager.GetAvailableDefinitions())
                {
                    if (i >= GRID_MAX) break;
                    cells[i] = CreateTowerButton(def, typeId, HotkeyLayout[i]);
                    i++;
                }
            }
            else if (selection is TowerInstance tower)
            {
                // WC3 layout convention: primary action top-left (Q), sell bottom-right (B).
                cells[0]            = CreateUpgradeButton(tower, HotkeyLayout[0]);
                cells[GRID_MAX - 1] = CreateSellButton(tower, HotkeyLayout[GRID_MAX - 1]);
            }
            else if (selection is BuildSiteVisual bsv)
            {
                // Cancel is the only action available on an in-progress build.
                // Placed at top-left (Q) — primary slot for a single-action menu.
                cells[0] = CreateCancelButton(bsv, HotkeyLayout[0]);
            }

            // Remaining cells become empty slots so the 5×3 grid layout is preserved.
            for (int i = 0; i < GRID_MAX; i++)
            {
                if (cells[i] == null) cells[i] = CreateEmptySlot();
            }

            for (int row = 0; row < GRID_ROWS; row++)
            {
                var rowEl = new VisualElement();
                rowEl.AddToClassList("cmd-row");
                for (int col = 0; col < GRID_COLS; col++)
                    rowEl.Add(cells[row * GRID_COLS + col]);
                commandGrid.Add(rowEl);
            }
        }

        // Tower button: clicking begins placement; hovering drives the Tool Tip.
        private VisualElement CreateTowerButton(TowerDefinition def, int typeId, Key hotkey)
        {
            var btn = CreateActionButton(
                costText: $"{def.GoldCost}g",
                hotkey:   hotkey,
                onClick:  () =>
                {
                    if (placementController != null)
                        placementController.BeginPlacement(def, typeId);
                    else
                        Debug.LogWarning("[HUDController] No TowerPlacementController assigned.");
                });

            btn.RegisterCallback<MouseEnterEvent>(_ => ShowTooltip(def));
            btn.RegisterCallback<MouseLeaveEvent>(_ => ClearTooltip());
            return btn;
        }

        private static VisualElement CreateEmptySlot()
        {
            var slot = new VisualElement();
            slot.AddToClassList("cmd-btn");
            slot.AddToClassList("empty-slot");
            slot.pickingMode = PickingMode.Ignore;
            return slot;
        }

        /// <summary>
        /// Builds the standard action button: a Button containing a centered icon
        /// placeholder, plus optional hotkey badge (top-left) and cost badge
        /// (bottom-left). Both badges are pure visual overlays — click events still
        /// reach the Button. The hotkey, when non-None, is registered in
        /// <see cref="hotkeyBindings"/> so Update can fire <paramref name="onClick"/>
        /// on keypress (gated on the button's <c>enabledSelf</c>).
        /// </summary>
        private Button CreateActionButton(string costText, Key hotkey, System.Action onClick)
        {
            var btn = new Button(() => onClick?.Invoke());
            btn.AddToClassList("cmd-btn");

            // Icon — added FIRST so it sits underneath the absolute-positioned badges.
            var iconPlaceholder = new VisualElement();
            iconPlaceholder.AddToClassList("cmd-icon-placeholder");
            iconPlaceholder.pickingMode = PickingMode.Ignore;
            btn.Add(iconPlaceholder);

            // Hotkey badge — top-left.
            if (hotkey != Key.None)
            {
                var hkLabel = new Label(KeyToDisplay(hotkey));
                hkLabel.AddToClassList("cmd-hotkey");
                hkLabel.pickingMode = PickingMode.Ignore;
                btn.Add(hkLabel);
                hotkeyBindings.Add(new HotkeyBinding(hotkey, btn, onClick));
            }

            // Cost badge — bottom-left. Omitted when no cost is meaningful (e.g., Upgrade
            // before the upgrade system has a tier-cost lookup).
            if (!string.IsNullOrEmpty(costText))
            {
                var costLabel = new Label(costText);
                costLabel.AddToClassList("cmd-cost");
                costLabel.pickingMode = PickingMode.Ignore;
                btn.Add(costLabel);
            }
            return btn;
        }

        // Upgrade and Sell — visuals + hotkeys wired; click is a no-op because the
        // upgrade/sell systems aren't built yet. Buttons are SetEnabled(false) so the
        // hotkey handler also skips them (it gates on enabledSelf).
        private VisualElement CreateUpgradeButton(TowerInstance tower, Key hotkey)
        {
            var btn = CreateActionButton(
                costText: "",      // tier cost unknown until upgrade system lands
                hotkey:   hotkey,
                onClick:  () => { /* TODO: upgrade flow */ });
            btn.SetEnabled(false);
            return btn;
        }

        private VisualElement CreateSellButton(TowerInstance tower, Key hotkey)
        {
            int sellValue = tower.Definition != null
                ? Mathf.RoundToInt(tower.Definition.GoldCost * 0.7f)
                : 0;
            var btn = CreateActionButton(
                costText: sellValue > 0 ? $"+{sellValue}g" : "",
                hotkey:   hotkey,
                onClick:  () => { /* TODO: sell flow */ });
            btn.SetEnabled(false);
            return btn;
        }

        // Cancel action for an in-progress build. Fires the owner-only RPC; the
        // server cancels the matching job (or, for shelved sites, refunds + despawns
        // directly), full gold is refunded, the BuildSiteVisual is despawned, and
        // OnSelectionChanged fires with null — HUD/visualizer/ring all clear
        // automatically.
        private VisualElement CreateCancelButton(BuildSiteVisual bsv, Key hotkey)
        {
            int refund = bsv.GoldSpent;
            return CreateActionButton(
                costText: refund > 0 ? $"+{refund}g" : "",
                hotkey:   hotkey,
                onClick:  () => bsv.RequestCancelRpc());
        }

        // Renders a Key as a single-character badge ("Q", "1", etc.). Letter and number
        // keys produce their own glyph via ToString; if we ever bind non-letter keys
        // (e.g., F1 or Space), extend this with a mapping table.
        private static string KeyToDisplay(Key key) => key.ToString();

        // ----- Portrait / selection context ----------------------------------

        /// <summary>
        /// Called by the selection system when a unit is selected or deselected.
        /// Pass null or empty to clear (nothing selected).
        /// </summary>
        public void SetSelectedUnitName(string unitName)
        {
            if (portraitName == null) return;
            portraitName.text = string.IsNullOrEmpty(unitName) ? "" : unitName;
        }

        private void HandleSelectionChanged(ISelectable selection)
        {
            // Sections 2/3/4 (portrait, info, tooltip) stay visible regardless;
            // their *contents* update based on selection. Section 5 (action menu)
            // hides via PopulateGridForSelection when there are no actions.
            PopulateInfoPanel(selection);
            PopulateGridForSelection(selection);
        }

        /// <summary>
        /// Drives the portrait name (section 3 header), level (section 2 footer),
        /// contextual stat lines (section 3 body), and the build-progress sub-view
        /// (section 3 — shown only when a BuildSiteVisual is selected).
        /// </summary>
        private void PopulateInfoPanel(ISelectable selection)
        {
            // Name
            SetSelectedUnitName(selection?.DisplayName);

            // Level — placeholder until upgrade system lands.
            //   Builder → "Lv. 1" (per design; may carry experience later)
            //   Tower   → "Lv. 1" (will reflect tower upgrade tier when implemented)
            //   Nothing → blank
            if (levelLabel != null)
                levelLabel.text = selection != null ? "Lv. 1" : "";

            // Build-progress block visibility: shown only for BuildSiteVisual.
            // Stat lines remain underneath and just stay empty for that case.
            bool isBuildSite = selection is BuildSiteVisual;
            if (buildProgressContainer != null)
                buildProgressContainer.style.display =
                    isBuildSite ? DisplayStyle.Flex : DisplayStyle.None;

            // Stat lines — clear and rebuild based on selection kind.
            // The enemy-info cached references (health bar + label) are invalidated
            // by Clear() and re-cached if a new Enemy gets selected below.
            enemyHealthBar  = null;
            enemyHealthFill = null;
            enemyHealthText = null;

            if (statLines != null)
            {
                statLines.Clear();
                if (selection is Builder builder)
                {
                    AddStatLine($"Build range: {builder.BuildRange:0.0}");
                }
                else if (selection is TowerInstance tower)
                {
                    var def = tower.Definition;
                    if (def != null)
                    {
                        if (def.Damage > 0) AddStatLine($"Damage: {def.Damage}");
                        if (def.Range > 0) AddStatLine($"Range: {def.Range:0.0}");
                        if (def.FireRate > 0) AddStatLine($"Fire rate: {def.FireRate:0.0}/s");
                        if (def.SlowFactor < 1f)
                            AddStatLine($"Slow: {(1f - def.SlowFactor) * 100f:0}%");
                    }
                }
                else if (selection is EnemyHealth enemy)
                {
                    BuildEnemyInfo(enemy);
                }
                // BuildSiteVisual: no stat lines — progress bar conveys the state.
            }
        }

        // ----- Enemy info -------------------------------------------------

        /// <summary>
        /// Builds the enemy info stat block (HP bar + speed + bounty) inside the
        /// stat-lines container. The bar and label references are cached so
        /// <see cref="UpdateEnemyInfoIfShown"/> can drive them every frame as the
        /// enemy takes damage.
        /// </summary>
        private void BuildEnemyInfo(EnemyHealth enemy)
        {
            var def = enemy.Definition;

            // ----- Health bar (X / Y) -----
            // A thin horizontal bar with a green fill and a centered "X / Y" label
            // on top. Styled with inline-style so we don't need to add USS classes
            // — keeps this self-contained.
            var hpRow = new VisualElement();
            hpRow.style.flexDirection = FlexDirection.Row;
            hpRow.style.alignItems    = Align.Center;
            hpRow.style.marginTop     = 4;
            hpRow.style.marginBottom  = 4;

            var hpLabel = new Label("HP");
            hpLabel.style.minWidth = 28;
            hpLabel.style.color    = new Color(0.85f, 0.85f, 0.85f);
            hpRow.Add(hpLabel);

            // Background + fill share a parent so the fill can be styled as a
            // percentage width inside the background.
            var hpBackground = new VisualElement();
            hpBackground.style.flexGrow        = 1;
            hpBackground.style.height          = 14;
            hpBackground.style.backgroundColor = new Color(0.1f, 0.1f, 0.1f, 0.85f);
            hpBackground.style.borderTopWidth = hpBackground.style.borderBottomWidth =
                hpBackground.style.borderLeftWidth = hpBackground.style.borderRightWidth = 1;
            var borderColor = new Color(0.3f, 0.3f, 0.3f);
            hpBackground.style.borderTopColor = hpBackground.style.borderBottomColor =
                hpBackground.style.borderLeftColor = hpBackground.style.borderRightColor = borderColor;

            var hpFill = new VisualElement();
            hpFill.style.height          = Length.Percent(100);
            hpFill.style.width           = Length.Percent(100);
            hpFill.style.backgroundColor = new Color(0.3f, 0.85f, 0.3f);
            hpFill.pickingMode           = PickingMode.Ignore;
            hpBackground.Add(hpFill);

            // Overlay "X / Y" label, centered above the bar.
            var hpText = new Label();
            hpText.pickingMode             = PickingMode.Ignore;
            hpText.style.position          = Position.Absolute;
            hpText.style.left              = 0;
            hpText.style.right             = 0;
            hpText.style.top               = 0;
            hpText.style.bottom            = 0;
            hpText.style.unityTextAlign    = TextAnchor.MiddleCenter;
            hpText.style.color             = Color.white;
            hpText.style.fontSize          = 11;
            hpBackground.Add(hpText);

            hpRow.Add(hpBackground);
            statLines.Add(hpRow);

            // Cache references for per-frame updates.
            enemyHealthBar  = hpBackground;
            enemyHealthFill = hpFill;
            enemyHealthText = hpText;

            // Initial value (will be refreshed every frame in UpdateEnemyInfoIfShown).
            UpdateEnemyHpDisplay(enemy);

            // ----- Speed + Bounty stat lines -----
            if (def != null)
            {
                AddStatLine($"Speed: {def.MoveSpeed:0.0}");
                AddStatLine($"Bounty: {def.GoldReward} g");
                // (Weaknesses/resistances will go here once the resistance system lands.)
            }
        }

        private void UpdateEnemyInfoIfShown()
        {
            if (enemyHealthFill == null) return; // no Enemy selected
            var sel = SelectionState.Instance?.SelectedObject;
            if (sel is EnemyHealth enemy && (UnityEngine.Object)enemy != null)
                UpdateEnemyHpDisplay(enemy);
        }

        private void UpdateEnemyHpDisplay(EnemyHealth enemy)
        {
            float cur = Mathf.Max(0f, enemy.CurrentHp);
            float max = Mathf.Max(1f, enemy.MaxHp);
            float pct = Mathf.Clamp01(cur / max);

            if (enemyHealthFill != null)
                enemyHealthFill.style.width = Length.Percent(pct * 100f);
            if (enemyHealthText != null)
                enemyHealthText.text = $"{Mathf.CeilToInt(cur)} / {Mathf.CeilToInt(max)}";
        }

        private void AddStatLine(string text)
        {
            var label = new Label(text);
            label.AddToClassList("stat-line");
            statLines.Add(label);
        }

        // ----- Tooltip ----------------------------------------------------

        private void ShowTooltip(TowerDefinition def)
        {
            if (ttTitle == null) return;

            ttTitle.text = def.DisplayName;
            ttDesc.text  = def.Description ?? "";

            if (def.Damage > 0 || def.Range > 0)
            {
                ttStats.text = $"DMG: {def.Damage}  ·  Range: {def.Range:0}";
                if (def.FireRate > 0)
                    ttStats.text += $"\nFire rate: {def.FireRate:0.0}/s";
                if (def.SlowFactor < 1f)
                    ttStats.text += $"\nSlow: {(1f - def.SlowFactor) * 100f:0}%";
            }
            else
            {
                ttStats.text = "(stats pending)";
            }

            int sellValue = Mathf.RoundToInt(def.GoldCost * 0.7f);
            ttCost.text = $"Cost: {def.GoldCost}g  ·  Sell: {sellValue}g";
        }

        private void ClearTooltip()
        {
            if (ttTitle == null) return;
            ttTitle.text = "";
            ttDesc.text  = "";
            ttStats.text = "";
            ttCost.text  = "";
        }

        // ----- Rejection messages -----------------------------------------

        private void ShowRejectionMessage(string message)
        {
            if (rejectionLabel == null) return;

            rejectionLabel.text = message;
            rejectionLabel.style.display = DisplayStyle.Flex;

            if (rejectionFadeCoroutine != null)
                StopCoroutine(rejectionFadeCoroutine);

            rejectionFadeCoroutine = StartCoroutine(HideRejectionAfterDelay());
        }

        private IEnumerator HideRejectionAfterDelay()
        {
            yield return new WaitForSeconds(rejectionMessageDuration);
            if (rejectionLabel != null)
                rejectionLabel.style.display = DisplayStyle.None;
            rejectionFadeCoroutine = null;
        }

        // ----- Portrait click: center camera on selection -----------------

        // WC3 / SC2 convention: clicking the portrait recenters the camera on
        // whoever is selected. Zoom is preserved (CameraController.JumpTo only
        // moves the pivot). No-op when nothing is selected or the camera isn't wired.
        private void OnPortraitClicked(ClickEvent evt)
        {
            var sel = SelectionState.Instance?.SelectedObject;
            if (sel == null) return;
            if (cameraController == null) return;

            var t = sel.SelectionTransform;
            if (t == null) return;

            cameraController.JumpTo(t.position);
        }

        // ----- Match-end overlay (Victory / Defeat + Retry) ---------------

        private void BuildMatchEndOverlay(VisualElement root)
        {
            matchEndOverlay = new VisualElement();
            matchEndOverlay.style.position        = Position.Absolute;
            matchEndOverlay.style.left            = 0;
            matchEndOverlay.style.right           = 0;
            matchEndOverlay.style.top             = 0;
            matchEndOverlay.style.bottom          = 0;
            matchEndOverlay.style.alignItems      = Align.Center;
            matchEndOverlay.style.justifyContent  = Justify.Center;
            matchEndOverlay.style.backgroundColor = new Color(0f, 0f, 0f, 0.6f);
            matchEndOverlay.style.display         = DisplayStyle.None;
            // The overlay swallows pointer events so the player can't click towers
            // or builders through it while it's visible.
            matchEndOverlay.pickingMode           = PickingMode.Position;

            var panel = new VisualElement();
            panel.style.minWidth         = 320;
            panel.style.paddingTop       = 24;
            panel.style.paddingBottom    = 24;
            panel.style.paddingLeft      = 32;
            panel.style.paddingRight     = 32;
            panel.style.backgroundColor  = new Color(0.08f, 0.08f, 0.10f, 0.95f);
            panel.style.borderTopWidth   = panel.style.borderBottomWidth =
                panel.style.borderLeftWidth = panel.style.borderRightWidth = 2;
            var border = new Color(0.4f, 0.4f, 0.45f);
            panel.style.borderTopColor   = panel.style.borderBottomColor =
                panel.style.borderLeftColor = panel.style.borderRightColor = border;
            panel.style.alignItems       = Align.Center;

            matchEndTitle = new Label("Victory");
            matchEndTitle.style.fontSize    = 32;
            matchEndTitle.style.color       = Color.white;
            matchEndTitle.style.marginBottom = 16;
            matchEndTitle.style.unityFontStyleAndWeight = FontStyle.Bold;
            panel.Add(matchEndTitle);

            var retryBtn = new Button(OnRetryClicked) { text = "Retry" };
            retryBtn.style.minWidth      = 120;
            retryBtn.style.height        = 36;
            retryBtn.style.fontSize      = 16;
            retryBtn.style.marginTop     = 8;
            panel.Add(retryBtn);

            matchEndOverlay.Add(panel);
            root.Add(matchEndOverlay);
        }

        private void HandlePhaseChanged(MatchPhase previous, MatchPhase next)
        {
            if (matchEndOverlay == null) return;

            switch (next)
            {
                case MatchPhase.Victory:
                    if (matchEndTitle != null)
                    {
                        matchEndTitle.text = "Victory";
                        matchEndTitle.style.color = new Color(1f, 0.84f, 0.2f);
                    }
                    matchEndOverlay.style.display = DisplayStyle.Flex;
                    break;

                case MatchPhase.Defeat:
                    if (matchEndTitle != null)
                    {
                        matchEndTitle.text = "Defeat";
                        matchEndTitle.style.color = new Color(0.95f, 0.25f, 0.25f);
                    }
                    matchEndOverlay.style.display = DisplayStyle.Flex;
                    break;

                default:
                    matchEndOverlay.style.display = DisplayStyle.None;
                    break;
            }
        }

        // Reloads the active scene and restarts the host. Host-only — testing
        // convenience until a real lobby/restart flow exists. The static
        // sceneLoaded callback survives the scene reload (HUDController dies),
        // re-arms StartHost once the fresh scene has finished loading, and
        // unsubscribes itself.
        private void OnRetryClicked()
        {
            var nm = NetworkManager.Singleton;
            if (nm == null)
            {
                Debug.LogWarning("[HUDController] Retry clicked but NetworkManager is null.");
                return;
            }
            if (!nm.IsServer)
            {
                Debug.LogWarning("[HUDController] Retry only works on the host. " +
                                 "Clients should ask the host to retry.");
                return;
            }

            Scene active = SceneManager.GetActiveScene();
            s_pendingHostRestartBuildIndex = active.buildIndex;
            SceneManager.sceneLoaded += OnSceneLoadedForRetry;

            nm.Shutdown();
            SceneManager.LoadScene(active.buildIndex);
        }

        private static int s_pendingHostRestartBuildIndex = -1;

        private static void OnSceneLoadedForRetry(Scene loaded, LoadSceneMode mode)
        {
            if (loaded.buildIndex != s_pendingHostRestartBuildIndex) return;

            SceneManager.sceneLoaded -= OnSceneLoadedForRetry;
            s_pendingHostRestartBuildIndex = -1;

            var nm = NetworkManager.Singleton;
            if (nm != null) nm.StartHost();
            else Debug.LogWarning("[HUDController] Retry: no NetworkManager in reloaded scene.");
        }

        // ----- Helpers ----------------------------------------------------

        private static T Require<T>(VisualElement root, string name) where T : VisualElement
        {
            var el = root.Q<T>(name);
            if (el == null)
                Debug.LogWarning($"[HUDController] Element not found: '{name}' ({typeof(T).Name}). " +
                                 $"Check that the name matches the UXML.");
            return el;
        }

        private static void SetPickIgnore(VisualElement root, string name)
        {
            var el = root.Q<VisualElement>(name);
            if (el != null) el.pickingMode = PickingMode.Ignore;
        }
    }
}