using System.Collections.Generic;
using ProjectM.Simulation;
using Unity.Entities;
using Unity.NetCode;
using UnityEngine;
using UnityEngine.UIElements;

namespace ProjectM.Client
{
    /// <summary>
    /// Client-only screen HUD on UI Toolkit, skinned with the curated Synty sci-fi-soldier kit
    /// (<see cref="HudTheme"/>) over <see cref="MenuUi"/>'s Aether palette so it reads in one visual language with
    /// the menu / pause / settings. A managed presentation <see cref="SystemBase"/> (<see cref="PresentationSystemGroup"/>)
    /// that OBSERVES the local player ghost + the global cycle / ledger / goal each frame and pushes values into a
    /// runtime UIDocument (shared PanelSettings, sortingOrder 50 so it sits behind the pause overlay's 100). The
    /// root is <c>pickingMode = Ignore</c> so the HUD never eats world clicks — only the build-palette slots pick.
    /// Layout (good-HUD spatial convention): persistent self-state hugs the corners (health bottom-left, resources
    /// top-left, threat top-right, build deck bottom-center); transient mission state (phase / countdown / wave /
    /// goal) lives center-top; a low-health vignette + hurt-flash + a scheme-aware build-mode control-hint bar give
    /// just-in-time feedback. EVERY skinned element is null-safe: with no <see cref="HudTheme"/> it falls back to
    /// the flat-colour HUD. Presentation only (client world, no simulation, no rollback double-fire).
    /// </summary>
    [WorldSystemFilter(WorldSystemFilterFlags.ClientSimulation)]
    [UpdateInGroup(typeof(PresentationSystemGroup))]
    public partial class HudSystem : SystemBase
    {
        // ---- palette (Aether language; Synty white skins are tinted into these) ----
        static readonly Color AetherCyan = new(0.30f, 0.85f, 1f);
        static readonly Color OreAmber = new(1f, 0.72f, 0.35f);
        static readonly Color BioGreen = new(0.55f, 0.85f, 0.45f);
        static readonly Color ChargeViolet = new(0.80f, 0.45f, 1f);
        static readonly Color PanelDark = new(0.08f, 0.11f, 0.15f, 0.90f);
        static readonly Color PanelWarm = new(0.16f, 0.09f, 0.09f, 0.88f);
        static readonly Color PipDim = new(0.25f, 0.30f, 0.36f, 0.9f);
        static readonly Color BlightRed = new(0.85f, 0.10f, 0.08f);
        static readonly Color ThreatWarm = new(1f, 0.62f, 0.4f);
        static readonly Color SlotIdleBg = new(0.09f, 0.11f, 0.15f, 0.92f);
        static readonly Color SlotSelBg = new(0.16f, 0.26f, 0.32f, 0.95f);
        static readonly Color SlotIdleBorder = new(1f, 1f, 1f, 0.08f);
        const int MaxPips = 12;
        const float ExpeditionRegionXMin = 500f; // camera x past this = the +1000 expedition region (DR-013)

        GameObject _hudGo;
        UIDocument _doc;
        bool _built;
        bool _themed; // HudTheme + PanelBox present (drives sprite-tint vs flat-colour retint)

        // vitals
        VisualElement _healthFill, _cooldownFill, _shieldRow, _cdRow;
        Label _healthText;

        // threat
        VisualElement _threatPanel, _threatIcon;
        Label _threatNum;

        // macro: banner + location + goal
        VisualElement _banner, _goalContainer, _goalPipsRow, _goalBar, _goalFill;
        Label _phaseText, _cycleText, _locationText, _goalText;
        readonly List<VisualElement> _pips = new();

        // resources
        Label _aetherNum, _oreNum, _bioNum, _chargeNum;

        // build palette + hints
        VisualElement _paletteRow, _hintBar, _facingArrow;
        bool _paletteBuilt, _hintBuilt, _hintConveyor;
        byte _hintScheme = 255;
        readonly Dictionary<byte, PaletteItem> _palette = new();

        // overlays
        VisualElement _vignette, _downed;
        float _prevHp, _flash;
        bool _haveHp;
        // personal inventory panel (read-only; toggled with I)
        VisualElement _invPanel, _invList, _equipList;
        bool _invOpen;

        EntityQuery _huskQuery;

        struct PaletteItem { public VisualElement Root; public Label Cost; public int CostAmount; public byte CostRes; public VisualElement Glow; public VisualElement Icon; }

        protected override void OnCreate()
        {
            _huskQuery = GetEntityQuery(ComponentType.ReadOnly<EnemyTag>());
        }

        protected override void OnStartRunning()
        {
            if (_hudGo != null) return;
            MenuUi.EnsureEventSystem();
            _hudGo = new GameObject("~HUD");
            _doc = _hudGo.AddComponent<UIDocument>();
            _doc.panelSettings = MenuUi.LoadPanelSettings();
            _doc.sortingOrder = 50; // behind the pause overlay (100)
        }

        protected override void OnDestroy()
        {
            if (_hudGo != null) Object.Destroy(_hudGo);
        }

        protected override void OnUpdate()
        {
            if (_doc == null) return;
            if (!_built)
            {
                var r = _doc.rootVisualElement;
                if (r == null) return; // panel not initialised yet (next frame)
                BuildTree(r);
                _built = true;
            }

            // Job-safety insurance (matches the sibling presentation systems + CLAUDE.md): finish any jobs writing
            // the components we read on the main thread before reading them. No job writes these today, but this
            // stays correct the day a Health/stats writer is parallelised.
            EntityManager.CompleteDependencyBeforeRO<Health>();
            EntityManager.CompleteDependencyBeforeRO<EffectiveCharacterStats>();
            EntityManager.CompleteDependencyBeforeRO<EffectiveAbilityStats>();
            EntityManager.CompleteDependencyBeforeRO<AbilityCooldown>();
            EntityManager.CompleteDependencyBeforeRO<RespawnInvuln>();

            float dt = SystemAPI.Time.DeltaTime; // wall-frame delta — correct in a presentation system
            bool haveTick = SystemAPI.TryGetSingleton<NetworkTime>(out var nt);
            int huskCount = _huskQuery.CalculateEntityCount();

            // ---- Macro: phase + cycle + countdown (center-top banner) ----
            bool haveCycle = SystemAPI.TryGetSingleton<CycleState>(out var cyc);
            bool siege = haveCycle && cyc.Phase == CyclePhase.Siege;
            if (haveCycle)
            {
                var endTick = new NetworkTick(cyc.PhaseEndTick);
                string detail;
                if (siege)
                    detail = "WAVE " + cyc.WaveNumber + "   -   " + huskCount + " HUSKS";
                else if (haveTick && cyc.PhaseEndTick != 0 && endTick.IsValid && endTick.IsNewerThan(nt.ServerTick))
                    detail = "INCURSION IN " + (endTick.TicksSince(nt.ServerTick) / 60 + 1) + "s";
                else
                    detail = "";
                var col = PhaseColor(cyc.Phase);
                _phaseText.text = PhaseLabel(cyc.Phase) + (detail.Length > 0 ? "   -   " + detail : "");
                _phaseText.style.color = col;
                _cycleText.text = "CYCLE " + cyc.CycleNumber;
                _banner.style.borderBottomColor = col;
                RetintPanel(_banner, siege ? PanelWarm : PanelDark);
            }
            else
            {
                _phaseText.text = "";
                _cycleText.text = "";
            }

            // ---- Location + gate hint (banner sub-line) ----
            var cam = Camera.main;
            bool onExpedition = cam != null && cam.transform.position.x > ExpeditionRegionXMin;
            _locationText.text = onExpedition
                ? "ON EXPEDITION   -   carve the frontier, then return"
                : siege
                    ? "DEFEND THE BASE   -   hold the line"
                    : "MINE THE CRYSTALS   -   any attack harvests Ore, then BUILD";
            _locationText.style.color = onExpedition ? new Color(1f, 0.8f, 0.4f)
                : siege ? new Color(1f, 0.55f, 0.4f) : new Color(0.6f, 0.95f, 0.7f);

            // ---- Goal (hex-pip meter, or a continuous bar for large targets) ----
            if (SystemAPI.TryGetSingleton<GoalProgress>(out var goal))
            {
                _goalContainer.style.display = DisplayStyle.Flex;
                float gfrac = goal.Target > 0 ? Mathf.Clamp01(goal.Charge / (float)goal.Target) : 0f;
                _goalText.text = "GOAL  " + goal.Charge + " / " + goal.Target;
                if (goal.Target >= 1 && goal.Target <= MaxPips)
                {
                    _goalPipsRow.style.display = DisplayStyle.Flex;
                    _goalBar.style.display = DisplayStyle.None;
                    int active = Mathf.Min(goal.Charge, goal.Target); // Charge is the integer pip count; never over-fill
                    for (int i = 0; i < _pips.Count; i++)
                    {
                        bool show = i < goal.Target;
                        _pips[i].style.display = show ? DisplayStyle.Flex : DisplayStyle.None;
                        if (show) SetPip(_pips[i], i < active);
                    }
                }
                else
                {
                    _goalPipsRow.style.display = DisplayStyle.None;
                    _goalBar.style.display = DisplayStyle.Flex;
                    HudUi.SetFill(_goalFill, gfrac);
                }
            }
            else
            {
                _goalContainer.style.display = DisplayStyle.None;
            }

            // ---- Resources (feed palette affordability) ----
            int aether = 0, ore = 0, bio = 0, charge = 0;
            if (SystemAPI.TryGetSingletonEntity<ResourceLedger>(out var ledgerE))
            {
                var buf = SystemAPI.GetBuffer<StorageEntry>(ledgerE);
                for (int i = 0; i < buf.Length; i++)
                {
                    var en = buf[i];
                    if (en.ItemId == ResourceId.Aether) aether = en.Count;
                    else if (en.ItemId == ResourceId.Ore) ore = en.Count;
                    else if (en.ItemId == ResourceId.Biomass) bio = en.Count;
                    else if (en.ItemId == ResourceId.Charge) charge = en.Count;
                }
            }
            _aetherNum.text = aether.ToString();
            _oreNum.text = ore.ToString();
            _bioNum.text = bio.ToString();
            _chargeNum.text = charge.ToString();
            // EB-2 quiet-turret cue (GLOBAL, not per-turret, so the deterministic Charge split never reads as one
            // broken turret): a dry base during a siege tells the player to build a Fabricator.
            if (siege && charge == 0 && !onExpedition)
            {
                _locationText.text = "TURRETS OUT OF CHARGE   -   build a Fabricator (Ore -> Charge)";
                _locationText.style.color = new Color(1f, 0.4f, 0.9f);
            }

            // ---- Threat readout (top-right) — hidden entirely at base with zero husks; its reappearance is the cue ----
            bool showThreat = siege || huskCount > 0;
            _threatPanel.style.display = showThreat ? DisplayStyle.Flex : DisplayStyle.None;
            if (showThreat)
            {
                float intensity = Mathf.Clamp01(huskCount / 30f);
                Color tc = siege ? Color.Lerp(ThreatWarm, BlightRed, intensity) : ThreatWarm;
                _threatNum.text = huskCount.ToString();
                _threatNum.style.color = tc;
                _threatIcon.style.unityBackgroundImageTintColor = tc;
                RetintPanel(_threatPanel, siege ? PanelWarm : PanelDark);
            }

            // ---- Build palette + control hints (bottom-center) ----
            UpdatePalette(aether, ore, bio, onExpedition);
            bool buildActive = BuildPaletteState.Active && !onExpedition && _paletteBuilt;
            if (buildActive)
            {
                byte scheme = AimPresentation.Scheme;
                bool conv = BuildPaletteState.Selected == StructureType.Conveyor;
                if (!_hintBuilt || _hintScheme != scheme || _hintConveyor != conv) RebuildHints(scheme, conv);
                if (conv && _facingArrow != null)
                    _facingArrow.style.rotate = new StyleRotate(new Rotate(new Angle(FacingDegrees(BuildPaletteState.Direction))));
                _hintBar.style.display = DisplayStyle.Flex;
            }
            else
            {
                _hintBar.style.display = DisplayStyle.None;
            }

            // ---- Per-player vitals ----
            bool found = false;
            float hp = 0f, maxHp = 1f, cdFrac = 1f;
            bool dead = false, shielded = false;

            foreach (var (health, effChar, effAbility, cd, invuln, entity) in
                     SystemAPI.Query<RefRO<Health>, RefRO<EffectiveCharacterStats>, RefRO<EffectiveAbilityStats>,
                             RefRO<AbilityCooldown>, RefRO<RespawnInvuln>>()
                         .WithAll<GhostOwnerIsLocal, PlayerTag>().WithEntityAccess())
            {
                found = true;
                hp = health.ValueRO.Current;
                maxHp = effChar.ValueRO.MaxHealth > 0f ? effChar.ValueRO.MaxHealth : health.ValueRO.Max;
                dead = SystemAPI.IsComponentEnabled<Dead>(entity);

                uint nextFire = cd.ValueRO.NextFireTick;
                int cdTicks = effAbility.ValueRO.CooldownTicks;
                var nextTick = new NetworkTick(nextFire);
                cdFrac = (haveTick && nextFire != 0 && cdTicks > 0 && nextTick.IsValid && nextTick.IsNewerThan(nt.ServerTick))
                    ? Mathf.Clamp01(1f - nextTick.TicksSince(nt.ServerTick) / (float)cdTicks)
                    : 1f;

                uint invulnUntil = invuln.ValueRO.UntilTick;
                var invulnTick = new NetworkTick(invulnUntil);
                shielded = haveTick && invulnUntil != 0 && invulnTick.IsValid && invulnTick.IsNewerThan(nt.ServerTick);
                break;
            }

            _doc.rootVisualElement.style.display = (found || haveCycle) ? DisplayStyle.Flex : DisplayStyle.None;

            // ---- Low-health vignette + hurt flash (full-screen) ----
            _flash = HudVisualMath.DecayFlash(_flash, dt);
            if (found)
            {
                float frac = maxHp > 0f ? Mathf.Clamp01(hp / maxHp) : 0f;
                if (_haveHp && hp < _prevHp - 1f) _flash = HudVisualMath.HurtFlashKick;
                _prevHp = hp; _haveHp = true;

                float vigOp = dead ? 0f : HudVisualMath.CombinedOpacity(frac, _flash);
                _vignette.style.opacity = vigOp;
                _vignette.style.display = vigOp > 0.001f ? DisplayStyle.Flex : DisplayStyle.None;

                HudUi.SetFill(_healthFill, frac);
                _healthFill.style.backgroundColor = shielded
                    ? new Color(0.45f, 0.85f, 1f)
                    : Color.Lerp(new Color(0.92f, 0.16f, 0.16f), new Color(0.25f, 0.9f, 0.5f), frac);
                _healthText.text = Mathf.CeilToInt(Mathf.Max(0f, hp)) + " / " + Mathf.CeilToInt(maxHp);
                _shieldRow.style.display = shielded ? DisplayStyle.Flex : DisplayStyle.None;

                HudUi.SetFill(_cooldownFill, cdFrac);
                // A READY weapon (full bar) recedes; a CHARGING one is bright — so the inverted-vs-health polarity reads.
                if (_cdRow != null) _cdRow.style.opacity = cdFrac >= 1f ? 0.4f : 1f;
                _downed.style.display = dead ? DisplayStyle.Flex : DisplayStyle.None;
            }
            else
            {
                _haveHp = false; _flash = 0f;
                _vignette.style.display = DisplayStyle.None;
                _downed.style.display = DisplayStyle.None;
            }
            // ---- Personal inventory (read-only; toggle with I, deposit-all with G via InventoryDepositSendSystem) ----
            var invKb = UnityEngine.InputSystem.Keyboard.current;
            if (invKb != null && invKb.iKey.wasPressedThisFrame) _invOpen = !_invOpen;
            if (_invOpen && found)
            {
                EntityManager.CompleteDependencyBeforeRO<InventorySlot>();
                EntityManager.CompleteDependencyBeforeRO<EquipmentSlot>();
                bool haveItemDb = SystemAPI.TryGetSingleton<ItemDatabase>(out var itemDb);
                _invPanel.style.display = DisplayStyle.Flex;

                _invList.Clear();
                int shown = 0;
                foreach (var bag in SystemAPI.Query<DynamicBuffer<InventorySlot>>()
                             .WithAll<GhostOwnerIsLocal, PlayerTag>())
                {
                    for (int i = 0; i < bag.Length; i++)
                    {
                        var slot = bag[i];
                        if (slot.ItemId == 0 || slot.Count <= 0) continue;
                        AddInvRow(slot.ItemId, ItemName(haveItemDb, itemDb, slot.ItemId), ItemTint(slot.ItemId), slot.Count,
                            IsEquippable(haveItemDb, itemDb, slot.ItemId));
                        shown++;
                    }
                    break;
                }
                if (shown == 0)
                    _invList.Add(HudUi.Text("(empty)", 13, MenuUi.SubCol, TextAnchor.MiddleLeft));

                _equipList.Clear();
                foreach (var slots in SystemAPI.Query<DynamicBuffer<EquipmentSlot>>()
                             .WithAll<GhostOwnerIsLocal, PlayerTag>())
                {
                    for (byte s = 0; s < EquipSlotId.Count && s < slots.Length; s++)
                    {
                        ushort id = slots[s].ItemId;
                        string label = SlotName(s) + ":  " + (id == 0 ? "-" : ItemName(haveItemDb, itemDb, id));
                        AddEquipRow(s, label, id != 0);
                    }
                    break;
                }
            }
            else
            {
                _invPanel.style.display = DisplayStyle.None;
            }
        }

        // ---- per-frame helpers ----

        void RetintPanel(VisualElement p, Color c)
        {
            if (_themed) p.style.unityBackgroundImageTintColor = c;
            else p.style.backgroundColor = c;
        }

        void SetPip(VisualElement pip, bool active)
        {
            var theme = HudTheme.Get();
            var spr = active ? theme?.PipActive : theme?.PipInactive;
            if (spr != null)
            {
                pip.style.backgroundImage = new StyleBackground(Background.FromSprite(spr));
                pip.style.unityBackgroundImageTintColor = active ? AetherCyan : PipDim;
                pip.style.backgroundSize = new StyleBackgroundSize(new BackgroundSize(BackgroundSizeType.Contain));
            }
            else
            {
                pip.style.backgroundColor = active ? AetherCyan : PipDim;
                MenuUi.Round(pip, 3);
            }
        }

        void UpdatePalette(int aether, int ore, int bio, bool onExpedition)
        {
            if (!_paletteBuilt && SystemAPI.TryGetSingletonEntity<StructureCatalog>(out var catE))
            {
                var cat = SystemAPI.GetBuffer<StructureCatalogEntry>(catE);
                for (int i = 0; i < cat.Length; i++)
                    AddPaletteItem(cat[i].Type, cat[i].CostAmount, cat[i].CostResourceId);
                _paletteBuilt = true;
            }
            if (!_paletteBuilt) { _paletteRow.style.display = DisplayStyle.None; return; }

            _paletteRow.style.display = onExpedition ? DisplayStyle.None : DisplayStyle.Flex;
            foreach (var kv in _palette)
            {
                var item = kv.Value;
                int have = item.CostRes == ResourceId.Aether ? aether : item.CostRes == ResourceId.Biomass ? bio : ore;
                bool affordable = have >= item.CostAmount;
                bool selected = BuildPaletteState.Selected == kv.Key;
                item.Root.style.opacity = affordable ? 1f : 0.5f;
                item.Cost.style.color = affordable ? new Color(0.7f, 0.95f, 0.8f) : new Color(1f, 0.5f, 0.4f);
                if (item.Icon != null)
                    item.Icon.style.unityBackgroundImageTintColor = affordable ? AetherCyan : new Color(0.5f, 0.55f, 0.6f);
                MenuUi.Border(item.Root, selected ? MenuUi.Accent : SlotIdleBorder, selected ? 2 : 1);
                item.Root.style.backgroundColor = selected ? SlotSelBg : SlotIdleBg;
                if (item.Glow != null) item.Glow.style.opacity = selected ? 0.6f : 0f;
            }
        }

        void AddPaletteItem(byte type, int cost, byte costRes)
        {
            if (type == 0 || _palette.ContainsKey(type)) return;
            var theme = HudTheme.Get();

            var root = new VisualElement();
            root.style.width = 86;
            root.style.marginLeft = 4; root.style.marginRight = 4;
            root.style.paddingTop = 8; root.style.paddingBottom = 6;
            root.style.alignItems = Align.Center;
            root.style.backgroundColor = SlotIdleBg;
            root.pickingMode = PickingMode.Position;
            MenuUi.Round(root, 6);
            MenuUi.Border(root, SlotIdleBorder, 1);

            // selection glow: a soft Synty glow filling the slot behind everything, opacity toggled on select.
            var glow = new VisualElement();
            glow.style.position = Position.Absolute;
            glow.style.left = 3; glow.style.right = 3; glow.style.top = 4; glow.style.bottom = 4;
            glow.pickingMode = PickingMode.Ignore;
            glow.style.opacity = 0f;
            if (theme != null && theme.Glow != null)
            {
                glow.style.backgroundImage = new StyleBackground(Background.FromSprite(theme.Glow));
                glow.style.unityBackgroundImageTintColor = AetherCyan;
                glow.style.backgroundSize = new StyleBackgroundSize(new BackgroundSize(BackgroundSizeType.Cover));
            }
            root.Add(glow);

            var iconEl = HudUi.Icon(theme != null ? theme.StructureIcon(type) : null, 44, AetherCyan);
            root.Add(iconEl);

            var nameLabel = HudUi.Text(StructureName(type), 12, MenuUi.TextCol, TextAnchor.MiddleCenter);
            nameLabel.style.marginTop = 2;
            root.Add(nameLabel);

            var costRow = new VisualElement();
            costRow.style.flexDirection = FlexDirection.Row;
            costRow.style.alignItems = Align.Center;
            costRow.style.marginTop = 2;
            costRow.pickingMode = PickingMode.Ignore;
            var costIcon = HudUi.Icon(ResourceSprite(theme, costRes), 14, ResourceTint(costRes));
            costIcon.style.marginRight = 3;
            costRow.Add(costIcon);
            var costLabel = HudUi.Display(cost.ToString(), 13, new Color(0.7f, 0.95f, 0.8f), TextAnchor.MiddleCenter);
            costRow.Add(costLabel);
            root.Add(costRow);

            byte t = type;
            root.RegisterCallback<ClickEvent>(_ =>
                BuildPaletteState.Select(BuildPaletteState.Selected == t ? (byte)0 : t));

            _paletteRow.Add(root);
            _palette[type] = new PaletteItem { Root = root, Cost = costLabel, CostAmount = cost, CostRes = costRes, Glow = glow, Icon = iconEl };
        }

        void RebuildHints(byte scheme, bool conveyor)
        {
            _hintBar.Clear();
            _facingArrow = null;
            var theme = HudTheme.Get();
            bool pad = scheme == InputSchemeId.Gamepad;
            AddHint(pad ? theme?.PadPlace : theme?.KbmPlace, pad ? "A" : "LMB", "PLACE");
            AddHint(pad ? theme?.PadCancel : theme?.KbmCancel, pad ? "B" : "RMB", "CANCEL");
            if (conveyor)
            {
                // Rotate hint + a LIVE facing arrow (resolves the DR-021 conveyor-facing indicator). Only conveyors
                // rotate, so this chip is gated to them — the other buildables don't show a meaningless ROTATE.
                var chip = MakeChip();
                chip.Add(HudUi.Glyph(pad ? theme?.PadRotate : null, pad ? "LB" : "R", 26));
                var lbl = HudUi.Text("FACING", 12, MenuUi.SubCol, TextAnchor.MiddleLeft);
                lbl.style.marginLeft = 5; lbl.style.marginRight = 6;
                chip.Add(lbl);
                _facingArrow = HudUi.Icon(theme != null ? theme.ConveyorIcon : null, 24, AetherCyan);
                chip.Add(_facingArrow);
                _hintBar.Add(chip);
            }
            AddHint(pad ? theme?.PadExit : null, pad ? "MENU" : "ESC", "EXIT");
            _hintScheme = scheme;
            _hintConveyor = conveyor;
            _hintBuilt = true;
        }

        VisualElement MakeChip()
        {
            var chip = new VisualElement();
            chip.style.flexDirection = FlexDirection.Row;
            chip.style.alignItems = Align.Center;
            chip.style.marginLeft = 8; chip.style.marginRight = 8;
            chip.pickingMode = PickingMode.Ignore;
            return chip;
        }

        void AddHint(Sprite glyph, string fallback, string action)
        {
            var chip = MakeChip();
            chip.Add(HudUi.Glyph(glyph, fallback, 26));
            var lbl = HudUi.Text(action, 12, MenuUi.SubCol, TextAnchor.MiddleLeft);
            lbl.style.marginLeft = 5;
            chip.Add(lbl);
            _hintBar.Add(chip);
        }

        // ---- UITK construction ----

        void BuildTree(VisualElement root)
        {
            var theme = HudTheme.Get();
            _themed = theme != null && theme.PanelBox != null;

            root.style.position = Position.Absolute;
            root.style.left = 0; root.style.right = 0; root.style.top = 0; root.style.bottom = 0;
            root.pickingMode = PickingMode.Ignore; // never eat game-world clicks

            BuildVignette(root);
            BuildVitals(root);
            BuildThreat(root);
            BuildMacro(root);
            BuildResources(root);
            BuildPaletteRow(root);
            BuildHintBar(root);
            BuildDowned(root);
            BuildInventory(root);
        }

        void BuildVignette(VisualElement root)
        {
            _vignette = new VisualElement();
            _vignette.style.position = Position.Absolute;
            _vignette.style.left = 0; _vignette.style.right = 0; _vignette.style.top = 0; _vignette.style.bottom = 0;
            _vignette.pickingMode = PickingMode.Ignore;
            var theme = HudTheme.Get();
            if (theme != null && theme.Vignette != null)
            {
                _vignette.style.backgroundImage = new StyleBackground(Background.FromSprite(theme.Vignette));
                _vignette.style.unityBackgroundImageTintColor = BlightRed;
                _vignette.style.backgroundSize = new StyleBackgroundSize(new BackgroundSize(BackgroundSizeType.Cover));
            }
            else
            {
                _vignette.style.backgroundColor = new Color(BlightRed.r, BlightRed.g, BlightRed.b, 1f);
            }
            _vignette.style.display = DisplayStyle.None;
            root.Add(_vignette);
        }

        void BuildVitals(VisualElement root)
        {
            var panel = HudUi.Panel(PanelDark);
            panel.style.position = Position.Absolute;
            panel.style.left = 40; panel.style.bottom = 40;
            panel.style.paddingLeft = 14; panel.style.paddingRight = 14;
            panel.style.paddingTop = 12; panel.style.paddingBottom = 12;
            panel.style.alignItems = Align.FlexStart;
            var theme = HudTheme.Get();

            // shield chip (shown only while the respawn shield is active)
            _shieldRow = new VisualElement();
            _shieldRow.style.flexDirection = FlexDirection.Row;
            _shieldRow.style.alignItems = Align.Center;
            _shieldRow.style.marginBottom = 6;
            _shieldRow.pickingMode = PickingMode.Ignore;
            var shieldIcon = HudUi.Icon(theme != null ? theme.ShieldIcon : null, 22, AetherCyan);
            shieldIcon.style.marginRight = 6;
            _shieldRow.Add(shieldIcon);
            _shieldRow.Add(HudUi.Text("SHIELDED", 13, new Color(0.45f, 0.85f, 1f), TextAnchor.MiddleLeft));
            _shieldRow.style.display = DisplayStyle.None;
            panel.Add(_shieldRow);

            // cooldown row: weapon icon + thin bar
            _cdRow = new VisualElement();
            _cdRow.style.flexDirection = FlexDirection.Row;
            _cdRow.style.alignItems = Align.Center;
            _cdRow.style.marginBottom = 6;
            _cdRow.pickingMode = PickingMode.Ignore;
            var cdIcon = HudUi.Icon(theme != null ? theme.CooldownIcon : null, 22, AetherCyan);
            cdIcon.style.marginRight = 8;
            _cdRow.Add(cdIcon);
            var cdBar = HudUi.Bar(420, 12, new Color(0.4f, 0.8f, 1f), out _cooldownFill);
            _cdRow.Add(cdBar);
            panel.Add(_cdRow);

            // health row: health icon + big bar with numeric overlay
            var hpRow = new VisualElement();
            hpRow.style.flexDirection = FlexDirection.Row;
            hpRow.style.alignItems = Align.Center;
            hpRow.pickingMode = PickingMode.Ignore;
            var hpIcon = HudUi.Icon(theme != null ? theme.HealthIcon : null, 34, new Color(0.95f, 0.4f, 0.4f));
            hpIcon.style.marginRight = 8;
            hpRow.Add(hpIcon);
            var hpBar = HudUi.Bar(420, 40, new Color(0.25f, 0.9f, 0.5f), out _healthFill);
            _healthText = HudUi.Display("100 / 100", 24, Color.white, TextAnchor.MiddleCenter);
            _healthText.style.position = Position.Absolute;
            _healthText.style.left = 0; _healthText.style.right = 0; _healthText.style.top = 0; _healthText.style.bottom = 0;
            hpBar.Add(_healthText);
            hpRow.Add(hpBar);
            panel.Add(hpRow);

            root.Add(panel);
        }

        void BuildThreat(VisualElement root)
        {
            _threatPanel = HudUi.Panel(PanelDark);
            _threatPanel.style.position = Position.Absolute;
            _threatPanel.style.right = 40; _threatPanel.style.top = 28;
            _threatPanel.style.paddingLeft = 16; _threatPanel.style.paddingRight = 16;
            _threatPanel.style.paddingTop = 8; _threatPanel.style.paddingBottom = 8;
            _threatPanel.style.alignItems = Align.FlexEnd;
            var theme = HudTheme.Get();

            var row = new VisualElement();
            row.style.flexDirection = FlexDirection.Row;
            row.style.alignItems = Align.Center;
            row.pickingMode = PickingMode.Ignore;
            _threatIcon = HudUi.Icon(theme != null ? theme.ThreatIcon : null, 36, ThreatWarm);
            _threatIcon.style.marginRight = 8;
            row.Add(_threatIcon);
            _threatNum = HudUi.Display("0", 34, ThreatWarm, TextAnchor.MiddleRight);
            row.Add(_threatNum);
            _threatPanel.Add(row);

            var caption = HudUi.Text("HUSKS", 13, MenuUi.SubCol, TextAnchor.MiddleRight);
            caption.style.letterSpacing = 4;
            _threatPanel.Add(caption);

            _threatPanel.style.display = DisplayStyle.None;
            root.Add(_threatPanel);
        }

        void BuildMacro(VisualElement root)
        {
            var macro = HudUi.Group(Align.Center);
            macro.style.position = Position.Absolute;
            macro.style.top = 16; macro.style.left = 0; macro.style.right = 0;
            var theme = HudTheme.Get();

            // banner: objective icon + phase line + cycle, phase-coloured underline
            _banner = HudUi.Panel(PanelDark);
            _banner.style.flexDirection = FlexDirection.Row;
            _banner.style.alignItems = Align.Center;
            _banner.style.paddingLeft = 22; _banner.style.paddingRight = 22;
            _banner.style.paddingTop = 8; _banner.style.paddingBottom = 8;
            _banner.style.borderBottomWidth = 2;
            _banner.style.borderBottomColor = AetherCyan;
            var bIcon = HudUi.Icon(theme != null ? theme.GoalIcon : null, 26, AetherCyan);
            bIcon.style.marginRight = 10;
            _banner.Add(bIcon);
            _phaseText = HudUi.Display("", 30, AetherCyan, TextAnchor.MiddleCenter);
            _banner.Add(_phaseText);
            _cycleText = HudUi.Text("", 14, MenuUi.SubCol, TextAnchor.MiddleCenter);
            _cycleText.style.marginLeft = 14;
            _banner.Add(_cycleText);
            macro.Add(_banner);

            _locationText = HudUi.Text("", 15, new Color(0.6f, 0.85f, 1f), TextAnchor.MiddleCenter);
            _locationText.style.marginTop = 5;
            macro.Add(_locationText);

            // goal: hex-pip meter (or fallback bar) + numeral
            _goalContainer = HudUi.Group(Align.Center);
            _goalContainer.style.marginTop = 8;

            var goalLine = new VisualElement();
            goalLine.style.flexDirection = FlexDirection.Row;
            goalLine.style.alignItems = Align.Center;
            goalLine.pickingMode = PickingMode.Ignore;

            _goalPipsRow = new VisualElement();
            _goalPipsRow.style.flexDirection = FlexDirection.Row;
            _goalPipsRow.style.alignItems = Align.Center;
            _goalPipsRow.pickingMode = PickingMode.Ignore;
            for (int i = 0; i < MaxPips; i++)
            {
                var pip = new VisualElement();
                pip.style.width = 22; pip.style.height = 22;
                pip.style.marginLeft = 2; pip.style.marginRight = 2;
                pip.style.flexShrink = 0;
                pip.pickingMode = PickingMode.Ignore;
                pip.style.display = DisplayStyle.None;
                _pips.Add(pip);
                _goalPipsRow.Add(pip);
            }
            goalLine.Add(_goalPipsRow);

            _goalText = HudUi.Display("GOAL  0 / 10", 16, AetherCyan, TextAnchor.MiddleCenter);
            _goalText.style.marginLeft = 10;
            goalLine.Add(_goalText);
            _goalContainer.Add(goalLine);

            // fallback continuous bar (large targets)
            _goalBar = HudUi.Bar(360, 16, new Color(0.8f, 0.6f, 1f), out _goalFill);
            _goalBar.style.marginTop = 4;
            _goalBar.style.display = DisplayStyle.None;
            _goalContainer.Add(_goalBar);

            macro.Add(_goalContainer);
            root.Add(macro);
        }

        void BuildResources(VisualElement root)
        {
            var strip = HudUi.Panel(PanelDark);
            strip.style.position = Position.Absolute;
            strip.style.left = 40; strip.style.top = 28;
            strip.style.flexDirection = FlexDirection.Row;
            strip.style.alignItems = Align.Center;
            strip.style.paddingLeft = 14; strip.style.paddingRight = 14;
            strip.style.paddingTop = 8; strip.style.paddingBottom = 8;
            var theme = HudTheme.Get();

            strip.Add(ResourceChip(theme != null ? theme.AetherIcon : null, AetherCyan, "0", out _aetherNum, 26, 20));
            strip.Add(ResourceChip(theme != null ? theme.OreIcon : null, OreAmber, "0", out _oreNum, 30, 22));
            strip.Add(ResourceChip(theme != null ? theme.BioIcon : null, BioGreen, "0", out _bioNum, 26, 20));
            strip.Add(ResourceChip(null, ChargeViolet, "0", out _chargeNum, 26, 20)); // EB-2 turret ammo (flat violet, no icon)

            root.Add(strip);
        }

        VisualElement ResourceChip(Sprite icon, Color tint, string initial, out Label num, float iconSize, int fontSize)
        {
            var chip = new VisualElement();
            chip.style.flexDirection = FlexDirection.Row;
            chip.style.alignItems = Align.Center;
            chip.style.marginLeft = 9; chip.style.marginRight = 9;
            chip.pickingMode = PickingMode.Ignore;
            var ic = HudUi.Icon(icon, iconSize, tint);
            ic.style.marginRight = 6;
            chip.Add(ic);
            num = HudUi.Display(initial, fontSize, tint, TextAnchor.MiddleLeft);
            chip.Add(num);
            return chip;
        }

        void BuildPaletteRow(VisualElement root)
        {
            _paletteRow = new VisualElement();
            _paletteRow.style.position = Position.Absolute;
            _paletteRow.style.bottom = 24; _paletteRow.style.left = 0; _paletteRow.style.right = 0;
            _paletteRow.style.flexDirection = FlexDirection.Row;
            _paletteRow.style.justifyContent = Justify.Center;
            _paletteRow.pickingMode = PickingMode.Ignore; // the row passes clicks through; its slots pick
            root.Add(_paletteRow);
        }

        void BuildHintBar(VisualElement root)
        {
            _hintBar = new VisualElement();
            _hintBar.style.position = Position.Absolute;
            _hintBar.style.bottom = 138; _hintBar.style.left = 0; _hintBar.style.right = 0;
            _hintBar.style.flexDirection = FlexDirection.Row;
            _hintBar.style.justifyContent = Justify.Center;
            _hintBar.pickingMode = PickingMode.Ignore;
            _hintBar.style.display = DisplayStyle.None;
            root.Add(_hintBar);
        }

        void BuildDowned(VisualElement root)
        {
            _downed = new VisualElement();
            _downed.style.position = Position.Absolute;
            _downed.style.left = 0; _downed.style.right = 0; _downed.style.top = 0; _downed.style.bottom = 0;
            _downed.style.alignItems = Align.Center;
            _downed.style.justifyContent = Justify.Center;
            _downed.pickingMode = PickingMode.Ignore;
            var theme = HudTheme.Get();
            if (theme != null && theme.Vignette != null)
            {
                _downed.style.backgroundImage = new StyleBackground(Background.FromSprite(theme.Vignette));
                _downed.style.unityBackgroundImageTintColor = new Color(0.45f, 0f, 0f, 0.6f);
                _downed.style.backgroundSize = new StyleBackgroundSize(new BackgroundSize(BackgroundSizeType.Cover));
            }
            else
            {
                _downed.style.backgroundColor = new Color(0.35f, 0f, 0f, 0.35f);
            }
            _downed.Add(HudUi.Display("DOWNED - RESPAWNING", 52, new Color(1f, 0.45f, 0.4f), TextAnchor.MiddleCenter));
            _downed.style.display = DisplayStyle.None;
            root.Add(_downed);
        }

        void BuildInventory(VisualElement root)
        {
            _invPanel = HudUi.Panel(PanelDark);
            _invPanel.style.position = Position.Absolute;
            _invPanel.style.right = 40; _invPanel.style.bottom = 40;
            _invPanel.style.minWidth = 224;
            _invPanel.style.paddingLeft = 14; _invPanel.style.paddingRight = 14;
            _invPanel.style.paddingTop = 10; _invPanel.style.paddingBottom = 10;
            _invPanel.style.alignItems = Align.FlexStart;
            _invPanel.pickingMode = PickingMode.Ignore;

            var header = HudUi.Display("INVENTORY", 16, AetherCyan, TextAnchor.MiddleLeft);
            header.style.marginBottom = 6;
            _invPanel.Add(header);

            _invList = new VisualElement();
            _invList.pickingMode = PickingMode.Ignore;
            _invPanel.Add(_invList);

            var equipHeader = HudUi.Display("EQUIPMENT", 14, AetherCyan, TextAnchor.MiddleLeft);
            equipHeader.style.marginTop = 8; equipHeader.style.marginBottom = 4;
            _invPanel.Add(equipHeader);

            _equipList = new VisualElement();
            _equipList.pickingMode = PickingMode.Ignore;
            _invPanel.Add(_equipList);

            var hint = HudUi.Text("I close   -   click item=equip / slot=unequip   -   G deposit", 11, MenuUi.SubCol, TextAnchor.MiddleLeft);
            hint.style.marginTop = 8;
            _invPanel.Add(hint);

            _invPanel.style.display = DisplayStyle.None;
            root.Add(_invPanel);
        }

        void AddInvRow(ushort itemId, string name, Color tint, int count, bool equippable)
        {
            var row = new VisualElement();
            row.style.flexDirection = FlexDirection.Row;
            row.style.justifyContent = Justify.SpaceBetween;
            row.style.minWidth = 196;
            row.style.marginTop = 2;
            row.Add(HudUi.Text(name + (equippable ? "  (equip)" : ""), 13, tint, TextAnchor.MiddleLeft));
            row.Add(HudUi.Display("x" + count, 13, Color.white, TextAnchor.MiddleRight));
            if (equippable)
            {
                row.pickingMode = PickingMode.Position;
                ushort id = itemId;
                row.RegisterCallback<ClickEvent>(_ => EquipSendSystem.Equip(id));
            }
            else row.pickingMode = PickingMode.Ignore;
            _invList.Add(row);
        }

        static string ItemName(bool haveDb, ItemDatabase db, ushort id)
        {
            if (haveDb && db.Value.IsCreated)
            {
                ref var blob = ref db.Value.Value;
                if (blob.TryGetItem(id, out var def)) return def.Name.ToString();
            }
            if (id == ResourceId.Aether) return "Aether";
            if (id == ResourceId.Ore) return "Ore";
            if (id == ResourceId.Biomass) return "Biomass";
            return "Item " + id;
        }

        static Color ItemTint(ushort id)
        {
            if (id == ResourceId.Aether) return AetherCyan;
            if (id == ResourceId.Ore) return OreAmber;
            if (id == ResourceId.Biomass) return BioGreen;
            return new Color(0.85f, 0.85f, 0.9f);
        }
        static bool IsEquippable(bool haveDb, ItemDatabase db, ushort id)
        {
            if (!haveDb || !db.Value.IsCreated) return false;
            ref var b = ref db.Value.Value;
            return b.TryGetItem(id, out var def) && def.EquipSlot < EquipSlotId.Count;
        }

        static string SlotName(byte slot)
        {
            switch (slot)
            {
                case EquipSlotId.Weapon: return "Weapon";
                case EquipSlotId.Armor: return "Armor";
                case EquipSlotId.Trinket: return "Trinket";
                case EquipSlotId.Tool: return "Tool";
                default: return "Slot " + slot;
            }
        }

        void AddEquipRow(byte slot, string label, bool occupied)
        {
            var row = new VisualElement();
            row.style.flexDirection = FlexDirection.Row;
            row.style.justifyContent = Justify.SpaceBetween;
            row.style.minWidth = 196;
            row.style.marginTop = 2;
            row.Add(HudUi.Text(label, 13, occupied ? AetherCyan : MenuUi.SubCol, TextAnchor.MiddleLeft));
            if (occupied)
            {
                row.pickingMode = PickingMode.Position;
                byte s = slot;
                row.RegisterCallback<ClickEvent>(_ => EquipSendSystem.Unequip(s));
                row.Add(HudUi.Text("unequip", 11, new Color(1f, 0.6f, 0.5f), TextAnchor.MiddleRight));
            }
            else row.pickingMode = PickingMode.Ignore;
            _equipList.Add(row);
        }


        static Color ResourceTint(byte resId)
            => resId == ResourceId.Aether ? AetherCyan : resId == ResourceId.Biomass ? BioGreen : OreAmber;

        static Sprite ResourceSprite(HudTheme t, byte resId)
        {
            if (t == null) return null;
            return resId == ResourceId.Aether ? t.AetherIcon : resId == ResourceId.Biomass ? t.BioIcon : t.OreIcon;
        }

        // Conveyor facing (BuildPaletteState.Direction 0=+X,1=-X,2=+Z,3=-Z) → arrow rotation; the arrow art points up (+Z).
        static float FacingDegrees(byte dir)
        {
            switch (dir)
            {
                case 0: return 90f;   // +X
                case 1: return 270f;  // -X
                case 3: return 180f;  // -Z
                default: return 0f;   // +Z
            }
        }

        static Color PhaseColor(byte phase)
        {
            switch (phase)
            {
                case CyclePhase.Calm: return new Color(0.45f, 0.9f, 0.7f);
                case CyclePhase.Siege: return new Color(1f, 0.45f, 0.3f);
                default: return Color.white;
            }
        }

        static string PhaseLabel(byte phase)
        {
            switch (phase)
            {
                case CyclePhase.Calm: return "AT BASE";
                case CyclePhase.Siege: return "UNDER SIEGE";
                default: return "";
            }
        }

        static string StructureName(byte type)
        {
            switch (type)
            {
                case StructureType.Turret: return "Turret";
                case StructureType.Wall: return "Wall";
                case StructureType.Pylon: return "Pylon";
                case StructureType.Harvester: return "Harvester";
                case StructureType.Fabricator: return "Fabricator";
                case StructureType.Conveyor: return "Conveyor";
                default: return "?";
            }
        }
    }
}