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

namespace ProjectM.Client
{
    /// <summary>
    /// DR-046 base class-select + prep-loadout panels (Staging) + the room-exit portal prompt (RoomExplore) —
    /// extracted from <see cref="HudSystem"/> into their own client-only, observe-only presentation
    /// <see cref="SystemBase"/> in <see cref="PresentationSystemGroup"/>. Owns its own runtime UIDocument sharing
    /// <see cref="MenuUi.LoadPanelSettings"/> (sortingOrder 54). Recomputes the local class + ore/bio/aether + the
    /// Staging gate + the RoomExplore portal proximity locally; clicks enqueue through
    /// <see cref="ClassSelectSendSystem"/> / <see cref="PrepPurchaseSendSystem"/> / <see cref="PortalInteractSendSystem"/>.
    /// NOTE (behavior-preserving): the class/prep Staging gate reproduces the original's FULL condition — it also
    /// requires the <see cref="MetaUpgradeCatalog"/> + <see cref="MetaTierState"/> buffer to be present (the panels
    /// were gated on the same <c>metaShow</c> boolean as the meta shop).
    /// </summary>
    [WorldSystemFilter(WorldSystemFilterFlags.ClientSimulation)]
    [UpdateInGroup(typeof(PresentationSystemGroup))]
    public partial class ClassPrepPortalHudSystem : SystemBase
    {
        GameObject _go;
        UIDocument _doc;
        bool _built;

        VisualElement _classPanel, _prepPanel, _prepRowsHost;
        Label _classTitle, _prepTitle, _portalPrompt;
        Button _classWarBtn, _classRangerBtn;
        bool _classPanelBuilt, _prepPanelBuilt, _portalBuilt;
        int _classShownFor, _prepShownFor;

        protected override void OnStartRunning()
        {
            if (_go != null) return;
            MenuUi.EnsureEventSystem();
            _go = new GameObject("~HUDClassPrepPortal");
            _doc = _go.AddComponent<UIDocument>();
            _doc.panelSettings = MenuUi.LoadPanelSettings();
            _doc.sortingOrder = 54;
        }

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

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

            bool haveRun = SystemAPI.TryGetSingleton<RunInfo>(out var runInfo);
            bool haveCycle = SystemAPI.TryGetSingleton<CycleState>(out var cyc);
            bool siege = haveCycle && cyc.Phase == CyclePhase.Siege;

            // Resources from the ledger (last entry per type wins, matching the core loop).
            int aether = 0, ore = 0, bio = 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;
                }
            }

            // Local class from the replicated AbilityRef (tracks the dev class-switch; PlayerClass is server-only).
            byte localClass = ClassTraits.WarriorClass;
            bool haveLocalPlayer = false;
            foreach (var ar in SystemAPI.Query<RefRO<AbilityRef>>().WithAll<PlayerTag, GhostOwnerIsLocal>())
            {
                localClass = ClassTraits.ClassForAbility(ar.ValueRO.Id);
                haveLocalPlayer = true;
                break;
            }

            // Faithful reproduction of the original `metaShow` gate: class/prep were shown on the SAME condition as
            // the meta shop, which requires the meta catalog + tier buffer to exist.
            DynamicBuffer<MetaTierState> metaRecord = default;
            bool metaShow = haveRun && runInfo.Lifecycle == RunLifecycle.Staging && haveLocalPlayer && !siege
                && SystemAPI.TryGetSingleton<MetaUpgradeCatalog>(out var metaCat) && metaCat.Value.IsCreated
                && SystemAPI.TryGetSingletonBuffer<MetaTierState>(out metaRecord, true);

            UpdateClassPanel(metaShow, localClass);            // DR-046: base class pick (Staging)
            UpdatePrepPanel(metaShow, ore, bio, aether);       // DR-046: base prep loadout (Staging)
            UpdatePortalPrompt(haveRun ? runInfo : default, haveRun); // DR-046: room-exit portal prompt (RoomExplore)
        }

        void UpdateClassPanel(bool show, byte classId)
        {
            if (!show) { if (_classPanel != null) _classPanel.style.display = DisplayStyle.None; _classShownFor = 0; return; }
            var root = _doc != null ? _doc.rootVisualElement : null; if (root == null) return;
            if (!_classPanelBuilt) { BuildClassPanel(root); _classPanelBuilt = true; }
            int sig = classId + 1;
            if (_classShownFor != sig)
            {
                bool ranger = classId == ClassTraits.RangerClass;
                _classWarBtn.text = ranger ? "WARRIOR" : "WARRIOR  ✓";
                _classRangerBtn.text = ranger ? "RANGER  ✓" : "RANGER";
                _classWarBtn.SetEnabled(ranger);
                _classRangerBtn.SetEnabled(!ranger);
                _classShownFor = sig;
            }
            _classPanel.style.display = DisplayStyle.Flex;
        }

        void BuildClassPanel(VisualElement root)
        {
            _classPanel = new VisualElement { pickingMode = PickingMode.Ignore };
            _classPanel.style.position = Position.Absolute;
            _classPanel.style.left = 12; _classPanel.style.top = Length.Percent(22);
            _classPanel.style.display = DisplayStyle.None;
            var box = new VisualElement();
            box.style.backgroundColor = new Color(0.07f, 0.09f, 0.12f, 0.92f);
            MenuUi.Round(box, 10);
            box.style.paddingLeft = 12; box.style.paddingRight = 12; box.style.paddingTop = 10; box.style.paddingBottom = 10;
            _classTitle = new Label("CLASS");
            _classTitle.style.color = MenuUi.Accent; _classTitle.style.fontSize = 14;
            _classTitle.style.unityFontStyleAndWeight = FontStyle.Bold; _classTitle.style.marginBottom = 8;
            box.Add(_classTitle);
            _classWarBtn = MenuUi.Button("WARRIOR", () => ClassSelectSendSystem.RequestClass(ClassTraits.WarriorClass));
            _classWarBtn.style.marginBottom = 4; box.Add(_classWarBtn);
            _classRangerBtn = MenuUi.Button("RANGER", () => ClassSelectSendSystem.RequestClass(ClassTraits.RangerClass));
            box.Add(_classRangerBtn);
            _classPanel.Add(box); root.Add(_classPanel);
        }

        void UpdatePrepPanel(bool show, int ore, int bio, int aether)
        {
            if (!show) { if (_prepPanel != null) _prepPanel.style.display = DisplayStyle.None; _prepShownFor = 0; return; }
            var root = _doc != null ? _doc.rootVisualElement : null; if (root == null) return;
            if (!_prepPanelBuilt) { BuildPrepPanel(root); _prepPanelBuilt = true; }
            uint boughtMask = 0;
            foreach (var mods in SystemAPI.Query<DynamicBuffer<StatModifier>>().WithAll<PlayerTag, GhostOwnerIsLocal>())
            {
                for (int m = 0; m < mods.Length; m++)
                {
                    uint sid = mods[m].SourceId;
                    if (sid >= Tuning.PrepSourceIdBase && sid < Tuning.PrepSourceIdBase + Tuning.PrepSourceIdSpan)
                        boughtMask |= (uint)(1 << (int)(sid - Tuning.PrepSourceIdBase));
                }
                break;
            }
            int sig = ore * 7 ^ bio * 13 ^ aether * 31 ^ (int)boughtMask * 101;
            if (sig == 0) sig = 1;
            if (_prepShownFor != sig)
            {
                _prepRowsHost.Clear();
                for (int i = 0; i < PrepCatalog.Count; i++)
                {
                    var r = PrepCatalog.Rows[i];
                    int have = r.CostResId == ResourceId.Aether ? aether : r.CostResId == ResourceId.Biomass ? bio : ore;
                    bool bought = (boughtMask & (uint)(1 << r.Id)) != 0;
                    string resName = r.CostResId == ResourceId.Aether ? "Aether" : r.CostResId == ResourceId.Biomass ? "Biomass" : "Ore";
                    string label = PrepLabel(r.Id) + (bought ? "   BOUGHT" : "   -   " + r.Cost + " " + resName);
                    byte buyId = r.Id;
                    var row = MenuUi.Button(label, () => PrepPurchaseSendSystem.RequestPrep(buyId));
                    row.style.width = 240; row.style.marginBottom = 4;
                    row.style.whiteSpace = WhiteSpace.Normal; row.style.unityTextAlign = TextAnchor.MiddleLeft;
                    row.SetEnabled(!bought && have >= r.Cost);
                    _prepRowsHost.Add(row);
                }
                _prepShownFor = sig;
            }
            _prepPanel.style.display = DisplayStyle.Flex;
        }

        static string PrepLabel(byte id) => id == 0 ? "+30 Max HP" : id == 1 ? "+12% Move Speed"
            : id == 2 ? "+20% Melee Damage" : "+20% Ranged Damage";

        void BuildPrepPanel(VisualElement root)
        {
            _prepPanel = new VisualElement { pickingMode = PickingMode.Ignore };
            _prepPanel.style.position = Position.Absolute;
            _prepPanel.style.left = 12; _prepPanel.style.top = Length.Percent(45);
            _prepPanel.style.display = DisplayStyle.None;
            var box = new VisualElement();
            box.style.backgroundColor = new Color(0.07f, 0.09f, 0.12f, 0.92f);
            MenuUi.Round(box, 10);
            box.style.paddingLeft = 12; box.style.paddingRight = 12; box.style.paddingTop = 10; box.style.paddingBottom = 10;
            _prepTitle = new Label("PREP LOADOUT  (lasts the run)");
            _prepTitle.style.color = MenuUi.Accent; _prepTitle.style.fontSize = 14;
            _prepTitle.style.unityFontStyleAndWeight = FontStyle.Bold; _prepTitle.style.marginBottom = 8;
            box.Add(_prepTitle);
            _prepRowsHost = new VisualElement(); box.Add(_prepRowsHost);
            _prepPanel.Add(box); root.Add(_prepPanel);
        }

        void UpdatePortalPrompt(RunInfo runInfo, bool haveRun)
        {
            var root = _doc != null ? _doc.rootVisualElement : null; if (root == null) return;
            if (!_portalBuilt) { BuildPortalPrompt(root); _portalBuilt = true; }
            bool show = false, inRange = false;
            if (haveRun && runInfo.Lifecycle == RunLifecycle.RoomExplore
                && SystemAPI.TryGetSingleton<BaseAnchor>(out var anchor))
            {
                show = true; // room cleared -> ALWAYS steer the player to the (now visible) portal, not only when in range
                float3 portalPos = RegionMath.ExpeditionPortalPos(BaseGridMath.PlotCenter(anchor), (byte)(runInfo.CurrentRoom & 1));
                foreach (var lt in SystemAPI.Query<RefRO<LocalTransform>>().WithAll<PlayerTag, GhostOwnerIsLocal>())
                {
                    inRange = math.distance(lt.ValueRO.Position.xz, portalPos.xz) <= Tuning.PortalInteractRange;
                    if (inRange)
                    {
                        var kb = UnityEngine.InputSystem.Keyboard.current;
                        if (kb != null && kb.eKey.wasPressedThisFrame) PortalInteractSendSystem.Interact();
                    }
                    break;
                }
                _portalPrompt.text = inRange
                    ? "PRESS E TO LEAVE  —  the haul comes home"
                    : "ROOM CLEAR  —  reach the glowing portal to move on";
            }
            _portalPrompt.style.display = show ? DisplayStyle.Flex : DisplayStyle.None;
        }

        void BuildPortalPrompt(VisualElement root)
        {
            _portalPrompt = HudUi.Display("PRESS E TO LEAVE  —  the haul comes home", 20, new Color(0.55f, 0.95f, 1f), TextAnchor.MiddleCenter);
            _portalPrompt.style.position = Position.Absolute;
            _portalPrompt.style.left = 0; _portalPrompt.style.right = 0; _portalPrompt.style.bottom = 240;
            _portalPrompt.pickingMode = PickingMode.Ignore;
            _portalPrompt.style.display = DisplayStyle.None;
            root.Add(_portalPrompt);
        }
    }
}