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>
    /// The Staging-only permanent-upgrade shop (meta shop) — extracted from <see cref="HudSystem"/> into its own
    /// client-only, observe-only presentation <see cref="SystemBase"/> in <see cref="PresentationSystemGroup"/>.
    /// Owns its own runtime UIDocument sharing <see cref="MenuUi.LoadPanelSettings"/> (sortingOrder 51). Recomputes
    /// its inputs locally: the local class from the replicated <see cref="AbilityRef"/>
    /// (<see cref="ClassTraits.ClassForAbility"/>), Aether from the <see cref="ResourceLedger"/> buffer, siege from
    /// <see cref="CycleState"/>, and the Staging gate from <see cref="RunInfo"/>. Row clicks enqueue through
    /// <see cref="MetaSpendSendSystem.RequestPurchase"/> — the server re-validates everything.
    /// </summary>
    [WorldSystemFilter(WorldSystemFilterFlags.ClientSimulation)]
    [UpdateInGroup(typeof(PresentationSystemGroup))]
    public partial class MetaShopHudSystem : SystemBase
    {
        GameObject _go;
        UIDocument _doc;
        bool _built;

        VisualElement _metaPanel, _metaRowsHost;
        Label _metaShopTitle;
        bool _metaShopBuilt;
        int _metaShownFor; // last (class, tiers, aether) signature the shop rows were built for

        protected override void OnStartRunning()
        {
            if (_go != null) return;
            MenuUi.EnsureEventSystem();
            _go = new GameObject("~HUDMetaShop");
            _doc = _go.AddComponent<UIDocument>();
            _doc.panelSettings = MenuUi.LoadPanelSettings();
            _doc.sortingOrder = 51;
        }

        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;

            // Aether from the ledger (the sole meta-shop currency; last entry wins, matching the core loop).
            int aether = 0;
            if (SystemAPI.TryGetSingletonEntity<ResourceLedger>(out var ledgerE))
            {
                var buf = SystemAPI.GetBuffer<StorageEntry>(ledgerE);
                for (int i = 0; i < buf.Length; i++)
                    if (buf[i].ItemId == ResourceId.Aether) aether = buf[i].Count;
            }

            // Local class derives from the replicated AbilityRef (tracks the dev class-switch; PlayerClass is
            // server-only); tiers from the replicated MetaTierState record on the director ghost.
            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;
            }

            bool metaShow = false;
            BlobAssetReference<MetaUpgradeCatalogBlob> metaPool = default;
            DynamicBuffer<MetaTierState> metaRecord = default;
            if (haveRun && runInfo.Lifecycle == RunLifecycle.Staging && haveLocalPlayer && !siege
                && SystemAPI.TryGetSingleton<MetaUpgradeCatalog>(out var metaCat) && metaCat.Value.IsCreated
                && SystemAPI.TryGetSingletonBuffer<MetaTierState>(out metaRecord, true))
            {
                metaPool = metaCat.Value;
                metaShow = true;
            }
            UpdateMetaShop(metaShow, localClass, aether, metaPool, metaRecord);
        }

        void UpdateMetaShop(bool show, byte classId, int aether,
            BlobAssetReference<MetaUpgradeCatalogBlob> pool, DynamicBuffer<MetaTierState> record)
        {
            if (!show)
            {
                if (_metaPanel != null) _metaPanel.style.display = DisplayStyle.None;
                _metaShownFor = 0;
                return;
            }
            var root = _doc != null ? _doc.rootVisualElement : null;
            if (root == null) return;
            if (!_metaShopBuilt)
            {
                BuildMetaShop(root);
                _metaShopBuilt = true;
            }

            // Rebuild the rows only when class / owned tiers / affordability actually change (Staging-only, <=8 rows).
            int sig = classId * 131 ^ aether * 31;
            for (int i = 0; i < record.Length; i++)
                sig ^= (record[i].ClassId * 7 + record[i].UpgradeId * 13 + record[i].Tier) * (i + 3);
            if (sig == 0) sig = 1;
            if (_metaShownFor != sig)
            {
                _metaRowsHost.Clear();
                _metaShopTitle.text = (classId == ClassTraits.RangerClass ? "RANGER" : "WARRIOR")
                    + "  PERMANENT UPGRADES   -   AETHER " + aether;
                ref var defs = ref pool.Value;
                byte classBit = BoonMath.MaskFor(classId);
                for (int d = 0; d < defs.Defs.Length; d++)
                {
                    if ((defs.Defs[d].ClassMask & classBit) == 0) continue;
                    byte id = defs.Defs[d].Id;
                    byte owned = MetaMath.TierOf(record, classId, id);
                    if (owned > defs.Defs[d].MaxTier) owned = defs.Defs[d].MaxTier; // D-F5 display clamp (seed AND spend AND shop)
                    bool maxed = owned >= defs.Defs[d].MaxTier;
                    int cost = MetaMath.CostForTier(in defs.Defs[d], owned);
                    string label = defs.Defs[d].Name.ToString()
                        + (maxed ? "   MAXED" : "   -   " + cost + " Aether")
                        + "\n" + defs.Defs[d].Desc.ToString();
                    byte buyId = id; // closure copy, never the loop variable
                    var row = MenuUi.Button(label, () => MetaSpendSendSystem.RequestPurchase(buyId));
                    row.style.width = 290;
                    row.style.height = StyleKeyword.Auto; // two-line labels must grow the row (overlap fix)
                    row.style.paddingTop = 6; row.style.paddingBottom = 6;
                    row.style.marginBottom = 4;
                    row.style.whiteSpace = WhiteSpace.Normal;
                    row.style.unityTextAlign = TextAnchor.MiddleLeft;
                    row.SetEnabled(!maxed && aether >= cost); // honest UI; the server re-validates everything anyway
                    // Owned-tier pips (replaces the "[2/5]" text — reads at a glance).
                    var pipRow = new VisualElement { pickingMode = PickingMode.Ignore };
                    pipRow.style.flexDirection = FlexDirection.Row;
                    pipRow.style.marginTop = 3;
                    for (int p = 0; p < defs.Defs[d].MaxTier; p++)
                    {
                        var tp = new VisualElement { pickingMode = PickingMode.Ignore };
                        tp.style.width = 9; tp.style.height = 9;
                        tp.style.marginRight = 3;
                        MenuUi.Round(tp, 4.5f);
                        tp.style.backgroundColor = p < owned ? MenuUi.Accent : new Color(1f, 1f, 1f, 0.14f);
                        pipRow.Add(tp);
                    }
                    row.Add(pipRow);
                    _metaRowsHost.Add(row);
                }
                _metaShownFor = sig;
            }
            _metaPanel.style.display = DisplayStyle.Flex;
        }

        void BuildMetaShop(VisualElement root)
        {
            _metaPanel = new VisualElement { pickingMode = PickingMode.Ignore };
            _metaPanel.style.position = Position.Absolute;
            _metaPanel.style.right = 12;
            _metaPanel.style.top = Length.Percent(22);
            _metaPanel.style.alignItems = Align.FlexEnd;
            _metaPanel.style.display = DisplayStyle.None;

            var box = new VisualElement();
            box.style.backgroundColor = new Color(0.07f, 0.09f, 0.12f, 0.92f);
            box.style.borderTopLeftRadius = 10; box.style.borderTopRightRadius = 10;
            box.style.borderBottomLeftRadius = 10; box.style.borderBottomRightRadius = 10;
            box.style.paddingLeft = 12; box.style.paddingRight = 12;
            box.style.paddingTop = 10; box.style.paddingBottom = 10;

            _metaShopTitle = new Label("PERMANENT UPGRADES");
            _metaShopTitle.style.color = MenuUi.Accent;
            _metaShopTitle.style.fontSize = 14;
            _metaShopTitle.style.unityFontStyleAndWeight = FontStyle.Bold;
            _metaShopTitle.style.marginBottom = 8;
            box.Add(_metaShopTitle);

            _metaRowsHost = new VisualElement();
            box.Add(_metaRowsHost);

            _metaPanel.Add(box);
            root.Add(_metaPanel);
        }
    }
}