using System;
using System.Collections.Generic;
using AcDream.App.UI;
using AcDream.Core.Items;

namespace AcDream.App.UI.Layout;

/// <summary>
/// Binds the ~21 equip slots mounted under the paperdoll (gmPaperDollUI 0x21000024, nested in the
/// inventory frame 0x21000023) to live equipped-item data and makes them drag-drop WIELD targets.
/// The acdream analogue of gmPaperDollUI::PostInit + GetLocationInfoFromElementID (named-retail decomp
/// 175480 / 173620). Slice 1: equip slots only — no 3D doll viewport (that's Slice 2).
/// Unwield is handled by InventoryController (dragging an equipped item onto the pack grid).
/// </summary>
public sealed class PaperdollController : IItemListDragHandler
{
    // WEAPON_READY_SLOT_LOC (acclient.h:3235): the weapon-hand doll slot accepts any wieldable weapon.
    private const EquipMask WeaponSlotMask =
        EquipMask.MeleeWeapon | EquipMask.MissileWeapon | EquipMask.Held | EquipMask.TwoHanded;

    // element-id → EquipMask (verified: dump paperdoll-0x21000024.txt ↔ deep-dive §3a ↔ acclient.h:3193).
    // The 3 Aetheria sigil slots (0x10000595/96/97) are SetVisible(0) in retail — skipped (Slice 1 scope).
    private static readonly (uint Element, EquipMask Mask)[] SlotMap =
    {
        (0x100005ABu, EquipMask.HeadWear),        // 0x1
        (0x100001E2u, EquipMask.ChestWear),       // 0x2
        (0x100001E3u, EquipMask.UpperLegWear),    // 0x40
        (0x100005B0u, EquipMask.HandWear),        // 0x20
        (0x100005B3u, EquipMask.FootWear),        // 0x100
        (0x100005ACu, EquipMask.ChestArmor),      // 0x200
        (0x100005ADu, EquipMask.AbdomenArmor),    // 0x400
        (0x100005AEu, EquipMask.UpperArmArmor),   // 0x800
        (0x100005AFu, EquipMask.LowerArmArmor),   // 0x1000
        (0x100005B1u, EquipMask.UpperLegArmor),   // 0x2000
        (0x100005B2u, EquipMask.LowerLegArmor),   // 0x4000
        (0x100001DAu, EquipMask.NeckWear),        // 0x8000
        (0x100001DBu, EquipMask.WristWearLeft),   // 0x10000
        (0x100001DDu, EquipMask.WristWearRight),  // 0x20000
        (0x100001DCu, EquipMask.FingerWearLeft),  // 0x40000
        (0x100001DEu, EquipMask.FingerWearRight), // 0x80000
        (0x100001E1u, EquipMask.Shield),          // 0x200000
        (0x100001E0u, EquipMask.MissileAmmo),     // 0x800000 (LIKELY — gate-verify, AP row)
        (0x100001DFu, WeaponSlotMask),            // 0x3500000 composite
        (0x1000058Eu, EquipMask.TrinketOne),      // 0x4000000
        (0x100005E9u, EquipMask.Cloak),           // 0x8000000
    };

    private readonly ClientObjectTable _objects;
    private readonly Func<uint> _playerGuid;
    private readonly Func<ItemType, uint, uint, uint, uint, uint> _iconIds;
    private readonly Action<uint, uint>? _sendWield;     // (itemGuid, equipMask) → GetAndWieldItem 0x001A
    private readonly List<(EquipMask Mask, UiItemList List)> _slots = new();

    private PaperdollController(
        ImportedLayout layout, ClientObjectTable objects, Func<uint> playerGuid,
        Func<ItemType, uint, uint, uint, uint, uint> iconIds, Action<uint, uint>? sendWield,
        uint emptySlotSprite)
    {
        _objects = objects; _playerGuid = playerGuid; _iconIds = iconIds; _sendWield = sendWield;

        for (int i = 0; i < SlotMap.Length; i++)
        {
            var (element, mask) = SlotMap[i];
            if (layout.FindElement(element) is not UiItemList list) continue;
            list.RegisterDragHandler(this);
            list.Cell.SourceKind  = ItemDragSource.Equipment;
            list.Cell.SlotIndex   = i;              // SlotMap position = this equipped item's drag-payload SourceSlot when dragged out to unwield
            list.Cell.EmptySprite = emptySlotSprite; // visible empty-slot frame so every position is seen + usable. The live
                                                     // 3D character (the "figure" — Slice 1/2 correction: NOT a per-slot
                                                     // silhouette) is the doll viewport, which arrives in Slice 2 with the Slots toggle.
            // Cell.SpriteResolve + the default accept/reject sprites (ItemSlot_DragOver_Accept ring
            // 0x060011F9 / reject circle 0x060011F8 — the discrete-slot frames, NOT the inventory grid's
            // insert-arrow 0x060011F7) are already wired by DatWidgetFactory when it built the UiItemList;
            // no need to re-set them here.
            _slots.Add((mask, list));
        }

        _objects.ObjectAdded   += OnObjectChanged;
        _objects.ObjectMoved   += OnObjectMoved;
        _objects.ObjectRemoved += OnObjectChanged;
        _objects.ObjectUpdated += OnObjectChanged;

        Populate();
    }

    public static PaperdollController Bind(
        ImportedLayout layout, ClientObjectTable objects, Func<uint> playerGuid,
        Func<ItemType, uint, uint, uint, uint, uint> iconIds, Action<uint, uint>? sendWield = null,
        uint emptySlotSprite = 0u)
        => new PaperdollController(layout, objects, playerGuid, iconIds, sendWield, emptySlotSprite);

    private void OnObjectChanged(ClientObject o) { if (Concerns(o)) Populate(); }
    private void OnObjectMoved(ClientObject o, uint from, uint to)
    { if (Concerns(o) || from == _playerGuid() || to == _playerGuid()) Populate(); }

    /// <summary>The object belongs to the player (wielded gear or pack contents) — so a change to it may
    /// add/remove/repaint a doll slot. Player-scoped: an NPC's or vendor's wielded item (which also carries
    /// CurrentlyEquippedLocation from the wire) must NOT trigger a repaint. A player-equipped item always
    /// has WielderId==p (login, from CreateObject) or ContainerId==p (live/optimistic wield, set by
    /// WieldItemOptimistic), so the equip-location need not be tested here; OnObjectMoved adds the from/to
    /// player backstop for moves that transiently satisfy neither (e.g. unwield into a side bag).</summary>
    private bool Concerns(ClientObject o)
    {
        uint p = _playerGuid();
        return o.WielderId == p || o.ContainerId == p;
    }

    public void Populate()
    {
        uint p = _playerGuid();

        // The player's equipped gear (one pass). Scoped to the player so a vendor's/NPC's wielded item
        // (which can also carry CurrentWieldedLocation) can't leak into the doll.
        var equipped = new List<ClientObject>();
        foreach (var o in _objects.Objects)
            if (o.CurrentlyEquippedLocation != EquipMask.None && (o.WielderId == p || o.ContainerId == p))
                equipped.Add(o);

        foreach (var (mask, list) in _slots)
        {
            ClientObject? worn = null;
            foreach (var o in equipped)
                if ((o.CurrentlyEquippedLocation & mask) != EquipMask.None) { worn = o; break; }

            if (worn is null) { list.Cell.Clear(); continue; }
            uint tex = _iconIds(worn.Type, worn.IconId, worn.IconUnderlayId, worn.IconOverlayId, worn.Effects);
            list.Cell.SetItem(worn.ObjectId, tex);
        }
    }

    private EquipMask MaskFor(UiItemList list)
    {
        foreach (var (mask, l) in _slots) if (ReferenceEquals(l, list)) return mask;
        return EquipMask.None;
    }

    // ── IItemListDragHandler ──────────────────────────────────────────────────────────────────────
    /// <summary>No-op: a wielded item stays put until the server confirms (same as the inventory grid,
    /// unlike the toolbar's remove-on-lift). Unwield happens on DROP onto the pack grid — InventoryController.</summary>
    public void OnDragLift(UiItemList sourceList, UiItemSlot sourceCell, ItemDragPayload payload) { }

    /// <summary>Accept iff the dragged item can be worn here (its ValidLocations intersects the slot mask).
    /// Retail: gmPaperDollUI::OnItemListDragOver (decomp 174302).</summary>
    public bool OnDragOver(UiItemList targetList, UiItemSlot targetCell, ItemDragPayload payload)
    {
        var item = _objects.Get(payload.ObjId);
        if (item is null) return false;
        return (item.ValidLocations & MaskFor(targetList)) != EquipMask.None;
    }

    /// <summary>Wield the dropped item: optimistic local equip (instant) + GetAndWieldItem 0x001A.
    /// wieldMask = ValidLocations & slotMask resolves the specific bit (the composite weapon slot, the
    /// chosen finger). Retail: gmPaperDollUI HandleDropRelease → GetAndWieldItem.</summary>
    public void HandleDropRelease(UiItemList targetList, UiItemSlot targetCell, ItemDragPayload payload)
    {
        var item = _objects.Get(payload.ObjId);
        if (item is null) return;
        EquipMask wieldMask = item.ValidLocations & MaskFor(targetList);
        if (wieldMask == EquipMask.None) return;       // not wieldable here (defensive; OnDragOver already rejected)
        _objects.WieldItemOptimistic(payload.ObjId, _playerGuid(), wieldMask);
        _sendWield?.Invoke(payload.ObjId, (uint)wieldMask);
    }

    /// <summary>Detach event handlers (idempotent).</summary>
    public void Dispose()
    {
        _objects.ObjectAdded   -= OnObjectChanged;
        _objects.ObjectMoved   -= OnObjectMoved;
        _objects.ObjectRemoved -= OnObjectChanged;
        _objects.ObjectUpdated -= OnObjectChanged;
    }
}