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

namespace AcDream.App.UI.Layout;

/// <summary>
/// Binds the 24 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, IRetainedPanelController
{
    public const uint DollViewportId = 0x100001D5u;
    public const uint DollDragMaskId = 0x100001D6u;

    // ── Slots-toggle public surface ───────────────────────────────────────────────────────────────
    /// <summary>
    /// The 9 armor-slot element-ids whose Visible state the Slots button (0x100005BE) toggles.
    /// Doll-view: hidden. Slot-view: shown.  Source: gmPaperDollUI::ListenToElementMessage decomp
    /// 175674-175706 — these are the only 9 ids that element flips. The 12 ordinary non-armor
    /// lists remain visible in both views; the three Aetheria lists are independently unlock-gated.
    /// </summary>
    public static readonly uint[] ArmorSlotElementIds =
    {
        0x100005abu, 0x100005acu, 0x100005adu, 0x100005aeu, 0x100005afu,
        0x100005b0u, 0x100005b1u, 0x100005b2u, 0x100005b3u,
    };

    /// <summary>
    /// View-state model for the Slots toggle (pure logic, no UI coupling).
    /// Default is doll-view (SlotView == false): the 3-D character is visible,
    /// the 9 armor slots are hidden.  Calling Toggle() alternates between views.
    /// </summary>
    public sealed class PaperdollViewState
    {
        public bool SlotView { get; private set; }          // false = doll-view (default)
        public bool DollVisible    => !SlotView;
        public bool ArmorSlotsVisible => SlotView;
        public void Toggle() => SlotView = !SlotView;
    }

    private readonly ClientObjectTable _objects;
    private readonly Func<uint> _playerGuid;
    private readonly Func<ItemType, uint, uint, uint, uint, uint> _iconIds;
    private readonly Func<ItemType, uint, uint, uint, uint, uint>? _dragIconIds;
    private readonly Action<uint, uint>? _sendWield;     // (itemGuid, equipMask) → GetAndWieldItem 0x001A
    private readonly ItemInteractionController? _itemInteraction;
    private readonly SelectionState _selection;
    private readonly PaperdollClickMap? _clickMap;
    private readonly List<(EquipMask Mask, UiItemList List)> _slots = new();
    private readonly List<(AetheriaUnlockState Bit, UiItemList List)> _aetheriaSlots = new();

    // ── Slots-toggle state ────────────────────────────────────────────────────────────────────────
    private readonly PaperdollViewState _viewState = new();
    private readonly List<UiItemList> _armorSlots = new();
    private UiElement? _dollViewport;   // UiViewport wired in Slice 3; UiElement? keeps this task independent
    private UiElement? _dollDragMask;
    private bool _disposed;

    private PaperdollController(
        ImportedLayout layout, ClientObjectTable objects, Func<uint> playerGuid,
        Func<ItemType, uint, uint, uint, uint, uint> iconIds, SelectionState selection,
        Action<uint, uint>? sendWield,
        uint emptySlotSprite, UiDatFont? datFont, ItemInteractionController? itemInteraction,
        PaperdollClickMap? clickMap,
        Func<ItemType, uint, uint, uint, uint, uint>? dragIconIds,
        IReadOnlyDictionary<uint, uint>? emptySlotSprites)
    {
        _objects = objects; _playerGuid = playerGuid; _iconIds = iconIds; _sendWield = sendWield;
        _dragIconIds = dragIconIds;
        _itemInteraction = itemInteraction;
        _selection = selection ?? throw new ArgumentNullException(nameof(selection));
        _clickMap = clickMap;

        for (int i = 0; i < PaperdollSlotBackgrounds.Definitions.Length; i++)
        {
            var (element, mask, _, unlockBit) = PaperdollSlotBackgrounds.Definitions[i];
            if (layout.FindElement(element) is not UiItemList list) continue;
            list.RegisterDragHandler(this);
            list.Cell.SourceKind  = ItemDragSource.Equipment;
            list.Cell.SlotIndex   = i;              // definition position = equipped drag-payload SourceSlot
            list.Cell.EmptySprite = emptySlotSprites is not null
                && emptySlotSprites.TryGetValue(element, out uint authoredSprite)
                    ? authoredSprite
                    : emptySlotSprite;
            list.Cell.Clicked = () =>
            {
                uint itemId = list.Cell.ItemId;
                if (itemId != 0 && _itemInteraction?.OfferPrimaryClick(itemId)
                    is not null and not ItemPrimaryClickResult.NotActive)
                    return;
                if (itemId != 0)
                    _selection.Select(itemId, SelectionChangeSource.Paperdoll);
            };
            list.Cell.DoubleClicked = () =>
            {
                if (list.Cell.ItemId != 0)
                    _itemInteraction?.ActivateItem(list.Cell.ItemId);
            };
                                                     // 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));
            if (unlockBit != AetheriaUnlockState.None)
                _aetheriaSlots.Add((unlockBit, list));
        }

        _objects.ObjectAdded   += OnObjectChanged;
        _objects.ObjectMoved   += OnObjectMoved;
        _objects.ObjectRemoved += OnObjectChanged;
        _objects.ObjectUpdated += OnObjectChanged;
        _selection.Changed += OnSelectionChanged;

        // ── Slots-toggle wiring ───────────────────────────────────────────────────────────────────
        foreach (var id in ArmorSlotElementIds)
            if (layout.FindElement(id) is UiItemList armor) _armorSlots.Add(armor);

        _dollViewport = layout.FindElement(DollViewportId);   // doll viewport (may be null until Slice 3)
        // The authored map decides whether the pixel is a body hit and which worn
        // item is visually upper there. Target-use deliberately substitutes self.
        // The cursor remains pending over UI; retail resolves target cursors from
        // the SmartBox world object rather than the paperdoll viewport.
        Action<int, int> clickDoll = HandleDollClick;
        if (_dollViewport is UiViewport doll)
            doll.ClickedAt = clickDoll;

        // Retail's authored click/drag mask sits above the viewport and owns
        // doll hit-testing (gmPaperDollUI::ListenToElementMessage). Binding only
        // the viewport cannot win a live hit against this full-height overlay.
        switch (layout.FindElement(DollDragMaskId))
        {
            case UiButton dragMaskButton:
                _dollDragMask = dragMaskButton;
                dragMaskButton.OnClickAt = clickDoll;
                break;
            case UiDatElement dragMaskElement:
                _dollDragMask = dragMaskElement;
                dragMaskElement.ClickThrough = false;
                dragMaskElement.OnClickAt = clickDoll;
                break;
        }

        var slotsBtnEl = layout.FindElement(0x100005BEu);
        if (slotsBtnEl is UiButton slotsBtn)
        {
            slotsBtn.OnClick = () => { _viewState.Toggle(); ApplyView(); };
            // The dat element has no face sprite, so without a label the button is invisible. Give it a
            // left-aligned WHITE "Slots" caption (retail is white, not gold) so it's findable + clickable.
            if (datFont is not null)
            {
                slotsBtn.Label      = "Slots";
                slotsBtn.LabelFont  = datFont;
                slotsBtn.LabelColor = System.Numerics.Vector4.One;   // white (was gold)
                slotsBtn.LabelAlign = UiButton.LabelAlignment.Left;  // sit at the left, before the slots
            }
        }

        ApplyView();   // initial state = doll-view (armor slots hidden)

        Populate();
    }

    public static PaperdollController Bind(
        ImportedLayout layout, ClientObjectTable objects, Func<uint> playerGuid,
        Func<ItemType, uint, uint, uint, uint, uint> iconIds, SelectionState selection,
        Action<uint, uint>? sendWield = null,
        uint emptySlotSprite = 0u, UiDatFont? datFont = null,
        ItemInteractionController? itemInteraction = null,
        PaperdollClickMap? clickMap = null,
        Func<ItemType, uint, uint, uint, uint, uint>? dragIconIds = null,
        IReadOnlyDictionary<uint, uint>? emptySlotSprites = null)
        => new PaperdollController(
            layout, objects, playerGuid, iconIds, selection, sendWield, emptySlotSprite,
            datFont, itemInteraction, clickMap, dragIconIds, emptySlotSprites);

    private void HandleDollClick(int x, int y)
    {
        EquipMask bodyLocation = _clickMap?.GetBodyLocation(x, y) ?? EquipMask.None;
        uint hitObject = PaperdollSelectionPolicy.GetUpperInventoryObject(
            _objects,
            _playerGuid(),
            bodyLocation);
        if (hitObject == 0)
            return;

        // Retail targets self for any valid paperdoll body hit while target mode
        // is active; ordinary clicks select the upper worn object or player fallback.
        // gmPaperDollUI::ListenToElementMessage @ 0x004A5C30.
        if (_itemInteraction?.OfferSelfPrimaryClick()
            is not null and not ItemPrimaryClickResult.NotActive)
            return;

        _selection.Select(hitObject, SelectionChangeSource.Paperdoll);
    }

    private void OnObjectChanged(ClientObject o)
    {
        if (o.ObjectId == _playerGuid())
            ApplyAetheriaVisibility();
        else if (Concerns(o))
            Populate();
    }
    private void OnObjectMoved(ClientObject o, uint from, uint to)
    { if (Concerns(o) || from == _playerGuid() || to == _playerGuid()) Populate(); }
    private void OnSelectionChanged(SelectionTransition _) => ApplySelectionIndicators();

    /// <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);
            uint dragTex = _dragIconIds?.Invoke(
                worn.Type, worn.IconId, worn.IconUnderlayId, worn.IconOverlayId, worn.Effects) ?? 0u;
            list.Cell.SetItem(worn.ObjectId, tex, dragIconTexture: dragTex);
        }
        ApplyAetheriaVisibility();
        ApplySelectionIndicators();
    }

    /// <summary>
    /// Retail <c>gmPaperDollUI::UpdateAetheria @ 0x004A3E50</c>: property 0x142
    /// bits 1/2/4 independently expose the blue/yellow/red sigil lists. Missing
    /// player state is the locked state, matching PostInit before PlayerDescription.
    /// </summary>
    private void ApplyAetheriaVisibility()
    {
        AetheriaUnlockState unlocked = AetheriaUnlocks.Read(_objects.Get(_playerGuid()));
        foreach (var (bit, list) in _aetheriaSlots)
            list.Visible = (unlocked & bit) != AetheriaUnlockState.None;
    }

    private void ApplySelectionIndicators()
    {
        foreach (var (_, list) in _slots)
        {
            list.Cell.Selected = list.Cell.ItemId != 0
                && list.Cell.ItemId == _selection.SelectedObjectId;
        }
    }

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

    // ── IItemListDragHandler ──────────────────────────────────────────────────────────────────────
    /// <summary>Selects the wielded item before the waiting mesh appears. The item itself stays put
    /// until the server confirms, like the inventory grid and 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)
    {
        // UIElement_ItemList::ItemList_BeginDrag @ 0x004E32D0.
        if (payload.ObjId != 0 && _selection.SelectedObjectId != payload.ObjId)
            _selection.Select(payload.ObjId, SelectionChangeSource.Paperdoll);
    }

    /// <summary>Accept iff the dragged item can be worn here (its ValidLocations intersects the slot mask).
    /// Retail: gmPaperDollUI::OnItemListDragOver (decomp 174302).</summary>
    public ItemDragAcceptance OnDragOver(UiItemList targetList, UiItemSlot targetCell, ItemDragPayload payload)
    {
        // gmPaperDollUI::OnItemListDragOver @ 0x004A4270 ignores shortcut
        // aliases through its (DropItemFlags & 0xE) == 0 gate.
        if (payload.SourceKind == ItemDragSource.ShortcutBar)
            return ItemDragAcceptance.None;
        var item = _objects.Get(payload.ObjId);
        if (item is null)
            return ItemDragAcceptance.Reject;
        return (item.ValidLocations & MaskFor(targetList)) != EquipMask.None
            ? ItemDragAcceptance.Accept
            : ItemDragAcceptance.Reject;
    }

    /// <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)
    {
        // gmPaperDollUI::HandleDropRelease @ 0x004A4D80 applies the same flag
        // gate before accepting/wielding the physical object.
        if (payload.SourceKind == ItemDragSource.ShortcutBar)
            return;
        var item = _objects.Get(payload.ObjId);
        if (item is null) return;
        EquipMask wieldMask = ItemEquipRules.ResolvePaperdollDropWieldMask(item, 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>
    /// Pushes the current <see cref="PaperdollViewState"/> onto the live widgets:
    /// hides/shows the doll viewport and each armor slot according to the toggle.
    /// Called once at construction (doll-view default) and on every button click.
    /// </summary>
    private void ApplyView()
    {
        if (_dollViewport is not null) _dollViewport.Visible = _viewState.DollVisible;
        if (_dollDragMask is not null) _dollDragMask.Visible = _viewState.DollVisible;
        foreach (var a in _armorSlots) a.Visible = _viewState.ArmorSlotsVisible;
    }

    /// <summary>Detach event handlers (idempotent).</summary>
    public void Dispose()
    {
        if (_disposed) return;
        _disposed = true;
        _objects.ObjectAdded   -= OnObjectChanged;
        _objects.ObjectMoved   -= OnObjectMoved;
        _objects.ObjectRemoved -= OnObjectChanged;
        _objects.ObjectUpdated -= OnObjectChanged;
        _selection.Changed -= OnSelectionChanged;
        if (_dollViewport is UiViewport doll)
            doll.ClickedAt = null;
        switch (_dollDragMask)
        {
            case UiButton button:
                button.OnClickAt = null;
                break;
            case UiDatElement element:
                element.OnClickAt = null;
                break;
        }
    }
}