using System.Globalization;
using AcDream.App.Rendering;
using AcDream.Core.CharGen;
using AcDream.Runtime;
using AcDream.Runtime.Session;

namespace AcDream.App.UI.Layout;

/// <summary>
/// The Appearance page (<c>gmCGAppearancePage</c>, root <c>0x100003d4</c>) —
/// Campaign CC slice CC6b-MOUNT, the final piece of CC6. Decomp anchors:
/// <c>gmCGAppearancePage::InitializePage @ 0x0047FDD0</c> (widget ids, the
/// 180° initial heading), <c>::ListenToElementMessage @ 0x0047EF30</c> (EVERY
/// dispatch this page implements — gender buttons at cases <c>0x9d</c>/
/// <c>0x9e</c>; Face/Clothes sub-tabs at <c>0x9f</c>/<c>0xa0</c>; the nine
/// spin controls' decrement/increment arrow children, keyed by PARENT id, at
/// cases <c>0</c>/<c>1</c>; the same nine spins' own BODY click (select-as-
/// current-part, no index change) at cases <c>0xa5</c>-<c>0xa9</c> and the
/// mirrored headgear/shirt/trousers/footwear cases; the nine color swatches
/// at cases <c>5</c>-<c>0xd</c> -&gt; <c>SetColor(0..8)</c>; the shade
/// scrollbar at case <c>0x17</c> -&gt; <c>SetShade</c>; rotate at
/// <c>0x19</c>/<c>0x1a</c>; zoom at <c>0x1b</c>/<c>0x1c</c>),
/// <c>::SetColor @ 0x0047DD50</c> and <c>::SetShade @ 0x0047C860</c> (the
/// per-part color/shade routing table this page's <see cref="Part"/> switch
/// mirrors, including the NOSE/MOUTH/SKIN-all-route-to-skin-shade quirk and
/// EYES having no shade at all), <c>::Update @ 0x0047E8F0</c> (the heritage
/// 6/0xc/0xd Clothes-button + Nose/Mouth-spin hide, Eyes-arrows-disable
/// gate).
///
/// <para>
/// <b>Spin arrow geometry (live-DAT probe, CC6b-MOUNT):</b> every one of the
/// nine spin elements (<c>0x100003af-b3</c>, <c>b5-b8</c>) is uniformly
/// 200px wide with two LOCALLY-reused arrow child ids (<c>0x1000030a</c>
/// decrement at local x=[80,127), <c>0x1000030b</c> increment at
/// x=[127,174)) that <c>DatWidgetFactory</c>'s <c>UiButton</c> consumes into
/// one flat clickable leaf — there is no separate addressable arrow widget
/// to bind. This page reproduces retail's two-arrow-plus-body-click shape
/// entirely through <see cref="UiButton.OnClickAt"/>'s local x coordinate
/// (no new <c>DatWidgetFactory</c> widget type needed — see this campaign's
/// color-wheel scouting finding below, which reached the identical "existing
/// types suffice" conclusion for the whole page).
/// </para>
///
/// <para>
/// <b>Color-wheel family scouting (campaign plan risk item 4, RESOLVED):</b>
/// a live-DAT probe (<c>CharacterCreationLiveDatTests</c>) found every
/// color-wheel-family id resolves through EXISTING <c>DatWidgetFactory</c>
/// mappings: the nine swatch buttons (<c>0x1000030f-0x10000317</c>, retail's
/// <c>SetColor(0..8)</c> targets) author Type 1 -&gt; <c>UiButton</c>; their
/// nine Type-3 companion "selected" overlays (<c>0x10000318-0x10000320</c>,
/// retail's <c>m_tColorWheel[...][0x10][iCurColor*7]-&gt;SetVisible</c>
/// highlight ring) and the GradCircle (<c>0x1000030e</c>) author Type 3 -&gt;
/// <c>UiDatElement</c>; the shade scrollbar (<c>0x10000321</c>) authors
/// Type 0xB -&gt; <c>UiScrollbar</c>, matching the decomp's own
/// <c>DynamicCast(0xb)</c>. NO new widget type was added. This page uses the
/// swatch buttons' own <see cref="UiButton.Selected"/> state for the
/// highlight instead of toggling the separate companion overlay elements —
/// a documented substitution (same class as AD-103's swallowed-child
/// pattern), not a pixel-identical port of retail's own two-widget
/// mechanism.
/// </para>
///
/// <para>
/// <b>Icon-only style lists have no name string (register-worthy scope
/// cut):</b> CC1's <see cref="ChargenHairStyle"/>/<see cref="ChargenEyeStrip"/>/
/// <see cref="ChargenFaceStrip"/> carry an <c>IconId</c>, not a name — retail
/// shows an actual icon thumbnail in these four spins (hair/eyes/nose/
/// mouth). Icon rendering is out of this round's scope; the spin shows a
/// 1-based ordinal instead. The four clothing spins (headgear/shirt/
/// trousers/footwear) DO carry a real <see cref="ChargenGearOption.Name"/>
/// and show it directly.
/// </para>
/// </summary>
internal sealed class CharacterCreationAppearancePage : IDisposable
{
    private const uint Unset = RuntimeCharacterCreationAppearance.Unset;

    internal enum Part
    {
        Hair = 1,
        Eyes = 2,
        Nose = 3,
        Mouth = 4,
        Skin = 5,
        Headgear = 6,
        Shirt = 7,
        Trousers = 8,
        Footwear = 9,
    }

    private enum Choice
    {
        Face,
        Clothes,
    }

    internal const uint FemaleButtonId = 0x100003A7u;
    internal const uint MaleButtonId = 0x100003A8u;
    internal const uint FaceButtonId = 0x100003A9u;
    internal const uint ClothesButtonId = 0x100003AAu;
    internal const uint FaceChoicesId = 0x100003AEu;
    internal const uint ClothesChoicesId = 0x100003B4u;
    internal const uint HairSpinId = 0x100003AFu;
    internal const uint EyesSpinId = 0x100003B0u;
    internal const uint NoseSpinId = 0x100003B1u;
    internal const uint MouthSpinId = 0x100003B2u;
    internal const uint SkinSpinId = 0x100003B3u;
    internal const uint HeadgearSpinId = 0x100003B5u;
    internal const uint ShirtSpinId = 0x100003B6u;
    internal const uint TrousersSpinId = 0x100003B7u;
    internal const uint FootwearSpinId = 0x100003B8u;
    internal const uint RotateClockwiseId = 0x10000323u;
    internal const uint RotateCounterClockwiseId = 0x10000324u;
    internal const uint ZoomInId = 0x10000325u;
    internal const uint ZoomOutId = 0x10000326u;
    internal const uint GradCircleId = 0x1000030Eu;
    internal const uint ShadeScrollId = 0x10000321u;
    internal const uint ViewportId = 0x100003BBu;

    /// <summary>Retail's nine <c>SetColor(0..8)</c> swatch buttons, in
    /// index order — verbatim off <c>ListenToElementMessage</c>'s cases
    /// <c>5</c>-<c>0xd</c> (<c>elementId - 0x1000030a</c>).</summary>
    internal static readonly uint[] SwatchIds =
    [
        0x1000030Fu, 0x10000310u, 0x10000311u, 0x10000312u, 0x10000313u,
        0x10000314u, 0x10000315u, 0x10000316u, 0x10000317u,
    ];

    /// <summary>Live-DAT-measured arrow geometry, uniform across all nine
    /// spins (every one is 200px wide): decrement child at local
    /// x=[80,127), increment child at x=[127,174). Anything outside both
    /// zones is the spin's own BODY click (retail cases <c>0xa5</c>-<c>0xa9</c>
    /// and their headgear/shirt/trousers/footwear mirrors).</summary>
    private const float DecrementZoneStart = 80f;
    private const float IncrementZoneStart = 127f;
    private const float IncrementZoneEnd = 174f;

    private readonly CharacterCreationRuntimeBindings _bindings;
    private readonly UiButton? _femaleButton;
    private readonly UiButton? _maleButton;
    private readonly UiButton? _faceButton;
    private readonly UiButton? _clothesButton;
    private readonly UiElement? _faceChoices;
    private readonly UiElement? _clothesChoices;
    private readonly Dictionary<Part, UiButton> _spins = [];
    private readonly UiButton?[] _swatches = new UiButton?[SwatchIds.Length];
    private readonly UiScrollbar? _shadeScroll;
    private readonly UiButton? _rotateClockwise;
    private readonly UiButton? _rotateCounterClockwise;
    private readonly UiButton? _zoomIn;
    private readonly UiButton? _zoomOut;

    private Choice _currentChoice = Choice.Face;
    private Part _currentPart = Part.Hair;
    private bool _eyesArrowsDisabled;
    private bool _disposed;

    /// <summary>Late-bound preview control seam — see
    /// <see cref="IChargenPreviewControl"/>'s own doc comment for why this
    /// page cannot receive the real renderer at construction time.</summary>
    internal IChargenPreviewControl? PreviewControl { get; set; }

    /// <summary>The authored viewport (<c>0x100003bb</c>) — the composition
    /// root assigns its <c>Renderer</c> once the graphics backend exists,
    /// mirroring the paperdoll's own late <c>viewport.Renderer = ...</c>
    /// assignment.</summary>
    internal UiViewport? Viewport { get; }

    internal CharacterCreationAppearancePage(
        UiElement pageRoot,
        CharacterCreationRuntimeBindings bindings)
    {
        _bindings = bindings;

        _femaleButton = Find<UiButton>(pageRoot, FemaleButtonId);
        if (_femaleButton is not null)
            _femaleButton.OnClick = () => _bindings.SelectGender(2u);
        _maleButton = Find<UiButton>(pageRoot, MaleButtonId);
        if (_maleButton is not null)
            _maleButton.OnClick = () => _bindings.SelectGender(1u);

        _faceButton = Find<UiButton>(pageRoot, FaceButtonId);
        if (_faceButton is not null)
            _faceButton.OnClick = () => SelectChoice(Choice.Face);
        _clothesButton = Find<UiButton>(pageRoot, ClothesButtonId);
        if (_clothesButton is not null)
            _clothesButton.OnClick = () => SelectChoice(Choice.Clothes);

        _faceChoices = Find<UiElement>(pageRoot, FaceChoicesId);
        _clothesChoices = Find<UiElement>(pageRoot, ClothesChoicesId);

        BindSpin(pageRoot, HairSpinId, Part.Hair);
        BindSpin(pageRoot, EyesSpinId, Part.Eyes);
        BindSpin(pageRoot, NoseSpinId, Part.Nose);
        BindSpin(pageRoot, MouthSpinId, Part.Mouth);
        BindSpin(pageRoot, SkinSpinId, Part.Skin);
        BindSpin(pageRoot, HeadgearSpinId, Part.Headgear);
        BindSpin(pageRoot, ShirtSpinId, Part.Shirt);
        BindSpin(pageRoot, TrousersSpinId, Part.Trousers);
        BindSpin(pageRoot, FootwearSpinId, Part.Footwear);

        for (int i = 0; i < SwatchIds.Length; i++)
        {
            UiButton? swatch = Find<UiButton>(pageRoot, SwatchIds[i]);
            if (swatch is null)
                continue;
            int index = i;
            swatch.OnClick = () => SelectColor(index);
            _swatches[i] = swatch;
        }

        _shadeScroll = Find<UiScrollbar>(pageRoot, ShadeScrollId);
        if (_shadeScroll is not null)
            _shadeScroll.ScalarChanged = SetShadeFromScalar;

        Viewport = Find<UiViewport>(pageRoot, ViewportId);

        _rotateClockwise = Find<UiButton>(pageRoot, RotateClockwiseId);
        if (_rotateClockwise is not null)
            _rotateClockwise.OnClick = () => PreviewControl?.RotateClockwise();
        _rotateCounterClockwise = Find<UiButton>(pageRoot, RotateCounterClockwiseId);
        if (_rotateCounterClockwise is not null)
            _rotateCounterClockwise.OnClick = () => PreviewControl?.RotateCounterClockwise();
        _zoomIn = Find<UiButton>(pageRoot, ZoomInId);
        if (_zoomIn is not null)
            _zoomIn.OnClick = () => PreviewControl?.ZoomIn();
        _zoomOut = Find<UiButton>(pageRoot, ZoomOutId);
        if (_zoomOut is not null)
            _zoomOut.OnClick = () => PreviewControl?.ZoomOut();

        ApplyChoiceVisibility();
    }

    internal void Refresh(
        IRuntimeCharacterCreationView view,
        RuntimeCharacterCreationSnapshot snapshot)
    {
        if (_disposed)
            return;

        if (_femaleButton is not null)
            _femaleButton.Selected = snapshot.GenderKey == 2u;
        if (_maleButton is not null)
            _maleButton.Selected = snapshot.GenderKey == 1u;

        // gmCGAppearancePage::Update @ ~0x0047EB46-0x0047EE95: heritage
        // 6 (Gearknight) / 0xc (Olthoi) / 0xd (OlthoiAcid) hide the Clothes
        // sub-tab (and, with it, every clothing spin behind it), hide the
        // Nose/Mouth spins directly, and disable the Eyes spin's arrows —
        // none of these three heritages have separate clothing, nose, or
        // mouth strip choices.
        bool clothesHidden = IsClothesHiddenHeritage(snapshot.HeritageId);
        if (_clothesButton is not null)
            _clothesButton.Visible = !clothesHidden;
        if (_spins.TryGetValue(Part.Nose, out UiButton? noseSpin))
            noseSpin.Visible = !clothesHidden;
        if (_spins.TryGetValue(Part.Mouth, out UiButton? mouthSpin))
            mouthSpin.Visible = !clothesHidden;
        _eyesArrowsDisabled = clothesHidden;
        if (clothesHidden && _currentChoice == Choice.Clothes)
        {
            // Update forces SetChoice(ECG_CHOICE_FACE) when Clothes becomes
            // unreachable so the page never gets stuck showing a hidden tab.
            _currentChoice = Choice.Face;
            _currentPart = Part.Hair;
        }
        ApplyChoiceVisibility();

        if (TryGetGender(view, snapshot, out ChargenGenderOptions? gender))
            RefreshSpins(gender, snapshot.Appearance);

        RefreshColorAndShadeControls(view, snapshot);
        RebuildPreview(view, snapshot);
    }

    // ── Gender / Face-Clothes sub-tab ──────────────────────────────────

    private void SelectChoice(Choice choice)
    {
        if (_disposed)
            return;
        _currentChoice = choice;
        // gmCGAppearancePage::ListenToElementMessage cases 0x9f/0xa0:
        // Face -> SetSelection(ECG_PARTS_HAIR); Clothes ->
        // SetSelection(ECG_PARTS_HEADGEAR).
        _currentPart = choice == Choice.Face ? Part.Hair : Part.Headgear;
        ApplyChoiceVisibility();
        RefreshColorAndShadeControlsFromLatestSnapshot();
    }

    private void ApplyChoiceVisibility()
    {
        if (_faceChoices is not null)
            _faceChoices.Visible = _currentChoice == Choice.Face;
        if (_clothesChoices is not null)
            _clothesChoices.Visible = _currentChoice == Choice.Clothes;
        if (_faceButton is not null)
            _faceButton.Selected = _currentChoice == Choice.Face;
        if (_clothesButton is not null)
            _clothesButton.Selected = _currentChoice == Choice.Clothes;
    }

    // ── Spins (style cycling + select-as-current-part) ─────────────────

    private void BindSpin(UiElement pageRoot, uint id, Part part)
    {
        UiButton? spin = Find<UiButton>(pageRoot, id);
        if (spin is null)
            return;
        _spins[part] = spin;

        if (part == Part.Skin)
        {
            // Skin has no style index at all — retail disables its arrow
            // children outright (SetAttribute_Bool(...,0xd,1) in
            // InitializePage/Update's heritage branches). Every click just
            // selects Skin as the current part for the color/shade controls.
            spin.OnClickAt = (_, _) => SelectPart(Part.Skin);
            return;
        }

        spin.OnClickAt = (x, _) =>
        {
            if (x >= DecrementZoneStart && x < IncrementZoneStart)
                CycleStyle(part, -1);
            else if (x >= IncrementZoneStart && x < IncrementZoneEnd)
                CycleStyle(part, +1);
            else
                SelectPart(part);
        };
    }

    private void SelectPart(Part part)
    {
        if (_disposed)
            return;
        _currentPart = part;
        RefreshColorAndShadeControlsFromLatestSnapshot();
    }

    private void CycleStyle(Part part, int delta)
    {
        if (_disposed)
            return;
        if (part == Part.Eyes && _eyesArrowsDisabled)
        {
            SelectPart(part);
            return;
        }

        IRuntimeCharacterCreationView? view = _bindings.View();
        if (view is null)
            return;
        RuntimeCharacterCreationSnapshot snapshot = view.Snapshot;
        if (!TryGetGender(view, snapshot, out ChargenGenderOptions? gender))
            return;

        ChargenAppearanceSlot? slot = StyleSlotFor(part);
        if (slot is null)
        {
            SelectPart(part);
            return;
        }

        int count = StyleCount(part, gender);
        uint current = StyleCurrent(part, snapshot.Appearance);
        // Headgear alone allows the Unset ("no headgear") ring position —
        // CharGenState::SetHeadgearStyle's decomp-derived (count+1)-position
        // ring (0..count-1, Unset); every other style spin cycles [0,count).
        uint next = CycleIndex(current, delta, count, allowUnset: part == Part.Headgear);
        _bindings.SetAppearanceIndex?.Invoke(slot.Value, next);
        SelectPart(part);
    }

    /// <summary>
    /// Retail's decomp-derived wrap: <paramref name="allowUnset"/> reproduces
    /// <c>CharGenState::SetHeadgearStyle</c>'s literal signed-int32 ring of
    /// <paramref name="count"/>+1 positions (every real index, plus
    /// <see cref="Unset"/> — decrementing from index 0 lands on Unset,
    /// incrementing from Unset lands on index 0, matching
    /// <c>ListenToElementMessage</c>'s cases <c>6</c> exactly). Every other
    /// style spin has no decomp-observable Unset-cycling case (retail always
    /// has a real 0-based index by the time the user can click — see
    /// AP-214's <c>RandomizeCharacter</c>-at-open finding, which acdream
    /// does not port this round) — an Unset start there is an edge case
    /// retail itself never reaches, so the first click either direction just
    /// starts cycling from index 0 rather than reconstructing an unfounded
    /// wrap direction.
    /// </summary>
    internal static uint CycleIndex(uint current, int delta, int count, bool allowUnset)
    {
        if (count <= 0)
            return Unset;

        if (allowUnset)
        {
            int cur = current == Unset ? count : (int)current;
            int size = count + 1;
            int next = Mod(cur + delta, size);
            return next == count ? Unset : (uint)next;
        }

        if (current == Unset)
            return 0u;
        return (uint)Mod((int)current + delta, count);
    }

    private static int Mod(int value, int modulus) =>
        ((value % modulus) + modulus) % modulus;

    // ── Color swatches + shade scroll ───────────────────────────────────

    private void SelectColor(int index)
    {
        if (_disposed)
            return;
        IRuntimeCharacterCreationView? view = _bindings.View();
        if (view is null)
            return;
        RuntimeCharacterCreationSnapshot snapshot = view.Snapshot;
        if (!TryGetGender(view, snapshot, out ChargenGenderOptions? gender))
            return;
        ChargenAppearanceSlot? slot = ColorSlotFor(_currentPart);
        if (slot is null)
            return;

        // gmCGAppearancePage::ListenToElementMessage's swatch cases each
        // gate on the current part's own color-list length before calling
        // SetColor — a swatch beyond the list clicks through to nothing.
        int count = ColorCount(_currentPart, gender);
        if (index >= count)
            return;

        _bindings.SetAppearanceIndex?.Invoke(slot.Value, (uint)index);
    }

    private void SetShadeFromScalar(float scalar)
    {
        if (_disposed)
            return;
        ChargenShadeSlot? slot = ShadeSlotFor(_currentPart);
        if (slot is null)
            return;
        _bindings.SetShade?.Invoke(slot.Value, scalar);
    }

    private void RefreshColorAndShadeControlsFromLatestSnapshot()
    {
        IRuntimeCharacterCreationView? view = _bindings.View();
        if (view is not null)
            RefreshColorAndShadeControls(view, view.Snapshot);
    }

    private void RefreshColorAndShadeControls(
        IRuntimeCharacterCreationView view,
        RuntimeCharacterCreationSnapshot snapshot)
    {
        ChargenAppearanceSlot? colorSlot = ColorSlotFor(_currentPart);
        uint currentColor = colorSlot is null ? Unset : ColorCurrent(_currentPart, snapshot.Appearance);
        for (int i = 0; i < _swatches.Length; i++)
        {
            if (_swatches[i] is { } swatch)
                swatch.Selected = colorSlot is not null && currentColor == (uint)i;
        }

        ChargenShadeSlot? shadeSlot = ShadeSlotFor(_currentPart);
        if (_shadeScroll is null)
            return;
        _shadeScroll.Enabled = shadeSlot is not null;
        if (shadeSlot is { } slot)
        {
            double shade = ShadeCurrent(slot, snapshot.Appearance);
            float scalar = shade < 0.0 ? 0f : (float)Math.Clamp(shade, 0.0, 1.0);
            _shadeScroll.SetScalarPosition(scalar);
        }
    }

    // ── Spin labels ──────────────────────────────────────────────────

    private void RefreshSpins(ChargenGenderOptions gender, RuntimeCharacterCreationAppearance a)
    {
        SetStyleSpinLabel(Part.Hair, gender.HairStyles.Count, a.HairStyle);
        SetStyleSpinLabel(Part.Eyes, gender.EyeStrips.Count, a.EyesStrip);
        SetStyleSpinLabel(Part.Nose, gender.NoseStrips.Count, a.NoseStrip);
        SetStyleSpinLabel(Part.Mouth, gender.MouthStrips.Count, a.MouthStrip);
        SetGearSpinLabel(Part.Headgear, gender.Headgears, a.HeadgearStyle);
        SetGearSpinLabel(Part.Shirt, gender.Shirts, a.ShirtStyle);
        SetGearSpinLabel(Part.Trousers, gender.Pants, a.TrousersStyle);
        SetGearSpinLabel(Part.Footwear, gender.Footwear, a.FootwearStyle);
    }

    private void SetStyleSpinLabel(Part part, int count, uint index)
    {
        if (!_spins.TryGetValue(part, out UiButton? spin))
            return;
        spin.Label = index != Unset && index < (uint)count
            ? (index + 1).ToString(CultureInfo.InvariantCulture)
            : "-";
    }

    private void SetGearSpinLabel(Part part, IReadOnlyList<ChargenGearOption> options, uint index)
    {
        if (!_spins.TryGetValue(part, out UiButton? spin))
            return;
        spin.Label = index != Unset && index < (uint)options.Count
            ? options[(int)index].Name
            : "None";
    }

    // ── Preview rebuild ──────────────────────────────────────────────

    private void RebuildPreview(
        IRuntimeCharacterCreationView view,
        RuntimeCharacterCreationSnapshot snapshot)
    {
        if (PreviewControl is null
            || snapshot.HeritageId == 0u
            || snapshot.GenderKey == 0u)
        {
            return;
        }

        RuntimeCharacterCreationAppearance a = snapshot.Appearance;
        var selection = new ChargenAppearanceSelection(
            a.EyesStrip, a.NoseStrip, a.MouthStrip,
            a.HairStyle, a.HairColor, a.EyeColor,
            a.HeadgearStyle, a.HeadgearColor,
            a.ShirtStyle, a.ShirtColor,
            a.TrousersStyle, a.TrousersColor,
            a.FootwearStyle, a.FootwearColor,
            a.SkinShade, a.HairShade, a.HeadgearShade,
            a.ShirtShade, a.TrousersShade, a.FootwearShade);

        PreviewControl.Rebuild(view.Options, snapshot.HeritageId, (int)snapshot.GenderKey, selection);
    }

    // ── Per-part routing tables (retail SetColor @0x0047DD50 / SetShade @0x0047C860) ──

    private static ChargenAppearanceSlot? StyleSlotFor(Part part) => part switch
    {
        Part.Hair => ChargenAppearanceSlot.HairStyle,
        Part.Eyes => ChargenAppearanceSlot.EyesStrip,
        Part.Nose => ChargenAppearanceSlot.NoseStrip,
        Part.Mouth => ChargenAppearanceSlot.MouthStrip,
        Part.Headgear => ChargenAppearanceSlot.HeadgearStyle,
        Part.Shirt => ChargenAppearanceSlot.ShirtStyle,
        Part.Trousers => ChargenAppearanceSlot.TrousersStyle,
        Part.Footwear => ChargenAppearanceSlot.FootwearStyle,
        _ => null, // Skin.
    };

    /// <summary>Retail's SIX colorable parts (<c>SetColor</c>'s cases
    /// <c>0,1,5,6,7,8</c>) — Nose/Mouth/Skin have no color list at all.</summary>
    private static ChargenAppearanceSlot? ColorSlotFor(Part part) => part switch
    {
        Part.Hair => ChargenAppearanceSlot.HairColor,
        Part.Eyes => ChargenAppearanceSlot.EyeColor,
        Part.Headgear => ChargenAppearanceSlot.HeadgearColor,
        Part.Shirt => ChargenAppearanceSlot.ShirtColor,
        Part.Trousers => ChargenAppearanceSlot.TrousersColor,
        Part.Footwear => ChargenAppearanceSlot.FootwearColor,
        _ => null,
    };

    /// <summary>Retail's <c>SetShade</c> switch: Hair has its own shade;
    /// Nose/Mouth/Skin ALL route to skin shade (cases 2/3/4 share one body
    /// in the decompiled switch — a genuine retail quirk, not a porting
    /// shortcut); Eyes has NO case at all (eye color has no shade
    /// indirection anywhere in this campaign's model).</summary>
    private static ChargenShadeSlot? ShadeSlotFor(Part part) => part switch
    {
        Part.Hair => ChargenShadeSlot.Hair,
        Part.Nose => ChargenShadeSlot.Skin,
        Part.Mouth => ChargenShadeSlot.Skin,
        Part.Skin => ChargenShadeSlot.Skin,
        Part.Headgear => ChargenShadeSlot.Headgear,
        Part.Shirt => ChargenShadeSlot.Shirt,
        Part.Trousers => ChargenShadeSlot.Trousers,
        Part.Footwear => ChargenShadeSlot.Footwear,
        _ => null, // Eyes.
    };

    private static int StyleCount(Part part, ChargenGenderOptions gender) => part switch
    {
        Part.Hair => gender.HairStyles.Count,
        Part.Eyes => gender.EyeStrips.Count,
        Part.Nose => gender.NoseStrips.Count,
        Part.Mouth => gender.MouthStrips.Count,
        Part.Headgear => gender.Headgears.Count,
        Part.Shirt => gender.Shirts.Count,
        Part.Trousers => gender.Pants.Count,
        Part.Footwear => gender.Footwear.Count,
        _ => 0,
    };

    /// <summary>Hair/Eyes have their own real per-gender color lists;
    /// the four clothing slots share the gender's single
    /// <see cref="ChargenGenderOptions.ClothingColors"/> list (register
    /// AP-208).</summary>
    private static int ColorCount(Part part, ChargenGenderOptions gender) => part switch
    {
        Part.Hair => gender.HairColors.Count,
        Part.Eyes => gender.EyeColors.Count,
        Part.Headgear or Part.Shirt or Part.Trousers or Part.Footwear =>
            gender.ClothingColors.Count,
        _ => 0,
    };

    private static uint StyleCurrent(Part part, RuntimeCharacterCreationAppearance a) => part switch
    {
        Part.Hair => a.HairStyle,
        Part.Eyes => a.EyesStrip,
        Part.Nose => a.NoseStrip,
        Part.Mouth => a.MouthStrip,
        Part.Headgear => a.HeadgearStyle,
        Part.Shirt => a.ShirtStyle,
        Part.Trousers => a.TrousersStyle,
        Part.Footwear => a.FootwearStyle,
        _ => Unset,
    };

    private static uint ColorCurrent(Part part, RuntimeCharacterCreationAppearance a) => part switch
    {
        Part.Hair => a.HairColor,
        Part.Eyes => a.EyeColor,
        Part.Headgear => a.HeadgearColor,
        Part.Shirt => a.ShirtColor,
        Part.Trousers => a.TrousersColor,
        Part.Footwear => a.FootwearColor,
        _ => Unset,
    };

    private static double ShadeCurrent(ChargenShadeSlot slot, RuntimeCharacterCreationAppearance a) => slot switch
    {
        ChargenShadeSlot.Skin => a.SkinShade,
        ChargenShadeSlot.Hair => a.HairShade,
        ChargenShadeSlot.Headgear => a.HeadgearShade,
        ChargenShadeSlot.Shirt => a.ShirtShade,
        ChargenShadeSlot.Trousers => a.TrousersShade,
        ChargenShadeSlot.Footwear => a.FootwearShade,
        _ => 0.0,
    };

    private static bool IsClothesHiddenHeritage(uint heritageId) =>
        heritageId == (uint)ChargenHeritageGroup.Gearknight
        || heritageId == (uint)ChargenHeritageGroup.Olthoi
        || heritageId == (uint)ChargenHeritageGroup.OlthoiAcid;

    private static bool TryGetGender(
        IRuntimeCharacterCreationView view,
        RuntimeCharacterCreationSnapshot snapshot,
        [System.Diagnostics.CodeAnalysis.NotNullWhen(true)] out ChargenGenderOptions? gender)
    {
        gender = null;
        if (snapshot.HeritageId == 0u || snapshot.GenderKey == 0u)
            return false;
        if (!view.Options.TryGetHeritage(snapshot.HeritageId, out ChargenHeritageOptions? heritage))
            return false;
        return heritage.GendersByKey.TryGetValue((int)snapshot.GenderKey, out gender);
    }

    private static T? Find<T>(UiElement root, uint id) where T : UiElement =>
        UiElement.FindDescendant(root, id) as T;

    public void Dispose()
    {
        if (_disposed)
            return;
        _disposed = true;
        if (_femaleButton is not null) _femaleButton.OnClick = null;
        if (_maleButton is not null) _maleButton.OnClick = null;
        if (_faceButton is not null) _faceButton.OnClick = null;
        if (_clothesButton is not null) _clothesButton.OnClick = null;
        foreach (UiButton spin in _spins.Values)
            spin.OnClickAt = null;
        _spins.Clear();
        foreach (UiButton? swatch in _swatches)
        {
            if (swatch is not null)
                swatch.OnClick = null;
        }
        if (_shadeScroll is not null)
            _shadeScroll.ScalarChanged = null;
        if (_rotateClockwise is not null) _rotateClockwise.OnClick = null;
        if (_rotateCounterClockwise is not null) _rotateCounterClockwise.OnClick = null;
        if (_zoomIn is not null) _zoomIn.OnClick = null;
        if (_zoomOut is not null) _zoomOut.OnClick = null;
        // PreviewControl is owned by the composition root (disposed with
        // the leased ChargenPreviewRenderer) — just drop the reference.
        PreviewControl = null;
    }
}