using System;
using System.Collections.Generic;
using System.Numerics;
using AcDream.App.UI.Layout;

namespace AcDream.App.UI;

/// <summary>
/// Retail <c>UIOption_CheckboxBitfield64</c> (Type <c>0x10000044</c>) — a block of
/// individually toggleable mask checkboxes (the Chat tab's per-window text-filter
/// block).
///
/// <para>
/// <b>OP2 rework (2026-08-11 — `docs/research/2026-08-11-op2-review-mechanism.md`
/// MUST-FIX 3/4):</b> the OP2 slice's class doc claimed the authored template
/// (<c>0x10000520</c> in <c>0x2100002B</c>) "carries NO children and NO media" and
/// synthesized a fake per-row <see cref="ElementInfo"/> (<c>Type=1</c>, invented
/// <c>RowHeight=14</c>) for every added row. Both claims were refuted by the committed
/// fixture: <c>0x10000520</c> authors its OWN row-template list (dat property
/// <c>0x64</c> → <c>{0x2100002B, 0x10000521}</c>), and retail
/// <c>UIOption_CheckboxBitfield64::CreateChildren @0x00485DF0</c> builds every row by
/// calling <c>UIElement_ListBox::AddItemFromTemplateList(this, 0, nullptr)</c> in a
/// loop — i.e. <c>UIOption_CheckboxBitfield64</c> genuinely IS a
/// <c>UIElement_ListBox</c>: it calls the ListBox mechanism on itself
/// (<c>AddItemFromTemplateList</c>/<c>GetItem</c>/<c>CalculatePaperSize</c>/
/// <c>ListenToElementMessage</c>). The template <c>0x10000521</c> is a 272×20 container
/// holding checkbox <c>0x10000219</c> (260×14, Type 1) which itself holds the 13×13
/// five-state LED child <c>0x10000328</c> — every row's art/font/insets now come from
/// that authored subtree via <see cref="TemplateResolver"/>, the SAME seam
/// <see cref="UiTemplateListBox"/> exposes (this class does not wrap a
/// <see cref="UiTemplateListBox"/> instance because retail's block does not itself
/// scroll — the ENCLOSING Chat page ListBox scrolls the whole option list, and this
/// block is one composite row within it — but it reuses the identical
/// resolve-and-stack row-instantiation shape).
/// </para>
/// </summary>
public sealed class UiCheckboxBitfield64 : UiPanel
{
    /// <summary>
    /// Retail element id of the checkbox inside the authored row template
    /// (<c>0x10000521</c>'s sole child). Hardcoded in retail's own C++
    /// (<c>GetChildRecursive(row, 0x10000219)</c> inside <c>CreateChildren</c>), not
    /// something generically derivable from the template — ports that literal constant.
    /// </summary>
    public const uint TemplateCheckboxElementId = 0x10000219u;

    /// <summary>One added checkbox row.</summary>
    public readonly record struct Row(
        ulong LowMask, ulong HighMask, string Label, string? Tooltip,
        UiElement RowRoot, UiButton Toggle);

    private readonly List<Row> _rows = new();
    private float _contentHeight;

    /// <summary>The rows added so far, in <see cref="AddChild(ulong, ulong, string, string?)"/> call order.</summary>
    public IReadOnlyList<Row> Rows => _rows;

    /// <summary>Current low 64 bits of the option's bitfield value.</summary>
    public ulong CurrentLow { get; private set; }

    /// <summary>Current high 64 bits of the option's bitfield value.</summary>
    public ulong CurrentHigh { get; private set; }

    private ulong _defaultLow, _defaultHigh;

    /// <summary>
    /// The authored row template (dat property 0x64 on THIS element). Retail authors
    /// exactly one entry, <c>{0x2100002B, 0x10000521}</c>, and reuses it for every row
    /// (<c>AddItemFromTemplateList(this, 0, nullptr)</c> called once per row).
    /// </summary>
    public IReadOnlyList<UiTemplateListEntry> Templates { get; }

    /// <summary>
    /// AP-195 (Campaign OP slice OP5): block-level "all mask bits set" LED media
    /// (dat property <c>0x10000082</c> on THIS element, <c>0x06004D17</c> on the
    /// installed DAT). 0 when the authoring template carries none — the LED override
    /// is then simply never applied (rows keep their per-row authored art).
    /// </summary>
    public uint CheckedLedSprite { get; }

    /// <summary>AP-195 counterpart of <see cref="CheckedLedSprite"/>: block-level
    /// "checked but not every mask bit set" LED media (dat property
    /// <c>0x10000083</c>, <c>0x06004D19</c>).</summary>
    public uint UncheckedLedSprite { get; }

    /// <summary>Same seam as <see cref="UiTemplateListBox.TemplateResolver"/> — a page
    /// controller wires this with real DAT access (Campaign OP slice OP5+). Left null
    /// by <c>DatWidgetFactory</c> itself.</summary>
    public Func<uint, uint, UiElement?>? TemplateResolver { get; set; }

    /// <summary>Dat font for row labels — kept for callers that built rows before this
    /// rework shipped; unused now that labels are set directly on the resolved
    /// template's own checkbox widget, whose font already comes from the authored
    /// template.</summary>
    public UiDatFont? LabelFont { get; set; }

    // SpriteResolve (forwarded to each row's built subtree) is inherited from UiPanel —
    // same resolver shape, no need to redeclare it.

    /// <summary>Fired with the new (low, high) value after any row toggles — a LIVE
    /// user edit only (retail's <c>Apply(1)</c> path). NEVER fired by
    /// <see cref="SetCurrentValue"/> (the OnShown/Reset/Defaults re-seed path — pushing
    /// an externally-sourced value must not loop back into "the user changed this").
    /// </summary>
    public Action<ulong, ulong>? ValueChanged { get; set; }

    public UiCheckboxBitfield64(
        IReadOnlyList<UiTemplateListEntry> templates,
        uint checkedLedSprite = 0u,
        uint uncheckedLedSprite = 0u)
    {
        Templates = templates;
        CheckedLedSprite = checkedLedSprite;
        UncheckedLedSprite = uncheckedLedSprite;
        BackgroundColor = Vector4.Zero;
        BorderColor = Vector4.Zero;
    }

    /// <summary>
    /// Retail <c>UIOption::SetDefaultValue(low, high)</c>: sets the restore-to-defaults
    /// target. Also seeds the current value while no rows exist yet (construction
    /// order mirrors retail: <c>SetDefaultValue</c> then N <c>AddChild</c> calls, so
    /// each row's initial checked state reads the seeded default).
    /// </summary>
    public void SetDefaultValue(ulong low, ulong high)
    {
        _defaultLow = low;
        _defaultHigh = high;
        if (_rows.Count == 0)
        {
            CurrentLow = low;
            CurrentHigh = high;
        }
    }

    /// <summary>Reverts to the last <see cref="SetDefaultValue"/> target and refreshes
    /// every row's checked state — the Defaults-button verb (research doc §3.3).</summary>
    public void RestoreDefaultValue()
    {
        CurrentLow = _defaultLow;
        CurrentHigh = _defaultHigh;
        RefreshRowVisuals();
        ValueChanged?.Invoke(CurrentLow, CurrentHigh);
    }

    /// <summary>
    /// Pushes an externally-sourced (low, high) value onto the widget — the page-model
    /// re-seed path (retail's <c>Refresh</c> re-run after
    /// <c>OptionPage::RestoreSavedValues</c>/<c>RestoreDefaultValues</c>/the OnShown
    /// <c>SaveCurrentValue</c> re-read). Updates <see cref="CurrentLow"/>/
    /// <see cref="CurrentHigh"/> and every row's checked state + AP-195 LED media, but
    /// deliberately does NOT invoke <see cref="ValueChanged"/> — the caller (an
    /// <c>IOptionRow</c> wrapper) already owns whatever notification it needs, and
    /// firing here would loop a re-seed back into "the user changed this" (the same
    /// live/refresh distinction <c>BoolOptionRow</c>'s <c>refresh</c> delegate makes).
    /// </summary>
    public void SetCurrentValue(ulong low, ulong high)
    {
        CurrentLow = low;
        CurrentHigh = high;
        RefreshRowVisuals();
    }

    /// <summary>
    /// Retail <c>UIOption_CheckboxBitfield64::AddChild(lowMask, highMask, labelId,
    /// tooltipId)</c> → <c>CreateChildren</c>'s per-row loop: instantiates the authored
    /// row template (<see cref="Templates"/>[0], the only entry) through
    /// <see cref="TemplateResolver"/>, locates its embedded checkbox
    /// (<see cref="TemplateCheckboxElementId"/>) via retail's own
    /// <c>GetChildRecursive</c>, and stamps this row's label/click/checked-state onto
    /// it. <paramref name="label"/>/<paramref name="tooltip"/> are already-resolved
    /// strings — string-table lookup is the caller's job (matches
    /// <see cref="UiMenu.MenuItem"/>'s own already-resolved-Label convention).
    /// </summary>
    /// <returns>The row's checkbox widget, or null (loud-logged) when no template is
    /// authored, no resolver is wired, the resolver produced nothing, or the resolved
    /// subtree does not contain <see cref="TemplateCheckboxElementId"/> — any of which
    /// means retail's authored shape is missing or the resolver seam is unwired, not
    /// something this widget should silently paper over.</returns>
    public UiButton? AddChild(ulong lowMask, ulong highMask, string label, string? tooltip = null)
    {
        if (Templates.Count == 0)
        {
            Console.WriteLine("[D.2b] UiCheckboxBitfield64.AddChild: no authored row template (property 0x64 empty) — cannot build a row.");
            return null;
        }
        Func<uint, uint, UiElement?>? resolver = TemplateResolver;
        if (resolver is null)
        {
            Console.WriteLine("[D.2b] UiCheckboxBitfield64.AddChild: TemplateResolver not wired yet — cannot build a row.");
            return null;
        }

        UiTemplateListEntry entry = Templates[0]; // retail always reuses template index 0
        UiElement? row = resolver(entry.TemplateLayoutId, entry.TemplateElementId);
        if (row is null)
        {
            Console.WriteLine($"[D.2b] UiCheckboxBitfield64.AddChild: resolver returned null for template 0x{entry.TemplateLayoutId:X8}/0x{entry.TemplateElementId:X8}.");
            return null;
        }

        UiButton? checkbox = FindCheckboxRecursive(row);
        if (checkbox is null)
        {
            Console.WriteLine($"[D.2b] UiCheckboxBitfield64.AddChild: resolved row template did not contain checkbox 0x{TemplateCheckboxElementId:X8} — row will not respond to clicks.");
            return null;
        }

        checkbox.Label = label;
        // Retail CreateChildren @0x00485DF0 stamps the row tooltip via
        // SetTooltip (OP2 re-review §2.2). Its @0x00485E3E companion — the
        // SetAttribute_Int(cb, 0x10000084, i) row-INDEX stamp retail later
        // reads back to find which row a click meant — is deliberately
        // replaced by the typed mask closure below: equivalent routing,
        // without a stringly attribute round-trip.
        checkbox.TooltipText = tooltip;
        checkbox.OnClick = () => ToggleRow(lowMask, highMask, checkbox);

        row.Left = 0f;
        row.Top = _contentHeight;
        _contentHeight += row.Height;
        base.AddChild(row);

        // AP-195 self-sizing tail: retail's own CreateChildren ends with
        // ResizeTo(GetWidth(), CalculatePaperSize(0, -1)) because
        // UIOption_CheckboxBitfield64 IS a UIElement_ListBox (its PostInit
        // tail-calls UIElement_Scrollable::PostInit) — the block grows to fit its
        // rows instead of keeping its authored 272x100 extent. Width is untouched
        // (GetWidth() — the ListBox's own authored column width); only Height
        // grows, exactly matching the stacked _contentHeight this class already
        // tracks per row. A dedicated ListBox-unification pass (reusing
        // UiTemplateListBox's own viewport) remains future work per AP-195's own
        // disposition menu; this direct resize is the recorded-rationale half of
        // that menu — see UiTemplateListBox.AddPrebuiltRow for how a page
        // controller reflows the ENCLOSING ListBox around this widget's now-final
        // height instead of the pre-build authored one.
        Height = _contentHeight;

        var newRow = new Row(lowMask, highMask, label, tooltip, row, checkbox);
        _rows.Add(newRow);
        ApplyRowVisuals(newRow);
        return checkbox;
    }

    private static UiButton? FindCheckboxRecursive(UiElement node)
    {
        if (node.DatElementId == TemplateCheckboxElementId && node is UiButton button)
            return button;
        foreach (UiElement child in node.Children)
        {
            UiButton? found = FindCheckboxRecursive(child);
            if (found is not null) return found;
        }
        return null;
    }

    /// <summary>
    /// Retail <c>UIOption_CheckboxBitfield64::Refresh @0x004859C0</c>'s ANY-set half:
    /// a row is checked when ANY bit of its mask is set in the current value — NOT
    /// when every bit is set. <c>lowHit = current.low &amp; mask.low; highHit =
    /// current.high &amp; mask.high; checked = (lowHit | highHit) != 0</c>.
    /// </summary>
    private bool IsAnySet(ulong lowMask, ulong highMask)
        => (CurrentLow & lowMask) != 0 || (CurrentHigh & highMask) != 0;

    /// <summary>
    /// AP-195: retail <c>Refresh</c>'s ALL-set half, computed by the SAME pass as
    /// <see cref="IsAnySet"/> — <c>(current.low &amp; mask.low) == mask.low &amp;&amp;
    /// (current.high &amp; mask.high) == mask.high</c>. Drives which of
    /// <see cref="CheckedLedSprite"/>/<see cref="UncheckedLedSprite"/> a checked row's
    /// LED shows: composite masks (e.g. the Gameplay row's <c>0x83912021</c>, five
    /// bits) can be PARTIALLY satisfied — checked (any-set) but not fully (all-set) —
    /// which single-bit rows (e.g. "General") can never observably distinguish.
    /// </summary>
    private bool IsAllSet(ulong lowMask, ulong highMask)
        => (CurrentLow & lowMask) == lowMask && (CurrentHigh & highMask) == highMask;

    /// <summary>
    /// Retail <c>UIOption_CheckboxBitfield64::ListenToElementMessage @0x00485AE0</c>:
    /// <c>BitUtils::SetBitsOnOrOff(&amp;m_current, mask, onOff)</c> — decomp-confirmed
    /// OR-in-on / AND-NOT-off (TS-72's toggle-math half was always correct; only the
    /// checked-state predicate above needed fixing).
    /// </summary>
    private void ToggleRow(ulong lowMask, ulong highMask, UiButton toggle)
    {
        bool turnOn = !IsAnySet(lowMask, highMask);
        if (turnOn)
        {
            CurrentLow |= lowMask;
            CurrentHigh |= highMask;
        }
        else
        {
            CurrentLow &= ~lowMask;
            CurrentHigh &= ~highMask;
        }
        ApplyRowVisualsForMask(lowMask, highMask, toggle);
        ValueChanged?.Invoke(CurrentLow, CurrentHigh);
    }

    private void RefreshRowVisuals()
    {
        foreach (Row row in _rows)
            ApplyRowVisuals(row);
    }

    private void ApplyRowVisuals(Row row) => ApplyRowVisualsForMask(row.LowMask, row.HighMask, row.Toggle);

    /// <summary>
    /// One row's complete <c>Refresh</c> visual: the ANY-set checked bool
    /// (<see cref="UiButton.Selected"/>, always) plus AP-195's ALL-set-driven LED
    /// media swap (<see cref="UiButton.FaceFileOverride"/>) — retail's own gate: the
    /// swap ONLY applies while ANY-set is true; a fully-unchecked row keeps its
    /// authored per-row art untouched (<c>Refresh @0x004859C0</c>'s
    /// <c>if (ebx == 0) { ... media swap ... }</c> branch, where <c>ebx == 0</c> is
    /// the ANY-set case per the byte trace in this class's own research citations).
    /// </summary>
    private void ApplyRowVisualsForMask(ulong lowMask, ulong highMask, UiButton toggle)
    {
        bool anySet = IsAnySet(lowMask, highMask);
        toggle.Selected = anySet;
        if (!anySet)
        {
            toggle.FaceFileOverride = null;
            return;
        }
        uint overrideSprite = IsAllSet(lowMask, highMask) ? CheckedLedSprite : UncheckedLedSprite;
        toggle.FaceFileOverride = overrideSprite != 0u ? overrideSprite : null;
    }
}