using System;

namespace AcDream.App.UI.Layout;

/// <summary>
/// Owns which of the two vitals windows is visible — retail's
/// "Side By Side Vitals" character option (Options → Character tab).
///
/// <para>
/// Retail authors TWO complete vitals windows and swaps their visibility on
/// the option bit; nothing is rearranged in place:
/// </para>
/// <list type="bullet">
/// <item><description><c>gmFloatyVitalsUI</c> (LayoutDesc 0x2100006C, the
/// stacked 160x58 window): <c>UpdateFromPlayerModule @0x004CF140</c> —
/// visible iff <c>PlayerModule::SideBySideVitals() == 0</c>.</description></item>
/// <item><description><c>gmFloatySideVitalsUI</c> (LayoutDesc 0x21000075, the
/// 460x26 single-row window): <c>UpdateFromPlayerModule @0x004D0810</c> —
/// visible iff the bit is set.</description></item>
/// <item><description>Live apply: <c>gmGamePlayUI::RecvNotice_PlayerOptionChanged
/// @0x004E9DA0</c> flips both windows the moment the
/// <c>SideBySideVitals_PlayerOption</c> (0x13) changes; both
/// <c>UpdateFromPlayerModule</c> bodies re-apply on PlayerDescReceived.</description></item>
/// <item><description>The bit is <c>PlayerModule::SideBySideVitals @0x005D3070</c>
/// = <c>(options_ &gt;&gt; 0x15) &amp; 1</c> — CharacterOptions1 0x00200000,
/// option id 0x13, riding the 0x01A1 PlayerModule blob (not a 0x0005
/// auto-save id) — <c>CharacterOptionTable</c> row confirmed against ACE.</description></item>
/// </list>
///
/// <para>
/// acdream shape: the option lives in the J4 Runtime owner
/// (<c>RuntimeCharacterState.Options</c>); this controller polls the borrowed
/// bit once per frame from <c>RetailUiRuntime.Tick</c> (the OP campaign's
/// established live-apply seam) and applies BOTH windows' visibility on the
/// edge — covering the mount-time default, the PlayerModule blob arriving
/// after mount, and the Character tab's live toggle with one mechanism.
/// Both window names ride <c>stateManagedVisibilityWindows</c> so the saved
/// window layout never restores a visibility this option owns.
/// </para>
/// </summary>
public sealed class VitalsSideBySideController
{
    private readonly UiRoot _root;
    private readonly Func<bool> _sideBySideVitals;
    private readonly string _stackedWindow;
    private readonly string _sideWindow;
    private bool? _applied;

    public VitalsSideBySideController(
        UiRoot root,
        Func<bool> sideBySideVitals,
        string stackedWindow,
        string sideWindow)
    {
        _root = root ?? throw new ArgumentNullException(nameof(root));
        _sideBySideVitals = sideBySideVitals
            ?? throw new ArgumentNullException(nameof(sideBySideVitals));
        _stackedWindow = stackedWindow;
        _sideWindow = sideWindow;
    }

    /// <summary>The last applied bit (null before the first apply). Exposed for tests.</summary>
    public bool? Applied => _applied;

    public void Tick()
    {
        bool sideBySide = _sideBySideVitals();
        if (_applied == sideBySide) return;
        _applied = sideBySide;

        // Retail's exact swap (RecvNotice_PlayerOptionChanged @0x004E9DBE):
        // option ON → stacked hidden, side shown; OFF → the opposite.
        if (sideBySide)
        {
            _root.HideWindow(_stackedWindow);
            _root.ShowWindow(_sideWindow);
        }
        else
        {
            _root.ShowWindow(_stackedWindow);
            _root.HideWindow(_sideWindow);
        }
    }
}