using System;
using System.Numerics;
using AcDream.App.UI;

namespace AcDream.App.UI.Layout;

/// <summary>
/// Per-window controller for the vitals layout (LayoutDesc 0x2100006C).
/// Mirrors retail <c>gmVitalsUI::PostInit</c>: grab the three meter elements
/// by their dat element ids and bind live data providers (fill fraction + cur/max
/// text) to each. This is the ONLY per-window code in the whole importer — pure
/// data wiring, not graphics.
///
/// <para>The slice sprites + dat font on each <see cref="UiMeter"/> are already
/// set by <see cref="DatWidgetFactory"/> during tree construction; this controller
/// only binds the dynamic vitals data. Do not touch meter rendering fields here.</para>
///
/// <para>Element ids confirmed from
/// <c>docs/research/2026-06-15-layoutdesc-format.md §11</c>
/// (vitals window 0x2100006C dump).</para>
/// </summary>
public static class VitalsController
{
    /// <summary>Dat element id for the Health meter (0x100000E6).</summary>
    public const uint Health  = 0x100000E6;
    /// <summary>Dat element id for the Stamina meter (0x100000EC).</summary>
    public const uint Stamina = 0x100000EC;
    /// <summary>Dat element id for the Mana meter (0x100000EE).</summary>
    public const uint Mana    = 0x100000EE;

    /// <summary>
    /// Bind live vitals data providers to the Health, Stamina, and Mana meter
    /// elements found in <paramref name="layout"/>. Any meter whose id is absent
    /// from the layout is silently skipped — partial layouts (e.g. test fakes)
    /// do not cause errors.
    /// </summary>
    /// <param name="layout">Imported vitals layout tree.</param>
    /// <param name="healthPct">Provider returning Health fill fraction [0..1].</param>
    /// <param name="staminaPct">Provider returning Stamina fill fraction [0..1].</param>
    /// <param name="manaPct">Provider returning Mana fill fraction [0..1].</param>
    /// <param name="healthText">Provider returning Health "cur/max" overlay text.</param>
    /// <param name="staminaText">Provider returning Stamina "cur/max" overlay text.</param>
    /// <param name="manaText">Provider returning Mana "cur/max" overlay text.</param>
    public static void Bind(
        ImportedLayout layout,
        Func<float>  healthPct,
        Func<float>  staminaPct,
        Func<float>  manaPct,
        Func<string> healthText,
        Func<string> staminaText,
        Func<string> manaText)
    {
        BindMeter(layout, Health,  healthPct,  healthText);
        BindMeter(layout, Stamina, staminaPct, staminaText);
        BindMeter(layout, Mana,    manaPct,    manaText);
    }

    /// <summary>White cur/max numbers — matches the former <c>UiMeter.LabelColor</c> default.</summary>
    private static readonly Vector4 NumberColor = new(1f, 1f, 1f, 1f);

    private static void BindMeter(
        ImportedLayout layout, uint id,
        Func<float>  pct,
        Func<string> text)
    {
        // Silently skip if the id is absent — missing meters are not an error (partial layouts).
        if (layout.FindElement(id) is not UiMeter m) return;

        m.Fill = () => pct();

        // Retail gmVitalsUI renders the cur/max as a real UIElement_Text centered over the
        // bar — NOT a meter-internal label. Attach a centered UiText (non-interactive
        // decoration) that fills + stretches with the meter, and stop the meter drawing its
        // own label. UiText.Centered uses the SAME centering formula the meter's overlay did,
        // so the numbers stay pixel-identical (locked by the visual gate).
        m.Label = () => null;

        var number = new UiText
        {
            Left = 0f, Top = 0f, Width = m.Width, Height = m.Height,
            Anchors = AnchorEdges.Left | AnchorEdges.Top | AnchorEdges.Right | AnchorEdges.Bottom,
            Centered = true,
            DatFont  = m.DatFont,        // the same dat font the meter used for its label
            ClickThrough = true,         // decoration: no focus / selection / drag
            AcceptsFocus = false,
            IsEditControl = false,
            CapturesPointerDrag = false,
            LinesProvider = () =>
            {
                var s = text();
                return string.IsNullOrEmpty(s)
                    ? Array.Empty<UiText.Line>()
                    : new[] { new UiText.Line(s, NumberColor) };
            },
        };
        m.AddChild(number);
    }
}