using System.Windows.Media;

namespace ytLive.Models;

/// <summary>
/// The transient zoom layer. It is a real scene element, but a special one: while
/// active the SceneCompositor draws it LAST (layer n+1, above everything) as a live
/// 2x view of a FIXED capture window (the box/2 region centred on where the creator
/// clicked), sampled from the just-composited frame — so it captures ALL layers and
/// keeps showing the same content no matter where the box is dragged (creator ruling
/// 2026-10-08). Its X/Y/W/H are the movable BOX placement; CaptureX/CaptureY is the
/// anchored capture window. While inactive it is an invisible placeholder that is
/// never persisted (LayoutStore hand-rolls only Source/WebcamSceneConfig rows) — the
/// VM re-inserts it on load and on scene creation, mirroring how backgrounds heal.
/// </summary>
public sealed class ZoomSceneElement : SceneElement
{
    /// <summary>True only while a zoom box is live; flips Kind so the layer leaves
    /// the baked static base and composites per-frame.</summary>
    public bool IsZoomActive { get; set; }

    /// <summary>Master-space top-left of the fixed capture window. Set once by
    /// <c>ActivateZoom</c>; moving the box must never touch it.</summary>
    public double CaptureX { get; set; }
    public double CaptureY { get; set; }

    public override ElementKind Kind => IsZoomActive ? ElementKind.Dynamic : ElementKind.Static;

    public override bool IsZoomLayer => true;

    public override bool IsDraggable => false;

    /// <summary>Never rendered by the element template or the resolver — the preview
    /// magnifier (ZoomBox) and the output compositor's zoom pass own its pixels.</summary>
    public override ImageSource? DisplaySource => null;
}