namespace ytLive.Services;

/// <summary>
/// A normalized CPU frame (32bpp BGRA, tightly packed). The capture path hands
/// these to the UI thread, which copies them into the shared WriteableBitmap.
/// Deliberately the only pixel type the rest of the app knows about — every
/// future capture source (screen, background-removed webcam) feeds the same seam.
/// </summary>
public sealed class VideoFrame
{
    public int Width { get; }
    public int Height { get; }
    public byte[] BgraPixels { get; }
    public int Stride => Width * 4;

    /// <summary>Producer frame epoch — a monotonically increasing number stamped by
    /// sources that RECYCLE their pixel buffers (the screen-capture ring, take-11 spike
    /// fix). Consumers that key caches on buffer identity (the compositor's paste cache)
    /// MUST include it, or a recycled array false-hits with stale content. Producers
    /// that hand out fresh arrays per frame leave it 0 — identity alone is then enough.</summary>
    public long Epoch { get; init; }

    /// <summary>Producer contract: every alpha byte in <see cref="BgraPixels"/> is 255
    /// (DWM capture surfaces and MediaCapture video carry no alpha — the OS fills 255).
    /// Lets the compositor take a straight-copy fast path for a full-canvas opaque
    /// layer instead of 2M per-pixel blends. NEVER set it for paths whose pixels can
    /// be transparent (static art, web overlays, chat, the social-bar strip).</summary>
    public bool IsOpaque { get; init; }

    public VideoFrame(int width, int height, byte[] bgraPixels)
    {
        Width = width;
        Height = height;
        BgraPixels = bgraPixels;
    }
}