using System.Windows;

namespace ytLive.Models;

/// <summary>
/// The vertical (9:16) tier's camera rules — TASK 57, the "vv" feature.
///
/// The vertical tier is a centred band crop of the SAME 1920×1080 master the
/// 16:9 tiers use, so a camera placed for 16:9 lands outside the cropped
/// window and vanishes from the vertical output. The vertical tier therefore
/// keeps its OWN placement per scene: a small tile inside the band, snapped to
/// one of six spots — the band splits into a top and a bottom half, each with
/// a left, a centre and a right slot.
///
/// Geometry only: the preview and the compositor both read the element's own
/// X/Y/W/H + ClipShape, so the placement is resolved by swapping those values
/// when the tier changes. No render-path change.
/// </summary>
public static class VerticalCameraLayout
{
    /// <summary>The vertical tier's camera tile over the master frame —
    /// 270×152 master px = 480×270 in the 1080×1920 output.</summary>
    public const double TileWidth = 270;
    public const double TileHeight = 152;

    /// <summary>How far the tile keeps from the band's outer edge — the app's
    /// own placement margin (32 master px) used by the default webcam spot.</summary>
    public const double Inset = 32;

    /// <summary>True for the portrait tier (the vertical 1080×1920 one).</summary>
    public static bool IsVerticalTier(QualityOption quality) => quality.Height > quality.Width;

    /// <summary>The half of the band a tile lives in — top or bottom.</summary>
    public static Rect AreaFor(Rect band, bool bottom)
        => new(band.Left, bottom ? band.Top + band.Height / 2 : band.Top, band.Width, band.Height / 2);

    /// <summary>The largest a camera may be inside the band: one whole area.</summary>
    public static (double Width, double Height) MaxSizeFor(Rect band)
        => (band.Width, band.Height / 2);

    /// <summary>
    /// The spot a tile snaps to: the area (top/bottom) and the column
    /// (left/centre/right) its centre falls in, then the tile's top-left for
    /// that spot — inset from the band's outer edge, and never outside the band
    /// (a tile wider than the inset eats it).
    /// </summary>
    public static (double X, double Y) SpotFor(Rect band, double width, double height, double centreX, double centreY)
    {
        var bottom = centreY >= band.Top + band.Height / 2;
        var area = AreaFor(band, bottom);
        var third = area.Width / 3;

        double x;
        if (centreX < area.Left + third) x = area.Left + Inset;
        else if (centreX < area.Left + 2 * third) x = area.Left + (area.Width - width) / 2;
        else x = area.Right - Inset - width;

        var y = bottom ? area.Bottom - Inset - height : area.Top + Inset;

        x = Math.Clamp(x, band.Left, Math.Max(band.Left, band.Right - width));
        y = Math.Clamp(y, band.Top, Math.Max(band.Top, band.Bottom - height));
        return (x, y);
    }

    /// <summary>The default tile spot: the bottom-right corner of the band —
    /// the same corner the 16:9 default webcam placement uses.</summary>
    public static (double X, double Y) DefaultSpot(Rect band, double width, double height)
        => SpotFor(band, width, height, band.Right, band.Bottom);
}