using System;
using Goo;
using Sandbox;
using Sandbox.UI;
using PanelTransform = Goo.PanelTransform;   // rule 18: ambiguous with Sandbox.UI otherwise

namespace Goo.FpsUI;

// Shared, stateless view helpers. Each returns a fresh Container (never cache a Container).
static class Parts
{
    public enum Corner { TopLeft, TopCenter, TopRight, BottomLeft, BottomRight, Center }

    // Absolute fill spanning `frac` (0..1) of its Relative parent's width, full height.
    public static Container FillRect( string key, float frac, Color color, float radius ) => new()
    {
        Key = key, Position = PositionMode.Absolute, Top = 0, Left = 0,
        Height = Length.Percent( 100 ),
        Width = Length.Percent( Math.Clamp( frac, 0f, 1f ) * 100f ),
        BorderRadius = radius, BackgroundColor = color,
    };

    // Absolute full-cover tint at a given opacity (flashes, warnings).
    public static Container Overlay( string key, Color color, float opacity, float radius ) => new()
    {
        Key = key, Position = PositionMode.Absolute, Top = 0, Left = 0,
        Width = Length.Percent( 100 ), Height = Length.Percent( 100 ),
        BorderRadius = radius, BackgroundColor = color, Opacity = opacity,
    };

    // Pin `child` to a screen corner/center inside a Relative, full-size root. `m` is the edge inset.
    // Container properties are init-only (record struct), so we use `with` expressions per corner.
    public static Container Anchor( string key, Corner c, float m, Container child )
    {
        var box = new Container
        {
            Key = key, Position = PositionMode.Absolute, PointerEvents = PointerEvents.None,
            Children = { child },
        };
        return c switch
        {
            Corner.TopLeft     => box with { Top = m, Left = m },
            Corner.TopRight    => box with { Top = m, Right = m },
            Corner.BottomLeft  => box with { Bottom = m, Left = m },
            Corner.BottomRight => box with { Bottom = m, Right = m },
            Corner.TopCenter   => box with
            {
                Top = m, Left = Length.Percent( 50 ),
                Transform = PanelTransform.Translate( Length.Percent( -50 ) ?? default, Length.Percent( 0 ) ?? default ),
            },
            _ => box with  // Center
            {
                Top = Length.Percent( 50 ), Left = Length.Percent( 50 ),
                Transform = PanelTransform.Translate( Length.Percent( -50 ) ?? default, Length.Percent( -50 ) ?? default ),
            },
        };
    }

    // Pin `child` horizontally centered, offset `dy` px from the screen center (positive = down, negative = up).
    public static Container CenterOffset( string key, float dy, Container child ) => new()
    {
        Key = key, Position = PositionMode.Absolute, PointerEvents = PointerEvents.None,
        Top = Length.Percent( 50 ), Left = Length.Percent( 50 ),
        Transform = PanelTransform.Translate( Length.Percent( -50 ) ?? default, Px.Of( dy ) ),
        Children = { child },
    };

    // Pin `child`'s top-left corner at a pixel offset from the screen center (positive dx = right, positive dy = down).
    public static Container Offset( string key, float dx, float dy, Container child ) => new()
    {
        Key = key, Position = PositionMode.Absolute, PointerEvents = PointerEvents.None,
        Top = Length.Percent( 50 ), Left = Length.Percent( 50 ),
        Transform = PanelTransform.Translate( Px.Of( dx ), Px.Of( dy ) ),
        Children = { child },
    };

    // Semi-opaque rounded backing behind a HUD readout, so text/bars stay legible over the world.
    // Wraps one child and sizes to it, all card styling comes from the theme.
    public static Container Panel( string key, FpsTheme t, Container child ) => new()
    {
        Key = key, Position = PositionMode.Relative,
        Padding = t.PanelPad, BorderRadius = t.PanelRadius,
        BackgroundColor = t.BackingBg,
        Children = { child },
    };

    // A full-size, pointer-through, Relative root used by every standalone widget and the FpsHud.
    public static Container Root( string key ) => new()
    {
        Key = key, Width = Length.Percent( 100 ), Height = Length.Percent( 100 ),
        Position = PositionMode.Relative, PointerEvents = PointerEvents.None,
    };
}