using Amphora;
using Annulus;
using Azimuth;
using Blacklight.Core;
using Blacklight.Core.Cameras;
using Blacklight.Core.Drawables;
using Glass.Blacklight;
using System;
using Prism;

namespace Glass.Testbed.TestCases.Layout
{
    /// <summary>
    /// A nameplate pinned to the Arrow in the game scene.
    /// </summary>
    public class WorldAnchorTestCase : TestCase
    {
        private static readonly Vector ArrowHome = new Vector(120, -70);
        private const double ArrowOrbitRadius = 60;
        private const double ArrowOrbitSecondsPerTurn = 9;

        private readonly World world;

        private Arrow arrow;
        private EntityHandle arrowHandle;
        private WorldAnchoredPanel arrowNameplate;
        private TextMaterial anchorReadoutMaterial;
        private double arrowOrbitPhase;

        public WorldAnchorTestCase(World world)
        {
            this.world = world;
        }

        protected override void Populate()
        {
            arrow = new Arrow(5, 2)
            {
                InsideColor = new Color(0.5, 0.5, 0),
                ShellColor = new Color(0.75, 0.75, 0),
                ShellModelSpaceThickness = 0,
                ShellPixelThickness = 3,
            };

            arrowHandle = world.cel.AddEntity(arrow, new AffineMatrix(0, ArrowHome));

            AddCaption("The nameplate tracks the world.arrow as the world.arrow orbits");
            AddCaption("Drag to pan and wheel to zoom");

            // Use a Panel rather than a Label, since the text changes every frame.
            anchorReadoutMaterial = Widgets.Caption("anchor: measuring...");
            Panel anchorReadout = anchorReadoutMaterial.BuildControl(Constraints.Unbounded);

            anchorReadout.Bounds = ContentAggregator.NewRow(anchorReadout.Bounds.Height);
            Add(anchorReadout);

            Material nameplateMaterial = UiPacksheetMaterials.YellowPanel;
            var nameplateLabel = new Label(Widgets.ButtonLabelStyle, "world.arrow", Constraints.Unbounded);

            Vector nameplateSize = nameplateMaterial.BoundsSizeFor(nameplateLabel.Bounds.Size);

            arrowNameplate = new WorldAnchoredPanel(
                point => world.camera.WorldToWorldOf(world.uiWorld.camera).TransformPoint(point))
            {
                DebugName = "world.arrow nameplate",
                Material = nameplateMaterial,
                Bounds = Rect.FromPositionAndSize(Vector.Zero, nameplateSize),
                WorldPosition = ArrowHome,

                OffsetFromAnchor = new Vector(-nameplateSize.X / 2, -nameplateSize.Y - 14),
            };

            nameplateLabel.FillParent(arrowNameplate);
            Add(arrowNameplate);
        }

        /// <summary>
        /// Walks the arrow around its home position so the nameplate has something to track without the user
        /// having to drag the camera.
        /// </summary>
        public override void Update(Duration elapsed)
        {
            arrowOrbitPhase += elapsed.TotalSeconds / ArrowOrbitSecondsPerTurn * 2 * Math.PI;

            Amphora.PortableMath.SinCosOfRadians(arrowOrbitPhase, out double sin, out double cos);
            Vector position = ArrowHome + new Vector(cos * ArrowOrbitRadius, sin * ArrowOrbitRadius);

            var entity = new Entity<Arrow>(arrow, new AffineMatrix(arrowOrbitPhase, position));
            world.cel.ReplaceEntity(arrowHandle, ref entity);

            arrowNameplate.WorldPosition = position;

            Vector glassPosition = world.camera.WorldToWorldOf(world.uiWorld.camera).TransformPoint(position);
            anchorReadoutMaterial.Text = $"anchor: world ({position.X:F0}, {position.Y:F0})" +
                $"  ->  glass ({glassPosition.X:F0}, {glassPosition.Y:F0})";
        }
    }
}