using System.Collections.Generic;
using System.Reflection;
using Annulus;
using Blacklight.Core;
using UnitTestSharp;
using DrawingPoint = System.Drawing.Point;
using DrawingSize = System.Drawing.Size;

namespace Glass.Blacklight.UnitTests
{
    // Draws from CursorSheet.png, which is 8 by 4, red in its left four columns and blue in its right four.
    public class CursorSyncTests : TestFixture
    {
        private const string Sheet = "Glass.Blacklight.UnitTests.CursorSheet.png";

        [SpriteSheet(spriteSizeX: 4, spriteSizeY: 4, borderSize: 0, Sheet)]
        public sealed class FlatSheet
        {
        }

        public sealed class RecordingSurface : ICursorSurface
        {
            public List<CursorImage> Set { get; } = new List<CursorImage>();

            public int Cleared { get; private set; }

            public bool CursorVisible { get; set; }

            public bool TrySetCursor(CursorImage cursor)
            {
                Set.Add(cursor);

                return true;
            }

            public void ClearCursor()
            {
                ++Cleared;
            }
        }

        public sealed class UnknownCursor : Cursor
        {
        }

        private static readonly Assembly Art = typeof(CursorSyncTests).Assembly;

        private static readonly SpriteCursor Red =
            new SpriteCursor(MaterialLibrary<FlatSheet>.CreateSprite(new Point(0, 0)), new Point(1, 2));

        private static readonly SpriteCursor Blue =
            new SpriteCursor(MaterialLibrary<FlatSheet>.CreateSprite(new Point(1, 0)), new Point(1, 2));

        public class ApplyTests : TestFixture
        {
            public void ASpriteCursor_SetsItsImageAtItsHotspot()
            {
                var surface = new RecordingSurface();

                new CursorSync(surface, scale: 1, Art).Apply(Red);

                CheckEqual(1, surface.Set.Count);
                CheckEqual(new DrawingSize(4, 4), surface.Set[0].Size);
                CheckEqual(new DrawingPoint(1, 2), surface.Set[0].Hotspot);
            }

            public void AScale_EnlargesTheImageAndHotspot()
            {
                var surface = new RecordingSurface();

                new CursorSync(surface, scale: 2, Art).Apply(Red);

                CheckEqual(new DrawingSize(8, 8), surface.Set[0].Size);
                CheckEqual(new DrawingPoint(2, 4), surface.Set[0].Hotspot);
            }

            public void TheSameCursorAgain_SetsNothingMore()
            {
                var surface = new RecordingSurface();
                var sync = new CursorSync(surface, scale: 1, Art);

                sync.Apply(Red);
                sync.Apply(Red);

                CheckEqual(1, surface.Set.Count);
                CheckEqual(0, surface.Cleared);
            }

            public void ADifferentCursor_SetsItsImage()
            {
                var surface = new RecordingSurface();
                var sync = new CursorSync(surface, scale: 1, Art);

                sync.Apply(Red);
                sync.Apply(Blue);

                CheckEqual(2, surface.Set.Count);
                CheckEqual(255, surface.Set[1].Rgba[2]);
            }

            public void NoCursorAtFirst_LeavesTheSurfaceAlone()
            {
                var surface = new RecordingSurface();

                new CursorSync(surface, scale: 1, Art).Apply(null);

                CheckEqual(0, surface.Set.Count);
                CheckEqual(0, surface.Cleared);
            }

            public void NoCursorAfterASpriteCursor_HandsTheCursorBackOnce()
            {
                var surface = new RecordingSurface();
                var sync = new CursorSync(surface, scale: 1, Art);

                sync.Apply(Red);
                sync.Apply(null);
                sync.Apply(null);

                CheckEqual(1, surface.Cleared);
            }

            public void ACursorItCannotDraw_CountsAsNone()
            {
                var surface = new RecordingSurface();
                var sync = new CursorSync(surface, scale: 1, Art);

                sync.Apply(Red);
                sync.Apply(new UnknownCursor());

                CheckEqual(1, surface.Cleared);
            }
        }
    }
}