using System;
using System.Collections.Generic;
using Annulus.BezierCurves;
using Annulus.CSG;
using Azimuth;

namespace Annulus.UnitTests.CSG
{
    public class DiskQueryTests : UnitTestSharp.TestFixture
    {
        public static QuadraticBezierCurve Piece(Vector start, Vector control, Vector end)
        {
            return new QuadraticBezierCurve { startPoint = start, controlPoint = control, endPoint = end };
        }

        public static QuadraticBezierCurve Line(Vector start, Vector end)
        {
            return Piece(start, Vector.Lerp(start, end, 0.5), end);
        }

        public static QuadraticBezierCurve[] Lens(Scalar bulge)
        {
            return new QuadraticBezierCurve[]
            {
                Piece(new Vector(-1, 0), new Vector(0, -bulge), new Vector(1, 0)),
                Piece(new Vector(1, 0), new Vector(0, bulge), new Vector(-1, 0)),
            };
        }

        public class StopTests : UnitTestSharp.TestFixture
        {
            public void OpposingPieceCloserThanTheCurvatureRadius_StopsAtTheOpposingPiece()
            {
                DiskStop stop = DiskQuery.Stop(Lens(bulge: 1), point: new Vector(0, -0.5), inward: new Vector(0, 1),
                    ownPiece: 0, ownParameter: 0.5);

                CheckEqual((Scalar)0.5, stop.Radius);
                CheckEqual(1, stop.AcrossPiece);
                CheckEqual((Scalar)0.5, stop.AcrossParameter);
                CheckEqual(new Vector(0, 0), stop.Centre);
                CheckFalse(stop.IsCurvatureLimit);
            }

            public void CurvatureRadiusSmallerThanTheOpposingDistance_StopsAtTheCurvatureLimit()
            {
                DiskStop stop = DiskQuery.Stop(Lens(bulge: 2), point: new Vector(0, -1), inward: new Vector(0, 1),
                    ownPiece: 0, ownParameter: 0.5);

                CheckEqual((Scalar)0.5, stop.Radius);
                CheckEqual(0, stop.AcrossPiece);
                CheckEqual((Scalar)0.5, stop.AcrossParameter);
                CheckEqual(new Vector(0, -0.5), stop.Centre);
                CheckTrue(stop.IsCurvatureLimit);
            }

            public void PointOffTheVertexWhereTheOwnPieceCurvesTighter_StopsAtTheOwnPieceFarSide()
            {
                Scalar side = Math.Sqrt(0.5);

                DiskStop stop = DiskQuery.Stop(Lens(bulge: 2), point: new Vector(0.5, -0.75),
                    inward: new Vector(-side, side), ownPiece: 0, ownParameter: 0.75);

                CheckEqual(side, stop.Radius);
                CheckEqual(0, stop.AcrossPiece);
                CheckEqual((Scalar)0.25, stop.AcrossParameter);
                CheckEqual(new Vector(0, -0.25), stop.Centre);
                CheckFalse(stop.IsCurvatureLimit);
            }

            public void SmoothJointOnItsSharedNormal_StopsAtTheCurvatureRadiusOfTheCurvedPiece()
            {
                QuadraticBezierCurve[] pieces = new QuadraticBezierCurve[]
                {
                    Line(new Vector(0, 0), new Vector(4, 0)),
                    Piece(new Vector(4, 0), new Vector(6, 0), new Vector(8, 8)),
                    Line(new Vector(8, 8), new Vector(0, 8)),
                    Line(new Vector(0, 8), new Vector(0, 0)),
                };

                DiskStop stop = DiskQuery.Stop(pieces, point: new Vector(4, 0), inward: new Vector(0, 1),
                    ownPiece: 0, ownParameter: 1);

                CheckEqual((Scalar)1, stop.Radius);
                CheckEqual(1, stop.AcrossPiece);
                CheckEqual((Scalar)0, stop.AcrossParameter);
                CheckEqual(new Vector(4, 1), stop.Centre);
                CheckTrue(stop.IsCurvatureLimit);
            }

            public void CurvatureFallingAwayAfterTheJoint_StopsAtTheCurvatureRadius()
            {
                QuadraticBezierCurve[] pieces = new QuadraticBezierCurve[]
                {
                    Line(new Vector(0, 0), new Vector(4, 0)),
                    Piece(new Vector(4, 0), new Vector(6, 0), new Vector(9, 8)),
                    Line(new Vector(9, 8), new Vector(0, 8)),
                    Line(new Vector(0, 8), new Vector(0, 0)),
                };

                DiskStop stop = DiskQuery.Stop(pieces, point: new Vector(4, 0), inward: new Vector(0, 1),
                    ownPiece: 0, ownParameter: 1);

                CheckEqual((Scalar)1, stop.Radius);
                CheckEqual(1, stop.AcrossPiece);
                CheckEqual((Scalar)0, stop.AcrossParameter);
                CheckEqual(new Vector(4, 1), stop.Centre);
                CheckTrue(stop.IsCurvatureLimit);
            }

            public void CurvatureFallingAwayBeforeTheJoint_StopsAtTheCurvatureRadius()
            {
                QuadraticBezierCurve[] pieces = new QuadraticBezierCurve[]
                {
                    Line(new Vector(0, 0), new Vector(0, 8)),
                    Line(new Vector(0, 8), new Vector(-9, 8)),
                    Piece(new Vector(-9, 8), new Vector(-6, 0), new Vector(-4, 0)),
                    Line(new Vector(-4, 0), new Vector(0, 0)),
                };

                DiskStop stop = DiskQuery.Stop(pieces, point: new Vector(-4, 0), inward: new Vector(0, 1),
                    ownPiece: 2, ownParameter: 1);

                CheckEqual((Scalar)1, stop.Radius);
                CheckEqual(2, stop.AcrossPiece);
                CheckEqual((Scalar)1, stop.AcrossParameter);
                CheckEqual(new Vector(-4, 1), stop.Centre);
                CheckTrue(stop.IsCurvatureLimit);
            }

            public void ConvexCornerEndingTheOwnPiece_StopsAtZeroRadius()
            {
                DiskStop stop = DiskQuery.Stop(Lens(bulge: 1), point: new Vector(1, 0), inward: new Vector(-1, 0),
                    ownPiece: 0, ownParameter: 1);

                CheckEqual((Scalar)0, stop.Radius);
                CheckEqual(0, stop.AcrossPiece);
                CheckEqual((Scalar)1, stop.AcrossParameter);
                CheckEqual(new Vector(1, 0), stop.Centre);
                CheckFalse(stop.IsCurvatureLimit);
            }

            public void ConvexCornerStartingTheOwnPiece_StopsAtZeroRadius()
            {
                DiskStop stop = DiskQuery.Stop(Lens(bulge: 1), point: new Vector(-1, 0), inward: new Vector(1, 0),
                    ownPiece: 0, ownParameter: 0);

                CheckEqual((Scalar)0, stop.Radius);
                CheckEqual(0, stop.AcrossPiece);
                CheckEqual((Scalar)0, stop.AcrossParameter);
                CheckEqual(new Vector(-1, 0), stop.Centre);
                CheckFalse(stop.IsCurvatureLimit);
            }

            public void ReflexFanDirection_StopsAtTheDiskTangentToTheFarWall()
            {
                QuadraticBezierCurve[] pieces = new QuadraticBezierCurve[]
                {
                    Line(new Vector(-1, 0), new Vector(4, 0)),
                    Line(new Vector(4, 0), new Vector(4, 2)),
                    Line(new Vector(4, 2), new Vector(2, 2)),
                    Line(new Vector(2, 2), new Vector(2, 6)),
                    Line(new Vector(2, 6), new Vector(-1, 6)),
                    Line(new Vector(-1, 6), new Vector(-1, 0)),
                };
                Scalar side = Math.Sqrt(0.5);
                Scalar radius = 4 - 2 * Math.Sqrt(2);

                DiskStop stop = DiskQuery.Stop(pieces, point: new Vector(2, 2), inward: new Vector(-side, -side),
                    ownPiece: 2, ownParameter: 1);

                CheckEqual(radius, stop.Radius);
                CheckEqual(0, stop.AcrossPiece);
                CheckEqual((Scalar)((5 - 2 * Math.Sqrt(2)) / 5), stop.AcrossParameter);
                CheckEqual(new Vector(radius, radius), stop.Centre);
                CheckFalse(stop.IsCurvatureLimit);
            }

            public void CurvedPieceLeaningAwayFromTheRay_StopsAtItsInteriorMinimum()
            {
                QuadraticBezierCurve[] pieces = new QuadraticBezierCurve[]
                {
                    Line(new Vector(-6, -6), new Vector(0, 0)),
                    Piece(new Vector(0, 0), new Vector(1.5, 0), new Vector(3, 4)),
                    Line(new Vector(3, 4), new Vector(3, 100)),
                    Line(new Vector(3, 100), new Vector(-100, 100)),
                    Line(new Vector(-100, 100), new Vector(-6, -6)),
                };
                Scalar radius = 65.0 / 24;

                DiskStop stop = DiskQuery.Stop(pieces, point: new Vector(0, 0),
                    inward: new Vector(-16.0 / 65, 63.0 / 65), ownPiece: 0, ownParameter: 1);

                CheckEqual(radius, stop.Radius);
                CheckEqual(1, stop.AcrossPiece);
                CheckEqual((Scalar)0.5, stop.AcrossParameter);
                CheckEqual(new Vector(-2.0 / 3, 21.0 / 8), stop.Centre);
                CheckFalse(stop.IsCurvatureLimit);
            }

            public void MinimumAtTheJointBetweenTwoOtherPieces_ReportsTheEarlierPiece()
            {
                QuadraticBezierCurve[] pieces = new QuadraticBezierCurve[]
                {
                    Line(new Vector(-1, 0), new Vector(4, 0)),
                    Line(new Vector(4, 0), new Vector(4, 2)),
                    Line(new Vector(4, 2), new Vector(2, 2)),
                    Line(new Vector(2, 2), new Vector(2, 6)),
                    Line(new Vector(2, 6), new Vector(-1, 6)),
                    Line(new Vector(-1, 6), new Vector(-1, 0)),
                };

                DiskStop stop = DiskQuery.Stop(pieces, point: new Vector(1, 0), inward: new Vector(0, 1),
                    ownPiece: 0, ownParameter: 0.4);

                CheckEqual((Scalar)1.25, stop.Radius);
                CheckEqual(2, stop.AcrossPiece);
                CheckEqual((Scalar)1, stop.AcrossParameter);
                CheckEqual(new Vector(1, 1.25), stop.Centre);
                CheckFalse(stop.IsCurvatureLimit);
            }

            public void RayLeavingTheShape_Throws()
            {
                CheckThrow(typeof(InvalidOperationException));
                DiskQuery.Stop(Lens(bulge: 1), point: new Vector(0, -0.5), inward: new Vector(0, -1), ownPiece: 0,
                    ownParameter: 0.5);
            }

            public void SinglePiece_Throws()
            {
                CheckThrow(typeof(ArgumentException));
                DiskQuery.Stop(new QuadraticBezierCurve[] { Lens(bulge: 1)[0] }, point: new Vector(0, -0.5),
                    inward: new Vector(0, 1), ownPiece: 0, ownParameter: 0.5);
            }

            public void ZeroTangentAtTheQueryPoint_Throws()
            {
                QuadraticBezierCurve[] pieces = new QuadraticBezierCurve[]
                {
                    Piece(new Vector(0, 0), new Vector(0, 0), new Vector(1, 0)),
                    Line(new Vector(1, 0), new Vector(0, 0)),
                };

                CheckThrow(typeof(ArgumentException));
                DiskQuery.Stop(pieces, point: new Vector(0, 0), inward: new Vector(0, 1), ownPiece: 0,
                    ownParameter: 0);
            }
        }
    }
}