using System;
using Annulus.CSG;
using Azimuth;

namespace Annulus.UnitTests.CSG
{
    public class BoundaryTrianglesTests : UnitTestSharp.TestFixture
    {
        public static Scalar Area(Vector[] corners)
        {
            Scalar returnMe = 0;
            for (int i = 0; i < corners.Length; i += 3)
            {
                returnMe += (corners[i + 1] - corners[i]).CrossProduct(corners[i + 2] - corners[i]) / 2;
            }

            return returnMe;
        }

        public class InteriorTests : UnitTestSharp.TestFixture
        {
            public void FewerThanThreePoints_GivesNoTriangles()
            {
                CheckEqual(0, BoundaryTriangles.Interior(new Vector[] { new Vector(0, 0), new Vector(1, 0) }).Length);
            }

            public void Triangle_GivesItself()
            {
                Vector[] corners = BoundaryTriangles.Interior(
                    new Vector[] { new Vector(0, 0), new Vector(2, 0), new Vector(0, 2) });

                CheckEqual(3, corners.Length);
                CheckEqual((Scalar)2, Area(corners));
            }

            public void Square_GivesTwoTriangles()
            {
                Vector[] corners = BoundaryTriangles.Interior(new Vector[]
                {
                    new Vector(0, 0), new Vector(1, 0), new Vector(1, 1), new Vector(0, 1),
                });

                CheckEqual(6, corners.Length);
                CheckEqual((Scalar)1, Area(corners));
            }

            public void EveryTriangleRunsCounterclockwise()
            {
                Vector[] corners = BoundaryTriangles.Interior(new Vector[]
                {
                    new Vector(0, 0), new Vector(2, 0), new Vector(2, 1), new Vector(1, 1), new Vector(1, 2),
                    new Vector(0, 2),
                });

                for (int i = 0; i < corners.Length; i += 3)
                {
                    CheckTrue(Area(new Vector[] { corners[i], corners[i + 1], corners[i + 2] }) > 0);
                }
            }

            public void ConcaveOutline_FillsExactlyItsArea()
            {
                Vector[] corners = BoundaryTriangles.Interior(new Vector[]
                {
                    new Vector(0, 0), new Vector(2, 0), new Vector(2, 1), new Vector(1, 1), new Vector(1, 2),
                    new Vector(0, 2),
                });

                CheckEqual(12, corners.Length);
                CheckEqual((Scalar)3, Area(corners));
            }

            public void ClockwiseOutline_Throws()
            {
                CheckThrow(typeof(InvalidOperationException));
                BoundaryTriangles.Interior(new Vector[]
                {
                    new Vector(0, 0), new Vector(0, 1), new Vector(1, 1), new Vector(1, 0),
                });
            }
        }

        public class CurveTests : UnitTestSharp.TestFixture
        {
            public void ShapeOfStraightPieces_HasNoCurveTriangles()
            {
                BoundaryLabelling labelling = new BoundaryLabelling(BoundaryLabellingTests.LShape());

                CheckEqual(0, labelling.CurveTriangles.Length);
            }

            public void Crescent_HasOneTriangleForEachPart()
            {
                BoundaryLabelling labelling = new BoundaryLabelling(BoundaryPartsTests.Crescent());

                CheckEqual(4, labelling.CurveTriangles.Length);
                CheckEqual(new Vector(-1, 0), labelling.CurveTriangles[0].Start);
                CheckEqual(new Vector(-2.0 / 3, -1), labelling.CurveTriangles[0].Control);
                CheckEqual(new Vector(-1.0 / 3, -4.0 / 3), labelling.CurveTriangles[0].End);
            }

            public void CurveTrianglesRecordWhichWayTheirPartBows()
            {
                BoundaryLabelling labelling = new BoundaryLabelling(BoundaryPartsTests.Crescent());
                bool[] bowsIn = { false, false, false, true };

                for (int i = 0; i < bowsIn.Length; ++i)
                {
                    CheckEqual(bowsIn[i], labelling.CurveTriangles[i].BowsIn);
                    CheckEqual(0, labelling.CurveTriangles[i].Region);
                }
            }

            public void PartsOfAFansReflexJoint_HaveNoCurveTriangle()
            {
                BoundaryPart point = BoundaryInvariantsTests.Part(new Vector(1, 1), new Vector(1, 1), new Vector(1, 1));
                point.IsPoint = true;

                CheckEqual(0, BoundaryTriangles.Curve(new BoundaryPart[] { point }).Length);
            }
        }

        public class LabellingTests : UnitTestSharp.TestFixture
        {
            public void EachRegionIsFilledWithItsOutlinesAreaAndNothingElse()
            {
                BoundaryLabelling labelling = new BoundaryLabelling(BoundaryLabellingTests.LShape());
                Scalar total = 0;

                CheckEqual(labelling.Regions.Length, labelling.InteriorTriangles.Length);
                for (int i = 0; i < labelling.Regions.Length; ++i)
                {
                    CheckEqual(BoundaryOutlinesTests.Area(labelling.Outlines[i]), Area(labelling.InteriorTriangles[i]));
                    total += Area(labelling.InteriorTriangles[i]);
                }

                CheckEqual((Scalar)22, total);
            }

            public void RegionsOfTheRoundedRectangle_FillItsArea()
            {
                BoundaryLabelling labelling = new BoundaryLabelling(BoundaryLabellingTests.RoundedRectangle());
                Scalar total = 0;

                foreach (Vector[] corners in labelling.InteriorTriangles)
                {
                    total += Area(corners);
                }

                CheckEqual((Scalar)22, total);
            }
        }
    }
}