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

namespace Annulus.UnitTests.CSG
{
    public class BoundaryOutlinesTests : UnitTestSharp.TestFixture
    {
        public static Scalar Area(Vector[] outline)
        {
            Scalar returnMe = 0;
            for (int i = 0; i < outline.Length; ++i)
            {
                Vector from = outline[i];
                Vector to = outline[(i + 1) % outline.Length];
                returnMe += from.CrossProduct(to) / 2;
            }

            return returnMe;
        }

        public class BuildTests : UnitTestSharp.TestFixture
        {
            public void Square_GivesEachSideItsQuadrantCounterclockwise()
            {
                BoundaryLabelling labelling = new BoundaryLabelling(BoundaryLabellingTests.Rectangle(1, 1));

                CheckEqual(4, labelling.Outlines.Length);
                foreach (Vector[] outline in labelling.Outlines)
                {
                    CheckEqual(4, outline.Length);
                    CheckEqual((Scalar)1, Area(outline));
                }

                CheckEqual(new Vector(-1, 0), labelling.Outlines[0][0]);
                CheckEqual(new Vector(-1, -1), labelling.Outlines[0][1]);
                CheckEqual(new Vector(0, -1), labelling.Outlines[0][2]);
                CheckEqual(new Vector(0, 0), labelling.Outlines[0][3]);
            }

            public void Rectangle_GivesTheLongSideTheTrapezoidBetweenTheSpokes()
            {
                BoundaryLabelling labelling = new BoundaryLabelling(BoundaryLabellingTests.Rectangle(2, 1));
                Scalar[] areas = { 1, 4, 1, 1, 1 };

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

            public void LShape_RegionsTileTheShape()
            {
                BoundaryLabelling labelling = new BoundaryLabelling(BoundaryLabellingTests.LShape());
                Scalar total = 0;

                CheckEqual(7, labelling.Outlines.Length);
                foreach (Vector[] outline in labelling.Outlines)
                {
                    total += Area(outline);
                }

                CheckEqual((Scalar)22, total);
            }

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

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

                CheckEqual((Scalar)22, total);
            }

            public void RegionWithNoLiveCuts_WalksTheWholeLoop()
            {
                BoundaryLabelling labelling = new BoundaryLabelling(DiskQueryTests.Lens(bulge: 2));

                CheckEqual(1, labelling.Outlines.Length);
                CheckEqual(2, labelling.Outlines[0].Length);
                CheckEqual(new Vector(-1, 0), labelling.Outlines[0][0]);
                CheckEqual(new Vector(1, 0), labelling.Outlines[0][1]);
            }

            public void ConcaveCrescentPiece_AddsItsControlPointToTheOutline()
            {
                BoundaryLabelling labelling = new BoundaryLabelling(BoundaryPartsTests.Crescent());
                bool found = false;

                foreach (Vector[] outline in labelling.Outlines)
                {
                    if (Array.IndexOf(outline, new Vector(0, -1)) >= 0)
                    {
                        found = true;
                    }
                }

                CheckTrue(found);
            }

            public void SpokeThatReachesNoVertex_Throws()
            {
                BoundaryPart[] parts =
                {
                    new BoundaryPart { Region = 0, StartCut = 0, EndCut = 1 },
                    new BoundaryPart { Region = 1, StartCut = 1, EndCut = 0 },
                };
                BoundaryCut[] cuts =
                {
                    new BoundaryCut { Vertex = -1 },
                    new BoundaryCut { Vertex = -1 },
                };

                CheckThrow(typeof(InvalidOperationException));
                BoundaryOutlines.Build(parts, cuts, new BoundaryVertex[0], new BoundaryInterval[0], regionCount: 2);
            }
        }
    }
}