using System;
using UnitTestSharp;

namespace Blacklight.Bezier.UnitTests
{
    public class InputUncertaintyTests : TestFixture
    {
        public class UnitRoundoffTests : TestFixture
        {
            public void IsHalfTheGapAboveOne()
            {
                CheckEqual(InputUncertainty.FloatSpacing(1) / 2, InputUncertainty.UnitRoundoff);
            }
        }

        public class FloatSpacingTests : TestFixture
        {
            public void One_IsTheGapToTheNextFloat()
            {
                CheckEqual(Math.Pow(2, -23), InputUncertainty.FloatSpacing(1));
            }

            public void NegativeValue_UsesItsMagnitude()
            {
                CheckEqual(InputUncertainty.FloatSpacing(1), InputUncertainty.FloatSpacing(-1));
            }

            public void Zero_IsTheSmallestSubnormal()
            {
                CheckEqual((double)float.Epsilon, InputUncertainty.FloatSpacing(0));
            }

            public void RoundsToFloatFirst()
            {
                CheckEqual(InputUncertainty.FloatSpacing(1), InputUncertainty.FloatSpacing(1 + 1e-10));
            }
        }

        public class OfTests : TestFixture
        {
            public void OnTheCurve_IsZero()
            {
                ShellSample sample = ShellSample.FromPosition(2, 2, 10);
                CheckEqual(0.0, InputUncertainty.Of(sample, new ReferenceResult(0, 2)));
            }

            public void StraightBelowTheVertex_IsTheSpacingOfY()
            {
                ShellSample sample = ShellSample.FromPosition(0, -2, 10);
                CheckEqual(Math.Pow(2, -22), InputUncertainty.Of(sample, ReferenceDistance.Solve(sample)));
            }

            public void NearTheCurveFarOut_IsFarBelowTheSpacingOfY()
            {
                ShellSample sample = SampleSets.AlongNormal(foot: 1000, offset: 1, end: 1e7);
                double uncertainty = InputUncertainty.Of(sample, ReferenceDistance.Solve(sample));
                CheckGreater(InputUncertainty.FloatSpacing(sample.Y) / 100, uncertainty);
            }
        }
    }
}