namespace Just.PreciseMath.Tests.SanityChecks;

public class DoubleDoubleSubtractionChecks
{
    public static IEnumerable<TheoryDataRow<DoubleDouble, DoubleDouble, DoubleDouble>> ReferenceCases =>
    [
        (new DoubleDouble(2.0), new DoubleDouble(1.0), new DoubleDouble(1.0)),
        (new DoubleDouble(1.0), new DoubleDouble(2.0), new DoubleDouble(-1.0)),
        (new DoubleDouble(3.75), new DoubleDouble(2.5), new DoubleDouble(1.25)),
        (new DoubleDouble(2.5), new DoubleDouble(3.75), new DoubleDouble(-1.25)),
        (new DoubleDouble(65536.0), new DoubleDouble(1.0), new DoubleDouble(65535.0)),
        (new DoubleDouble(65536.0), new DoubleDouble(65535.0), new DoubleDouble(1.0)),
        (DoubleDouble.Parse("812563124576179134673", System.Globalization.CultureInfo.InvariantCulture), new DoubleDouble(127.0), DoubleDouble.Parse("812563124576179134546", System.Globalization.CultureInfo.InvariantCulture)),
        (DoubleDouble.Parse("812563124576179134546", System.Globalization.CultureInfo.InvariantCulture), new DoubleDouble(127.0), DoubleDouble.Parse("812563124576179134419", System.Globalization.CultureInfo.InvariantCulture)),
        (DoubleDouble.Parse("812563124576179134546", System.Globalization.CultureInfo.InvariantCulture), DoubleDouble.Parse("812563124576179134504", System.Globalization.CultureInfo.InvariantCulture), new DoubleDouble(42.0)),
        (DoubleDouble.Parse("812563124576179134546", System.Globalization.CultureInfo.InvariantCulture), new DoubleDouble(0.5), DoubleDouble.Parse("812563124576179134545.5", System.Globalization.CultureInfo.InvariantCulture)),
        (DoubleDouble.Parse("812563124576179134546", System.Globalization.CultureInfo.InvariantCulture), DoubleDouble.Parse("812563124576179134546", System.Globalization.CultureInfo.InvariantCulture), new DoubleDouble(0.0)),
    ];

    [Theory]
    [MemberData(nameof(ReferenceCases))]
    public void SubtractionShouldProduceExpectedResults(DoubleDouble left, DoubleDouble right, DoubleDouble expected)
    {
        DoubleDouble result = left - right;

        result.High.ShouldBe(expected.High);
        result.Low.ShouldBe(expected.Low);
        result.ShouldBe(expected);
    }
}