using System;
using Prism;
using UnitTestSharp;

namespace Konis.UnitTests
{
    public class GradientDefTests : TestFixture
    {
        private static Gradient BlackToWhite()
        {
            return Gradient.Between(Colors.Black, Colors.White);
        }

        public class GradientTests : TestFixture
        {
            public void IsNullUntilGiven()
            {
                CheckNull(new GradientDef().Gradient);
            }

            public void IsSetByAnInitializer()
            {
                Gradient gradient = BlackToWhite();

                CheckTrue(ReferenceEquals(gradient, new GradientDef { Gradient = gradient }.Gradient));
            }
        }

        public class ValidateTests : TestFixture
        {
            public void WithAGradient_Passes()
            {
                new GradientDef { Gradient = BlackToWhite() }.Validate();
            }

            public void WithoutAGradient_Throws()
            {
                CheckThrow(typeof(InvalidOperationException));
                new GradientDef().Validate();
            }
        }

        public class TableTests : TestFixture
        {
            public void IsNullWithoutAGradient()
            {
                CheckNull(new GradientDef().Table);
            }

            public void IsBakedFromTheGradientAsItIsSet()
            {
                var def = new GradientDef { Gradient = BlackToWhite() };

                CheckEqual(Colors.Black.ToArgb(), def.Table.Sample(0));
                CheckEqual(Colors.White.ToArgb(), def.Table.Sample(1));
            }

            public void AfterTheGradientIsReplacedByReflection_IsBakedFromTheNewOne()
            {
                var def = new GradientDef { Gradient = BlackToWhite() };
                GradientTable before = def.Table;

                typeof(GradientDef).GetProperty(nameof(GradientDef.Gradient)).SetValue(
                    def, Gradient.Constant(Colors.Red));

                CheckFalse(ReferenceEquals(before, def.Table));
                CheckEqual(Colors.Red.ToArgb(), def.Table.Sample(0.5));
            }

            public void AfterTheGradientIsReplacedWithNull_IsNull()
            {
                var def = new GradientDef { Gradient = BlackToWhite() };

                typeof(GradientDef).GetProperty(nameof(GradientDef.Gradient)).SetValue(def, null);

                CheckNull(def.Table);
            }
        }
    }
}