namespace Amphora.UnitTests
{
    public class RanduTests : UnitTestSharp.TestFixture
    {
        public class SeedCtorTests : UnitTestSharp.TestFixture
        {
            public void StartsTheSequenceThatMultipliesBy65539()
            {
                var generator = new Randu(1);

                CheckEqual(65539UL, generator.NextUInt64() >> 33);
                CheckEqual(393225UL, generator.NextUInt64() >> 33);
                CheckEqual(1769499UL, generator.NextUInt64() >> 33);
            }

            public void MakesAnEvenSeedOdd()
            {
                var even = new Randu(2);
                var odd = new Randu(3);

                CheckEqual(odd.NextUInt64(), even.NextUInt64());
            }

            public void KeepsTheLowest31BitsOfTheSeed()
            {
                var wide = new Randu(0x80000002UL);
                var narrow = new Randu(3);

                CheckEqual(narrow.NextUInt64(), wide.NextUInt64());
            }
        }

        public class NextUInt64Tests : UnitTestSharp.TestFixture
        {
            public void PutsThe31BitStateAtTheTop()
            {
                var generator = new Randu(1);

                CheckEqual(0x0002000600000000UL, generator.NextUInt64());
                CheckEqual(0x000c001200000000UL, generator.NextUInt64());
                CheckEqual(0x0036003600000000UL, generator.NextUInt64());
                CheckEqual(0x00d800a200000000UL, generator.NextUInt64());
                CheckEqual(0x032a01e600000000UL, generator.NextUInt64());
                CheckEqual(0x0b6405b200000000UL, generator.NextUInt64());
            }
        }

        public class NextUInt32Tests : UnitTestSharp.TestFixture
        {
            public void ShiftsTheStateUpOneBit()
            {
                var generator = new Randu(1);

                CheckEqual(0x00020006U, generator.NextUInt32());
                CheckEqual(0x000c0012U, generator.NextUInt32());
                CheckEqual(0x00360036U, generator.NextUInt32());
                CheckEqual(0x00d800a2U, generator.NextUInt32());
                CheckEqual(0x032a01e6U, generator.NextUInt32());
                CheckEqual(0x0b6405b2U, generator.NextUInt32());
            }
        }
    }
}