using System;

namespace Amphora.UnitTests
{
    public class ReinterpretArrayTests : UnitTestSharp.TestFixture
    {
        public class AsIntsTests : UnitTestSharp.TestFixture
        {
            public void ReturnsTheSameArray()
            {
                var keys = new uint[] { 1, 2, 3 };

                CheckTrue(ReferenceEquals(keys, ReinterpretArray.AsInts(keys)));
            }

            public void IndexingReadsTheSameBitsAsInts()
            {
                int[] ints = ReinterpretArray.AsInts(new uint[] { 0, 5, uint.MaxValue, 1u << 31 });

                CheckEqual(0, ints[0]);
                CheckEqual(5, ints[1]);
                CheckEqual(-1, ints[2]);
                CheckEqual(int.MinValue, ints[3]);
            }

            public void EnumeratingAsACollectionStillSeesUints()
            {
                System.Collections.IEnumerable ints = ReinterpretArray.AsInts(new uint[] { uint.MaxValue });

                foreach (object element in ints)
                {
                    CheckEqual(typeof(uint), element.GetType());
                }
            }

            public void KeepsTheLength()
            {
                CheckEqual(7, ReinterpretArray.AsInts(new uint[7]).Length);
            }

            public void AWriteThroughTheIntsShowsInTheUints()
            {
                var keys = new uint[3];

                ReinterpretArray.AsInts(keys)[1] = -1;

                CheckEqual(uint.MaxValue, keys[1]);
            }

            public void AnEmptyArrayStaysEmpty()
            {
                CheckEqual(0, ReinterpretArray.AsInts(new uint[0]).Length);
            }

            public void NullStaysNull()
            {
                CheckNull(ReinterpretArray.AsInts(null));
            }

            public void TheIntViewIsTheSameObjectTheRuntimeKnowsAsUints()
            {
                object keys = ReinterpretArray.AsInts(new uint[2]);

                CheckEqual(typeof(uint[]), keys.GetType());
            }
        }

        public class AsUintsTests : UnitTestSharp.TestFixture
        {
            public void ReturnsTheSameArray()
            {
                var keys = new[] { 1, 2, 3 };

                CheckTrue(ReferenceEquals(keys, ReinterpretArray.AsUints(keys)));
            }

            public void IndexingReadsTheSameBitsAsUints()
            {
                uint[] uints = ReinterpretArray.AsUints(new[] { 0, 5, -1, int.MinValue });

                CheckEqual(0u, uints[0]);
                CheckEqual(5u, uints[1]);
                CheckEqual(uint.MaxValue, uints[2]);
                CheckEqual(1u << 31, uints[3]);
            }

            public void EnumeratingAsACollectionStillSeesInts()
            {
                System.Collections.IEnumerable uints = ReinterpretArray.AsUints(new[] { -1 });

                foreach (object element in uints)
                {
                    CheckEqual(typeof(int), element.GetType());
                }
            }

            public void AWriteThroughTheUintsShowsInTheInts()
            {
                var keys = new int[3];

                ReinterpretArray.AsUints(keys)[2] = 1u << 31;

                CheckEqual(int.MinValue, keys[2]);
            }

            public void NullStaysNull()
            {
                CheckNull(ReinterpretArray.AsUints(null));
            }

            public void ARoundTripGivesTheOriginalArray()
            {
                var keys = new uint[] { 4, 5 };

                CheckTrue(ReferenceEquals(keys, ReinterpretArray.AsUints(ReinterpretArray.AsInts(keys))));
            }
        }
    }
}