using System;
using UnitTestSharp;

namespace Blacklight.Core.UnitTests
{
    public class ArrayViewTests : TestFixture
    {
        public class CtorTests : TestFixture
        {
            public void TakesTheCount()
            {
                CheckEqual(3, new ArrayView<int>(new int[5], offset: 1, count: 3).Count);
            }

            public void EmptyRunAtTheEnd_IsAllowed()
            {
                CheckEqual(0, new ArrayView<int>(new int[5], offset: 5, count: 0).Count);
            }

            public void NullArray_Throws()
            {
                CheckThrow(typeof(ArgumentNullException));
                new ArrayView<int>(null, offset: 0, count: 0);
            }

            public void NegativeOffset_Throws()
            {
                CheckThrow(typeof(ArgumentOutOfRangeException));
                new ArrayView<int>(new int[5], offset: -1, count: 0);
            }

            public void OffsetPastTheEnd_Throws()
            {
                CheckThrow(typeof(ArgumentOutOfRangeException));
                new ArrayView<int>(new int[5], offset: 6, count: 0);
            }

            public void NegativeCount_Throws()
            {
                CheckThrow(typeof(ArgumentOutOfRangeException));
                new ArrayView<int>(new int[5], offset: 0, count: -1);
            }

            public void RunPastTheEnd_Throws()
            {
                CheckThrow(typeof(ArgumentOutOfRangeException));
                new ArrayView<int>(new int[5], offset: 2, count: 4);
            }
        }

        public class CountTests : TestFixture
        {
            public void Default_IsZero()
            {
                CheckEqual(0, default(ArrayView<int>).Count);
            }
        }

        public class IndexerTests : TestFixture
        {
            public void ReadsFromTheOffset()
            {
                var view = new ArrayView<int>(new[] { 10, 11, 12, 13, 14 }, offset: 1, count: 3);

                CheckEqual(11, view[0]);
                CheckEqual(13, view[2]);
            }

            public void SeesLaterChangesToTheArray()
            {
                int[] array = { 10, 11, 12 };
                var view = new ArrayView<int>(array, offset: 0, count: 3);

                array[1] = 99;

                CheckEqual(99, view[1]);
            }

            public void NegativeIndex_Throws()
            {
                var view = new ArrayView<int>(new int[5], offset: 1, count: 3);

                CheckThrow(typeof(IndexOutOfRangeException));
                _ = view[-1];
            }

            public void IndexAtCount_ThrowsEvenWithArrayLeftAfterIt()
            {
                var view = new ArrayView<int>(new int[5], offset: 1, count: 3);

                CheckThrow(typeof(IndexOutOfRangeException));
                _ = view[3];
            }
        }
    }
}