using FsCheck.Xunit;
using Reverse.Tests.Generators;
using System.Linq;
using Xunit;

namespace Reverse.Tests
{
    public class ReverserTests
    {
        [Theory]
        [InlineData(new int[] { 1 }, new int[] { 1 })]
        [InlineData(new int[] { 1, 2 }, new int[] { 2, 1 })]
        [InlineData(new int[] { 1, 2, 3 }, new int[] { 3, 2, 1 })]
        public void Reverse_WillReverseEntireArray(int[] input, int[] output)
        {
            Reverser.Reverse(input, input.Length);

            Assert.True(input.SequenceEqual(output));
        }

        [Fact]
        public void Reverse_WithSpecifiedIndex_ReversesItemsUpToThatIndex()
        {
            var input = new int[] { 1, 2, 3, 4 };
            var output = new int[] { 2, 1, 3, 4 };

            Reverser.Reverse(input, 2);

            Assert.True(input.SequenceEqual(output));
        }

        [Fact]
        public void Reverse_WithIndexOne_DoesNothing()
        {
            var input = new int[] { 1, 2 };
            var output = new int[] { 1, 2 };

            Reverser.Reverse(input, 1);

            Assert.True(input.SequenceEqual(output));
        }

        [Fact]
        public void Reverse_WithIndexGreaterThanArrayLength_DoesNothing()
        {
            var input = new int[] { 1, 2 };
            var output = new int[] { 1, 2 };

            Reverser.Reverse(input, input.Length + 1);

            Assert.True(input.SequenceEqual(output));
        }

        [Property(Arbitrary = new[] { typeof(PositiveIntegerGenerator) })]
        public void CreateRandomArray_ReturnsRandomArrayOfSpecifiedLength()
        {
            var result = Reverser.CreateRandomArray(5);

            Assert.Equal(5, result.Length);
        }

        [Property(Arbitrary = new[] { typeof(PositiveIntegerGenerator) })]
        public void CreateRandomArray_MaxElementValueIsEqualToSize(int size)
        {
            var result = Reverser.CreateRandomArray(size);

            Assert.Equal(size, result.Max());
        }

        [Property(Arbitrary = new[] { typeof(PositiveIntegerGenerator) })]
        public void CreateRandomArray_ReturnsRandomArrayWithDistinctElements(int size)
        {
            var array = Reverser.CreateRandomArray(size);

            var arrayGroup = array.GroupBy(x => x);
            var duplicateFound = arrayGroup.Any(x => x.Count() > 1);

            Assert.False(duplicateFound);
        }

        [Theory]
        [InlineData(new int[] { 1 })]
        [InlineData(new int[] { 1, 2 })]
        [InlineData(new int[] { 1, 1 })]
        public void IsArrayInAscendingOrder_WhenArrayElementsAreInNumericAscendingOrder_ReturnsTrue(int[] input)
        {
            var result = Reverser.IsArrayInAscendingOrder(input);

            Assert.True(result);
        }

        [Fact]
        public void IsArrayInOrder_WhenArrayElementsAreNotInNumericAscendingOrder_ReturnsFalse()
        {
            var result = Reverser.IsArrayInAscendingOrder(new int[] { 2, 1 });

            Assert.False(result);
        }
    }
}