using System;
using System.Collections.Generic;
using System.Linq;
using System.Utility;
using FluentAssertions;
using NUnit.Framework;

namespace Chernobyl.Collections.Generic
{
    [TestFixture, Description("Tests for the List type.")]
    public class ListTests
    {
        #region List.RemoveFirst(IList<T>, Predicate<T>)

        [Test, Description("Ensures RemoveFirst removes the correct item and returns the correct value.")]
        public void RemoveFirstRemovesAndReturnsCorrectValue()
        {
            var list = new List<int> { 0, 1, 1, 3, 4 };
            list.RemoveFirst(v => v == 1).Should().BeTrue();
            list.Should().Equal(new List<int> { 0, 1, 3, 4 });
        }

        [Test, Description("Ensures RemoveFirst does not remove any items and returns the correct value.")]
        public void RemoveFirstDoesNotRemoveItemAndReturnsCorrectValue()
        {
            var list = new List<int> { 0, 1, 1, 3, 4 };
            list.RemoveFirst(v => v == 5).Should().BeFalse();
            list.Should().Equal(new List<int> { 0, 1, 1, 3, 4 });
        }

        #endregion

        #region List.Pull(IList<T>, int)

        [Test, Description("Ensures Pull removes and returns the correct item.")]
        public void PullRemovesAndReturnsCorrectValue()
        {
            var list = new List<int> { 0, 1, 2, 3, 4 };
            list.Pull(3).IsEqualTo(3, "List.Pull");
            list.IsEqualTo(new List<int> { 0, 1, 2, 4 }, "List.Pull");
        }

        [Test, Description("Ensures Pull throws exception when provided index is less than zero.")]
        public void PullThrowsExceptionWhenIndexIsZero()
        {
            var list = new List<int> { 0, 1, 2, 3, 4 };
            Assert.Throws<ArgumentOutOfRangeException>(() => list.Pull(-1));
        }

        [Test, Description("Ensures Pull throws exception when provided index is outside list's bounds.")]
        public void PullThrowsExceptionWhenIndexIsOutsideListsBounds()
        {
            var list = new List<int> { 0, 1, 2, 3, 4 };
            Assert.Throws<ArgumentOutOfRangeException>(() => list.Pull(list.Count));
        }

        #endregion

        #region List.Pull(Random, IEnumerable<T>, int)

        readonly Random _rand = new Random();

        // ReSharper disable ReturnValueOfPureMethodIsNotUsed

        [Test, Description("Ensures Pull throws exception when count is less than zero.")]
        public void PullThrowsExceptionWhenCountIsLessThanZero()
        {
            var list = new List<int> { 0, 1, 2 };
            Assert.Throws<ArgumentOutOfRangeException>(() => list.Pull(_rand , -1).ToArray());
        }

        [Test, Description("Ensures Pull throws exception when count is greater than list count.")]
        public void PullThrowsExceptionWhenCountIsGreaterThanListCount()
        {
            var list = new List<int> { 0, 1, 2 };
            var count = list.Count + 1;
            Assert.Throws<ArgumentOutOfRangeException>(() => list.Pull(_rand, count).ToArray());
        }

        // ReSharper restore ReturnValueOfPureMethodIsNotUsed

        [Test, Description("Ensures Pull removes and returns the correct number of values from the list.")]
        public void PullRemovesAndReturnsCorrectValues()
        {
            var list = new List<int> { 0, 1, 2 };
            var originalCount = list.Count;
            var pullCount = 2;
            var items = list.Pull(_rand, pullCount).ToArray();

            items.Length.IsEqualTo(pullCount, "pulled length");
            list.Count.IsEqualTo(originalCount - pullCount, "original list length");
        }

        #endregion

        #region List.AtOrDefault(IList<T>, int)

        [Test, Description("Ensures AtOrDefault returns correct item when index is in bounds.")]
        public void AtOrDefaultReturnsItemWhenIndexIsInBounds()
        {
            IList<string> list = new List<string> { "X", "Y", "Z" };
            list.AtOrDefault(1).Should().Be("Y");
        }

        [Test, Description("Ensures AtOrDefault returns a default value when index is out of bounds.")]
        public void AtOrDefaultReturnsDefaultWhenIndexIsOutOfBounds()
        {
            IList<string> list = new List<string> { "X", "Y", "Z" };
            list.AtOrDefault(3).Should().Be(default);
        }

        #endregion
    }
}