using System;
using System.Linq;
using Developpez.Dotnet.Collections;
using NUnit.Framework;

namespace Developpez.Dotnet.Tests.Collections
{
    [TestFixture]
    public class StackSetTests
    {
        [Test]
        public void Test_EnumerationOrderIsLIFO()
        {
            var stack = new StackSet<int>();
            stack.Push(4);
            stack.Push(8);
            stack.Push(15);
            stack.Push(16);
            stack.Push(23);
            stack.Push(42);

            var expected = new[] { 42, 23, 16, 15, 8, 4 };
            var actual = stack.ToArray();
            CollectionAssert.AreEqual(expected, actual);
        }

        [Test]
        public void Test_PushMovesAlreadyPresentItemToTopOfStack()
        {
            var stack = new StackSet<int>();
            stack.Push(1);
            stack.Push(2);
            stack.Push(3);
            stack.Push(2);

            var expected = 2;
            var actual = stack.First();
            Assert.AreEqual(expected, actual);
            Assert.AreEqual(3, stack.Count);
        }

        [Test]
        public void Test_PeekReturnsFirstAddedItemAndDoesntRemoveIt()
        {
            var stack = new StackSet<int>();
            stack.Push(1);
            stack.Push(2);
            stack.Push(3);

            var expected = 3;
            var actual = stack.Peek();
            Assert.AreEqual(expected, actual);
            Assert.AreEqual(3, stack.Count);
        }

        [Test]
        public void Test_PopReturnsFirstAddedItemAndRemovesIt()
        {
            var stack = new StackSet<int>();
            stack.Push(1);
            stack.Push(2);
            stack.Push(3);

            var expected = 3;
            var actual = stack.Pop();
            Assert.AreEqual(expected, actual);
            Assert.AreEqual(2, stack.Count);
            expected = 2;
            actual = stack.Peek();
            Assert.AreEqual(expected, actual);
        }

        [Test]
        public void Test_PeekAndPopThrowIfStackIsEmpty()
        {
            var stack = new StackSet<int>();
            Assert.Throws<InvalidOperationException>(() => stack.Peek());
            Assert.Throws<InvalidOperationException>(() => stack.Pop());
        }

        [Test]
        public void Test_SpecificComparerIsUsedAndLatestValueIsKept()
        {
            StackSet<string> stack = new StackSet<string>(StringComparer.CurrentCultureIgnoreCase);
            stack.Push("hello");
            stack.Push("world");
            stack.Push("foo");
            stack.Push("bar");

            // Re-push value that is already present
            stack.Push("HELLO");

            string expected = "HELLO";
            string actual = stack.Peek();
            Assert.AreEqual(expected, actual);

            expected = "world";
            actual = stack.Last();
            Assert.AreEqual(expected, actual);

            stack.Push("FOO");

            string[] expected2 = new[] { "FOO", "HELLO", "bar", "world" };
            string[] actual2 = stack.ToArray();
            CollectionAssert.AreEqual(expected2, actual2);
        }
    }
}