using System;
using System.Collections.Generic;
using AMWD.Common.Cli;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace UnitTests.Common.Cli
{
	[TestClass]
	public class EnumerableWalkerTests
	{
		private List<string> list;

		[TestInitialize]
		public void Initialize()
		{
			list = new List<string>
			{
				"one",
				"two",
				"three",
				"four",
			};
		}

		[TestMethod]
		[ExpectedException(typeof(ArgumentNullException))]
		public void ShouldThrowExceptionOnNullReference()
		{
			// arrange

			// act
			_ = new EnumerableWalker<object>(null);

			// assert - ArgumentNullException
			Assert.Fail();
		}

		[TestMethod]
		public void ShouldReturnEnumerator()
		{
			// arrange
			var walker = new EnumerableWalker<string>(list);

			// act
			var enumerator = walker.GetEnumerator();

			// assert
			Assert.IsNotNull(enumerator);
		}

		[TestMethod]
		public void ShouldReturnGenericEnumerator()
		{
			// arrange
			var walker = new EnumerableWalker<string>(list);

			// act
			var enumerator = ((IEnumerable<string>)walker).GetEnumerator();

			// assert
			Assert.IsNotNull(enumerator);
		}

		[TestMethod]
		public void ShouldReturnItems()
		{
			// arrange
			var walker = new EnumerableWalker<string>(list);
			_ = walker.GetEnumerator();

			string[] items = new string[list.Count];

			// act
			for (int i = 0; i < list.Count; i++)
				items[i] = walker.GetNext();

			// assert
			for (int i = 0; i < list.Count; i++)
				Assert.AreEqual(list[i], items[i], $"Position {i} failed");
		}

		[TestMethod]
		public void ShouldReturnDefaultWhenNothingLeft()
		{
			// arrange
			var walker = new EnumerableWalker<string>(Array.Empty<string>());
			_ = walker.GetEnumerator();

			// act
			string item = walker.GetNext();

			// assert
			Assert.AreEqual(default(string), item);
		}
	}
}