using Calculator.Domain;
using MbUnit.Framework;

namespace Calculator.Test.presentation
{
    [TestFixture]
    public class NumberBuilderTest
    {
        private INumberBuilder CreateSUT()
        {
            return new NumberBuilder();
        }

        [Test]
        public void should_be_able_to_append_a_new_digit_to_a_number()
        {
            INumberBuilder sut = CreateSUT();

            sut.Append("1");
            Assert.AreEqual(CreateNumber(1), sut.Build());
            sut.Append("1");
            Assert.AreEqual(CreateNumber(11), sut.Build());
            sut.Append("9");
            Assert.AreEqual(CreateNumber(119), sut.Build());
        }

        [Test]
        public void Should_be_able_to_append_a_decimal_point()
        {
            INumberBuilder sut = CreateSUT();

            sut.Append("1");
            Assert.AreEqual(CreateNumber(1), sut.Build());
            sut.Append(".");
            Assert.AreEqual(CreateNumber(1.0), sut.Build());
            sut.Append("8");
            Assert.AreEqual(CreateNumber(1.8), sut.Build());
        }

        [Test]
        public void should_ignore_decimals_after_first_decimal()
        {
            INumberBuilder sut = CreateSUT();

            sut.Append("5");
            sut.Append(".");
            sut.Append("5");
            sut.Append(".");
            sut.Append("7");
            sut.Append(".");

            Assert.AreEqual(CreateNumber(5.57), sut.Build());
        }

        [Test]
        public void Should_be_able_to_remove_the_last_digit()
        {
            INumberBuilder sut = CreateSUT();

            sut.Append("1");
            sut.Append("2");
            sut.Append("3");
            sut.RemoveLastDigit();
            Assert.AreEqual(CreateNumber(12), sut.Build());
        }

        [Test]
        public void should_return_zero_when_trying_to_remove_the_last_digit_when_only_one_digit_has_been_entered()
        {
            INumberBuilder sut = CreateSUT();

            sut.Append("1");
            sut.RemoveLastDigit();
            Assert.AreEqual(CreateNumber(0), sut.Build());
        }

        [Test]
        public void should_return_zero_when_no_digits_are_entered_and_you_try_to_remove_the_last_digit()
        {
            INumberBuilder sut = CreateSUT();
            sut.RemoveLastDigit();
            Assert.AreEqual(CreateNumber(0), sut.Build());
        }

        private INumber CreateNumber(double fromNumber)
        {
            return new Number(fromNumber);
        }
    }
}