using MathEngine.Parser.Tokeniser;

namespace EngineTests
{
    /// <summary>
    /// Class for testing the Tokeniser
    /// </summary>
    [TestClass]
    public class TokeniserTests
    {
        /// <summary>
        /// Test the tokeniser on an empty string
        /// </summary>
        [TestMethod]
        public void TestTokeniseEmptystringReturnsEmptyList()
        {
            //Arrange
            string testString = "";
            Token one = new("1", Token.Type.Numeric, Token.NumericType.Decimal, 0);
            List<Token> expectedValue = new()
            {
                one,
                Token.Plus,
                one
            };
            //Act
            List<Token> returnedValue = Tokeniser.Tokenise(testString);
            //Assert
            Assert.AreEqual(returnedValue.Count, 0);
        }


        /// <summary>
        /// Test the tokeniser on a basic string
        /// </summary>
        [TestMethod]
        public void TestTokeniseBasicString()
        {
            //Arrange
            string testString = "1+1";
            Token one = new("1", Token.Type.Numeric, Token.NumericType.Decimal, 0);
            List<Token> expectedValue = new()
            {
                one,
                Token.Plus,
                one
            };
            //Act
            List<Token> returnedValue = Tokeniser.Tokenise(testString);
            //Assert
            Assert.IsTrue(expectedValue.SequenceEqual(returnedValue));
        }

        /// <summary>
        /// Test the tokeniser on a basic string, but with significant ammounts of whitespace
        /// </summary>
        [TestMethod]
        public void TestTokeniseBasicStringWithWhiteSpace()
        {
            //Arrange
            string testString = "  1   +   1              ";
            Token one = new("1", Token.Type.Numeric, Token.NumericType.Decimal, 0);
            List<Token> expectedValue = new()
            {
                one,
                Token.Plus,
                one
            };
            //Act
            List<Token> returnedValue = Tokeniser.Tokenise(testString);
            //Assert
            Assert.IsTrue(expectedValue.SequenceEqual(returnedValue));
        }

        /// <summary>
        /// Test the tokeniser on a string which contains a number which is not formatted correctly
        /// </summary>
        [TestMethod]
        public void TestTokeniseStringWithInvalidNumbr()
        {
            //Arrange
            string testString = "1+11.2.5";
            //Act and Assert
            Assert.ThrowsException<Exception>(() => Tokeniser.Tokenise(testString));            
        }


        /// <summary>
        /// Test the tokeniser with all operators
        /// </summary>
        [TestMethod]
        public void TestTokeniseStringWithAllOperators()
        {
            //Arrange
            string testString = "1+2-3*4/5";
            Token one = new("1", Token.Type.Numeric, Token.NumericType.Decimal, 0);
            Token two = new("2", Token.Type.Numeric, Token.NumericType.Decimal, 0);
            Token three = new("3", Token.Type.Numeric, Token.NumericType.Decimal, 0);
            Token four = new("4", Token.Type.Numeric, Token.NumericType.Decimal, 0);
            Token five = new("5", Token.Type.Numeric, Token.NumericType.Decimal, 0);
            List<Token> expectedValue = new()
            {
                one,
                Token.Plus,
                two,
                Token.Minus,
                three,
                Token.Multiply,
                four,
                Token.Divide,
                five
            };
            //Act
            List<Token> returnedValue = Tokeniser.Tokenise(testString);
            //Assert
            Assert.IsTrue(expectedValue.SequenceEqual(returnedValue));
        }
    }
}