using Xunit;

using MathEngine.Parser;
using MathEngine.Tokenizer;

using static MathEngine.Tokenizer.Token;

namespace EngineTests
{
    /// <summary>
    /// Class for testing the Parser
    /// </summary>
    public class ParserTests
    {
        public static IEnumerable<object[]> TestParserValidExpressionsCases
        {
            get
            {
                Token one = new("1", TokenType.Numeric);
                Token two = new("2", TokenType.Numeric);
                Token three = new("3", TokenType.Numeric);
                Token four = new("4", TokenType.Numeric);
                Token five = new("5", TokenType.Numeric);

                return new List<object[]> {
                    new object[] { "1+1", new Queue<Token>(new List<Token> { one, one, Token.Plus }) },
                    new object[] { "1-1", new Queue<Token>(new List<Token> { one, one, Token.Minus }) },
                    new object[] { "1*1", new Queue<Token>(new List<Token> { one, one, Token.Multiply }) },
                    new object[] { "1/1", new Queue<Token>(new List<Token> { one, one, Token.Divide }) },
                    new object[] { "1^1", new Queue<Token>(new List<Token> { one, one, Token.Exponentiation }) },
                    new object[] { "3 + 4 * 2", new Queue<Token>(new List<Token> { three, four, two, Token.Multiply, Token.Plus }) },
                    new object[] { "(1+2)*3", new Queue<Token>(new List<Token> {one, two, Token.Plus, three, Token.Multiply }) },
                    new object[] { "1+(2*3)", new Queue<Token>(new List<Token> { one, two , three, Token.Multiply, Token.Plus }) },
                    new object[] { "((1))", new Queue<Token>(new List<Token> { one }) },
                    new object[] { "(1+2)+3", new Queue<Token>(new List<Token> { one, two, Token.Plus, three, Token.Plus }) },
                    new object[] { "1+2*3-4/2", new Queue<Token>(new List<Token> { one, two, three, Token.Multiply, Token.Plus, four, two, Token.Divide, Token.Minus }) },
                    new object[] { "1-2-3", new Queue<Token>(new List<Token> {one, two, Token.Minus, three, Token.Minus }) },
                    new object[] { "2^3^4", new Queue<Token>(new List<Token> { two, three, four, Token.Exponentiation, Token.Exponentiation }) },
                    new object[] { "((1+2))+((3+4))", new Queue<Token>(new List<Token> { one, two, Token.Plus, three, four, Token.Plus, Token.Plus }) },
                    new object[] { "1 + ((2 + 3) * 4) - 5", new Queue<Token>(new List<Token> { one, two, three, Token.Plus, four, Token.Multiply, Token.Plus,five, Token.Minus }) },
                    new object[] { "1 ^ (2 + 3)", new Queue<Token>(new List<Token> { one, two, three, Token.Plus, Token.Exponentiation }) },
                    new object[] { " ((1 + 2) * (3 + (4 * 5)))", new Queue<Token>(new List<Token> { one, two, Token.Plus, three, four, five, Token.Multiply, Token.Plus, Token.Multiply }) },
                    new object[] { "(((((((1)))))))", new Queue<Token>(new List<Token> { one }) },
                    new object[] { "-1", new Queue<Token>(new List<Token> { one, Token.UnaryMinus }) },
                    new object[] { "+1", new Queue<Token>(new List<Token> { one, Token.UnaryPlus }) },
                    new object[] { "1+-1", new Queue<Token>(new List<Token> { one, one, Token.UnaryMinus, Token.Plus }) },
                    new object[] { "-(1+2)", new Queue<Token>(new List<Token> { one, two, Token.Plus, Token.UnaryMinus }) },
                    new object[] { "--1", new Queue<Token>(new List<Token> { one, Token.UnaryMinus, Token.UnaryMinus }) },
                    new object[] { "+-1", new Queue<Token>(new List<Token> { one, Token.UnaryMinus, Token.UnaryPlus }) },
                    new object[] { "-3^2", new Queue<Token>(new List<Token> { three, two, Token.Exponentiation, Token.UnaryMinus}) },
                    new object[] { "1++2", new Queue<Token>(new List<Token> { one, two, Token.UnaryPlus, Token.Plus}) },
                    new object[] { "1--2", new Queue<Token>(new List<Token> { one, two, Token.UnaryMinus, Token.Minus }) },
                    };
            }
        }



        /// <summary>
        /// Test the Parser on valid expressions
        /// </summary>
        [Theory]
        [MemberData(nameof(TestParserValidExpressionsCases))]
        public void TestParserValidExpressions(string expression, object expected_result)
        {
            List<Token> testList = ExpressionTokenizer.Tokenize(expression);

            Queue<Token> returned_rpn_qeue = Parser.Parse(testList);

            Assert.Equal(expected_result, returned_rpn_qeue);


        }

        public static IEnumerable<object[]> TestParserInValidExpressionsCases
        {
            get
            {
                Token one = new("1", TokenType.Numeric);
                Token two = new("2", TokenType.Numeric);
                Token three = new("3", TokenType.Numeric);
                Token four = new("4", TokenType.Numeric);
                Token five = new("5", TokenType.Numeric);

                return new List<object[]> {
                    new object[] { "1//1", new Queue<Token>(new List<Token> { one, one, Token.Plus }) },
                    };
            }
        }



        /// <summary>
        /// Test the Parser on invalid expressions
        /// These are expressions that are considered Parsing errors, such
        /// </summary>
        [Theory]
        [MemberData(nameof(TestParserInValidExpressionsCases))]
        public void TestParserInValidExpressions(string expression, object expected_result)
        {
            Assert.True(true);
            return;
            //List<Token> testList = ExpressionTokenizer.Tokenize(expression);

            //Queue<Token> returned_rpn_qeue = Parser.Parse(testList);

            //Assert.Equal(expected_result, returned_rpn_qeue);


        }
    }
}