using System.Linq.Expressions;

namespace YLErp.BasicTests
{
    [TestClass]
    public class LinqExpressionTest
    {
        [TestMethod]
        public void TestAddAssign()
        {
            var data = new LinqData { N1 = 3 };

            Expression<Func<LinqData, double>> propExp = n => n.N1;

            var pinvoke = Expression.Invoke(propExp, propExp.Parameters);
            var addExp = Expression.Add(pinvoke, Expression.Constant(2d, typeof(double)));
            var assign = Expression.Assign(propExp.Body, addExp);
            var action = Expression.Lambda<Action<LinqData>>(assign, propExp.Parameters).Compile();
            action(data);

            Assert.AreEqual(data.N1, 5);

            var data2 = new LinqData { N1 = 3 };
            var assign2 = Expression.AddAssign(propExp.Body, Expression.Constant(3d, typeof(double)));
            var action2 = Expression.Lambda<Action<LinqData>>(assign2, propExp.Parameters).Compile();
            action2(data2);

            Assert.AreEqual(data2.N1, 6);
        }

        [TestMethod]
        public void TestMultiplyAssign()
        {
            var data = new LinqData { N1 = 3 };

            Expression<Func<LinqData, double>> propExp = n => n.N1;

            var pinvoke = Expression.Invoke(propExp, propExp.Parameters);
            var multiply = Expression.Multiply(pinvoke, Expression.Constant(1 + 0.2, typeof(double)));
            var assign = Expression.Assign(propExp.Body, multiply);
            var action = Expression.Lambda<Action<LinqData>>(assign, propExp.Parameters).Compile();
            action(data);

            Assert.AreEqual(data.N1, 3.6, 1e-4);

            var data2 = new LinqData { N1 = 3 };
            var assign2 = Expression.MultiplyAssign(propExp.Body, Expression.Constant(1.5, typeof(double)));
            var action2 = Expression.Lambda<Action<LinqData>>(assign2, propExp.Parameters).Compile();
            action2(data2);

            Assert.AreEqual(data2.N1, 4.5, 1e-4);
        }

        class LinqData
        {
            public double N1 { get; set; }
        }
    }
}