using EC.Helper.RabbitFunc.Expressions;
using EC.Helper.RabbitFunc.Runtime;

namespace EC.Helper.RabbitFunc.Extern;

[ExternLambda]
internal class MaxLambdaExpression : SystemLambdaExpression
{
    public MaxLambdaExpression()
        : base(typeof(Math).GetMethod(nameof(Math.Max), new Type[] { typeof(double), typeof(double) }), "max", new BodyExpression(),
              Expression.Parameter(typeof(double), "left"),
              Expression.Parameter(typeof(double), "right"))
    { }

    private class BodyExpression : Expression
    {
        public override object Eval(RuntimeContext context)
        {
            var left = ParameterExpression.Access<double>(context, "left");
            var right = ParameterExpression.Access<double>(context, "right");
            return Math.Max(left, right);
        }
    }
}