using EC.Helper.RabbitFunc.Runtime;

namespace EC.Helper.RabbitFunc.Expressions;

public class UnaryExpression : Expression
{
    internal UnaryExpression(ExpressionType type, Expression operand)
        : base(type)
    {
        Operand = operand;
    }

    public Expression Operand { get; }

    public override object Eval(RuntimeContext context)
    {
        if (context == null)
            throw new ArgumentNullException(nameof(context));

        object value = Operand.Eval(context);
        switch (NodeType)
        {
            case ExpressionType.Negate:
                return (-(double)value);

            case ExpressionType.Not:
                return (!(bool)value);

            default:
                throw new RuntimeException("unknown unary:" + NodeType.ToString());
        }
    }

    public override string ToString()
    {
        switch (NodeType)
        {
            case ExpressionType.Negate:
                return Operand is BinaryExpression ? "-(" + Operand.ToString() + ")" : "-" + Operand.ToString();

            case ExpressionType.Not:
                return Operand is BinaryExpression ? "!(" + Operand.ToString() + ")" : "!" + Operand.ToString();

            default:
                throw new RuntimeException("unknown operator:" + NodeType.ToString());
        }
    }
}