using System.Xml.Linq;
using XNeedle.Parser.Elements;

namespace XNeedle.Transformation.Bangs
{
    public class BeforeBang : BangOperation
    {
        public override string Name => "before";

        public override Context Execute(Context ctx, IEnumerable<string> arguments)
        {
            if (ctx.Node == null)
            {
                throw new ArgumentNullException("!before needs a reachable node");
            }
            if (arguments.Count() < 1)
            {
                throw new ArgumentException("!before needs at least the tag name as argument.");
            }

            var tagname = arguments.ElementAt(0);
            var element = new XElement(tagname, "");
            ctx.Node.AddBeforeSelf(element);

            return new Context{ Node = element, SLoc = ctx.SLoc.AsSynthetic(), XPathSelector = tagname};
        }
    }
}