package luan.impl;

import luan.Luan;
import luan.LuanFunction;
import luan.LuanException;
import luan.LuanElement;
import luan.LuanTable;


final class FnCall extends CodeImpl implements Expressions {
	final Expr fnExpr;
	final Expressions args;
	final String fnName;

	FnCall(LuanElement el,Expr fnExpr,Expressions args) {
		super(el);
		this.fnExpr = fnExpr;
		this.args = args;
		this.fnName = fnExpr.el().text();
	}

	@Override public Object eval(LuanStateImpl luan) throws LuanException {
		return call( luan, fnExpr.eval(luan) );
	}

	private Object call(LuanStateImpl luan,Object o) throws LuanException {
		luan.push(el,fnName);
		try {
			if( o instanceof LuanFunction ) {
				LuanFunction fn = (LuanFunction)o;
				return fn.call( luan, Luan.array(args.eval(luan)) );
			}
			if( o instanceof LuanTable ) {
				LuanTable t = (LuanTable)o;
				Object h = t.getHandler("__call");
				if( h != null )
					return call(luan,h);
			}
			throw luan.exception( "attempt to call '"+fnName+"' (a " + Luan.type(o) + " value)" );
		} finally {
			luan.pop();
		}
	}

	@Override public String toString() {
		return "(FnCall "+fnName+" "+fnExpr+" "+args+")";
	}
}