package luan.impl;

import luan.Luan;
import luan.LuanException;
import luan.LuanTable;
import luan.LuanFunction;
import luan.LuanSource;
import luan.LuanMeta;
import luan.modules.StringLuan;
import luan.modules.BinaryLuan;
import luan.modules.JavaLuan;


final class IndexExpr extends BinaryOpExpr {

	IndexExpr(LuanSource.Element se,Expr op1,Expr op2) {
		super(se,op1,op2);
	}

	@Override public Object eval(LuanStateImpl luan) throws LuanException {
		return index(luan,op1.eval(luan),op2.eval(luan));
	}

	private Object index(LuanStateImpl luan,Object obj,Object key) throws LuanException {
		if( obj instanceof LuanTable ) {
			LuanTable tbl = (LuanTable)obj;
			Object value = tbl.get(key);
			if( value != null )
				return value;
			Object h = luan.getHandler("__index",tbl);
			if( h==null )
				return null;
			if( h instanceof LuanFunction ) {
				LuanFunction fn = (LuanFunction)h;
				return Luan.first(luan.bit(se).call(fn,"__index",new Object[]{tbl,key}));
			}
			if( h instanceof LuanMeta ) {
				LuanMeta meta = (LuanMeta)h;
				return meta.__index(luan,tbl,key);
			}
			return index(luan,h,key);
		}
		if( obj instanceof String )
			return StringLuan.__index(luan,(String)obj,key);
		if( obj instanceof byte[] )
			return BinaryLuan.__index(luan,(byte[])obj,key);
		if( obj != null ) {
			Object value = JavaLuan.__index(luan,obj,key);
			if( value != null )
				return value;
		}
		throw luan.bit(op1.se()).exception( "attempt to index '"+op1.se().text()+"' (a " + Luan.type(obj) + " value)" );
	}
}