/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.xpath.functions.array;

import java.util.List;

import javax.xml.transform.SourceLocator;

import org.apache.xpath.Expression;
import org.apache.xpath.XPathContext;
import org.apache.xpath.functions.FunctionOneArg;
import org.apache.xpath.objects.XObject;
import org.apache.xpath.objects.XPathArray;
import org.apache.xpath.operations.Variable;

/**
 * Implementation of the array:tail function.
 * 
 * @author Mukul Gandhi <mukulg@apache.org>
 * 
 * @xsl.usage advanced
 */
public class FuncArrayTail extends FunctionOneArg {
	
	private static final long serialVersionUID = 5783190267382201534L;
	
	/**
	 * Class constructor.
	 */
	public FuncArrayTail() {
		m_defined_arity = new Short[] { 1 };
	}

	public XObject execute(XPathContext xctxt) throws javax.xml.transform.TransformerException
	{
	    XObject result = null;
	       
	    SourceLocator srcLocator = xctxt.getSAXLocator();
	       
	    Expression arg0 = getArg0();
	    
	    XObject xObject = null;
	    
	    if (arg0 instanceof Variable) {
	       xObject = ((Variable)arg0).execute(xctxt);
	    }
	    else {
	       xObject = arg0.execute(xctxt);
	    }	    
	    
	    if (xObject instanceof XPathArray) {
	       XPathArray xpathArr = (XPathArray)xObject;
	       if (xpathArr.size() > 0) {
	    	  List<XObject> nativeArr = xpathArr.getNativeArray();
	    	  
	    	  List<XObject> newNativeArr = nativeArr.subList(1, nativeArr.size());
	    	  xpathArr = new XPathArray();
	    	  xpathArr.setNativeArray(newNativeArr);
	    	  
	    	  result = xpathArr;
	       }
	       else {
	    	  throw new javax.xml.transform.TransformerException("FOAY0001 : An array:tail function call's argument "
	    	  		                                                                     + "cannot be an empty array.", srcLocator);  
	       }
	    }
	    else {
	       throw new javax.xml.transform.TransformerException("FOAY0001 : The 1st argument of function array:tail, "
	       		                                                                         + "needs to be an array.", srcLocator); 
	    }
	    
	    return result;
	}

}
