/*
 * Copyright 2005-2011 the original author or authors.
 * 
 * Licensed 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.wamblee.xmlrouter.config;

import org.wamblee.xml.XMLDocument;
import org.wamblee.xml.XMLException;
import org.wamblee.xml.XMLProcessor;
import org.wamblee.xml.XPathExpression;

/**
 * Basic rule for XML routing. 
 * 
 * @author Erik Brakkee
 */
public class Rule {
     
    private XPathExpression condition; 
    private XMLProcessor processor; 
    private String destination; 

    /**
     * Constructs the rule. 
     * @param aCondition Condition to be satisfied. 
     * @param aProcessor XML Processor to be applied when the condition is valid. 
     * @param aDestination Destination for the result of this rule. 
     */
    public Rule(XPathExpression aCondition, XMLProcessor aProcessor, String aDestination) {
        condition = aCondition;
        processor = aProcessor;
        destination = aDestination;
    }
    
    /**
     * Applies the rule to a document. 
     * @param aDocument Document to apply rule ot. 
     * @return Transformed document or null if the rule did not apply. 
     * @throws XMLException In case the application of the rule gives an error. 
     */
    public XMLDocument apply(XMLDocument aDocument) throws XMLException {
        if ( !condition.booleanEval(aDocument)) { 
            return null; 
        }
        return aDocument.process(processor); 
    }
    
    public String getDestination() {
        return destination;
    }
}