/*
 * Copyright 2005-2010 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.xml;

import java.io.Serializable;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;
import java.util.Map;
import java.util.TreeMap;

import junit.framework.TestCase;

import org.dom4j.Attribute;
import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.DOMReader;
import org.dom4j.io.DOMWriter;

/**
 * XML test support utilities.
 * 
 * @author Erik Brakkee
 */
public final class XmlUtils {
    /**
     * Disabled constructor.
     * 
     */
    private XmlUtils() {
        // Empty
    }

    /**
     * Checks equality of two XML documents excluding comment and processing
     * nodes and trimming the text of the elements. In case of problems, it
     * provides an xpath-like expression describing where the problem is.
     * 
     * @param aMsg
     * @param aExpected
     * @param aActual
     */
    public static void assertEquals(String aMsg,
        org.w3c.dom.Document aExpected, org.w3c.dom.Document aActual) {
        assertEquals(aMsg, convert(aExpected), convert(aActual));
    }

    /**
     * Checks equality of two XML documents excluding comment and processing
     * nodes and trimming the text of the elements. In case of problems, it
     * provides an xpath-like expression describing where the problem is.
     * 
     * @param aMsg
     * @param aExpected
     * @param aActual
     */
    public static void assertEquals(String aMsg, Document aExpected,
        Document aActual) {
        assertEquals(aMsg + "/" + aExpected.getRootElement().getName(),
            aExpected.getRootElement(), aActual.getRootElement());
    }

    /**
     * Checks equality of two XML elements excluding comment and processing
     * nodes and trimming the text of the elements. In case of problems, it
     * provides an xpath-like expression describing where the problem is.
     * 
     * @param aMsg
     * @param aExpected
     * @param aActual
     */
    public static void assertEquals(String aMsg, Element aExpected,
        Element aActual) {
        // Name.
        TestCase.assertEquals(aMsg + "/name()", aExpected.getName(), aActual
            .getName());

        // Text
        TestCase.assertEquals(aMsg + "/text()", aExpected.getTextTrim(),
            aActual.getTextTrim());

        // Attributes
        List<Attribute> expectedAttrs = aExpected.attributes();
        Collections.sort(expectedAttrs, new AttributeComparator());

        List<Attribute> actualAttrs = aActual.attributes();
        Collections.sort(actualAttrs, new AttributeComparator());

        TestCase.assertEquals("count(" + aMsg + "/@*)", expectedAttrs.size(),
            actualAttrs.size());

        for (int i = 0; i < expectedAttrs.size(); i++) {
            String msg = aMsg + "/@" + expectedAttrs.get(i).getName();
            assertEquals(msg, expectedAttrs.get(i), actualAttrs.get(i));
        }

        // Nested elements.
        List<Element> expectedElems = aExpected.elements();
        List<Element> actualElems = aActual.elements();
        TestCase.assertEquals("count(" + aMsg + "/*)", expectedElems.size(),
            actualElems.size());

        // determine the how-manyth element of the given name we are at.
        // Maps element name to the last used index (or null if not yet used)
        Map<String, Integer> elementIndex = new TreeMap<String, Integer>();

        for (int i = 0; i < expectedElems.size(); i++) {
            String elemName = expectedElems.get(i).getName();
            Integer index = elementIndex.get(elemName);

            if (index == null) {
                index = 1;
            } else {
                index++;
            }

            elementIndex.put(elemName, index);

            String msg = aMsg + "/" + expectedElems.get(i).getName() + "[" +
                index + "]";

            assertEquals(msg, expectedElems.get(i), actualElems.get(i));
        }
    }

    /**
     * Checks equality of two attributes. In case of problems, it provides an
     * xpath-like expression describing where the problem is.
     * 
     * @param aMsg
     * @param aExpected
     * @param aActual
     */
    public static void assertEquals(String aMsg, Attribute aExpected,
        Attribute aActual) {
        TestCase.assertEquals(aMsg + ":name", aExpected.getName(), aActual
            .getName());
        TestCase.assertEquals(aMsg + ":value", aExpected.getValue(), aActual
            .getValue());
    }

    /**
     * Comparator which compares attributes by name.
     */
    private static final class AttributeComparator implements
        Comparator<Attribute>, Serializable {

        private static final long serialVersionUID = 7897287273519886301L;

        /*
         * (non-Javadoc)
         * 
         * @see java.util.Comparator#compare(T, T)
         */
        public int compare(Attribute aAttribute1, Attribute aAttribute2) {
            return aAttribute1.getName().compareTo(aAttribute2.getName());
        }
    }
    
    /**
     * Converts a dom4j document into a w3c DOM document.
     * 
     * @param aDocument
     *            Document to convert.
     * 
     * @return W3C DOM document.
     * 
     */
    public static org.w3c.dom.Document convert(org.dom4j.Document aDocument)
        throws DocumentException {
        return new DOMWriter().write(aDocument);
    } 

    /**
     * Converts a W3C DOM document into a dom4j document.
     * 
     * @param aDocument
     *            Document to convert.
     * 
     * @return Dom4j document.
     */
    public static org.dom4j.Document convert(org.w3c.dom.Document aDocument) {
        return new DOMReader().read(aDocument);
    }
    
}