/*
 * 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.ArrayList;
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.w3c.dom.Attr;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NamedNodeMap;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;

/**
 * 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, Document aExpected,
        Document aActual) {
        assertEquals(
            aMsg + "/" + aExpected.getDocumentElement().getLocalName(),
            aExpected.getDocumentElement(), aActual.getDocumentElement());
    }

    private static <T> List<T> convertMap(NamedNodeMap aMap, Class<T> aType) {
        List<T> result = new ArrayList<T>();
        for (int i = 0; i < aMap.getLength(); i++) {
            result.add((T) aMap.item(i));
        }
        return result;
    }

    private static List<Element> getChildElements(Element aElement) {
        List<Element> result = new ArrayList<Element>();
        NodeList children = aElement.getChildNodes();
        for (int i = 0; i < children.getLength(); i++) {
            Node node = children.item(i);
            if (node instanceof Element) {
                result.add((Element) node);
            }
        }
        return result;
    }
    
    private static String getDirectText(Element aElement) { 
        String res = "";
        NodeList children = aElement.getChildNodes();
        for (int i = 0; i < children.getLength(); i++) {
            Node node = children.item(i);
            if (node instanceof Text) {
                res += node.getTextContent() + " ";
            }
        }
        return trim(res); 
    }
    
    private static String trim(String aText) { 
        return aText.trim().replaceAll("\\n", " ").replaceAll("\\s+", " ");
    }

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

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

        // Attributes
        List<Attr> expectedAttrs = convertMap(aExpected.getAttributes(),
            Attr.class);

        Collections.sort(expectedAttrs, new AttributeComparator());

        List<Attr> actualAttrs = convertMap(aActual.getAttributes(), Attr.class);
        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 = getChildElements(aExpected);
        List<Element> actualElems = getChildElements(aActual);
        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).getLocalName();
            Integer index = elementIndex.get(elemName);

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

            elementIndex.put(elemName, index);

            String msg = aMsg + "/" + expectedElems.get(i).getLocalName() + "[" +
                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
     */
    private static void assertEquals(String aMsg, Attr aExpected, Attr 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<Attr>,
        Serializable {

        private static final long serialVersionUID = 7897287273519886301L;

        /*
         * (non-Javadoc)
         * 
         * @see java.util.Comparator#compare(T, T)
         */
        public int compare(Attr aAttribute1, Attr aAttribute2) {
            return aAttribute1.getName().compareTo(aAttribute2.getName());
        }
    }
}