/*
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 *
 * This software is open source.
 * See the bottom of this file for the licence.
 */

package org.dom4j.util;

import java.util.Comparator;

import org.dom4j.Attribute;
import org.dom4j.Branch;
import org.dom4j.CDATA;
import org.dom4j.CharacterData;
import org.dom4j.Comment;
import org.dom4j.Document;
import org.dom4j.DocumentType;
import org.dom4j.Element;
import org.dom4j.Entity;
import org.dom4j.Namespace;
import org.dom4j.Node;
import org.dom4j.ProcessingInstruction;
import org.dom4j.QName;
import org.dom4j.Text;

/**
 * <p>
 * <code>NodeComparator</code> is a {@link Comparator}of Node instances which
 * is capable of comparing Nodes for equality based on their values.
 * </p>
 * 
 * @author <a href="mailto:jstrachan@apache.org">James Strachan </a>
 * @version $Revision: 1.10 $
 */
public class NodeComparator implements Comparator {
    /**
     * Compares its two arguments for order. Returns a negative integer, zero,
     * or a positive integer as the first argument is less than, equal to, or
     * greater than the second.
     * 
     * <p>
     * The implementor must ensure that <tt>sgn(compare(x, y)) ==
     * -sgn(compare(y, x))</tt>
     * for all <tt>x</tt> and <tt>y</tt>. (This implies that
     * <tt>compare(x, y)</tt> must throw an exception if and only if
     * <tt>compare(y, x)</tt> throws an exception.)
     * </p>
     * 
     * <p>
     * The implementor must also ensure that the relation is transitive:
     * <tt>((compare(x, y)&gt;0) &amp;&amp; (compare(y, z)&gt;0))</tt> implies
     * <tt>compare(x, z)&gt;0</tt>.
     * </p>
     * 
     * <p>
     * Finally, the implementer must ensure that <tt>compare(x, y)==0</tt>
     * implies that <tt>sgn(compare(x, z))==sgn(compare(y, z))</tt> for all
     * <tt>z</tt>.
     * </p>
     * 
     * <p>
     * It is generally the case, but <i>not </i> strictly required that
     * <tt>(compare(x, y)==0) == (x.equals(y))</tt>. Generally speaking, any
     * comparator that violates this condition should clearly indicate this
     * fact. The recommended language is "Note: this comparator imposes
     * orderings that are inconsistent with equals."
     * </p>
     * 
     * @param o1
     *            the first object to be compared.
     * @param o2
     *            the second object to be compared.
     * 
     * @return a negative integer, zero, or a positive integer as the first
     *         argument is less than, equal to, or greater than the second.
     */
    public int compare(Object o1, Object o2) {
        if (o1 == o2) {
            return 0;
        } else if (o1 == null) {
            // null is less
            return -1;
        } else if (o2 == null) {
            return 1;
        }

        if (o1 instanceof Node) {
            if (o2 instanceof Node) {
                return compare((Node) o1, (Node) o2);
            } else {
                // Node implementations are greater
                return 1;
            }
        } else {
            if (o2 instanceof Node) {
                // Node implementations are greater
                return -1;
            } else {
                if (o1 instanceof Comparable) {
                    Comparable c1 = (Comparable) o1;

                    return c1.compareTo(o2);
                } else {
                    String name1 = o1.getClass().getName();
                    String name2 = o2.getClass().getName();

                    return name1.compareTo(name2);
                }
            }
        }
    }

    public int compare(Node n1, Node n2) {
        int nodeType1 = n1.getNodeType();
        int nodeType2 = n2.getNodeType();
        int answer = nodeType1 - nodeType2;

        if (answer != 0) {
            return answer;
        } else {
            switch (nodeType1) {
                case Node.ELEMENT_NODE:
                    return compare((Element) n1, (Element) n2);

                case Node.DOCUMENT_NODE:
                    return compare((Document) n1, (Document) n2);

                case Node.ATTRIBUTE_NODE:
                    return compare((Attribute) n1, (Attribute) n2);

                case Node.TEXT_NODE:
                    return compare((Text) n1, (Text) n2);

                case Node.CDATA_SECTION_NODE:
                    return compare((CDATA) n1, (CDATA) n2);

                case Node.ENTITY_REFERENCE_NODE:
                    return compare((Entity) n1, (Entity) n2);

                case Node.PROCESSING_INSTRUCTION_NODE:
                    return compare((ProcessingInstruction) n1,
                            (ProcessingInstruction) n2);

                case Node.COMMENT_NODE:
                    return compare((Comment) n1, (Comment) n2);

                case Node.DOCUMENT_TYPE_NODE:
                    return compare((DocumentType) n1, (DocumentType) n2);

                case Node.NAMESPACE_NODE:
                    return compare((Namespace) n1, (Namespace) n2);

                default:
                    throw new RuntimeException("Invalid node types. node1: "
                            + n1 + " and node2: " + n2);
            }
        }
    }

    public int compare(Document n1, Document n2) {
        int answer = compare(n1.getDocType(), n2.getDocType());

        if (answer == 0) {
            answer = compareContent(n1, n2);
        }

        return answer;
    }

    public int compare(Element n1, Element n2) {
        int answer = compare(n1.getQName(), n2.getQName());

        if (answer == 0) {
            // lets compare attributes
            int c1 = n1.attributeCount();
            int c2 = n2.attributeCount();
            answer = c1 - c2;

            if (answer == 0) {
                for (int i = 0; i < c1; i++) {
                    Attribute a1 = n1.attribute(i);
                    Attribute a2 = n2.attribute(a1.getQName());
                    answer = compare(a1, a2);

                    if (answer != 0) {
                        return answer;
                    }
                }

                answer = compareContent(n1, n2);
            }
        }

        return answer;
    }

    public int compare(Attribute n1, Attribute n2) {
        int answer = compare(n1.getQName(), n2.getQName());

        if (answer == 0) {
            answer = compare(n1.getValue(), n2.getValue());
        }

        return answer;
    }

    public int compare(QName n1, QName n2) {
        int answer = compare(n1.getNamespaceURI(), n2.getNamespaceURI());

        if (answer == 0) {
            answer = compare(n1.getQualifiedName(), n2.getQualifiedName());
        }

        return answer;
    }

    public int compare(Namespace n1, Namespace n2) {
        int answer = compare(n1.getURI(), n2.getURI());

        if (answer == 0) {
            answer = compare(n1.getPrefix(), n2.getPrefix());
        }

        return answer;
    }

    public int compare(CharacterData t1, CharacterData t2) {
        return compare(t1.getText(), t2.getText());
    }

    public int compare(DocumentType o1, DocumentType o2) {
        if (o1 == o2) {
            return 0;
        } else if (o1 == null) {
            // null is less
            return -1;
        } else if (o2 == null) {
            return 1;
        }

        int answer = compare(o1.getPublicID(), o2.getPublicID());

        if (answer == 0) {
            answer = compare(o1.getSystemID(), o2.getSystemID());

            if (answer == 0) {
                answer = compare(o1.getName(), o2.getName());
            }
        }

        return answer;
    }

    public int compare(Entity n1, Entity n2) {
        int answer = compare(n1.getName(), n2.getName());

        if (answer == 0) {
            answer = compare(n1.getText(), n2.getText());
        }

        return answer;
    }

    public int compare(ProcessingInstruction n1, ProcessingInstruction n2) {
        int answer = compare(n1.getTarget(), n2.getTarget());

        if (answer == 0) {
            answer = compare(n1.getText(), n2.getText());
        }

        return answer;
    }

    public int compareContent(Branch b1, Branch b2) {
        int c1 = b1.nodeCount();
        int c2 = b2.nodeCount();
        int answer = c1 - c2;

        if (answer == 0) {
            for (int i = 0; i < c1; i++) {
                Node n1 = b1.node(i);
                Node n2 = b2.node(i);
                answer = compare(n1, n2);

                if (answer != 0) {
                    break;
                }
            }
        }

        return answer;
    }

    public int compare(String o1, String o2) {
        if (o1 == o2) {
            return 0;
        } else if (o1 == null) {
            // null is less
            return -1;
        } else if (o2 == null) {
            return 1;
        }

        return o1.compareTo(o2);
    }
}

/*
 * Redistribution and use of this software and associated documentation
 * ("Software"), with or without modification, are permitted provided that the
 * following conditions are met:
 * 
 * 1. Redistributions of source code must retain copyright statements and
 * notices. Redistributions must also contain a copy of this document.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * 
 * 3. The name "DOM4J" must not be used to endorse or promote products derived
 * from this Software without prior written permission of MetaStuff, Ltd. For
 * written permission, please contact dom4j-info@metastuff.com.
 * 
 * 4. Products derived from this Software may not be called "DOM4J" nor may
 * "DOM4J" appear in their names without prior written permission of MetaStuff,
 * Ltd. DOM4J is a registered trademark of MetaStuff, Ltd.
 * 
 * 5. Due credit should be given to the DOM4J Project - http://www.dom4j.org
 * 
 * THIS SOFTWARE IS PROVIDED BY METASTUFF, LTD. AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL METASTUFF, LTD. OR ITS CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 * 
 * Copyright 2001-2005 (C) MetaStuff, Ltd. All Rights Reserved.
 */
