package org.codehaus.plexus.util.xml;

/*
 * Copyright The Codehaus Foundation.
 *
 * 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.
 */

import org.codehaus.plexus.util.xml.pull.XmlSerializer;

import java.io.IOException;
import java.io.Serializable;
import java.io.StringWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.ListIterator;
import java.util.Map;

Version:
$Id$ NOTE: remove all the util code in here when separated, this class should be pure data./**
 * @version $Id$ NOTE: remove all the util code in here when separated, this class should be pure data.
 */
public class Xpp3Dom
    implements Serializable
{
    private static final long serialVersionUID = 2567894443061173996L;

    protected String name;

    protected String value;

    protected Map<String, String> attributes;

    protected final List<Xpp3Dom> childList;

    protected Xpp3Dom parent;

    
Since:
3.2.0/**
     * @since 3.2.0
     */
    protected Object inputLocation;

    private static final String[] EMPTY_STRING_ARRAY = new String[0];

    private static final Xpp3Dom[] EMPTY_DOM_ARRAY = new Xpp3Dom[0];

    public static final String CHILDREN_COMBINATION_MODE_ATTRIBUTE = "combine.children";

    public static final String CHILDREN_COMBINATION_MERGE = "merge";

    public static final String CHILDREN_COMBINATION_APPEND = "append";

    
This default mode for combining children DOMs during merge means that where element names match, the process will
try to merge the element data, rather than putting the dominant and recessive elements (which share the same
element name) as siblings in the resulting DOM.
/**
     * This default mode for combining children DOMs during merge means that where element names match, the process will
     * try to merge the element data, rather than putting the dominant and recessive elements (which share the same
     * element name) as siblings in the resulting DOM.
     */
    public static final String DEFAULT_CHILDREN_COMBINATION_MODE = CHILDREN_COMBINATION_MERGE;

    public static final String SELF_COMBINATION_MODE_ATTRIBUTE = "combine.self";

    public static final String SELF_COMBINATION_OVERRIDE = "override";

    public static final String SELF_COMBINATION_MERGE = "merge";

    
This default mode for combining a DOM node during merge means that where element names match, the process will
try to merge the element attributes and values, rather than overriding the recessive element completely with the
dominant one. This means that wherever the dominant element doesn't provide the value or a particular attribute,
that value or attribute will be set from the recessive DOM node.
/**
     * This default mode for combining a DOM node during merge means that where element names match, the process will
     * try to merge the element attributes and values, rather than overriding the recessive element completely with the
     * dominant one. This means that wherever the dominant element doesn't provide the value or a particular attribute,
     * that value or attribute will be set from the recessive DOM node.
     */
    public static final String DEFAULT_SELF_COMBINATION_MODE = SELF_COMBINATION_MERGE;

    public Xpp3Dom( String name )
    {
        this.name = name;
        childList = new ArrayList<Xpp3Dom>();
    }

    
Since:
3.2.0/**
     * @since 3.2.0
     */
    public Xpp3Dom( String name, Object inputLocation )
    {
        this( name );
        this.inputLocation = inputLocation;
    }

    
Copy constructor.
/**
     * Copy constructor.
     */
    public Xpp3Dom( Xpp3Dom src )
    {
        this( src, src.getName() );
    }

    
Copy constructor with alternative name.
/**
     * Copy constructor with alternative name.
     */
    public Xpp3Dom( Xpp3Dom src, String name )
    {
        this.name = name;
        this.inputLocation = src.inputLocation;

        int childCount = src.getChildCount();

        childList = new ArrayList<Xpp3Dom>( childCount );

        setValue( src.getValue() );

        String[] attributeNames = src.getAttributeNames();
        for ( String attributeName : attributeNames )
        {
            setAttribute( attributeName, src.getAttribute( attributeName ) );
        }

        for ( int i = 0; i < childCount; i++ )
        {
            addChild( new Xpp3Dom( src.getChild( i ) ) );
        }
    }

    // ----------------------------------------------------------------------
    // Name handling
    // ----------------------------------------------------------------------

    public String getName()
    {
        return name;
    }

    // ----------------------------------------------------------------------
    // Value handling
    // ----------------------------------------------------------------------

    public String getValue()
    {
        return value;
    }

    public void setValue( String value )
    {
        this.value = value;
    }

    // ----------------------------------------------------------------------
    // Attribute handling
    // ----------------------------------------------------------------------

    public String[] getAttributeNames()
    {
        if ( null == attributes || attributes.isEmpty() )
        {
            return EMPTY_STRING_ARRAY;
        }
        else
        {
            return attributes.keySet().toArray( EMPTY_STRING_ARRAY );
        }
    }

    public String getAttribute( String name )
    {
        return ( null != attributes ) ? attributes.get( name ) : null;
    }

    
Set the attribute value
Params:
name – String not null
value – String not null/**
     * Set the attribute value
     * 
     * @param name String not null
     * @param value String not null
     */
    public void setAttribute( String name, String value )
    {
        if ( null == value )
        {
            throw new NullPointerException( "Attribute value can not be null" );
        }
        if ( null == name )
        {
            throw new NullPointerException( "Attribute name can not be null" );
        }
        if ( null == attributes )
        {
            attributes = new HashMap<String, String>();
        }

        attributes.put( name, value );
    }

    // ----------------------------------------------------------------------
    // Child handling
    // ----------------------------------------------------------------------

    public Xpp3Dom getChild( int i )
    {
        return childList.get( i );
    }

    public Xpp3Dom getChild( String name )
    {
        if ( name != null )
        {
            ListIterator<Xpp3Dom> it = childList.listIterator( childList.size() );
            while ( it.hasPrevious() )
            {
                Xpp3Dom child = it.previous();
                if ( name.equals( child.getName() ) )
                {
                    return child;
                }
            }
        }
        return null;
    }

    public void addChild( Xpp3Dom xpp3Dom )
    {
        xpp3Dom.setParent( this );
        childList.add( xpp3Dom );
    }

    public Xpp3Dom[] getChildren()
    {
        if ( null == childList || childList.isEmpty() )
        {
            return EMPTY_DOM_ARRAY;
        }
        else
        {
            return childList.toArray( EMPTY_DOM_ARRAY );
        }
    }

    public Xpp3Dom[] getChildren( String name )
    {
        return getChildrenAsList( name ).toArray( EMPTY_DOM_ARRAY );
    }

    private List<Xpp3Dom> getChildrenAsList( String name )
    {
        if ( null == childList )
        {
            return Collections.emptyList();
        }
        else
        {
            ArrayList<Xpp3Dom> children = null;

            for ( Xpp3Dom configuration : childList )
            {
                if ( name.equals( configuration.getName() ) )
                {
                    if ( children == null )
                    {
                        children = new ArrayList<Xpp3Dom>();
                    }
                    children.add( configuration );
                }
            }

            if ( children != null )
            {
                return children;
            }
            else
            {
                return Collections.emptyList();
            }
        }
    }

    public int getChildCount()
    {
        if ( null == childList )
        {
            return 0;
        }

        return childList.size();
    }

    public void removeChild( int i )
    {
        Xpp3Dom child = getChild( i );
        childList.remove( i );
        // In case of any dangling references
        child.setParent( null );
    }

    // ----------------------------------------------------------------------
    // Parent handling
    // ----------------------------------------------------------------------

    public Xpp3Dom getParent()
    {
        return parent;
    }

    public void setParent( Xpp3Dom parent )
    {
        this.parent = parent;
    }

    // ----------------------------------------------------------------------
    // Input location handling
    // ----------------------------------------------------------------------

    
Since:
3.2.0/**
     * @since 3.2.0
     */
    public Object getInputLocation()
    {
        return inputLocation;
    }

    
Since:
3.2.0/**
     * @since 3.2.0
     */
    public void setInputLocation( Object inputLocation )
    {
        this.inputLocation = inputLocation;
    }

    // ----------------------------------------------------------------------
    // Helpers
    // ----------------------------------------------------------------------

    public void writeToSerializer( String namespace, XmlSerializer serializer )
        throws IOException
    {
        // TODO: WARNING! Later versions of plexus-utils psit out an <?xml ?> header due to thinking this is a new
        // document - not the desired behaviour!
        SerializerXMLWriter xmlWriter = new SerializerXMLWriter( namespace, serializer );
        Xpp3DomWriter.write( xmlWriter, this );
        if ( xmlWriter.getExceptions().size() > 0 )
        {
            throw (IOException) xmlWriter.getExceptions().get( 0 );
        }
    }

    
Merges one DOM into another, given a specific algorithm and possible override points for that algorithm.

The algorithm is as follows:

 if the recessive DOM is null, there is nothing to do... return.
 Determine whether the dominant node will suppress the recessive one (flag=mergeSelf).
  

  
 retrieve the 'combine.self' attribute on the dominant node, and try to match against 'override'...
       if it matches 'override', then set mergeSelf == false...the dominant node suppresses the recessive one
       completely.
  
 otherwise, use the default value for mergeSelf, which is true...this is the same as specifying
       'combine.self' == 'merge' as an attribute of the dominant root node.
  
 If mergeSelf == true
  

  
 if the dominant root node's value is empty, set it to the recessive root node's value
  
 For each attribute in the recessive root node which is not set in the dominant root node, set it.
  
 Determine whether children from the recessive DOM will be merged or appended to the dominant DOM as
       siblings (flag=mergeChildren).
    

    
 if childMergeOverride is set (non-null), use that value (true/false)
    
 retrieve the 'combine.children' attribute on the dominant node, and try to match against
         'append'...
    
 if it matches 'append', then set mergeChildren == false...the recessive children will be appended as
         siblings of the dominant children.
    
 otherwise, use the default value for mergeChildren, which is true...this is the same as specifying
        'combine.children' == 'merge' as an attribute on the dominant root node.
    
  
 Iterate through the recessive children, and:
    

    
 if mergeChildren == true and there is a corresponding dominant child (matched by element name),
         merge the two.
    
 otherwise, add the recessive child as a new child on the dominant root node.
    
  

/**
     * Merges one DOM into another, given a specific algorithm and possible override points for that algorithm.<p>
     * The algorithm is as follows:
     * <ol>
     * <li> if the recessive DOM is null, there is nothing to do... return.</li>
     * <li> Determine whether the dominant node will suppress the recessive one (flag=mergeSelf).
     *   <ol type="A">
     *   <li> retrieve the 'combine.self' attribute on the dominant node, and try to match against 'override'...
     *        if it matches 'override', then set mergeSelf == false...the dominant node suppresses the recessive one
     *        completely.</li>
     *   <li> otherwise, use the default value for mergeSelf, which is true...this is the same as specifying
     *        'combine.self' == 'merge' as an attribute of the dominant root node.</li>
     *   </ol></li>
     * <li> If mergeSelf == true
     *   <ol type="A">
     *   <li> if the dominant root node's value is empty, set it to the recessive root node's value</li>
     *   <li> For each attribute in the recessive root node which is not set in the dominant root node, set it.</li>
     *   <li> Determine whether children from the recessive DOM will be merged or appended to the dominant DOM as
     *        siblings (flag=mergeChildren).
     *     <ol type="i">
     *     <li> if childMergeOverride is set (non-null), use that value (true/false)</li>
     *     <li> retrieve the 'combine.children' attribute on the dominant node, and try to match against
     *          'append'...</li>
     *     <li> if it matches 'append', then set mergeChildren == false...the recessive children will be appended as
     *          siblings of the dominant children.</li>
     *     <li> otherwise, use the default value for mergeChildren, which is true...this is the same as specifying
     *         'combine.children' == 'merge' as an attribute on the dominant root node.</li>
     *     </ol></li>
     *   <li> Iterate through the recessive children, and:
     *     <ol type="i">
     *     <li> if mergeChildren == true and there is a corresponding dominant child (matched by element name),
     *          merge the two.</li>
     *     <li> otherwise, add the recessive child as a new child on the dominant root node.</li>
     *     </ol></li>
     *   </ol></li>
     * </ol>
     */
    private static void mergeIntoXpp3Dom( Xpp3Dom dominant, Xpp3Dom recessive, Boolean childMergeOverride )
    {
        // TODO: share this as some sort of assembler, implement a walk interface?
        if ( recessive == null )
        {
            return;
        }

        boolean mergeSelf = true;

        String selfMergeMode = dominant.getAttribute( SELF_COMBINATION_MODE_ATTRIBUTE );

        if ( SELF_COMBINATION_OVERRIDE.equals( selfMergeMode ) )
        {
            mergeSelf = false;
        }

        if ( mergeSelf )
        {
            if ( isEmpty( dominant.getValue() ) && !isEmpty( recessive.getValue() ) )
            {
                dominant.setValue( recessive.getValue() );
                dominant.setInputLocation( recessive.getInputLocation() );
            }

            if ( recessive.attributes != null )
            {
                for ( String attr : recessive.attributes.keySet() )
                {
                    if ( isEmpty( dominant.getAttribute( attr ) ) )
                    {
                        dominant.setAttribute( attr, recessive.getAttribute( attr ) );
                    }
                }
            }

            if ( recessive.getChildCount() > 0 )
            {
                boolean mergeChildren = true;

                if ( childMergeOverride != null )
                {
                    mergeChildren = childMergeOverride;
                }
                else
                {
                    String childMergeMode = dominant.getAttribute( CHILDREN_COMBINATION_MODE_ATTRIBUTE );

                    if ( CHILDREN_COMBINATION_APPEND.equals( childMergeMode ) )
                    {
                        mergeChildren = false;
                    }
                }

                if ( !mergeChildren )
                {
                    Xpp3Dom[] dominantChildren = dominant.getChildren();
                    // remove these now, so we can append them to the recessive list later.
                    dominant.childList.clear();

                    for ( int i = 0, recessiveChildCount = recessive.getChildCount(); i < recessiveChildCount; i++ )
                    {
                        Xpp3Dom recessiveChild = recessive.getChild( i );
                        dominant.addChild( new Xpp3Dom( recessiveChild ) );
                    }

                    // now, re-add these children so they'll be appended to the recessive list.
                    for ( Xpp3Dom aDominantChildren : dominantChildren )
                    {
                        dominant.addChild( aDominantChildren );
                    }
                }
                else
                {
                    Map<String, Iterator<Xpp3Dom>> commonChildren = new HashMap<String, Iterator<Xpp3Dom>>();

                    for ( Xpp3Dom recChild : recessive.childList )
                    {
                        if ( commonChildren.containsKey( recChild.name ) )
                        {
                            continue;
                        }
                        List<Xpp3Dom> dominantChildren = dominant.getChildrenAsList( recChild.name );
                        if ( dominantChildren.size() > 0 )
                        {
                            commonChildren.put( recChild.name, dominantChildren.iterator() );
                        }
                    }

                    for ( int i = 0, recessiveChildCount = recessive.getChildCount(); i < recessiveChildCount; i++ )
                    {
                        Xpp3Dom recessiveChild = recessive.getChild( i );
                        Iterator<Xpp3Dom> it = commonChildren.get( recessiveChild.getName() );
                        if ( it == null )
                        {
                            dominant.addChild( new Xpp3Dom( recessiveChild ) );
                        }
                        else if ( it.hasNext() )
                        {
                            Xpp3Dom dominantChild = it.next();
                            mergeIntoXpp3Dom( dominantChild, recessiveChild, childMergeOverride );
                        }
                    }
                }
            }
        }
    }

    
Merge two DOMs, with one having dominance in the case of collision.
Params:
dominant – The dominant DOM into which the recessive value/attributes/children will be merged
recessive – The recessive DOM, which will be merged into the dominant DOM
childMergeOverride – Overrides attribute flags to force merging or appending of child elements into the
           dominant DOM
See Also:
CHILDREN_COMBINATION_MODE_ATTRIBUTE
SELF_COMBINATION_MODE_ATTRIBUTE/**
     * Merge two DOMs, with one having dominance in the case of collision.
     *
     * @see #CHILDREN_COMBINATION_MODE_ATTRIBUTE
     * @see #SELF_COMBINATION_MODE_ATTRIBUTE
     * @param dominant The dominant DOM into which the recessive value/attributes/children will be merged
     * @param recessive The recessive DOM, which will be merged into the dominant DOM
     * @param childMergeOverride Overrides attribute flags to force merging or appending of child elements into the
     *            dominant DOM
     */
    public static Xpp3Dom mergeXpp3Dom( Xpp3Dom dominant, Xpp3Dom recessive, Boolean childMergeOverride )
    {
        if ( dominant != null )
        {
            mergeIntoXpp3Dom( dominant, recessive, childMergeOverride );
            return dominant;
        }
        return recessive;
    }

    
Merge two DOMs, with one having dominance in the case of collision. Merge mechanisms (vs. override for nodes, or
vs. append for children) is determined by attributes of the dominant root node.
Params:
dominant – The dominant DOM into which the recessive value/attributes/children will be merged
recessive – The recessive DOM, which will be merged into the dominant DOM
See Also:
CHILDREN_COMBINATION_MODE_ATTRIBUTE
SELF_COMBINATION_MODE_ATTRIBUTE/**
     * Merge two DOMs, with one having dominance in the case of collision. Merge mechanisms (vs. override for nodes, or
     * vs. append for children) is determined by attributes of the dominant root node.
     *
     * @see #CHILDREN_COMBINATION_MODE_ATTRIBUTE
     * @see #SELF_COMBINATION_MODE_ATTRIBUTE
     * @param dominant The dominant DOM into which the recessive value/attributes/children will be merged
     * @param recessive The recessive DOM, which will be merged into the dominant DOM
     */
    public static Xpp3Dom mergeXpp3Dom( Xpp3Dom dominant, Xpp3Dom recessive )
    {
        if ( dominant != null )
        {
            mergeIntoXpp3Dom( dominant, recessive, null );
            return dominant;
        }
        return recessive;
    }

    // ----------------------------------------------------------------------
    // Standard object handling
    // ----------------------------------------------------------------------

    public boolean equals( Object obj )
    {
        if ( obj == this )
        {
            return true;
        }

        if ( !( obj instanceof Xpp3Dom ) )
        {
            return false;
        }

        Xpp3Dom dom = (Xpp3Dom) obj;

        if ( name == null ? dom.name != null : !name.equals( dom.name ) )
        {
            return false;
        }
        else if ( value == null ? dom.value != null : !value.equals( dom.value ) )
        {
            return false;
        }
        else if ( attributes == null ? dom.attributes != null : !attributes.equals( dom.attributes ) )
        {
            return false;
        }
        else if ( childList == null ? dom.childList != null : !childList.equals( dom.childList ) )
        {
            return false;
        }
        else
        {
            return true;
        }
    }

    public int hashCode()
    {
        int result = 17;
        result = 37 * result + ( name != null ? name.hashCode() : 0 );
        result = 37 * result + ( value != null ? value.hashCode() : 0 );
        result = 37 * result + ( attributes != null ? attributes.hashCode() : 0 );
        result = 37 * result + ( childList != null ? childList.hashCode() : 0 );
        return result;
    }

    public String toString()
    {
        // TODO: WARNING! Later versions of plexus-utils psit out an <?xml ?> header due to thinking this is a new
        // document - not the desired behaviour!
        StringWriter writer = new StringWriter();
        XMLWriter xmlWriter = new PrettyPrintXMLWriter( writer, "UTF-8", null );
        Xpp3DomWriter.write( xmlWriter, this );
        return writer.toString();
    }

    public String toUnescapedString()
    {
        // TODO: WARNING! Later versions of plexus-utils psit out an <?xml ?> header due to thinking this is a new
        // document - not the desired behaviour!
        StringWriter writer = new StringWriter();
        XMLWriter xmlWriter = new PrettyPrintXMLWriter( writer, "UTF-8", null );
        Xpp3DomWriter.write( xmlWriter, this, false );
        return writer.toString();
    }

    public static boolean isNotEmpty( String str )
    {
        return ( ( str != null ) && ( str.length() > 0 ) );
    }

    public static boolean isEmpty( String str )
    {
        return ( ( str == null ) || ( str.trim().length() == 0 ) );
    }

}