/**
 * The contents of this file are subject to the license and copyright
 * detailed in the LICENSE and NOTICE files at the root of the source
 * tree and available online at
 *
 * http://www.dspace.org/license/
 */
package org.dspace.app.xmlui.wing.element;

import org.dspace.app.xmlui.wing.WingConstants;
import org.dspace.app.xmlui.wing.WingContext;
import org.dspace.app.xmlui.wing.WingException;
import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.SAXException;
import org.xml.sax.ext.LexicalHandler;
import org.xml.sax.helpers.NamespaceSupport;

/**
 * A class representing the page division.
 * 
 * The body contains any number of divisions (div elements) which group content
 * into interactive and non interactive display blocks.
 * 
 * @author Scott Phillips
 */
public class Meta extends AbstractWingElement implements WingMergeableElement
{
    /** The name of the meta element */
    public static final String E_META = "meta";

    /** The divisions contained within this body */
    private boolean merged = false;

    /** User oriented metadata associated with this document */
    private UserMeta userMeta;

    /** Page oriented metadata associated with this document */
    private PageMeta pageMeta;
    
    /** Repository oriented metadata associated with this document */
    private RepositoryMeta repositoryMeta;
    
    protected Meta(WingContext context) throws WingException
    {
        // FIXME: don't statically assign authenticated status or
        // repositoryIdentifier.
        super(context);
        userMeta = new UserMeta(context);
        pageMeta = new PageMeta(context);
        repositoryMeta = new RepositoryMeta(context);
    }

    /**
     * Set a new user oriented metadata set.
     * 
     * @return The user oriented metadata set.
     * @throws org.dspace.app.xmlui.wing.WingException never.
     */
    public UserMeta setUserMeta() throws WingException
    {
        return this.userMeta;
    }

    /**
     * Set a new page oriented metadata set.
     * 
     * @return The page oriented metadata set.
     * @throws org.dspace.app.xmlui.wing.WingException never.
     */
    public PageMeta setPageMeta() throws WingException
    {
        return this.pageMeta;
    }
    
    /**
     * Set a new repository oriented metadata set.
     * 
     * @return The repository oriented metadata set.
     * @throws org.dspace.app.xmlui.wing.WingException never.
     */
    public RepositoryMeta setRepositoryMeta() throws WingException
    {
        return this.repositoryMeta;
    }
    
    /**
     * Determine if the given SAX event is a Meta element.
     * 
     * @param namespace
     *            The element's name space
     * @param localName
     *            The local, unqualified, name for this element
     * @param qName
     *            The qualified name for this element
     * @param attributes
     *            The element's attributes
     * @return True if this WingElement is equivalent to the given SAX Event.
     */
    @Override
    public boolean mergeEqual(String namespace, String localName, String qName,
            Attributes attributes) throws SAXException, WingException
    {
        if (!WingConstants.DRI.URI.equals(namespace))
        {
            return false;
        }

        return E_META.equals(localName);
    }

    /**
     * Merge the given sub-domain of metadata elements.
     * 
     * @param namespace
     *            The element's name space
     * @param localName
     *            The local, unqualified, name for this element *
     * @param qName
     *            The qualified name for this element
     * @param attributes
     *            The element's attributes
     * @return The child element
     */
    @Override
    public WingMergeableElement mergeChild(String namespace, String localName,
            String qName, Attributes attributes) throws SAXException,
            WingException
    {
        // User
        if (this.userMeta != null
                && this.userMeta.mergeEqual(namespace, localName, qName,
                        attributes))
        {
            UserMeta thisUserMeta = this.userMeta;
            this.userMeta = null;
            return thisUserMeta;
        }

        // page
        if (this.pageMeta != null
                && this.pageMeta.mergeEqual(namespace, localName, qName,
                        attributes))
        {
            PageMeta thisPageMeta = this.pageMeta;
            this.pageMeta = null;
            return thisPageMeta;
        }
        
        // repository
        if (this.repositoryMeta != null
                && this.repositoryMeta.mergeEqual(namespace, localName, qName,
                        attributes))
        {
            RepositoryMeta thisRepositoryMeta = this.repositoryMeta;
            this.repositoryMeta = null;
            return thisRepositoryMeta;
        }
        
        return null;
    }

    /**
     * Notify this element that it is being merged.
     * 
     * @return The attributes for this merged element
     */
    @Override
    public Attributes merge(Attributes attributes) throws SAXException,
            WingException
    {
        this.merged = true;
        return attributes;
    }

    /**
     * Translate to SAX events
     * 
     * @param contentHandler
     *            (Required) The registered contentHandler where SAX events
     *            should be routed too.
     * @param lexicalHandler
     *            (Required) The registered lexicalHandler where lexical 
     *            events (such as CDATA, DTD, etc) should be routed too.
     * @param namespaces
     *            (Required) SAX Helper class to keep track of namespaces able
     *            to determine the correct prefix for a given namespace URI.
     */
    @Override
    public void toSAX(ContentHandler contentHandler, LexicalHandler lexicalHandler, 
            NamespaceSupport namespaces) throws SAXException
    {
        if (!merged)
        {
            startElement(contentHandler, namespaces, E_META, null);
        }

        if (this.userMeta != null)
        {
            this.userMeta.toSAX(contentHandler, lexicalHandler, namespaces);
        }
        if (this.pageMeta != null)
        {
            this.pageMeta.toSAX(contentHandler, lexicalHandler, namespaces);
        }
        if (this.repositoryMeta != null)
        {
            this.repositoryMeta.toSAX(contentHandler, lexicalHandler, namespaces);
        }
           
        if (!merged)
        {
            endElement(contentHandler, namespaces, E_META);
        }
    }

    @Override
    public void dispose()
    {
        if (this.userMeta != null)
        {
            this.userMeta.dispose();
        }
        if (this.pageMeta != null)
        {
            this.pageMeta.dispose();
        }
        if (this.repositoryMeta != null)
        {
            this.repositoryMeta.dispose();
        }
        
        this.userMeta = null;
        this.pageMeta = null;
        this.repositoryMeta = null;
        
        super.dispose();
    }
}