/*
 * Copyright (C) 2005-2007 Alfresco Software Limited.
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.

 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.

 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

 * As a special exception to the terms and conditions of version 2.0 of 
 * the GPL, you may redistribute this Program in connection with Free/Libre 
 * and Open Source Software ("FLOSS") applications as described in Alfresco's 
 * FLOSS exception.  You should have recieved a copy of the text describing 
 * the FLOSS exception, and it is also available here: 
 * http://www.alfresco.com/legal/licensing"
 */
package org.alfresco.repo.content;

import java.io.Serializable;

import org.alfresco.service.cmr.repository.ContentReader;

/**
 * The location and lookup data for content.  The very least data required to
 * find content or assign a content writer is the content URL and any previous
 * content that may have logically existed.
 * <p>
 * Although this class is doesn't enforce any conditions on the context,
 * derived instances may have relationships that need to be maintained between
 * various context values.
 * 
 * @author Derek Hulley
 */
public class ContentContext implements Serializable
{
    private static final long serialVersionUID = 6476617391229895125L;

    /** An empty context. */
    public static final ContentContext NULL_CONTEXT = new ContentContext(null, null);

    private ContentReader existingContentReader;
    private String contentUrl;
    
    /**
     * Construct the instance with the content URL.
     * 
     * @param   existingContentReader   content with which to seed the new writer - may be <tt>null</tt>
     * @param   contentUrl              the content URL - may be <tt>null</tt>
     */
    public ContentContext(ContentReader existingContentReader, String contentUrl)
    {
        this.existingContentReader = existingContentReader;
        this.contentUrl = contentUrl;
    }
    
    @Override
    public String toString()
    {
        StringBuilder sb = new StringBuilder(128);
        sb.append("ContentContext")
          .append("[ contentUrl=").append(getContentUrl())
          .append(", existing=").append((getExistingContentReader() == null ? false : true))
          .append("]");
        return sb.toString();
    }

    /**
     * @return  Returns the content to seed the writer with - may be <tt>null</tt>
     */
    public ContentReader getExistingContentReader()
    {
        return existingContentReader;
    }

    /**
     * @return  Returns the content URL for the content's context - may be <tt>null</tt>
     */
    public String getContentUrl()
    {
        return contentUrl;
    }
    
}