/**
 * Copyright (c) 2003, www.pdfbox.org
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 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. Neither the name of pdfbox; nor the names of its
 *    contributors may be used to endorse or promote products derived from this
 *    software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS 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 THE REGENTS OR 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.
 *
 * http://www.pdfbox.org
 *
 */
package org.pdfbox;

import org.pdfbox.cos.COSArray;
import org.pdfbox.cos.COSBase;
import org.pdfbox.cos.COSDictionary;
import org.pdfbox.cos.COSName;
import org.pdfbox.cos.COSStream;
import org.pdfbox.cos.COSInteger;
import org.pdfbox.exceptions.COSVisitorException;
import org.pdfbox.pdfparser.PDFParser;
import org.pdfbox.pdfwriter.COSWriter;

import org.pdfbox.pdmodel.PDDocument;
import org.pdfbox.pdmodel.PDDocumentCatalog;
import org.pdfbox.pdmodel.PDPage;
import org.pdfbox.pdmodel.PDResources;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.ByteArrayOutputStream;
import java.io.OutputStream;

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.TreeMap;
import java.util.Map;

/**
 * Overlay on document with another one.<br>
 * e.g. Overlay an invoice with your company layout<br>
 * <br>
 * How it (should) work:<br>
 * If the document has 10 pages, and the layout 2 the following is the result:<br>
 * <pre>
 * Document: 1234567890
 * Layout  : 1212121212
 * </pre>
 * <br>
 *
 * @author Mario Ivankovits (mario@ops.co.at)
 * @author <a href="ben@benlitchfield.com">Ben Litchfield</a>
 *
 * @version $Revision: 1.6 $
 */
public class Overlay
{
    /**
     * COSName constant.
     */
    public static final COSName XOBJECT = COSName.getPDFName("XObject");
    /**
     * COSName constant.
     */
    public static final COSName PROC_SET = COSName.getPDFName("ProcSet");
    /**
     * COSName constant.
     */
    public static final COSName EXT_G_STATE = COSName.getPDFName("ExtGState" );

    private List layoutPages = new ArrayList(10);

    private PDDocument pdfOverlay;
    private PDDocument pdfDocument;
    private int pageCount = 0;
    private COSStream saveGraphicsStateStream;
    private COSStream restoreGraphicsStateStream;

    /**
     * This will overlay a document and write out the results.<br/><br/>
     *
     * usage: java org.pdfbox.Overlay &lt;overlay.pdf&gt; &lt;document.pdf&gt; &lt;result.pdf&gt;
     *
     * @param args The command line arguments.
     *
     * @throws IOException If there is an error reading/writing the document.
     * @throws COSVisitorException If there is an error writing the document.
     */
    public static void main( String[] args ) throws IOException, COSVisitorException
    {
        if( args.length != 3 )
        {
            usage();
            System.exit(1);
        }
        else
        {
            PDDocument overlay = null;
            PDDocument pdf = null;

            try
            {
                overlay = getDocument( args[0] );
                pdf = getDocument( args[1] );
                Overlay overlayer = new Overlay();
                overlayer.overlay( overlay, pdf );
                writeDocument( pdf, args[2] );
            }
            finally
            {
                if( overlay != null )
                {
                    overlay.close();
                }
                if( pdf != null )
                {
                    pdf.close();
                }
            }
        }
    }

    private static void writeDocument( PDDocument pdf, String filename ) throws IOException, COSVisitorException
    {
        FileOutputStream output = null;
        COSWriter writer = null;
        try
        {
            output = new FileOutputStream( filename );
            writer = new COSWriter( output );
            writer.write( pdf );
        }
        finally
        {
            if( writer != null )
            {
                writer.close();
            }
            if( output != null )
            {
                output.close();
            }
        }
    }

    private static PDDocument getDocument( String filename ) throws IOException
    {
        FileInputStream input = null;
        PDFParser parser = null;
        PDDocument result = null;
        try
        {
            input = new FileInputStream( filename );
            parser = new PDFParser( input );
            parser.parse();
            result = parser.getPDDocument();
        }
        finally
        {
            if( input != null )
            {
                input.close();
            }
        }
        return result;
    }

    private static void usage()
    {
        System.err.println( "usage: java " + Overlay.class.getName() + "<overlay.pdf> <document.pdf> <result.pdf>" );
    }

    /**
     * Private class.
     */
    private static class LayoutPage
    {
        private final COSBase contents;
        private final COSDictionary res;
        private final Map objectNameMap;

        /**
         * Constructor.
         *
         * @param contentsValue The contents.
         * @param resValue The resource dictionary
         * @param objectNameMapValue The map
         */
        public LayoutPage(COSBase contentsValue, COSDictionary resValue, Map objectNameMapValue)
        {
            contents = contentsValue;
            res = resValue;
            objectNameMap = objectNameMapValue;
        }
    }

    /**
     * This will overlay two documents onto each other.  The overlay document is
     * repeatedly overlayed onto the destination document for every page in the
     * destination.
     *
     * @param overlay The document to copy onto the destination
     * @param destination The file that the overlay should be placed on.
     *
     * @return The destination pdf, same as argument passed in.
     *
     * @throws IOException If there is an error accessing data.
     */
    public PDDocument overlay( PDDocument overlay, PDDocument destination ) throws IOException
    {
        pdfOverlay = overlay;
        pdfDocument = destination;

        PDDocumentCatalog overlayCatalog = pdfOverlay.getDocumentCatalog();
        collectLayoutPages( overlayCatalog.getAllPages() );

        COSDictionary saveGraphicsStateDic = new COSDictionary();
        saveGraphicsStateStream = new COSStream( saveGraphicsStateDic, pdfDocument.getDocument().getScratchFile() );
        OutputStream saveStream = saveGraphicsStateStream.createUnfilteredStream();
        saveStream.write( " q\n".getBytes() );
        saveStream.flush();

        restoreGraphicsStateStream = new COSStream( saveGraphicsStateDic, pdfDocument.getDocument().getScratchFile() );
        OutputStream restoreStream = restoreGraphicsStateStream.createUnfilteredStream();
        restoreStream.write( " Q\n".getBytes() );
        restoreStream.flush();


        PDDocumentCatalog pdfCatalog = pdfDocument.getDocumentCatalog();
        processPages( pdfCatalog.getAllPages() );

        return pdfDocument;
    }

    private void collectLayoutPages( List pages) throws IOException
    {
        Iterator pagesIter = pages.iterator();
        while( pagesIter.hasNext() )
        {