/*
 * 
 * $Id: PDFObject.java,v 1.3 2007/09/22 12:48:16 gil1 Exp $
 *
 * $Date: 2007/09/22 12:48:16 $
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public 
 * License as published by the Free Software Foundation; either 
 * version 2.1 of the License, or (at your option) any later version. 
 * 
 * This library 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 
 * Lesser General Public License for more details. 
 * 
 * You should have received a copy of the GNU Lesser General Public 
 * License along with this library; if not, write to the Free Software 
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA 
 */
package gnu.jpdf;

import java.io.*;
import java.util.*;

/**
 * This is the base class for all Objects that form the PDF document.
 *
 * @author Peter T Mount, http://www.retep.org.uk/pdf/
 * @author Eric Z. Beard, ericzbeard@hotmail.com
 * @version $Revision: 1.3 $, $Date: 2007/09/22 12:48:16 $
 */
public abstract class PDFObject implements Serializable {

    /*
   * NOTE: The original class is the work of Peter T. Mount, who released it 
   * in the uk.org.retep.pdf package.  It was modified by Eric Z. Beard as 
   * follows: 
   * The package name was changed to gnu.pdf.  
   * The formatting was changed a little bit.
   * It is still licensed under the LGPL.
     */
    /**
     * This is the object's PDF Type
     */
    private String type;

    /**
     * This is the unique serial number for this object.
     */
    protected int objser;

    /**
     * This allows any PDF object to refer to the document being constructed.
     */
    protected PDFDocument pdfDocument;

    /**
     * This is usually called by extensors to this class, and sets the PDF
     * Object Type
     *
     * @param type the PDF Object Type
     */
    public PDFObject(String type) {
        this.type = type;
    }

    /**
     * Returns the PDF Type of this object
     *
     * @return The PDF Type of this object
     */
    public String getType() {
        return type;
    }

    /**
     * Returns the unique serial number of this object.
     *
     * @return Unique serial number of this object.
     */
    public final int getSerialID() {
        return objser;
    }

    /**
     * Returns the PDF document this object belongs to.
     *
     * @return PDF containing this object
     */
    public final PDFDocument getPDFDocument() {
        return pdfDocument;
    }

    /**
     * <p>
     * Writes the object to the output stream. This method must be
     * overidden.</p>
     *
     * <p>
     * <b>Note:</b> It should not write any other objects, even if they are it's
     * Kids, as they will be written by the calling routine.</p>
     *
     * @param os OutputStream to send the object to
     * @exception IOException on error
     */
    public abstract void write(OutputStream os) throws IOException;

    /**
     * The write method should call this before writing anything to the
     * OutputStream. This will send the standard header for each object.
     *
     * <p>
     * Note: There are a few rare cases where this method is not called.
     *
     * @param os OutputStream to write to
     * @exception IOException on error
     */
    public final void writeStart(OutputStream os) throws IOException {
        os.write(Integer.toString(objser).getBytes());
        os.write(" 0 obj\n<<\n".getBytes());
        if (type != null) {
            os.write("/Type ".getBytes());
            os.write(type.getBytes());
            os.write("\n".getBytes());
        }
    }

    /**
     * The write method should call this after writing anything to the
     * OutputStream. This will send the standard footer for each object.
     *
     * <p>
     * Note: There are a few rare cases where this method is not called.
     *
     * @param os OutputStream to write to
     * @exception IOException on error
     */
    public final void writeEnd(OutputStream os) throws IOException {
        os.write(">>\nendobj\n".getBytes());
    }

    /**
     * Returns the unique serial number in PDF format
     *
     * @return the serial number in PDF format
     */
    @Override
    public String toString() {
        return "" + objser + " 0 R";
    }

    /**
     * This utility method returns a String containing an array definition based
     * on a Vector containing PDFObjects
     *
     * @param v Vector containing PDFObjects
     * @return String containing a PDF array
     */
    public static String toArray(Vector<? extends PDFObject> v) {
        if (v.size() == 0) {
            return "";
        }

        StringBuffer b = new StringBuffer();
        String bs = "[";
        for (PDFObject x : v) {
            b.append(bs);
            b.append(x.toString());
            bs = " ";
        }
        b.append("]");
        return b.toString();
    }
}
