/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.
 */

/* $Id: PDFPages.java 1761020 2016-09-16 11:17:35Z ssteiner $ */

package org.apache.fop.pdf;

import java.util.ArrayList;
import java.util.List;

class representing a /Pages object.
A /Pages object is an ordered collection of pages (/Page objects)
(Actually, /Pages can contain further /Pages as well but this
implementation doesn't allow this)
/**
 * class representing a /Pages object.
 *
 * A /Pages object is an ordered collection of pages (/Page objects)
 * (Actually, /Pages can contain further /Pages as well but this
 * implementation doesn't allow this)
 */
public class PDFPages extends PDFObject {

    
the /Page objects
/**
     * the /Page objects
     */
    protected List kids = new ArrayList();

    
the number of /Page objects
/**
     * the number of /Page objects
     */
    protected int count;

    // private PDFPages parent;

    
create a /Pages object. NOTE: The PDFPages
object must be created before the PDF document is
generated, but it is not written to the stream immediately.
It must also be allocated an object ID (so that the kids
can refer to the parent) so that the XRef table needs to
be updated before this object is written.
/**
     * create a /Pages object. NOTE: The PDFPages
     * object must be created before the PDF document is
     * generated, but it is not written to the stream immediately.
     * It must also be allocated an object ID (so that the kids
     * can refer to the parent) so that the XRef table needs to
     * be updated before this object is written.
     */
    public PDFPages(PDFDocument document) {
        setObjectNumber(document);
    }

    
add a /Page object.
Params:
page – the PDFPage to add./**
     * add a /Page object.
     *
     * @param page the PDFPage to add.
     */
    public void addPage(PDFPage page) {
        page.setParent(this);
        this.incrementCount();
    }

    
Use this method to notify the PDFPages object that a child page
Params:
page – the child page/**
     * Use this method to notify the PDFPages object that a child page
     * @param page the child page
     */
    public void notifyKidRegistered(PDFPage page) {
        int idx = page.getPageIndex();
        if (idx >= 0) {
            while (idx > this.kids.size() - 1) {
                this.kids.add(null);
            }
            if (this.kids.get(idx) != null) {
                throw new IllegalStateException("A page already exists at index "
                        + idx + " (zero-based).");
            }
            this.kids.set(idx, page.makeReference());
        } else {
            this.kids.add(page.makeReference());
        }
    }

    
get the count of /Page objects
Returns:
the number of pages/**
     * get the count of /Page objects
     *
     * @return the number of pages
     */
    public int getCount() {
        return this.count;
    }

    
increment the count of /Page objects
/**
     * increment the count of /Page objects
     */
    public void incrementCount() {
        this.count++;
        // log.debug("Incrementing count to " + this.getCount());
    }

    
{@inheritDoc}
/**
     * {@inheritDoc}
     */
    public String toPDFString() {
        StringBuffer sb = new StringBuffer(64);
        sb.append("<< /Type /Pages\n/Count ")
                .append(this.getCount())
                .append("\n/Kids [");
        for (Object kid : kids) {
            if (kid == null) {
                throw new IllegalStateException("Gap in the kids list!");
            }
            sb.append(kid).append(" ");
        }
        sb.append("] >>");
        return sb.toString();
    }

}