/*
 * $Id$
 * Copyright (C) 2001 The Apache Software Foundation. All rights reserved.
 * For details on use and redistribution please refer to the
 * LICENSE file included with these sources.
 */

package org.apache.fop.layoutmgr;

import org.apache.fop.fo.FObj;

import java.util.ArrayList;
import java.util.ListIterator;
import java.util.NoSuchElementException;

public class LMiter implements ListIterator {


    private ListIterator m_baseIter;
    private FObj m_curFO;
    protected ArrayList m_listLMs;
    protected int m_curPos = 0;

    public LMiter(ListIterator baseIter) {
        m_baseIter = baseIter;
        m_listLMs = new ArrayList(10);
    }

    public boolean hasNext() {
        return (m_curPos < m_listLMs.size()) ? true : preLoadNext();
    }

    protected boolean preLoadNext() {
        // skip over child FObj's that don't add lms
        while (m_baseIter.hasNext()) {
            FObj fobj = (FObj) m_baseIter.next();
            //m_listLMs.add(fobj.getLayoutManager());
            fobj.addLayoutManager(m_listLMs);
            if(m_curPos < m_listLMs.size()) {
                return true;
            }
        }
        return false;
    }

    public boolean hasPrevious() {
        return (m_curPos > 0);
    }

    public Object previous() throws NoSuchElementException {
        if (m_curPos > 0) {
            return m_listLMs.get(--m_curPos);
        } else
            throw new NoSuchElementException();
    }

    public Object next() throws NoSuchElementException {
        if (m_curPos < m_listLMs.size()) {
            return m_listLMs.get(m_curPos++);
        } else
            throw new NoSuchElementException();
    }

    public void remove() throws NoSuchElementException {
        if (m_curPos > 0) {
            m_listLMs.remove(--m_curPos);
            // Note: doesn't actually remove it from the base!
        } else
            throw new NoSuchElementException();

    }


    public void add(Object o) throws UnsupportedOperationException {
        throw new UnsupportedOperationException("LMiter doesn't support add");
    }

    public void set(Object o) throws UnsupportedOperationException {
        throw new UnsupportedOperationException("LMiter doesn't support set");
    }

    public int nextIndex() {
        return m_curPos;
    }

    public int previousIndex() {
        return m_curPos - 1;
    }

}