// This Source Code is in the Public Domain per: http://litesoft.org/License.txt
package org.litesoft.sequences;

import java.util.*;

import org.litesoft.core.typeutils.*;

public class SequenceBlockChain extends SequenceBlock
{
    private SequenceBlock mFirst;
    private SequenceBlock mNext;

    private SequenceBlockChain( SequenceBlock pFirst, SequenceBlock pNext )
    {
        mFirst = pFirst;
        mNext = pNext;
    }

    public static SequenceBlock create( SequenceBlock pExisting, SequenceBlock pNew )
    {
        pExisting = Objects.deNull( pExisting, SequenceBlockImpl.INITIAL );
        pNew = Objects.deNull( pNew, SequenceBlockImpl.INITIAL );
        return !pExisting.hasMore() ? pNew : !pNew.hasMore() ? pExisting : new SequenceBlockChain( pExisting, pNew );
    }

    public long getCurBlockEndExclusive()
    {
        return mNext.getCurBlockEndExclusive();
    }

    public long available()
    {
        return mFirst.available() + mNext.available();
    }

    public boolean hasMore()
    {
        return mFirst.hasMore() || mNext.hasMore();
    }

    public long next()
            throws NoSuchElementException
    {
        return mFirst.hasMore() ? mFirst.next() : mNext.next();
    }

    protected Long peekNext()
    {
        Long aLong = mFirst.peekNext();
        return (aLong != null) ? aLong : mNext.peekNext();
    }
}