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

import java.util.*;

public final class SequenceBlockImpl extends SequenceBlock
{
    public static final SequenceBlock INITIAL = new SequenceBlockImpl( 1, 1 );

    private long mNextValue;
    private long mCurBlockEndExclusive;

    public SequenceBlockImpl( long pNextValue, long pCurBlockEndExclusive )
    {
        mNextValue = pNextValue;
        mCurBlockEndExclusive = pCurBlockEndExclusive;
    }

    public long getCurBlockEndExclusive()
    {
        return mCurBlockEndExclusive;
    }

    public long available()
    {
        return mCurBlockEndExclusive - mNextValue;
    }

    public boolean hasMore()
    {
        return mCurBlockEndExclusive > mNextValue;
    }

    public long next()
            throws NoSuchElementException
    {
        if ( hasMore() )
        {
            return mNextValue++;
        }
        throw new NoSuchElementException( "SequenceBlock Exhausted" );
    }

    protected Long peekNext()
    {
        return !hasMore() ? null : mNextValue;
    }
}