package org.apache.cassandra.io.sstable;
/*
 * 
 * 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.
 * 
 */


import java.io.Closeable;
import java.io.IOException;
import java.util.Collection;
import java.util.Iterator;

import org.apache.commons.collections.iterators.CollatingIterator;

import org.apache.cassandra.db.DecoratedKey;
import org.apache.cassandra.utils.FBUtilities;
import org.apache.cassandra.utils.ReducingIterator;

public class ReducingKeyIterator implements Iterator<DecoratedKey>, Closeable
{
    private final CollatingIterator ci;
    private final ReducingIterator<DecoratedKey, DecoratedKey> iter;

    public ReducingKeyIterator(Collection<SSTableReader> sstables)
    {
        ci = FBUtilities.getCollatingIterator();
        for (SSTableReader sstable : sstables)
        {
            ci.addIterator(new KeyIterator(sstable.descriptor));
        }

        iter = new ReducingIterator<DecoratedKey, DecoratedKey>(ci)
        {
            DecoratedKey reduced = null;

            public void reduce(DecoratedKey current)
            {
                reduced = current;
            }

            protected DecoratedKey getReduced()
            {
                return reduced;
            }
        };
    }

    public void close() throws IOException
    {
        for (Object o : ci.getIterators())
        {
            ((KeyIterator) o).close();
        }
    }

    public long getTotalBytes()
    {
        long m = 0;
        for (Object o : ci.getIterators())
        {
            m += ((KeyIterator) o).getTotalBytes();
        }
        return m;
    }

    public long getBytesRead()
    {
        long m = 0;
        for (Object o : ci.getIterators())
        {
            m += ((KeyIterator) o).getBytesRead();
        }
        return m;
    }

    public String getTaskType()
    {
        return "Secondary index build";
    }

    public boolean hasNext()
    {
        return iter.hasNext();
    }

    public DecoratedKey next()
    {
        return iter.next();
    }

    public void remove()
    {
        throw new UnsupportedOperationException();
    }
}