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/*******************************************************************************
 *
 * Copyright (c) 2004-2010 Oracle Corporation.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *
 *
 *******************************************************************************/ 

package hudson.cli;

import java.io.OutputStream;
import java.io.IOException;
import java.io.SequenceInputStream;

/**
 * {@link OutputStream} version of {@link SequenceInputStream}.
 *
 * Provides a single {@link OutputStream} view over multiple
 * {@link OutputStream}s (each of the fixed length.)
 *
 * @author Kohsuke Kawaguchi
 */
abstract class SequenceOutputStream extends OutputStream {

    protected static class Block {

        final OutputStream out;
        long capacity;

        public Block(OutputStream out, long capacity) {
            this.out = out;
            this.capacity = capacity;
        }
    }
    /**
     * Current block being written.
     */
    private Block block;

    protected SequenceOutputStream(Block block) {
        this.block = block;
    }

    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        while (len > 0) {
            int sz = (int) Math.min(len, block.capacity);
            block.out.write(b, off, sz);
            block.capacity -= sz;
            len -= sz;
            off += sz;
            swapIfNeeded();
        }
    }

    public void write(int b) throws IOException {
        block.out.write(b);
        block.capacity--;
        swapIfNeeded();
    }

    private void swapIfNeeded() throws IOException {
        if (block.capacity > 0) {
            return;
        }
        block.out.close();
        block = next(block);
    }

    @Override
    public void flush() throws IOException {
        block.out.flush();
    }

    @Override
    public void close() throws IOException {
        block.out.close();
        block = null;
    }

    /**
     * Fetches the next {@link OutputStream} to write to, along with their
     * capacity.
     */
    protected abstract Block next(Block current) throws IOException;
}