/*

 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package jdk.jshell.execution;

import java.io.IOException;

import java.io.OutputStream;

import java.io.UnsupportedEncodingException;

/**

 * Packetize an OutputStream, dividing it into named channels.

 *

 * @author Jan Lahoda

 */

class MultiplexingOutputStream extends OutputStream {

    private static final int PACKET_SIZE = 127;

    private final byte[] name;

    private final OutputStream delegate;

    MultiplexingOutputStream(String name, OutputStream delegate) {

        try {

            this.name = name.getBytes("UTF-8");

            this.delegate = delegate;

        } catch (UnsupportedEncodingException ex) {

            throw new IllegalStateException(ex); //should not happen

        }

    }

    @Override

    public void write(int b) throws IOException {

        write(new byte[] {(byte) b});

    }

    @Override

    public void write(byte[] b, int off, int len) throws IOException {

        synchronized (delegate) {

            int i = 0;

            while (len > 0) {

                int size = Math.min(PACKET_SIZE, len);

                byte[] data = new byte[name.length + 1 + size + 1];

                data[0] = (byte) name.length; //assuming the len is small enough to fit into byte

                System.arraycopy(name, 0, data, 1, name.length);

                data[name.length + 1] = (byte) size;

                System.arraycopy(b, off + i, data, name.length + 2, size);

                delegate.write(data);

                i += size;

                len -= size;

            }

            delegate.flush();

        }

    }

    @Override

    public void flush() throws IOException {

        super.flush();

        delegate.flush();

    }

    @Override

    public void close() throws IOException {

        super.close();

        delegate.close();

    }

}