**** BEGIN LICENSE BLOCK *****
Version: EPL 2.0/GPL 2.0/LGPL 2.1
The contents of this file are subject to the Eclipse Public
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.eclipse.org/legal/epl-v20.html
Software distributed under the License is distributed on an "AS
IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
implied. See the License for the specific language governing
rights and limitations under the License.
Copyright (C) 2009 Yoko Harada 
Alternatively, the contents of this file may be used under the terms of
either of the GNU General Public License Version 2 or later (the "GPL"),
or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
in which case the provisions of the GPL or the LGPL are applicable instead
of those above. If you wish to allow use of your version of this file only
under the terms of either the GPL or the LGPL, and not to allow others to
use your version of this file under the terms of the EPL, indicate your
decision by deleting the provisions above and replace them with the notice
and other provisions required by the GPL or the LGPL. If you do not delete
the provisions above, a recipient may use your version of this file under
the terms of any one of the EPL, the GPL or the LGPL.
 **** END LICENSE BLOCK *****
/**
 * **** BEGIN LICENSE BLOCK *****
 * Version: EPL 2.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Eclipse Public
 * 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.eclipse.org/legal/epl-v20.html
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2009 Yoko Harada <yokolet@gmail.com>
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the EPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the EPL, the GPL or the LGPL.
 * **** END LICENSE BLOCK *****
 */
package org.jruby.embed.io;

import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CoderResult;
import java.nio.charset.CodingErrorAction;

import static com.headius.backport9.buffer.Buffers.clearBuffer;
import static com.headius.backport9.buffer.Buffers.flipBuffer;

A WriterOutputStream converts java.io.Writer to java.io.OutputStream.
Author:
Yoko Harada /**
 * A WriterOutputStream converts java.io.Writer to java.io.OutputStream.
 *
 * @author Yoko Harada <yokolet@gmail.com>
 */
public class WriterOutputStream extends OutputStream {

    private final Writer writer;
    private boolean isOpen = true;
    private CharsetDecoder decoder;

    
Creates WriterOutputStream from given java.io.Writer object with a default encoding.
Params:
writer – java.io.Writer object to be converted to./**
     * Creates WriterOutputStream from given java.io.Writer object with a default encoding.
     *
     * @param writer java.io.Writer object to be converted to.
     */
    public WriterOutputStream(Writer writer) {
        this(writer, null);
    }

    
Creates WriterOutputStream from given java.io.Writer object with a specified encoding.
Params:
writer – java.io.Writer object to be converted to./**
     * Creates WriterOutputStream from given java.io.Writer object with a specified encoding.
     *
     * @param writer java.io.Writer object to be converted to.
     */
    public WriterOutputStream(Writer writer, String encoding) {
        this.writer = writer;       
        if (encoding == null && writer instanceof OutputStreamWriter) {
            // this encoding might be null when writer has been closed
            encoding = ((OutputStreamWriter) writer).getEncoding();
        }
        if (encoding == null) {
            encoding = Charset.defaultCharset().name();
        } else if (!Charset.isSupported(encoding)) {
            throw new IllegalArgumentException(encoding + " is not supported");
        }
        decoder = Charset.forName(encoding).newDecoder();
        decoder.onMalformedInput(CodingErrorAction.REPLACE);
        decoder.onUnmappableCharacter(CodingErrorAction.REPLACE);
    }

    
Closes this output stream and releases any system resources
associated with this stream. The general contract of close
is that it closes the output stream. A closed stream cannot perform
output operations and cannot be reopened.

Throws:
IOException –  if an I/O error occurs./**
     * Closes this output stream and releases any system resources
     * associated with this stream. The general contract of <code>close</code>
     * is that it closes the output stream. A closed stream cannot perform
     * output operations and cannot be reopened.
     * <p>
     * 
     * @exception  IOException  if an I/O error occurs.
     */
    @Override
    public void close() throws IOException {
        synchronized (writer) {
            if (!isOpen) {
                throw new IOException("This stream has been already closed.");
            }
            isOpen = false;
            decoder = null;
            writer.close();
        }
    }

    
Flushes this output stream and forces any buffered output bytes
to be written out. The general contract of flush is
that calling it is an indication that, if any bytes previously
written have been buffered by the implementation of the output
stream, such bytes should immediately be written to their
intended destination.

If the intended destination of this stream is an abstraction provided by
the underlying operating system, for example a file, then flushing the
stream guarantees only that bytes previously written to the stream are
passed to the operating system for writing; it does not guarantee that
they are actually written to a physical device such as a disk drive.

Throws:
IOException –  if an I/O error occurs./**
     * Flushes this output stream and forces any buffered output bytes
     * to be written out. The general contract of <code>flush</code> is
     * that calling it is an indication that, if any bytes previously
     * written have been buffered by the implementation of the output
     * stream, such bytes should immediately be written to their
     * intended destination.
     * <p>
     * If the intended destination of this stream is an abstraction provided by
     * the underlying operating system, for example a file, then flushing the
     * stream guarantees only that bytes previously written to the stream are
     * passed to the operating system for writing; it does not guarantee that
     * they are actually written to a physical device such as a disk drive.
     * <p>
     *
     * @exception  IOException  if an I/O error occurs.
     */
    @Override
    public void flush() throws IOException {
        synchronized (writer) {
            if (!isOpen) {
                return;
            }
            writer.flush();
        }
    }

    
Writes the specified byte to this output stream. The general
contract for write is that one byte is written
to the output stream. The byte to be written is the eight
low-order bits of the argument b. The 24
high-order bits of b are ignored.
Params:
b –   the byte.
Throws:
IOException –  if an I/O error occurs. In particular,
            an IOException may be thrown if the
            output stream has been closed./**
     * Writes the specified byte to this output stream. The general
     * contract for <code>write</code> is that one byte is written
     * to the output stream. The byte to be written is the eight
     * low-order bits of the argument <code>b</code>. The 24
     * high-order bits of <code>b</code> are ignored.
     *
     * @param      b   the <code>byte</code>.
     * @exception  IOException  if an I/O error occurs. In particular,
     *             an <code>IOException</code> may be thrown if the
     *             output stream has been closed.
     */
    @Override
    public void write(int b) throws IOException {
        byte[] bb = new byte[]{(byte) b};
        write(bb, 0, 1);
    }

    
Writes b.length bytes from the specified byte array
to this output stream. The general contract for write(b)
is that it should have exactly the same effect as the call
write(b, 0, b.length).
Params:
b –   the data.
Throws:
IOException –  if an I/O error occurs.
See Also:
OutputStream.write(byte[], int, int)/**
     * Writes <code>b.length</code> bytes from the specified byte array
     * to this output stream. The general contract for <code>write(b)</code>
     * is that it should have exactly the same effect as the call
     * <code>write(b, 0, b.length)</code>.
     *
     * @param      b   the data.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.OutputStream#write(byte[], int, int)
     */
    @Override
    public void write(byte[] b) throws IOException {
        write(b, 0, b.length);
    }

    
Writes len bytes from the specified byte array
starting at offset off to this output stream.
The general contract for write(b, off, len) is that
some of the bytes in the array b are written to the
output stream in order; element b[off] is the first
byte written and b[off+len-1] is the last byte written
by this operation.

If off is negative, or len is negative, or
off+len is greater than the length of the array
b, then an IndexOutOfBoundsException is thrown.
Params:
b –     the data.
off –   the start offset in the data.
len –   the number of bytes to write.
Throws:
IOException –  if an I/O error occurs. In particular,
            an IOException is thrown if the output
            stream is closed./**
     * Writes <code>len</code> bytes from the specified byte array
     * starting at offset <code>off</code> to this output stream.
     * The general contract for <code>write(b, off, len)</code> is that
     * some of the bytes in the array <code>b</code> are written to the
     * output stream in order; element <code>b[off]</code> is the first
     * byte written and <code>b[off+len-1]</code> is the last byte written
     * by this operation.
     * <p>
     * If <code>off</code> is negative, or <code>len</code> is negative, or
     * <code>off+len</code> is greater than the length of the array
     * <code>b</code>, then an <tt>IndexOutOfBoundsException</tt> is thrown.
     *
     * @param      b     the data.
     * @param      off   the start offset in the data.
     * @param      len   the number of bytes to write.
     * @exception  IOException  if an I/O error occurs. In particular,
     *             an <code>IOException</code> is thrown if the output
     *             stream is closed.
     */
    @Override
    public void write(byte[] b, int off, int len) throws IOException {
        synchronized (writer) {
            if (!isOpen) {
                return;
            }
            if (off < 0 || len <= 0 || (off + len) > b.length) {
                throw new IndexOutOfBoundsException();
            }
            ByteBuffer bytes = ByteBuffer.wrap(b, off, len);
            CharBuffer chars = CharBuffer.allocate(len);
            byte2char(bytes, chars);
            char[] cbuf = new char[chars.length()];
            chars.get(cbuf, 0, chars.length());
            writer.write(cbuf);
            writer.flush();
        }
    }

    private void byte2char(ByteBuffer bytes, CharBuffer chars) throws IOException {
        decoder.reset();
        clearBuffer(chars);
        CoderResult result = decoder.decode(bytes, chars, true);
        if (result.isError() || result.isOverflow()) {
            throw new IOException(result.toString());
        } else if (result.isUnderflow()) {
            flipBuffer(chars);
        }
    }
}