/*

 * 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.  Sun designates this

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

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package sun.net.httpserver;

import java.io.*;

import java.net.*;

import com.sun.net.httpserver.*;

import com.sun.net.httpserver.spi.*;

/**

 * a class which allows the caller to write an arbitrary

 * number of bytes to an underlying stream.

 * normal close() does not close the underlying stream

 *

 * This class is buffered.

 *

 * Each chunk is written in one go as :-

 * abcd\r\nxxxxxxxxxxxxxx\r\n

 *

 * abcd is the chunk-size, and xxx is the chunk data

 * If the length is less than 4 chars (in size) then the buffer

 * is written with an offset.

 * Final chunk is:

 * 0\r\n\r\n

 */

class ChunkedOutputStream extends FilterOutputStream

{

    private boolean closed = false;

    /* max. amount of user data per chunk */

    final static int CHUNK_SIZE = 4096;

    /* allow 4 bytes for chunk-size plus 4 for CRLFs */

    final static int OFFSET = 6; /* initial <=4 bytes for len + CRLF */

    private int pos = OFFSET;

    private int count = 0;

    private byte[] buf = new byte [CHUNK_SIZE+OFFSET+2];

    ExchangeImpl t;

    ChunkedOutputStream (ExchangeImpl t, OutputStream src) {

        super (src);

        this.t = t;

    }

    public void write (int b) throws IOException {

        if (closed) {

            throw new StreamClosedException ();

        }

        buf [pos++] = (byte)b;

        count ++;

        if (count == CHUNK_SIZE) {

            writeChunk();

        }

        assert count < CHUNK_SIZE;

    }

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

        if (closed) {

            throw new StreamClosedException ();

        }

        int remain = CHUNK_SIZE - count;

        if (len > remain) {

            System.arraycopy (b,off,buf,pos,remain);

            count = CHUNK_SIZE;

            writeChunk();

            len -= remain;

            off += remain;

            while (len >= CHUNK_SIZE) {

                System.arraycopy (b,off,buf,OFFSET,CHUNK_SIZE);

                len -= CHUNK_SIZE;

                off += CHUNK_SIZE;

                count = CHUNK_SIZE;

                writeChunk();

            }

        }

        if (len > 0) {

            System.arraycopy (b,off,buf,pos,len);

            count += len;

            pos += len;

        }

        if (count == CHUNK_SIZE) {

            writeChunk();

        }

    }

    /**

     * write out a chunk , and reset the pointers

     * chunk does not have to be CHUNK_SIZE bytes

     * count must == number of user bytes (<= CHUNK_SIZE)

     */

    private void writeChunk () throws IOException {

        char[] c = Integer.toHexString (count).toCharArray();

        int clen = c.length;

        int startByte = 4 - clen;

        int i;

        for (i=0; i<clen; i++) {

            buf[startByte+i] = (byte)c[i];

        }

        buf[startByte + (i++)] = '\r';

        buf[startByte + (i++)] = '\n';

        buf[startByte + (i++) + count] = '\r';

        buf[startByte + (i++) + count] = '\n';

        out.write (buf, startByte, i+count);

        count = 0;

        pos = OFFSET;

    }

    public void close () throws IOException {

        if (closed) {

            return;

        }

        flush();

        try {

            /* write an empty chunk */

            writeChunk();

            out.flush();

            LeftOverInputStream is = t.getOriginalInputStream();

            if (!is.isClosed()) {

                is.close();

            }

        /* some clients close the connection before empty chunk is sent */

        } catch (IOException e) {

        } finally {

            closed = true;

        }

        WriteFinishedEvent e = new WriteFinishedEvent (t);

        t.getHttpContext().getServerImpl().addEvent (e);

    }

    public void flush () throws IOException {

        if (closed) {

            throw new StreamClosedException ();

        }

        if (count > 0) {

            writeChunk();

        }

        out.flush();

    }

}