/*
 * Copyright (c) 2005, 2008, 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
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 */

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
/**
 * 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)
/**
     * 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();
    }
}