/*
 * Copyright 1999-2010 University of Chicago
 *
 * Licensed under the Apache 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.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software distributed under the License is
 * distributed on an "AS IS" BASIS,WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either
 * express or implied.
 *
 * See the License for the specific language governing permissions and limitations under the License.
 */
package org.globus.util.http;

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

public class HTTPChunkedOutputStream extends OutputStream {

    protected boolean closed = false;
    protected int count;
    protected byte[] buf;
    protected OutputStream out;

    public HTTPChunkedOutputStream(OutputStream out) {
        this(out, 4096);
    }

    public HTTPChunkedOutputStream(OutputStream out, int size) {
        this.out = out;
        this.buf = new byte[size];
        this.count = 0;
    }

    private void flushBuffer(boolean flush) throws IOException {
        String chunkLength = Integer.toString(this.count, 16);
        this.out.write(chunkLength.getBytes());
        this.out.write(HTTPProtocol.CRLF.getBytes());
        this.out.write(this.buf, 0, this.count);
        this.out.write(HTTPProtocol.CRLF.getBytes());
        this.count = 0;
        if (flush) {
            this.out.flush();
        }
    }

    private void checkNotClosed() throws IOException {
        if (this.closed) {
            throw new IOException("Already closed");
        }
    }

    public synchronized void write(int b)
        throws IOException {
        checkNotClosed();
        if (this.count >= this.buf.length) {
            flushBuffer(false);
        }
        this.buf[this.count++] = (byte)b;
    }

    public void write(byte b[])
        throws IOException {
        write(b, 0, b.length);
    }

    public synchronized void flush()
        throws IOException {
        if (this.closed) {
            return;
        }
        if (this.count > 0) {
            flushBuffer(true);
        }
    }

    public synchronized void close()
        throws IOException {
        if (this.closed) {
            return;
        }
        flush();
        // signal end of content with a zero-length chunk
        flushBuffer(true);
        this.closed = true;
    }

    public synchronized void write(byte b[], int off, int len)
        throws IOException {
        checkNotClosed();
        int remaining = len;
        int sofar = 0;
        while (remaining > 0) {
            int roomInBuf = this.buf.length - this.count;
            int lenToWrite = Math.min(roomInBuf, len);
            System.arraycopy(b, sofar + off, buf, this.count, lenToWrite);
            sofar += lenToWrite;
            this.count += lenToWrite;
            remaining -= lenToWrite;
            if (this.count >= this.buf.length) {
                flushBuffer(false);
            }
        }
    }

}