/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.impl.io;

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

import org.apache.http.io.SessionOutputBuffer;
import org.apache.http.util.Args;

Output stream that cuts off after a defined number of bytes. This class is used to send content of HTTP messages where the end of the content entity is determined by the value of the Content-Length header. Entities transferred using this stream can be maximum Long.MAX_VALUE long. 

Note that this class NEVER closes the underlying stream, even when close
gets called.  Instead, the stream will be marked as closed and no further
output will be permitted.
Since:
4.0/**
 * Output stream that cuts off after a defined number of bytes. This class
 * is used to send content of HTTP messages where the end of the content entity
 * is determined by the value of the {@code Content-Length header}.
 * Entities transferred using this stream can be maximum {@link Long#MAX_VALUE}
 * long.
 * <p>
 * Note that this class NEVER closes the underlying stream, even when close
 * gets called.  Instead, the stream will be marked as closed and no further
 * output will be permitted.
 *
 * @since 4.0
 */
public class ContentLengthOutputStream extends OutputStream {

    
Wrapped session output buffer.
/**
     * Wrapped session output buffer.
     */
    private final SessionOutputBuffer out;

    
The maximum number of bytes that can be written the stream. Subsequent
write operations will be ignored.
/**
     * The maximum number of bytes that can be written the stream. Subsequent
     * write operations will be ignored.
     */
    private final long contentLength;

    
Total bytes written /** Total bytes written */
    private long total;

    
True if the stream is closed. /** True if the stream is closed. */
    private boolean closed;

    
Wraps a session output buffer and cuts off output after a defined number
of bytes.
Params:
out – The session output buffer
contentLength – The maximum number of bytes that can be written to
the stream. Subsequent write operations will be ignored.
Since:
4.0/**
     * Wraps a session output buffer and cuts off output after a defined number
     * of bytes.
     *
     * @param out The session output buffer
     * @param contentLength The maximum number of bytes that can be written to
     * the stream. Subsequent write operations will be ignored.
     *
     * @since 4.0
     */
    public ContentLengthOutputStream(final SessionOutputBuffer out, final long contentLength) {
        super();
        this.out = Args.notNull(out, "Session output buffer");
        this.contentLength = Args.notNegative(contentLength, "Content length");
    }

    
Does not close the underlying socket output.
Throws:
IOException – If an I/O problem occurs./**
     * <p>Does not close the underlying socket output.</p>
     *
     * @throws IOException If an I/O problem occurs.
     */
    @Override
    public void close() throws IOException {
        if (!this.closed) {
            this.closed = true;
            this.out.flush();
        }
    }

    @Override
    public void flush() throws IOException {
        this.out.flush();
    }

    @Override
    public void write(final byte[] b, final int off, final int len) throws IOException {
        if (this.closed) {
            throw new IOException("Attempted write to closed stream.");
        }
        if (this.total < this.contentLength) {
            final long max = this.contentLength - this.total;
            int chunk = len;
            if (chunk > max) {
                chunk = (int) max;
            }
            this.out.write(b, off, chunk);
            this.total += chunk;
        }
    }

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

    @Override
    public void write(final int b) throws IOException {
        if (this.closed) {
            throw new IOException("Attempted write to closed stream.");
        }
        if (this.total < this.contentLength) {
            this.out.write(b);
            this.total++;
        }
    }

}