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/*
 * Copyright (c) 2000, 2017 Oracle and/or its affiliates. All rights reserved.
 * Copyright 2021 Contributors to the Eclipse Foundation
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

package com.sun.messaging.jmq.httptunnel.tunnel;

import java.io.*;

/**
 * Provides an input stream for reading data from an HTTP tunnel connection.
 */
public class HttpTunnelInputStream extends InputStream {
    private HttpTunnelConnection conn = null;
    private byte[] singlebyte = new byte[1];

    /**
     * Creates an InputStream for a HttpTunnelSocket.
     */
    protected HttpTunnelInputStream(HttpTunnelConnection conn) {
        this.conn = conn;
    }

    /**
     * Reads the next byte of data from the input stream. The value byte is returned as an int in the range
     * 0 to 255. If no byte is available because the end of the stream has been reached, the value
     * -1 is returned. This method blocks until input data is available, the end of the stream is detected, or
     * an exception is thrown.
     *
     * @return the next byte of data, or -1 if the end of the stream is reached.
     * @exception IOException if an I/O error occurs.
     */
    @Override
    public synchronized int read() throws IOException {
        int n = conn.readData(singlebyte);
        if (n == 0) {
            return -1;
        }

        return ((singlebyte[0]) & 0xff);
    }

    /**
     * Reads up to len bytes of data from the input stream into an array of bytes. An attempt is made to read
     * as many as len bytes, but a smaller number may be read, possibly zero. The number of bytes actually read
     * is returned as an integer.
     *
     * @param b the buffer into which the data is read.
     * @param off the start offset in array b at which the data is written.
     * @param len the maximum number of bytes to read.
     * @return the total number of bytes read into the buffer, or -1 if there is no more data because the end
     * of the stream has been reached.
     * @exception IOException if an I/O error occurs.
     */
    @Override
    public synchronized int read(byte b[], int off, int len) throws IOException {
        int n = conn.readData(b, off, len);
        if (n == 0) {
            return -1;
        }

        return n;
    }

    /**
     * Skips over and discards n bytes of data from this input stream. The skip method may, for a
     * variety of reasons, end up skipping over some smaller number of bytes, possibly 0. This may result from
     * any of a number of conditions; reaching end of file before n bytes have been skipped is only one
     * possibility. The actual number of bytes skipped is returned. If n is negative, no bytes are skipped.
     *
     * @param n the number of bytes to be skipped.
     * @return the actual number of bytes skipped.
     * @exception IOException if an I/O error occurs.
     */
    @Override
    public synchronized long skip(long n) throws IOException {
        int skipped = 0;
        int ret;

        while (skipped < n) {
            try {
                ret = conn.readData(null, 0, (int) n - skipped);
            } catch (IOException e) {
                if (skipped == 0) {
                    throw e;
                } else {
                    break;
                }
            }
            if (ret == 0) {
                break;
            }

            skipped += ret;
        }

        return skipped;
    }

    /**
     * Returns the number of bytes that can be read (or skipped over) from this input stream without blocking by the next
     * caller of a method for this input stream. The next caller might be the same thread or or another thread.
     *
     * @return the number of bytes that can be read from this input stream without blocking.
     * @exception IOException if an I/O error occurs.
     */
    @Override
    public synchronized int available() throws IOException {
        return conn.available();
    }

    /**
     * Closes this input stream and releases any system resources associated with the stream.
     *
     * @exception IOException if an I/O error occurs.
     */
    @Override
    public synchronized void close() throws IOException {
    }
}