/*

 * Copyright (c) 2003, 2014, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package sun.security.ssl;

import java.io.*;

import java.nio.*;

/**

 * A simple InputStream which uses ByteBuffers as it's backing store.

 * <P>

 * The only IOException should come if the InputStream has been closed.

 * All other IOException should not occur because all the data is local.

 * Data reads on an exhausted ByteBuffer returns a -1.

 *

 * @author  Brad Wetmore

 */

class ByteBufferInputStream extends InputStream {

    ByteBuffer bb;

    ByteBufferInputStream(ByteBuffer bb) {

        this.bb = bb;

    }

    /**

     * Returns a byte from the ByteBuffer.

     *

     * Increments position().

     */

    @Override

    public int read() throws IOException {

        if (bb == null) {

            throw new IOException("read on a closed InputStream");

        }

        if (bb.remaining() == 0) {

            return -1;

        }

        return (bb.get() & 0xFF);   // need to be in the range 0 to 255

    }

    /**

     * Returns a byte array from the ByteBuffer.

     *

     * Increments position().

     */

    @Override

    public int read(byte[] b) throws IOException {

        if (bb == null) {

            throw new IOException("read on a closed InputStream");

        }

        return read(b, 0, b.length);

    }

    /**

     * Returns a byte array from the ByteBuffer.

     *

     * Increments position().

     */

    @Override

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

        if (bb == null) {

            throw new IOException("read on a closed InputStream");

        }

        if (b == null) {

            throw new NullPointerException();

        } else if (off < 0 || len < 0 || len > b.length - off) {

            throw new IndexOutOfBoundsException();

        } else if (len == 0) {

            return 0;

        }

        int length = Math.min(bb.remaining(), len);

        if (length == 0) {

            return -1;

        }

        bb.get(b, off, length);

        return length;

    }

    /**

     * Skips over and discards <code>n</code> bytes of data from this input

     * stream.

     */

    @Override

    public long skip(long n) throws IOException {

        if (bb == null) {

            throw new IOException("skip on a closed InputStream");

        }

        if (n <= 0) {

            return 0;

        }

        /*

         * ByteBuffers have at most an int, so lose the upper bits.

         * The contract allows this.

         */

        int nInt = (int) n;

        int skip = Math.min(bb.remaining(), nInt);

        bb.position(bb.position() + skip);

        return nInt;

    }

    /**

     * 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.

     */

    @Override

    public int available() throws IOException {

        if (bb == null) {

            throw new IOException("available on a closed InputStream");

        }

        return bb.remaining();

    }

    /**

     * Closes this input stream and releases any system resources associated

     * with the stream.

     *

     * @exception  IOException  if an I/O error occurs.

     */

    @Override

    public void close() throws IOException {

        bb = null;

    }

    /**

     * Marks the current position in this input stream.

     */

    @Override

    public synchronized void mark(int readlimit) {}

    /**

     * Repositions this stream to the position at the time the

     * <code>mark</code> method was last called on this input stream.

     */

    @Override

    public synchronized void reset() throws IOException {

        throw new IOException("mark/reset not supported");

    }

    /**

     * Tests if this input stream supports the <code>mark</code> and

     * <code>reset</code> methods.

     */

    @Override

    public boolean markSupported() {

        return false;

    }

}