/*

 * Copyright (c) 2001, 2019, 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.nio.ch;

import java.io.*;

import java.nio.*;

import java.nio.channels.*;

import java.nio.channels.spi.*;

import java.util.Objects;

/**

 * This class is defined here rather than in java.nio.channels.Channels

 * so that code can be shared with SocketAdaptor.

 *

 * @author Mike McCloskey

 * @author Mark Reinhold

 * @since 1.4

 */

public class ChannelInputStream

    extends InputStream

{

    public static int read(ReadableByteChannel ch, ByteBuffer bb,

                           boolean block)

        throws IOException

    {

        if (ch instanceof SelectableChannel) {

            SelectableChannel sc = (SelectableChannel)ch;

            synchronized (sc.blockingLock()) {

                boolean bm = sc.isBlocking();

                if (!bm)

                    throw new IllegalBlockingModeException();

                if (bm != block)

                    sc.configureBlocking(block);

                int n = ch.read(bb);

                if (bm != block)

                    sc.configureBlocking(bm);

                return n;

            }

        } else {

            return ch.read(bb);

        }

    }

    protected final ReadableByteChannel ch;

    private ByteBuffer bb = null;

    private byte[] bs = null;           // Invoker's previous array

    private byte[] b1 = null;

    public ChannelInputStream(ReadableByteChannel ch) {

        this.ch = ch;

    }

    public synchronized int read() throws IOException {

        if (b1 == null)

            b1 = new byte[1];

        int n = this.read(b1);

        if (n == 1)

            return b1[0] & 0xff;

        return -1;

    }

    public synchronized int read(byte[] bs, int off, int len)

        throws IOException

    {

        Objects.checkFromIndexSize(off, len, bs.length);

        if (len == 0)

            return 0;

        ByteBuffer bb = ((this.bs == bs)

                         ? this.bb

                         : ByteBuffer.wrap(bs));

        bb.limit(Math.min(off + len, bb.capacity()));

        bb.position(off);

        this.bb = bb;

        this.bs = bs;

        return read(bb);

    }

    protected int read(ByteBuffer bb)

        throws IOException

    {

        return ChannelInputStream.read(ch, bb, true);

    }

    public int available() throws IOException {

        // special case where the channel is to a file

        if (ch instanceof SeekableByteChannel) {

            SeekableByteChannel sbc = (SeekableByteChannel)ch;

            long rem = Math.max(0, sbc.size() - sbc.position());

            return (rem > Integer.MAX_VALUE) ? Integer.MAX_VALUE : (int)rem;

        }

        return 0;

    }

    public synchronized long skip(long n) throws IOException {

        // special case where the channel is to a file

        if (ch instanceof SeekableByteChannel) {

            SeekableByteChannel sbc = (SeekableByteChannel)ch;

            long pos = sbc.position();

            long newPos;

            if (n > 0) {

                newPos = pos + n;

                long size = sbc.size();

                if (newPos < 0 || newPos > size) {

                    newPos = size;

                }

            } else {

                newPos = Long.max(pos + n, 0);

            }

            sbc.position(newPos);

            return newPos - pos;

        }

        return super.skip(n);

    }

    public void close() throws IOException {

        ch.close();

    }

}