/*

 * Copyright (c) 2005, 2007, 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.net.httpserver;

import java.io.*;

import com.sun.net.httpserver.*;

import com.sun.net.httpserver.spi.*;

/**

 * a (filter) input stream which can tell us if bytes are "left over"

 * on the underlying stream which can be read (without blocking)

 * on another instance of this class.

 *

 * The class can also report if all bytes "expected" to be read

 * were read, by the time close() was called. In that case,

 * bytes may be drained to consume them (by calling drain() ).

 *

 * isEOF() returns true, when all expected bytes have been read

 */

abstract class LeftOverInputStream extends FilterInputStream {

    ExchangeImpl t;

    ServerImpl server;

    protected boolean closed = false;

    protected boolean eof = false;

    byte[] one = new byte [1];

    public LeftOverInputStream (ExchangeImpl t, InputStream src) {

        super (src);

        this.t = t;

        this.server = t.getServerImpl();

    }

    /**

     * if bytes are left over buffered on *the UNDERLYING* stream

     */

    public boolean isDataBuffered () throws IOException {

        assert eof;

        return super.available() > 0;

    }

    public void close () throws IOException {

        if (closed) {

            return;

        }

        closed = true;

        if (!eof) {

            eof = drain (ServerConfig.getDrainAmount());

        }

    }

    public boolean isClosed () {

        return closed;

    }

    public boolean isEOF () {

        return eof;

    }

    protected abstract int readImpl (byte[]b, int off, int len) throws IOException;

    public synchronized int read () throws IOException {

        if (closed) {

            throw new IOException ("Stream is closed");

        }

        int c = readImpl (one, 0, 1);

        if (c == -1 || c == 0) {

            return c;

        } else {

            return one[0] & 0xFF;

        }

    }

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

        if (closed) {

            throw new IOException ("Stream is closed");

        }

        return readImpl (b, off, len);

    }

    /**

     * read and discard up to l bytes or "eof" occurs,

     * (whichever is first). Then return true if the stream

     * is at eof (ie. all bytes were read) or false if not

     * (still bytes to be read)

     */

    public boolean drain (long l) throws IOException {

        int bufSize = 2048;

        byte[] db = new byte [bufSize];

        while (l > 0) {

            long len = readImpl (db, 0, bufSize);

            if (len == -1) {

                eof = true;

                return true;

            } else {

                l = l - len;

            }

        }

        return false;

    }

}