/*

 * Copyright (c) 2013, 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.

 *

 * 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.

 */

/*

 * @test

 * @bug 8010837 8011136

 * @summary Test if available returns correct value when skipping beyond

 *          the end of a file.

 * @author Dan Xu

 */

import java.io.BufferedWriter;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.nio.charset.Charset;

import java.nio.file.Files;

import java.nio.file.Path;

public class NegativeAvailable {

    public static void main(String[] args) throws IOException {

        final int SIZE = 10;

        final int SKIP = 5;

        final int NEGATIVE_SKIP = -5;

        // Create a temporary file with size of 10 bytes.

        Path tmp = Files.createTempFile(null, null);

        try (BufferedWriter writer =

            Files.newBufferedWriter(tmp, Charset.defaultCharset())) {

            for (int i = 0; i < SIZE; i++) {

                writer.write('1');

            }

        }

        File tempFile = tmp.toFile();

        try (FileInputStream fis = new FileInputStream(tempFile)) {

            if (tempFile.length() != SIZE) {

                throw new RuntimeException("unexpected file size = "

                                           + tempFile.length());

            }

            long space = skipBytes(fis, SKIP, SIZE);

            space = skipBytes(fis, NEGATIVE_SKIP, space);

            space = skipBytes(fis, SKIP, space);

            space = skipBytes(fis, SKIP, space);

            space = skipBytes(fis, SKIP, space);

            space = skipBytes(fis, NEGATIVE_SKIP, space);

            space = skipBytes(fis, NEGATIVE_SKIP, space);

        }

        Files.deleteIfExists(tmp);

    }

    /**

     *  Skip toSkip number of bytes and return the remaining bytes of the file.

     */

    private static long skipBytes(FileInputStream fis, int toSkip, long space)

            throws IOException {

        long skip = fis.skip(toSkip);

        if (skip != toSkip) {

            throw new RuntimeException("skip() returns " + skip

                                       + " but expected " + toSkip);

        }

        long newSpace = space - toSkip;

        long remaining = newSpace > 0 ? newSpace : 0;

        int avail = fis.available();

        if (avail != remaining) {

            throw new RuntimeException("available() returns " + avail

                                       + " but expected " + remaining);

        }

        System.out.println("Skipped " + skip + " bytes "

                           + " available() returns " + avail);

        return newSpace;

    }

}