/*

 * Copyright (c) 2000, 2012, 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 6191269 6709457 8000330

 * @summary Test truncate method of FileChannel

 * @key randomness

 */

import java.io.*;

import java.nio.ByteBuffer;

import java.nio.channels.*;

import java.nio.file.Files;

import static java.nio.file.StandardOpenOption.*;

import static java.nio.charset.StandardCharsets.*;

import java.util.Random;

/**

 * Testing FileChannel's truncate method.

 */

public class Truncate {

    private static final Random generator = new Random();

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

        File blah = File.createTempFile("blah", null);

        blah.deleteOnExit();

        try {

            basicTest(blah);

            appendTest(blah);

            exceptionTests(blah);

        } finally {

            blah.delete();

        }

    }

    /**

     * Basic test of asserts in truncate's specification.

     */

    static void basicTest(File blah) throws Exception {

        for(int i=0; i<100; i++) {

            long testSize = generator.nextInt(1000) + 10;

            initTestFile(blah, testSize);

            try (FileChannel fc = (i < 50) ?

                 new RandomAccessFile(blah, "rw").getChannel() :

                 FileChannel.open(blah.toPath(), READ, WRITE))

                {

                    if (fc.size() != testSize)

                        throw new RuntimeException("Size failed");

                    long position = generator.nextInt((int)testSize*2);

                    fc.position(position);

                    long newSize = generator.nextInt((int)testSize*2);

                    fc.truncate(newSize);

                    // check new size

                    if (newSize > testSize) {

                        if (fc.size() != testSize)

                            throw new RuntimeException("Attempt to expand file changed size");

                    } else {

                        if (fc.size() != newSize)

                            throw new RuntimeException("Unexpected size after truncate");

                    }

                    // check new position

                    if (position > newSize) {

                        if (fc.position() != newSize)

                            throw new RuntimeException("Position greater than size");

                    } else {

                        if (fc.position() != position)

                            throw new RuntimeException("Truncate changed position");

                    };

                }

        }

    }

    /**

     * Test behavior of truncate method when file is opened for append

     */

    static void appendTest(File blah) throws Exception {

        for (int i=0; i<10; i++) {

            long testSize = generator.nextInt(1000) + 10;

            initTestFile(blah, testSize);

            try (FileChannel fc = (i < 5) ?

                 new FileOutputStream(blah, true).getChannel() :

                 FileChannel.open(blah.toPath(), APPEND))

                {

                    // truncate file

                    long newSize = generator.nextInt((int)testSize);

                    fc.truncate(newSize);

                    if (fc.size() != newSize)

                        throw new RuntimeException("Truncate failed");

                    // write one byte

                    ByteBuffer buf = ByteBuffer.allocate(1);

                    buf.put((byte)'x');

                    buf.flip();

                    fc.write(buf);

                    if (fc.size() != (newSize+1))

                        throw new RuntimeException("Unexpected size");

                }

        }

    }

    /**

     * Test exceptions specified by truncate method

     */

    static void exceptionTests(File blah) throws Exception {

        // check exceptions when channel opened for read access

        try (FileChannel fc = FileChannel.open(blah.toPath(), READ)) {

            long size = fc.size();

            // open channel

            checkException(fc, 0L, NonWritableChannelException.class);

            checkException(fc, -1L, NonWritableChannelException.class,

                           IllegalArgumentException.class);

            checkException(fc, size+1L, NonWritableChannelException.class);

            // closed channel

            fc.close();

            checkException(fc, 0L, ClosedChannelException.class);

            checkException(fc, -1L, ClosedChannelException.class,

                           IllegalArgumentException.class);

            checkException(fc, size+1L, ClosedChannelException.class);

        }

        // check exceptions when channel opened for write access

        try (FileChannel fc = FileChannel.open(blah.toPath(), WRITE)) {

            long size = fc.size();

            // open channel

            checkException(fc, -1L, IllegalArgumentException.class);

            // closed channel

            fc.close();

            checkException(fc, 0L, ClosedChannelException.class);

            checkException(fc, -1L, ClosedChannelException.class,

                           IllegalArgumentException.class);

            checkException(fc, size+1L, ClosedChannelException.class);

        }

    }

    /**

     * Checks that FileChannel truncate throws one of the expected exceptions

     * when invoked with the given size.

     */

    private static void checkException(FileChannel fc, long size, Class<?>... expected)

        throws IOException

    {

        Exception exc = null;

        try {

            fc.truncate(size);

        } catch (Exception actual) {

            exc = actual;

        }

        if (exc != null) {

            for (Class<?> clazz: expected) {

                if (clazz.isInstance(exc)) {

                    return;

                }

            }

        }

        System.err.println("Expected one of");

        for (Class<?> clazz: expected) {

            System.err.println(clazz);

        }

        if (exc == null) {

            throw new RuntimeException("No expection thrown");

        } else {

            throw new RuntimeException("Unexpected exception thrown", exc);

        }

    }

    /**

     * Creates file blah of specified size in bytes.

     */

    private static void initTestFile(File blah, long size) throws Exception {

        try (BufferedWriter writer = Files.newBufferedWriter(blah.toPath(), ISO_8859_1)) {

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

                writer.write("e");

            }

        }

    }

}