/*

 * Copyright (c) 2017, 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.

 *

 * 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 jdk.test.lib.util;

import jdk.test.lib.Platform;

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.io.IOException;

import java.io.PrintStream;

import java.io.UncheckedIOException;

import java.lang.ProcessBuilder.Redirect;

import java.nio.file.DirectoryNotEmptyException;

import java.nio.file.FileVisitResult;

import java.nio.file.Files;

import java.nio.file.NoSuchFileException;

import java.nio.file.Path;

import java.nio.file.Paths;

import java.nio.file.SimpleFileVisitor;

import java.nio.file.attribute.BasicFileAttributes;

import java.time.Instant;

import java.time.Duration;

import java.util.Arrays;

import java.util.ArrayList;

import java.util.ArrayDeque;

import java.util.HashSet;

import java.util.List;

import java.util.Optional;

import java.util.concurrent.atomic.AtomicBoolean;

import java.util.concurrent.atomic.AtomicReference;

import java.util.concurrent.TimeUnit;

/**

 * Common library for various test file utility functions.

 */

public final class FileUtils {

    private static final boolean IS_WINDOWS = Platform.isWindows();

    private static final int RETRY_DELETE_MILLIS = IS_WINDOWS ? 500 : 0;

    private static final int MAX_RETRY_DELETE_TIMES = IS_WINDOWS ? 15 : 0;

    /**

     * Deletes a file, retrying if necessary.

     *

     * @param path  the file to delete

     *

     * @throws NoSuchFileException

     *         if the file does not exist (optional specific exception)

     * @throws DirectoryNotEmptyException

     *         if the file is a directory and could not otherwise be deleted

     *         because the directory is not empty (optional specific exception)

     * @throws IOException

     *         if an I/O error occurs

     */

    public static void deleteFileWithRetry(Path path) throws IOException {

        try {

            deleteFileWithRetry0(path);

        } catch (InterruptedException x) {

            throw new IOException("Interrupted while deleting.", x);

        }

    }

    /**

     * Deletes a file, retrying if necessary.

     * No exception thrown if file doesn't exist.

     *

     * @param path  the file to delete

     *

     * @throws NoSuchFileException

     *         if the file does not exist (optional specific exception)

     * @throws DirectoryNotEmptyException

     *         if the file is a directory and could not otherwise be deleted

     *         because the directory is not empty (optional specific exception)

     * @throws IOException

     *         if an I/O error occurs

     */

    public static void deleteFileIfExistsWithRetry(Path path) throws IOException {

        try {

            if (!Files.notExists(path)) {

                deleteFileWithRetry0(path);

            }

        } catch (InterruptedException x) {

            throw new IOException("Interrupted while deleting.", x);

        }

    }

    private static void deleteFileWithRetry0(Path path)

            throws IOException, InterruptedException {

        int times = 0;

        IOException ioe = null;

        while (true) {

            try {

                Files.delete(path);

                // Checks for absence of the file. Semantics of Files.exists() is not the same.

                while (!Files.notExists(path)) {

                    times++;

                    if (times > MAX_RETRY_DELETE_TIMES) {

                        throw new IOException("File still exists after " + times + " waits.");

                    }

                    Thread.sleep(RETRY_DELETE_MILLIS);

                }

                break;

            } catch (NoSuchFileException | DirectoryNotEmptyException x) {

                throw x;

            } catch (IOException x) {

                // Backoff/retry in case another process is accessing the file

                times++;

                if (ioe == null) {

                    ioe = x;

                } else {

                    ioe.addSuppressed(x);

                }

                if (times > MAX_RETRY_DELETE_TIMES) {

                    throw ioe;

                }

                Thread.sleep(RETRY_DELETE_MILLIS);

            }

        }

    }

    /**

     * Deletes a directory and its subdirectories, retrying if necessary.

     *

     * @param dir  the directory to delete

     *

     * @throws  IOException

     *          If an I/O error occurs. Any such exceptions are caught

     *          internally. If only one is caught, then it is re-thrown.

     *          If more than one exception is caught, then the second and

     *          following exceptions are added as suppressed exceptions of the

     *          first one caught, which is then re-thrown.

     */

    public static void deleteFileTreeWithRetry(Path dir) throws IOException {

        IOException ioe = null;

        final List<IOException> excs = deleteFileTreeUnchecked(dir);

        if (!excs.isEmpty()) {

            ioe = excs.remove(0);

            for (IOException x : excs) {

                ioe.addSuppressed(x);

            }

        }

        if (ioe != null) {

            throw ioe;

        }

    }

    public static List<IOException> deleteFileTreeUnchecked(Path dir) {

        final List<IOException> excs = new ArrayList<>();

        try {

            java.nio.file.Files.walkFileTree(dir, new SimpleFileVisitor<>() {

                @Override

                public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {

                    try {

                        deleteFileWithRetry0(file);

                    } catch (IOException x) {

                        excs.add(x);

                    } catch (InterruptedException x) {

                        excs.add(new IOException("Interrupted while deleting.", x));

                        return FileVisitResult.TERMINATE;

                    }

                    return FileVisitResult.CONTINUE;

                }

                @Override

                public FileVisitResult postVisitDirectory(Path dir, IOException exc) {

                    try {

                        deleteFileWithRetry0(dir);

                    } catch (IOException x) {

                        excs.add(x);

                    } catch (InterruptedException x) {

                        excs.add(new IOException("Interrupted while deleting.", x));

                        return FileVisitResult.TERMINATE;

                    }

                    return FileVisitResult.CONTINUE;

                }

                @Override

                public FileVisitResult visitFileFailed(Path file, IOException exc) {

                    excs.add(exc);

                    return FileVisitResult.CONTINUE;

                }

            });

        } catch (IOException x) {

            excs.add(x);

        }

        return excs;

    }

    /**

     * Checks whether all file systems are accessible. This is performed

     * by checking free disk space on all mounted file systems via a

     * separate, spawned process. File systems are considered to be

     * accessible if this process completes successfully before a given

     * fixed duration has elapsed.

     *

     * @implNote On Unix this executes the {@code df} command in a separate

     * process and on Windows always returns {@code true}.

     */

    public static boolean areFileSystemsAccessible() throws IOException {

        boolean areFileSystemsAccessible = true;

        if (!IS_WINDOWS) {

            // try to check whether 'df' hangs

            System.out.println("\n--- df output ---");

            System.out.flush();

            Process proc = new ProcessBuilder("df").inheritIO().start();

            try {

                proc.waitFor(90, TimeUnit.SECONDS);

            } catch (InterruptedException ignored) {

            }

            try {

                int exitValue = proc.exitValue();

                if (exitValue != 0) {

                    System.err.printf("df process exited with %d != 0%n",

                        exitValue);

                    areFileSystemsAccessible = false;

                }

            } catch (IllegalThreadStateException ignored) {

                System.err.println("df command apparently hung");

                areFileSystemsAccessible = false;

            }

        }

        return areFileSystemsAccessible;

    }

    /**

     * Checks whether all file systems are accessible. This is performed

     * by checking free disk space on all mounted file systems via a

     * separate, spawned process. File systems are considered to be

     * accessible if this process completes successfully before a given

     * fixed duration has elapsed.

     *

     * @implNote On Unix this executes the {@code df} command in a separate

     * process and on Windows always returns {@code true}.

     *

     * @return whether file systems appear to be accessible

     *

     * @throws RuntimeException if there are duplicate mount points or some

     * other execution problem occurs

     */

    public static boolean areAllMountPointsAccessible() {

        final AtomicBoolean areMountPointsOK = new AtomicBoolean(true);

        if (!IS_WINDOWS) {

            Thread thr = new Thread(() -> {

                try {

                    Process proc = new ProcessBuilder("df").start();

                    BufferedReader reader = new BufferedReader

                        (new InputStreamReader(proc.getInputStream()));

                    // Skip the first line as it is the "df" output header.

                    if (reader.readLine() != null ) {

                        String prevMountPoint = null, mountPoint = null;

                        while ((mountPoint = reader.readLine()) != null) {

                            if (prevMountPoint != null &&

                                mountPoint.equals(prevMountPoint)) {

                                throw new RuntimeException

                                    ("System configuration error: " +

                                    "duplicate mount point " + mountPoint +

                                    " detected");

                            }

                            prevMountPoint = mountPoint;

                        }

                    }

                    try {

                        proc.waitFor(90, TimeUnit.SECONDS);

                    } catch (InterruptedException ignored) {

                    }

                    try {

                        int exitValue = proc.exitValue();

                        if (exitValue != 0) {

                            System.err.printf("df process exited with %d != 0%n",

                                exitValue);

                            areMountPointsOK.set(false);

                        }

                    } catch (IllegalThreadStateException ignored) {

                        System.err.println("df command apparently hung");

                        areMountPointsOK.set(false);

                    }

                } catch (IOException ioe) {

                    throw new RuntimeException(ioe);

                };

            });

            final AtomicReference throwableReference =

                new AtomicReference<Throwable>();

            thr.setUncaughtExceptionHandler(

                new Thread.UncaughtExceptionHandler() {

                    public void uncaughtException(Thread t, Throwable e) {

                        throwableReference.set(e);

                    }

                });

            thr.start();

            try {

                thr.join(120*1000L);

            } catch (InterruptedException ie) {

                throw new RuntimeException(ie);

            }

            Throwable uncaughtException = (Throwable)throwableReference.get();

            if (uncaughtException != null) {

                throw new RuntimeException(uncaughtException);

            }

            if (thr.isAlive()) {

                throw new RuntimeException("df thread did not join in time");

            }

        }

        return areMountPointsOK.get();

    }

    /**

     * List the open file descriptors (if supported by the 'lsof' command).

     * @param ps a printStream to send the output to

     * @throws UncheckedIOException if an error occurs

     */

    public static void listFileDescriptors(PrintStream ps) {

        Optional<String[]> lsof = Arrays.stream(lsCommands)

                .filter(args -> Files.isExecutable(Path.of(args[0])))

                .findFirst();

        lsof.ifPresent(args -> {

            try {

                ps.printf("Open File Descriptors:%n");

                long pid = ProcessHandle.current().pid();

                ProcessBuilder pb = new ProcessBuilder(args[0], args[1], Integer.toString((int) pid));

                pb.redirectErrorStream(true);   // combine stderr and stdout

                pb.redirectOutput(Redirect.PIPE);

                Process p = pb.start();

                Instant start = Instant.now();

                p.getInputStream().transferTo(ps);

                try {

                    int timeout = 10;

                    if (!p.waitFor(timeout, TimeUnit.SECONDS)) {

                        System.out.printf("waitFor timed out: %d%n", timeout);

                    }

                } catch (InterruptedException ie) {

                    throw new IOException("interrupted", ie);

                }

                ps.println();

            } catch (IOException ioe) {

                throw new UncheckedIOException("error listing file descriptors", ioe);

            }

        });

    }

    // Possible command locations and arguments

    static String[][] lsCommands = new String[][] {

            {"/usr/bin/lsof", "-p"},

            {"/usr/sbin/lsof", "-p"},

            {"/bin/lsof", "-p"},

            {"/sbin/lsof", "-p"},

            {"/usr/local/bin/lsof", "-p"},

            {"/usr/bin/pfiles", "-F"},   // Solaris

    };

}