/*
 * Copyright 2008-2009 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package net.hasor.utils.io;
import java.io.*;
import java.util.Collection;
import java.util.List;

/**
 * 文件工具
 * @version : 2011-6-3
 * @author 赵永春 (zyc@hasor.net)
 */
public abstract class FileUtils {
    /**
     * Reads the contents of a file into a String.
     * The file is always closed.
     *
     * @param file  the file to read, must not be <code>null</code>
     * @param encoding  the encoding to use, <code>null</code> means platform default
     * @return the file contents, never <code>null</code>
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     */
    public static String readFileToString(File file, String encoding) throws IOException {
        InputStream in = null;
        try {
            in = openInputStream(file);
            return IOUtils.toString(in, encoding);
        } finally {
            IOUtils.closeQuietly(in);
        }
    }

    /**
     * Reads the contents of a file into a String using the default encoding for the VM. 
     * The file is always closed.
     *
     * @param file  the file to read, must not be <code>null</code>
     * @return the file contents, never <code>null</code>
     * @throws IOException in case of an I/O error
     * @since Commons IO 1.3.1
     */
    public static String readFileToString(File file) throws IOException {
        return readFileToString(file, null);
    }

    /**
     * Reads the contents of a file into a byte array.
     * The file is always closed.
     *
     * @param file  the file to read, must not be <code>null</code>
     * @return the file contents, never <code>null</code>
     * @throws IOException in case of an I/O error
     * @since Commons IO 1.1
     */
    public static byte[] readFileToByteArray(File file) throws IOException {
        InputStream in = null;
        try {
            in = openInputStream(file);
            return IOUtils.toByteArray(in, file.length());
        } finally {
            IOUtils.closeQuietly(in);
        }
    }

    /**
     * Reads the contents of a file line by line to a List of Strings.
     * The file is always closed.
     *
     * @param file  the file to read, must not be <code>null</code>
     * @param encoding  the encoding to use, <code>null</code> means platform default
     * @return the list of Strings representing each line in the file, never <code>null</code>
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     * @since Commons IO 1.1
     */
    public static List<String> readLines(File file, String encoding) throws IOException {
        InputStream in = null;
        try {
            in = openInputStream(file);
            return IOUtils.readLines(in, encoding);
        } finally {
            IOUtils.closeQuietly(in);
        }
    }

    /**
     * Reads the contents of a file line by line to a List of Strings using the default encoding for the VM.
     * The file is always closed.
     *
     * @param file  the file to read, must not be <code>null</code>
     * @return the list of Strings representing each line in the file, never <code>null</code>
     * @throws IOException in case of an I/O error
     * @since Commons IO 1.3
     */
    public static List<String> readLines(File file) throws IOException {
        return readLines(file, null);
    }

    /**
     * Returns an Iterator for the lines in a <code>File</code>.
     * <p>
     * This method opens an <code>InputStream</code> for the file.
     * When you have finished with the iterator you should close the stream
     * to free internal resources. This can be done by calling the
     * {@link LineIterator#close()} or
     * {@link LineIterator#closeQuietly(LineIterator)} method.
     * <p>
     * The recommended usage pattern is:
     * <pre>
     * LineIterator it = FileUtils.lineIterator(file, "UTF-8");
     * try {
     *   while (it.hasNext()) {
     *     String line = it.nextLine();
     *     /// do something with line
     *   }
     * } finally {
     *   LineIterator.closeQuietly(iterator);
     * }
     * </pre>
     * <p>
     * If an exception occurs during the creation of the iterator, the
     * underlying stream is closed.
     *
     * @param file  the file to open for input, must not be <code>null</code>
     * @param encoding  the encoding to use, <code>null</code> means platform default
     * @return an Iterator of the lines in the file, never <code>null</code>
     * @throws IOException in case of an I/O error (file closed)
     * @since Commons IO 1.2
     */
    public static LineIterator lineIterator(File file, String encoding) throws IOException {
        InputStream in = null;
        try {
            in = openInputStream(file);
            return IOUtils.lineIterator(in, encoding);
        } catch (IOException ex) {
            IOUtils.closeQuietly(in);
            throw ex;
        } catch (RuntimeException ex) {
            IOUtils.closeQuietly(in);
            throw ex;
        }
    }

    /**
     * Returns an Iterator for the lines in a <code>File</code> using the default encoding for the VM.
     *
     * @param file  the file to open for input, must not be <code>null</code>
     * @return an Iterator of the lines in the file, never <code>null</code>
     * @throws IOException in case of an I/O error (file closed)
     * @since Commons IO 1.3
     * @see #lineIterator(File, String)
     */
    public static LineIterator lineIterator(File file) throws IOException {
        return lineIterator(file, null);
    }
    //-----------------------------------------------------------------------

    /**
     * Writes a String to a file creating the file if it does not exist.
     *
     * NOTE: As from v1.3, the parent directories of the file will be created
     * if they do not exist.
     *
     * @param file  the file to write
     * @param data  the content to write to the file
     * @param encoding  the encoding to use, <code>null</code> means platform default
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     */
    public static void writeStringToFile(File file, String data, String encoding) throws IOException {
        writeStringToFile(file, data, encoding, false);
    }

    /**
     * Writes a String to a file creating the file if it does not exist.
     *
     * @param file  the file to write
     * @param data  the content to write to the file
     * @param encoding  the encoding to use, <code>null</code> means platform default
     * @param append if <code>true</code>, then the String will be added to the
     * end of the file rather than overwriting
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     * @since Commons IO 2.1
     */
    public static void writeStringToFile(File file, String data, String encoding, boolean append) throws IOException {
        OutputStream out = null;
        try {
            out = openOutputStream(file, append);
            IOUtils.write(data, out, encoding);
        } finally {
            IOUtils.closeQuietly(out);
        }
    }

    /**
     * Writes a String to a file creating the file if it does not exist using the default encoding for the VM.
     *
     * @param file  the file to write
     * @param data  the content to write to the file
     * @throws IOException in case of an I/O error
     */
    public static void writeStringToFile(File file, String data) throws IOException {
        writeStringToFile(file, data, null, false);
    }

    /**
     * Writes a String to a file creating the file if it does not exist using the default encoding for the VM.
     *
     * @param file  the file to write
     * @param data  the content to write to the file
     * @param append if <code>true</code>, then the String will be added to the
     * end of the file rather than overwriting
     * @throws IOException in case of an I/O error
     * @since Commons IO 2.1
     */
    public static void writeStringToFile(File file, String data, boolean append) throws IOException {
        writeStringToFile(file, data, null, append);
    }

    /**
     * Writes a CharSequence to a file creating the file if it does not exist using the default encoding for the VM.
     *
     * @param file  the file to write
     * @param data  the content to write to the file
     * @throws IOException in case of an I/O error
     * @since Commons IO 2.0
     */
    public static void write(File file, CharSequence data) throws IOException {
        write(file, data, null, false);
    }

    /**
     * Writes a CharSequence to a file creating the file if it does not exist using the default encoding for the VM.
     *
     * @param file  the file to write
     * @param data  the content to write to the file
     * @param append if <code>true</code>, then the data will be added to the
     * end of the file rather than overwriting
     * @throws IOException in case of an I/O error
     * @since Commons IO 2.1
     */
    public static void write(File file, CharSequence data, boolean append) throws IOException {
        write(file, data, null, append);
    }

    /**
     * Writes a CharSequence to a file creating the file if it does not exist.
     *
     * @param file  the file to write
     * @param data  the content to write to the file
     * @param encoding  the encoding to use, <code>null</code> means platform default
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     * @since Commons IO 2.0
     */
    public static void write(File file, CharSequence data, String encoding) throws IOException {
        write(file, data, encoding, false);
    }

    /**
     * Writes a CharSequence to a file creating the file if it does not exist.
     *
     * @param file  the file to write
     * @param data  the content to write to the file
     * @param encoding  the encoding to use, <code>null</code> means platform default
     * @param append if <code>true</code>, then the data will be added to the
     * end of the file rather than overwriting
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     * @since IO 2.1
     */
    public static void write(File file, CharSequence data, String encoding, boolean append) throws IOException {
        String str = data == null ? null : data.toString();
        writeStringToFile(file, str, encoding, append);
    }

    /**
     * Writes a byte array to a file creating the file if it does not exist.
     * <p>
     * NOTE: As from v1.3, the parent directories of the file will be created
     * if they do not exist.
     *
     * @param file  the file to write to
     * @param data  the content to write to the file
     * @throws IOException in case of an I/O error
     * @since Commons IO 1.1
     */
    public static void writeByteArrayToFile(File file, byte[] data) throws IOException {
        writeByteArrayToFile(file, data, false);
    }

    /**
     * Writes a byte array to a file creating the file if it does not exist.
     *
     * @param file  the file to write to
     * @param data  the content to write to the file
     * @param append if <code>true</code>, then bytes will be added to the
     * end of the file rather than overwriting
     * @throws IOException in case of an I/O error
     * @since IO 2.1
     */
    public static void writeByteArrayToFile(File file, byte[] data, boolean append) throws IOException {
        OutputStream out = null;
        try {
            out = openOutputStream(file, append);
            out.write(data);
        } finally {
            IOUtils.closeQuietly(out);
        }
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to
     * the specified <code>File</code> line by line.
     * The specified character encoding and the default line ending will be used.
     * <p>
     * NOTE: As from v1.3, the parent directories of the file will be created
     * if they do not exist.
     *
     * @param file  the file to write to
     * @param encoding  the encoding to use, <code>null</code> means platform default
     * @param lines  the lines to write, <code>null</code> entries produce blank lines
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     * @since Commons IO 1.1
     */
    public static void writeLines(File file, String encoding, Collection<?> lines) throws IOException {
        writeLines(file, encoding, lines, null, false);
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to
     * the specified <code>File</code> line by line, optionally appending.
     * The specified character encoding and the default line ending will be used.
     *
     * @param file  the file to write to
     * @param encoding  the encoding to use, <code>null</code> means platform default
     * @param lines  the lines to write, <code>null</code> entries produce blank lines
     * @param append if <code>true</code>, then the lines will be added to the
     * end of the file rather than overwriting
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     * @since Commons IO 2.1
     */
    public static void writeLines(File file, String encoding, Collection<?> lines, boolean append) throws IOException {
        writeLines(file, encoding, lines, null, append);
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to
     * the specified <code>File</code> line by line.
     * The default VM encoding and the default line ending will be used.
     *
     * @param file  the file to write to
     * @param lines  the lines to write, <code>null</code> entries produce blank lines
     * @throws IOException in case of an I/O error
     * @since Commons IO 1.3
     */
    public static void writeLines(File file, Collection<?> lines) throws IOException {
        writeLines(file, null, lines, null, false);
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to
     * the specified <code>File</code> line by line.
     * The default VM encoding and the default line ending will be used.
     *
     * @param file  the file to write to
     * @param lines  the lines to write, <code>null</code> entries produce blank lines
     * @param append if <code>true</code>, then the lines will be added to the
     * end of the file rather than overwriting
     * @throws IOException in case of an I/O error
     * @since Commons IO 2.1
     */
    public static void writeLines(File file, Collection<?> lines, boolean append) throws IOException {
        writeLines(file, null, lines, null, append);
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to
     * the specified <code>File</code> line by line.
     * The specified character encoding and the line ending will be used.
     * <p>
     * NOTE: As from v1.3, the parent directories of the file will be created
     * if they do not exist.
     *
     * @param file  the file to write to
     * @param encoding  the encoding to use, <code>null</code> means platform default
     * @param lines  the lines to write, <code>null</code> entries produce blank lines
     * @param lineEnding  the line separator to use, <code>null</code> is system default
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     * @since Commons IO 1.1
     */
    public static void writeLines(File file, String encoding, Collection<?> lines, String lineEnding) throws IOException {
        writeLines(file, encoding, lines, lineEnding, false);
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to
     * the specified <code>File</code> line by line.
     * The specified character encoding and the line ending will be used.
     *
     * @param file  the file to write to
     * @param encoding  the encoding to use, <code>null</code> means platform default
     * @param lines  the lines to write, <code>null</code> entries produce blank lines
     * @param lineEnding  the line separator to use, <code>null</code> is system default
     * @param append if <code>true</code>, then the lines will be added to the
     * end of the file rather than overwriting
     * @throws IOException in case of an I/O error
     * @throws UnsupportedEncodingException if the encoding is not supported by the VM
     * @since Commons IO 2.1
     */
    public static void writeLines(File file, String encoding, Collection<?> lines, String lineEnding, boolean append) throws IOException {
        OutputStream out = null;
        try {
            out = openOutputStream(file, append);
            IOUtils.writeLines(lines, lineEnding, out, encoding);
        } finally {
            IOUtils.closeQuietly(out);
        }
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to
     * the specified <code>File</code> line by line.
     * The default VM encoding and the specified line ending will be used.
     *
     * @param file  the file to write to
     * @param lines  the lines to write, <code>null</code> entries produce blank lines
     * @param lineEnding  the line separator to use, <code>null</code> is system default
     * @throws IOException in case of an I/O error
     * @since Commons IO 1.3
     */
    public static void writeLines(File file, Collection<?> lines, String lineEnding) throws IOException {
        writeLines(file, null, lines, lineEnding, false);
    }

    /**
     * Writes the <code>toString()</code> value of each item in a collection to
     * the specified <code>File</code> line by line.
     * The default VM encoding and the specified line ending will be used.
     *
     * @param file  the file to write to
     * @param lines  the lines to write, <code>null</code> entries produce blank lines
     * @param lineEnding  the line separator to use, <code>null</code> is system default
     * @param append if <code>true</code>, then the lines will be added to the
     * end of the file rather than overwriting
     * @throws IOException in case of an I/O error
     * @since Commons IO 2.1
     */
    public static void writeLines(File file, Collection<?> lines, String lineEnding, boolean append) throws IOException {
        writeLines(file, null, lines, lineEnding, append);
    }
    //-----------------------------------------------------------------------

    /**
     * Opens a {@link FileInputStream} for the specified file, providing better
     * error messages than simply calling <code>new FileInputStream(file)</code>.
     * <p>
     * At the end of the method either the stream will be successfully opened,
     * or an exception will have been thrown.
     * <p>
     * An exception is thrown if the file does not exist.
     * An exception is thrown if the file object exists but is a directory.
     * An exception is thrown if the file exists but cannot be read.
     *
     * @param file  the file to open for input, must not be <code>null</code>
     * @return a new {@link FileInputStream} for the specified file
     * @throws FileNotFoundException if the file does not exist
     * @throws IOException if the file object is a directory
     * @throws IOException if the file cannot be read
     * @since Commons IO 1.3
     */
    public static FileInputStream openInputStream(File file) throws IOException {
        if (file.exists()) {
            if (file.isDirectory()) {
                throw new IOException("File '" + file + "' exists but is a directory");
            }
            if (file.canRead() == false) {
                throw new IOException("File '" + file + "' cannot be read");
            }
        } else {
            throw new FileNotFoundException("File '" + file + "' does not exist");
        }
        return new FileInputStream(file);
    }
    //-----------------------------------------------------------------------

    /**
     * Opens a {@link FileOutputStream} for the specified file, checking and
     * creating the parent directory if it does not exist.
     * <p>
     * At the end of the method either the stream will be successfully opened,
     * or an exception will have been thrown.
     * <p>
     * The parent directory will be created if it does not exist.
     * The file will be created if it does not exist.
     * An exception is thrown if the file object exists but is a directory.
     * An exception is thrown if the file exists but cannot be written to.
     * An exception is thrown if the parent directory cannot be created.
     *
     * @param file  the file to open for output, must not be <code>null</code>
     * @return a new {@link FileOutputStream} for the specified file
     * @throws IOException if the file object is a directory
     * @throws IOException if the file cannot be written to
     * @throws IOException if a parent directory needs creating but that fails
     * @since Commons IO 1.3
     */
    public static FileOutputStream openOutputStream(File file) throws IOException {
        return openOutputStream(file, false);
    }

    /**
     * Opens a {@link FileOutputStream} for the specified file, checking and
     * creating the parent directory if it does not exist.
     * <p>
     * At the end of the method either the stream will be successfully opened,
     * or an exception will have been thrown.
     * <p>
     * The parent directory will be created if it does not exist.
     * The file will be created if it does not exist.
     * An exception is thrown if the file object exists but is a directory.
     * An exception is thrown if the file exists but cannot be written to.
     * An exception is thrown if the parent directory cannot be created.
     *
     * @param file  the file to open for output, must not be <code>null</code>
     * @param append if <code>true</code>, then bytes will be added to the
     * end of the file rather than overwriting
     * @return a new {@link FileOutputStream} for the specified file
     * @throws IOException if the file object is a directory
     * @throws IOException if the file cannot be written to
     * @throws IOException if a parent directory needs creating but that fails
     * @since Commons IO 2.1
     */
    public static FileOutputStream openOutputStream(File file, boolean append) throws IOException {
        if (file.exists()) {
            if (file.isDirectory()) {
                throw new IOException("File '" + file + "' exists but is a directory");
            }
            if (file.canWrite() == false) {
                throw new IOException("File '" + file + "' cannot be written to");
            }
        } else {
            File parent = file.getParentFile();
            if (parent != null) {
                if (!parent.mkdirs() && !parent.isDirectory()) {
                    throw new IOException("Directory '" + parent + "' could not be created");
                }
            }
        }
        return new FileOutputStream(file, append);
    }
    //-----------------------------------------------------------------------

    /**
     * Deletes a directory recursively. 
     *
     * @param directory  directory to delete
     * @throws IOException in case deletion is unsuccessful
     */
    public static void deleteDirectory(File directory) throws IOException {
        if (!directory.exists()) {
            return;
        }
        if (!isSymlink(directory)) {
            cleanDirectory(directory);
        }
        if (!directory.delete()) {
            String message = "Unable to delete directory " + directory + ".";
            throw new IOException(message);
        }
    }

    /**
     * Cleans a directory without deleting it.
     *
     * @param directory directory to clean
     * @throws IOException in case cleaning is unsuccessful
     */
    public static void cleanDirectory(File directory) throws IOException {
        if (!directory.exists()) {
            String message = directory + " does not exist";
            throw new IllegalArgumentException(message);
        }
        if (!directory.isDirectory()) {
            String message = directory + " is not a directory";
            throw new IllegalArgumentException(message);
        }
        File[] files = directory.listFiles();
        if (files == null) {  // null if security restricted
            throw new IOException("Failed to list contents of " + directory);
        }
        IOException exception = null;
        for (File file : files) {
            try {
                forceDelete(file);
            } catch (IOException ioe) {
                exception = ioe;
            }
        }
        if (null != exception) {
            throw exception;
        }
    }

    /**
     * Deletes a file, never throwing an exception. If file is a directory, delete it and all sub-directories.
     * <p>
     * The difference between File.delete() and this method are:
     * <ul>
     * <li>A directory to be deleted does not have to be empty.</li>
     * <li>No exceptions are thrown when a file or directory cannot be deleted.</li>
     * </ul>
     *
     * @param file  file or directory to delete, can be {@code null}
     * @return {@code true} if the file or directory was deleted, otherwise
     * {@code false}
     *
     * @since 1.4
     */
    public static boolean deleteQuietly(File file) {
        if (file == null) {
            return false;
        }
        try {
            if (file.isDirectory()) {
                cleanDirectory(file);
            }
        } catch (Exception ignored) {
        }
        try {
            return file.delete();
        } catch (Exception ignored) {
            return false;
        }
    }

    /**
     * Schedules a directory recursively for deletion on JVM exit.
     *
     * @param directory  directory to delete, must not be {@code null}
     * @throws NullPointerException if the directory is {@code null}
     * @throws IOException in case deletion is unsuccessful
     */
    private static void deleteDirectoryOnExit(File directory) throws IOException {
        if (!directory.exists()) {
            return;
        }
        directory.deleteOnExit();
        if (!isSymlink(directory)) {
            cleanDirectoryOnExit(directory);
        }
    }

    /**
     * Cleans a directory without deleting it.
     *
     * @param directory  directory to clean, must not be {@code null}
     * @throws NullPointerException if the directory is {@code null}
     * @throws IOException in case cleaning is unsuccessful
     */
    private static void cleanDirectoryOnExit(File directory) throws IOException {
        if (!directory.exists()) {
            String message = directory + " does not exist";
            throw new IllegalArgumentException(message);
        }
        if (!directory.isDirectory()) {
            String message = directory + " is not a directory";
            throw new IllegalArgumentException(message);
        }
        File[] files = directory.listFiles();
        if (files == null) {  // null if security restricted
            throw new IOException("Failed to list contents of " + directory);
        }
        IOException exception = null;
        for (File file : files) {
            try {
                forceDeleteOnExit(file);
            } catch (IOException ioe) {
                exception = ioe;
            }
        }
        if (null != exception) {
            throw exception;
        }
    }

    /**
     * Determines whether the specified file is a Symbolic Link rather than an actual file.
     * <p>
     * Will not return true if there is a Symbolic Link anywhere in the path,
     * only if the specific file is.
     * <p>
     * <b>Note:</b> the current implementation always returns {@code false} if the system
     * is detected as Windows using {@link FilenameUtils#isSystemWindows()}
     *
     * @param file the file to check
     * @return true if the file is a Symbolic Link
     * @throws IOException if an IO error occurs while checking the file
     * @since 2.0
     */
    public static boolean isSymlink(File file) throws IOException {
        if (file == null) {
            throw new NullPointerException("File must not be null");
        }
        if (FilenameUtils.isSystemWindows()) {
            return false;
        }
        File fileInCanonicalDir = null;
        if (file.getParent() == null) {
            fileInCanonicalDir = file;
        } else {
            File canonicalDir = file.getParentFile().getCanonicalFile();
            fileInCanonicalDir = new File(canonicalDir, file.getName());
        }
        if (fileInCanonicalDir.getCanonicalFile().equals(fileInCanonicalDir.getAbsoluteFile())) {
            return false;
        } else {
            return true;
        }
    }

    /**
     * Deletes a file. If file is a directory, delete it and all sub-directories.
     * <p>
     * The difference between File.delete() and this method are:
     * <ul>
     * <li>A directory to be deleted does not have to be empty.</li>
     * <li>You get exceptions when a file or directory cannot be deleted.
     *      (java.io.File methods returns a boolean)</li>
     * </ul>
     *
     * @param file  file or directory to delete, must not be {@code null}
     * @throws NullPointerException if the directory is {@code null}
     * @throws FileNotFoundException if the file was not found
     * @throws IOException in case deletion is unsuccessful
     */
    public static void forceDelete(File file) throws IOException {
        if (file.isDirectory()) {
            deleteDirectory(file);
        } else {
            boolean filePresent = file.exists();
            if (!file.delete()) {
                if (!filePresent) {
                    throw new FileNotFoundException("File does not exist: " + file);
                }
                String message = "Unable to delete file: " + file;
                throw new IOException(message);
            }
        }
    }

    /**
     * Schedules a file to be deleted when JVM exits.
     * If file is directory delete it and all sub-directories.
     *
     * @param file  file or directory to delete, must not be {@code null}
     * @throws NullPointerException if the file is {@code null}
     * @throws IOException in case deletion is unsuccessful
     */
    public static void forceDeleteOnExit(File file) throws IOException {
        if (file.isDirectory()) {
            deleteDirectoryOnExit(file);
        } else {
            file.deleteOnExit();
        }
    }
}