/* Copyright (c) 2001-2005, The HSQL Development Group
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 *
 * Neither the name of the HSQL Development Group nor the names of its
 * contributors may be used to endorse or promote products derived from this
 * software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL HSQL DEVELOPMENT GROUP, HSQLDB.ORG,
 * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */


package org.hsqldb.lib;

import java.io.File;
import java.io.FileDescriptor;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Random;

import org.hsqldb.lib.java.JavaSystem;

/**
 * A collection of static file management methods.<p>
 * Also implements the default FileAccess method
 *
 * @author fredt@users
 * @author boucherb@users
 * @author Ocke Janssen oj@openoffice.org
 * @version 1.8.0
 * @since 1.7.2
 */
public class FileUtil implements FileAccess {

    private static FileUtil fileUtil;

    /** Creates a new instance of FileUtil */
    FileUtil() {}

    public static FileUtil getDefaultInstance() {

        if (fileUtil == null) {
            fileUtil = new FileUtil();
        }

        return fileUtil;
    }

    public boolean isStreamElement(java.lang.String elementName) {
        return (new File(elementName)).exists();
    }

    public java.io.InputStream openInputStreamElement(
            java.lang.String streamName) throws java.io.IOException {

        try {
            return new FileInputStream(new File(streamName));
        } catch (Throwable e) {
            throw toIOException(e);
        }
    }

    public void createParentDirs(java.lang.String filename) {
        makeParentDirectories(new File(filename));
    }

    public void removeElement(java.lang.String filename) {

        if (isStreamElement(filename)) {
            delete(filename);
        }
    }

    public void renameElement(java.lang.String oldName,
                              java.lang.String newName) {
        renameOverwrite(oldName, newName);
    }

    public java.io.OutputStream openOutputStreamElement(
            java.lang.String streamName) throws java.io.IOException {
        return new FileOutputStream(new File(streamName));
    }

    // end of FileAccess implementation
    // a new File("...")'s path is not canonicalized, only resolved
    // and normalized (e.g. redundant separator chars removed),
    // so as of JDK 1.4.2, this is a valid test for case insensitivity,
    // at least when it is assumed that we are dealing with a configuration
    // that only needs to consider the host platform's native file system,
    // even if, unlike for File.getCanonicalPath(), (new File("a")).exists() or
    // (new File("A")).exits(), regardless of the hosting system's
    // file path case sensitivity policy.
    public static final boolean fsIsIgnoreCase =
        (new File("A")).equals(new File("a"));

    // posix separator normalized to File.separator?
    // CHECKME: is this true for every file system under Java?
    public static final boolean fsNormalizesPosixSeparator =
        (new File("/")).getPath().endsWith(File.separator);

    // for JDK 1.1 createTempFile
    static final Random random = new Random(System.currentTimeMillis());

    /**
     * Delete the named file
     */
    public static void delete(String filename) {
        (new File(filename)).delete();
    }

    /**
     * Requests, in a JDK 1.1 compliant way, that the file or directory denoted
     * by the given abstract pathname be deleted when the virtual machine
     * terminates. <p>
     *
     * Deletion will be attempted only for JDK 1.2 and greater runtime
     * environments and only upon normal termination of the virtual
     * machine, as defined by the Java Language Specification. <p>
     *
     * Once deletion has been sucessfully requested, it is not possible to
     * cancel the request. This method should therefore be used with care. <p>
     *
     * @param f the abstract pathname of the file be deleted when the virtual
     *       machine terminates
     */
    public static void deleteOnExit(File f) {
        JavaSystem.deleteOnExit(f);
    }

    /**
     * Return true or false based on whether the named file exists.
     */
    public static boolean exists(String filename) {
        return (new File(filename)).exists();
    }

    public static boolean exists(String fileName, boolean resource,
                                 Class cla) {

        if (fileName == null || fileName.length() == 0) {
            return false;
        }

        return resource ? null != cla.getResource(fileName)
                        : FileUtil.exists(fileName);
    }

    /**
     * Rename the file with oldname to newname. If a file with newname already
     * exists, it is deleted before the renaming operation proceeds.
     *
     * If a file with oldname does not exist, no file will exist after the
     * operation.
     */
    public static void renameOverwrite(String oldname, String newname) {

        delete(newname);

        if (exists(oldname)) {
            File file = new File(oldname);

            file.renameTo(new File(newname));
        }
    }

    public static IOException toIOException(Throwable e) {

        if (e instanceof IOException) {
            return (IOException) e;
        } else {
            return new IOException(e.toString());
        }
    }

    /**
     * Retrieves the absolute path, given some path specification.
     *
     * @param path the path for which to retrieve the absolute path
     * @return the absolute path
     */
    public static String absolutePath(String path) {
        return (new File(path)).getAbsolutePath();
    }

    /**
     * Retrieves the canonical file for the given file, in a
     * JDK 1.1 complaint way.
     *
     * @param f the File for which to retrieve the absolute File
     * @return the canonical File
     */
    public static File canonicalFile(File f) throws IOException {
        return new File(f.getCanonicalPath());
    }

    /**
     * Retrieves the canonical file for the given path, in a
     * JDK 1.1 complaint way.
     *
     * @param path the path for which to retrieve the canonical File
     * @return the canonical File
     */
    public static File canonicalFile(String path) throws IOException {
        return new File(new File(path).getCanonicalPath());
    }

    /**
     * Retrieves the canonical path for the given File, in a
     * JDK 1.1 complaint way.
     *
     * @param f the File for which to retrieve the canonical path
     * @return the canonical path
     */
    public static String canonicalPath(File f) throws IOException {
        return f.getCanonicalPath();
    }

    /**
     * Retrieves the canonical path for the given path, in a
     * JDK 1.1 complaint way.
     *
     * @param path the path for which to retrieve the canonical path
     * @return the canonical path
     */
    public static String canonicalPath(String path) throws IOException {
        return new File(path).getCanonicalPath();
    }

    /**
     * Retrieves the canonical path for the given path, or the absolute
     * path if attemting to retrieve the canonical path fails.
     *
     * @param path the path for which to retrieve the canonical or
     *      absolute path
     * @return the canonical or absolute path
     */
    public static String canonicalOrAbsolutePath(String path) {

        try {
            return canonicalPath(path);
        } catch (Exception e) {
            return absolutePath(path);
        }
    }

    public static void makeParentDirectories(File f) {

        String parent = f.getParent();

        if (parent != null) {
            new File(parent).mkdirs();
        } else {

            // workaround for jdk 1.1 bug (returns null when there is a parent)
            parent = f.getPath();

            int index = parent.lastIndexOf('/');

            if (index > 0) {
                parent = parent.substring(0, index);

                new File(parent).mkdirs();
            }
        }
    }

    public class FileSync implements FileAccess.FileSync {

        FileDescriptor outDescriptor;

        FileSync(FileOutputStream os) throws java.io.IOException {
            outDescriptor = os.getFD();
        }

        public void sync() throws java.io.IOException {
            outDescriptor.sync();
        }
    }

    public FileAccess.FileSync getFileSync(java.io.OutputStream os)
    throws java.io.IOException {
        return new FileSync((FileOutputStream) os);
    }
}
