/*

 * Copyright (c) 2009, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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 java.nio.file;

import java.util.Set;

import java.util.EnumSet;

import java.security.SecureRandom;

import static java.security.AccessController.*;

import java.io.IOException;

import java.nio.file.attribute.FileAttribute;

import java.nio.file.attribute.PosixFilePermission;

import java.nio.file.attribute.PosixFilePermissions;

import static java.nio.file.attribute.PosixFilePermission.*;

import sun.security.action.GetPropertyAction;

/**

 * Helper class to support creation of temporary files and directories with

 * initial attributes.

 */

class TempFileHelper {

    private TempFileHelper() { }

    // temporary directory location

    private static final Path tmpdir =

        Paths.get(doPrivileged(new GetPropertyAction("java.io.tmpdir")));

    private static final boolean isPosix =

        FileSystems.getDefault().supportedFileAttributeViews().contains("posix");

    // file name generation, same as java.io.File for now

    private static final SecureRandom random = new SecureRandom();

    private static Path generatePath(String prefix, String suffix, Path dir) {

        long n = random.nextLong();

        n = (n == Long.MIN_VALUE) ? 0 : Math.abs(n);

        Path name = dir.getFileSystem().getPath(prefix + Long.toString(n) + suffix);

        // the generated name should be a simple file name

        if (name.getParent() != null)

            throw new IllegalArgumentException("Invalid prefix or suffix");

        return dir.resolve(name);

    }

    // default file and directory permissions (lazily initialized)

    private static class PosixPermissions {

        static final FileAttribute<Set<PosixFilePermission>> filePermissions =

            PosixFilePermissions.asFileAttribute(EnumSet.of(OWNER_READ, OWNER_WRITE));

        static final FileAttribute<Set<PosixFilePermission>> dirPermissions =

            PosixFilePermissions.asFileAttribute(EnumSet

                .of(OWNER_READ, OWNER_WRITE, OWNER_EXECUTE));

    }

    /**

     * Creates a file or directory in in the given given directory (or in the

     * temporary directory if dir is {@code null}).

     */

    private static Path create(Path dir,

                               String prefix,

                               String suffix,

                               boolean createDirectory,

                               FileAttribute<?>[] attrs)

        throws IOException

    {

        if (prefix == null)

            prefix = "";

        if (suffix == null)

            suffix = (createDirectory) ? "" : ".tmp";

        if (dir == null)

            dir = tmpdir;

        // in POSIX environments use default file and directory permissions

        // if initial permissions not given by caller.

        if (isPosix && (dir.getFileSystem() == FileSystems.getDefault())) {

            if (attrs.length == 0) {

                // no attributes so use default permissions

                attrs = new FileAttribute<?>[1];

                attrs[0] = (createDirectory) ? PosixPermissions.dirPermissions :

                                               PosixPermissions.filePermissions;

            } else {

                // check if posix permissions given; if not use default

                boolean hasPermissions = false;

                for (int i=0; i<attrs.length; i++) {

                    if (attrs[i].name().equals("posix:permissions")) {

                        hasPermissions = true;

                        break;

                    }

                }

                if (!hasPermissions) {

                    FileAttribute<?>[] copy = new FileAttribute<?>[attrs.length+1];

                    System.arraycopy(attrs, 0, copy, 0, attrs.length);

                    attrs = copy;

                    attrs[attrs.length-1] = (createDirectory) ?

                        PosixPermissions.dirPermissions :

                        PosixPermissions.filePermissions;

                }

            }

        }

        // loop generating random names until file or directory can be created

        SecurityManager sm = System.getSecurityManager();

        for (;;) {

            Path f;

            try {

                f = generatePath(prefix, suffix, dir);

            } catch (InvalidPathException e) {

                // don't reveal temporary directory location

                if (sm != null)

                    throw new IllegalArgumentException("Invalid prefix or suffix");

                throw e;

            }

            try {

                if (createDirectory) {

                    return Files.createDirectory(f, attrs);

                } else {

                    return Files.createFile(f, attrs);

                }

            } catch (SecurityException e) {

                // don't reveal temporary directory location

                if (dir == tmpdir && sm != null)

                    throw new SecurityException("Unable to create temporary file or directory");

                throw e;

            } catch (FileAlreadyExistsException e) {

                // ignore

            }

        }

    }

    /**

     * Creates a temporary file in the given directory, or in in the

     * temporary directory if dir is {@code null}.

     */

    static Path createTempFile(Path dir,

                               String prefix,

                               String suffix,

                               FileAttribute<?>[] attrs)

        throws IOException

    {

        return create(dir, prefix, suffix, false, attrs);

    }

    /**

     * Creates a temporary directory in the given directory, or in in the

     * temporary directory if dir is {@code null}.

     */

    static Path createTempDirectory(Path dir,

                                    String prefix,

                                    FileAttribute<?>[] attrs)

        throws IOException

    {

        return create(dir, prefix, null, true, attrs);

    }

}