/*

 * Copyright (c) 2013, 2021, 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.lang.invoke;

import sun.util.logging.PlatformLogger;

import java.io.FilePermission;

import java.nio.file.Files;

import java.nio.file.InvalidPathException;

import java.nio.file.Path;

import java.security.AccessController;

import java.security.PrivilegedAction;

import java.util.Objects;

import java.util.concurrent.atomic.AtomicBoolean;

/**

 * Helper class used by InnerClassLambdaMetafactory to log generated classes

 *

 * @implNote

 * <p> Because this class is called by LambdaMetafactory, make use

 * of lambda lead to recursive calls cause stack overflow.

 */

final class ProxyClassesDumper {

    private static final char[] HEX = {

        '0', '1', '2', '3', '4', '5', '6', '7',

        '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'

    };

    private static final char[] BAD_CHARS = {

        '\\', ':', '*', '?', '"', '<', '>', '|'

    };

    private static final String[] REPLACEMENT = {

        "%5C", "%3A", "%2A", "%3F", "%22", "%3C", "%3E", "%7C"

    };

    private final Path dumpDir;

    @SuppressWarnings("removal")

    public static ProxyClassesDumper getInstance(String path) {

        if (null == path) {

            return null;

        }

        try {

            path = path.trim();

            final Path dir = Path.of(path.isEmpty() ? "." : path);

            AccessController.doPrivileged(new PrivilegedAction<>() {

                    @Override

                    public Void run() {

                        validateDumpDir(dir);

                        return null;

                    }

                }, null, new FilePermission("<<ALL FILES>>", "read, write"));

            return new ProxyClassesDumper(dir);

        } catch (InvalidPathException ex) {

            PlatformLogger.getLogger(ProxyClassesDumper.class.getName())

                          .warning("Path " + path + " is not valid - dumping disabled", ex);

        } catch (IllegalArgumentException iae) {

            PlatformLogger.getLogger(ProxyClassesDumper.class.getName())

                          .warning(iae.getMessage() + " - dumping disabled");

        }

        return null;

    }

    private ProxyClassesDumper(Path path) {

        dumpDir = Objects.requireNonNull(path);

    }

    private static void validateDumpDir(Path path) {

        if (!Files.exists(path)) {

            throw new IllegalArgumentException("Directory " + path + " does not exist");

        } else if (!Files.isDirectory(path)) {

            throw new IllegalArgumentException("Path " + path + " is not a directory");

        } else if (!Files.isWritable(path)) {

            throw new IllegalArgumentException("Directory " + path + " is not writable");

        }

    }

    public static String encodeForFilename(String className) {

        final int len = className.length();

        StringBuilder sb = new StringBuilder(len);

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

            char c = className.charAt(i);

            // control characters

            if (c <= 31) {

                sb.append('%');

                sb.append(HEX[c >> 4 & 0x0F]);

                sb.append(HEX[c & 0x0F]);

            } else {

                int j = 0;

                for (; j < BAD_CHARS.length; j++) {

                    if (c == BAD_CHARS[j]) {

                        sb.append(REPLACEMENT[j]);

                        break;

                    }

                }

                if (j >= BAD_CHARS.length) {

                    sb.append(c);

                }

            }

        }

        return sb.toString();

    }

    public void dumpClass(String className, final byte[] classBytes) {

        Path file;

        try {

            file = dumpDir.resolve(encodeForFilename(className) + ".class");

        } catch (InvalidPathException ex) {

            PlatformLogger.getLogger(ProxyClassesDumper.class.getName())

                          .warning("Invalid path for class " + className);

            return;

        }

        try {

            Path dir = file.getParent();

            Files.createDirectories(dir);

            Files.write(file, classBytes);

        } catch (Exception ignore) {

            PlatformLogger.getLogger(ProxyClassesDumper.class.getName())

                          .warning("Exception writing to path at " + file.toString());

            // simply don't care if this operation failed

        }

    }

}