/*
 *  Licensed to the Apache Software Foundation (ASF) under one or more
 *  contributor license agreements.  See the NOTICE file distributed with
 *  this work for additional information regarding copyright ownership.
 *  The ASF licenses this file to You 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 org.apache.tomcat.util.buf;

import java.lang.reflect.Field;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.nio.ByteBuffer;

import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.compat.JreCompat;
import org.apache.tomcat.util.res.StringManager;

public class ByteBufferUtils {

    private static final StringManager sm = StringManager.getManager(ByteBufferUtils.class);
    private static final Log log = LogFactory.getLog(ByteBufferUtils.class);

    private static final Object unsafe;
    private static final Method cleanerMethod;
    private static final Method cleanMethod;
    private static final Method invokeCleanerMethod;

    static {
        ByteBuffer tempBuffer = ByteBuffer.allocateDirect(0);
        Method cleanerMethodLocal = null;
        Method cleanMethodLocal = null;
        Object unsafeLocal = null;
        Method invokeCleanerMethodLocal = null;
        if (JreCompat.isJre9Available()) {
            try {
                Class<?> clazz = Class.forName("sun.misc.Unsafe");
                Field theUnsafe = clazz.getDeclaredField("theUnsafe");
                theUnsafe.setAccessible(true);
                unsafeLocal = theUnsafe.get(null);
                invokeCleanerMethodLocal = clazz.getMethod("invokeCleaner", ByteBuffer.class);
                invokeCleanerMethodLocal.invoke(unsafeLocal, tempBuffer);
            } catch (IllegalAccessException | IllegalArgumentException
                    | InvocationTargetException | NoSuchMethodException | SecurityException
                    | ClassNotFoundException | NoSuchFieldException e) {
                log.warn(sm.getString("byteBufferUtils.cleaner"), e);
                unsafeLocal = null;
                invokeCleanerMethodLocal = null;
            }
        } else {
            try {
                cleanerMethodLocal = tempBuffer.getClass().getMethod("cleaner");
                cleanerMethodLocal.setAccessible(true);
                Object cleanerObject = cleanerMethodLocal.invoke(tempBuffer);
                cleanMethodLocal = cleanerObject.getClass().getMethod("clean");
                cleanMethodLocal.invoke(cleanerObject);
            } catch (NoSuchMethodException | SecurityException | IllegalAccessException |
                    IllegalArgumentException | InvocationTargetException e) {
                log.warn(sm.getString("byteBufferUtils.cleaner"), e);
                cleanerMethodLocal = null;
                cleanMethodLocal = null;
            }
        }
        cleanerMethod = cleanerMethodLocal;
        cleanMethod = cleanMethodLocal;
        unsafe = unsafeLocal;
        invokeCleanerMethod = invokeCleanerMethodLocal;
    }

    private ByteBufferUtils() {
        // Hide the default constructor since this is a utility class.
    }


    
Expands buffer to the given size unless it is already as big or bigger.
Buffers are assumed to be in 'write to' mode since there would be no need
to expand a buffer while it was in 'read from' mode.
Params:
in –        Buffer to expand
newSize –   The size t which the buffer should be expanded
Returns:
         The expanded buffer with any data from the input buffer
                 copied in to it or the original buffer if there was no
                 need for expansion/**
     * Expands buffer to the given size unless it is already as big or bigger.
     * Buffers are assumed to be in 'write to' mode since there would be no need
     * to expand a buffer while it was in 'read from' mode.
     *
     * @param in        Buffer to expand
     * @param newSize   The size t which the buffer should be expanded
     * @return          The expanded buffer with any data from the input buffer
     *                  copied in to it or the original buffer if there was no
     *                  need for expansion
     */
    public static ByteBuffer expand(ByteBuffer in, int newSize) {
        if (in.capacity() >= newSize) {
            return in;
        }

        ByteBuffer out;
        boolean direct = false;
        if (in.isDirect()) {
            out = ByteBuffer.allocateDirect(newSize);
            direct = true;
        } else {
            out = ByteBuffer.allocate(newSize);
        }

        // Copy data
        in.flip();
        out.put(in);

        if (direct) {
            cleanDirectBuffer(in);
        }

        return out;
    }

    public static void cleanDirectBuffer(ByteBuffer buf) {
        if (cleanMethod != null) {
            try {
                cleanMethod.invoke(cleanerMethod.invoke(buf));
            } catch (IllegalAccessException | IllegalArgumentException
                    | InvocationTargetException | SecurityException e) {
                if (log.isDebugEnabled()) {
                    log.debug(sm.getString("byteBufferUtils.cleaner"), e);
                }
            }
        } else if (invokeCleanerMethod != null) {
            try {
                invokeCleanerMethod.invoke(unsafe, buf);
            } catch (IllegalAccessException | IllegalArgumentException
                    | InvocationTargetException | SecurityException e) {
                if (log.isDebugEnabled()) {
                    log.debug(sm.getString("byteBufferUtils.cleaner"), e);
                }
            }
        }
    }

}