/*
 *  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.nio.ByteBuffer;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 * Simple wrapper for a {@link ByteBuffer} that remembers if the buffer has been flipped or not.
 */
public class ByteBufferHolder {

    private final ByteBuffer buf;
    private final AtomicBoolean flipped;

    /**
     * Constructs a holder for the specified buffer.
     *
     * @param buf the buffer
     * @param flipped initial flipped state
     */
    public ByteBufferHolder(ByteBuffer buf, boolean flipped) {
        this.buf = buf;
        this.flipped = new AtomicBoolean(flipped);
    }


    /**
     * Returns the wrapped buffer.
     *
     * @return the buffer
     */
    public ByteBuffer getBuf() {
        return buf;
    }


    /**
     * Returns whether the buffer has been flipped.
     *
     * @return true if flipped
     */
    public boolean isFlipped() {
        return flipped.get();
    }


    /**
     * Flips the buffer if not already flipped.
     *
     * @return true if the buffer was flipped by this call
     */
    public boolean flip() {
        if (flipped.compareAndSet(false, true)) {
            buf.flip();
            return true;
        } else {
            return false;
        }
    }
}