/*
 * Copyright 2013 The Netty Project
 *
 * The Netty Project 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 io.netty.buffer;

import io.netty.util.ResourceLeakDetector;
import io.netty.util.ResourceLeakTracker;
import io.netty.util.internal.ObjectUtil;

import java.nio.ByteOrder;

class SimpleLeakAwareByteBuf extends WrappedByteBuf {

    /**
     * This object's is associated with the {@link ResourceLeakTracker}. When {@link ResourceLeakTracker#close(Object)}
     * is called this object will be used as the argument. It is also assumed that this object is used when
     * {@link ResourceLeakDetector#track(Object)} is called to create {@link #leak}.
     */
    private final ByteBuf trackedByteBuf;
    final ResourceLeakTracker<ByteBuf> leak;

    SimpleLeakAwareByteBuf(ByteBuf wrapped, ByteBuf trackedByteBuf, ResourceLeakTracker<ByteBuf> leak) {
        super(wrapped);
        this.trackedByteBuf = ObjectUtil.checkNotNull(trackedByteBuf, "trackedByteBuf");
        this.leak = ObjectUtil.checkNotNull(leak, "leak");
    }

    SimpleLeakAwareByteBuf(ByteBuf wrapped, ResourceLeakTracker<ByteBuf> leak) {
        this(wrapped, wrapped, leak);
    }

    @Override
    public ByteBuf slice() {
        return newSharedLeakAwareByteBuf(super.slice());
    }

    @Override
    public ByteBuf retainedSlice() {
        return unwrappedDerived(super.retainedSlice());
    }

    @Override
    public ByteBuf retainedSlice(int index, int length) {
        return unwrappedDerived(super.retainedSlice(index, length));
    }

    @Override
    public ByteBuf retainedDuplicate() {
        return unwrappedDerived(super.retainedDuplicate());
    }

    @Override
    public ByteBuf readRetainedSlice(int length) {
        return unwrappedDerived(super.readRetainedSlice(length));
    }

    @Override
    public ByteBuf slice(int index, int length) {
        return newSharedLeakAwareByteBuf(super.slice(index, length));
    }

    @Override
    public ByteBuf duplicate() {
        return newSharedLeakAwareByteBuf(super.duplicate());
    }

    @Override
    public ByteBuf readSlice(int length) {
        return newSharedLeakAwareByteBuf(super.readSlice(length));
    }

    @Override
    public ByteBuf asReadOnly() {
        return newSharedLeakAwareByteBuf(super.asReadOnly());
    }

    @Override
    public ByteBuf touch() {
        return this;
    }

    @Override
    public ByteBuf touch(Object hint) {
        return this;
    }

    @Override
    public final boolean release() {
        if (super.release()) {
            closeLeak();
            return true;
        }
        return false;
    }

    @Override
    public final boolean release(int decrement) {
        if (super.release(decrement)) {
            closeLeak();
            return true;
        }
        return false;
    }

    private void closeLeak() {
        // Close the ResourceLeakTracker with the tracked ByteBuf as argument. This must be the same that was used when
        // calling DefaultResourceLeak.track(...).
        boolean closed = leak.close(trackedByteBuf);
        assert closed;
    }

    @Override
    public ByteBuf order(ByteOrder endianness) {
        if (order() == endianness) {
            return this;
        } else {
            return newSharedLeakAwareByteBuf(super.order(endianness));
        }
    }

    private ByteBuf unwrappedDerived(ByteBuf derived) {
        // We only need to unwrap SwappedByteBuf implementations as these will be the only ones that may end up in
        // the AbstractLeakAwareByteBuf implementations beside slices / duplicates and "real" buffers.
        ByteBuf unwrappedDerived = unwrapSwapped(derived);

        if (unwrappedDerived instanceof AbstractPooledDerivedByteBuf) {
            // Update the parent to point to this buffer so we correctly close the ResourceLeakTracker.
            ((AbstractPooledDerivedByteBuf) unwrappedDerived).parent(this);

            ResourceLeakTracker<ByteBuf> newLeak = AbstractByteBuf.leakDetector.track(derived);
            if (newLeak == null) {
                // No leak detection, just return the derived buffer.
                return derived;
            }
            return newLeakAwareByteBuf(derived, newLeak);
        }
        return newSharedLeakAwareByteBuf(derived);
    }

    @SuppressWarnings("deprecation")
    private static ByteBuf unwrapSwapped(ByteBuf buf) {
        if (buf instanceof SwappedByteBuf) {
            do {
                buf = buf.unwrap();
            } while (buf instanceof SwappedByteBuf);

            return buf;
        }
        return buf;
    }

    private SimpleLeakAwareByteBuf newSharedLeakAwareByteBuf(
            ByteBuf wrapped) {
        return newLeakAwareByteBuf(wrapped, trackedByteBuf, leak);
    }

    private SimpleLeakAwareByteBuf newLeakAwareByteBuf(
            ByteBuf wrapped, ResourceLeakTracker<ByteBuf> leakTracker) {
        return newLeakAwareByteBuf(wrapped, wrapped, leakTracker);
    }

    protected SimpleLeakAwareByteBuf newLeakAwareByteBuf(
            ByteBuf buf, ByteBuf trackedByteBuf, ResourceLeakTracker<ByteBuf> leakTracker) {
        return new SimpleLeakAwareByteBuf(buf, trackedByteBuf, leakTracker);
    }
}