/*
 *
 * 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.
 *
 */
#include "QueueGuard.h"
#include "ReplicatingSubscription.h"
#include "qpid/broker/Queue.h"
#include "qpid/broker/QueuedMessage.h"
#include "qpid/broker/QueueObserver.h"
#include "qpid/log/Statement.h"
#include <boost/bind.hpp>
#include <sstream>

namespace qpid {
namespace ha {

using namespace broker;
using sys::Mutex;
using framing::SequenceNumber;
using framing::SequenceSet;

class QueueGuard::QueueObserver : public broker::QueueObserver
{
  public:
    QueueObserver(QueueGuard& g) : guard(g) {}
    void enqueued(const broker::QueuedMessage& qm) { guard.enqueued(qm); }
    void dequeued(const broker::QueuedMessage& qm) { guard.dequeued(qm); }
    void acquired(const broker::QueuedMessage&) {}
    void requeued(const broker::QueuedMessage&) {}
  private:
    QueueGuard& guard;
};



QueueGuard::QueueGuard(broker::Queue& q, const BrokerInfo& info)
    : queue(q), subscription(0), range(q)
{
    // NOTE: The QueueGuard is created before the queue becomes active: either
    // when a backup is promoted, or when a new queue is created on the primary.
    std::ostringstream os;
    os << "Primary guard " << queue.getName() << "@" << info.getLogId() << ": ";
    logPrefix = os.str();
    observer.reset(new QueueObserver(*this));
    queue.addObserver(observer);
}

QueueGuard::~QueueGuard() { cancel(); }

// NOTE: Called with message lock held.
void QueueGuard::enqueued(const QueuedMessage& qm) {
    assert(qm.queue == &queue);
    // Delay completion
    QPID_LOG(trace, logPrefix << "Delayed completion of " << qm);
    qm.payload->getIngressCompletion().startCompleter();
    {
        Mutex::ScopedLock l(lock);
        assert(!delayed.contains(qm.position));
        delayed += qm.position;
    }
}

// NOTE: Called with message lock held.
void QueueGuard::dequeued(const QueuedMessage& qm) {
    assert(qm.queue == &queue);
    QPID_LOG(trace, logPrefix << "Dequeued " << qm);
    ReplicatingSubscription* rs=0;
    {
        Mutex::ScopedLock l(lock);
        rs = subscription;
    }
    if (rs) rs->dequeued(qm);
    complete(qm);
}

void QueueGuard::cancel() {
    queue.removeObserver(observer);
    {
        Mutex::ScopedLock l(lock);
        if (delayed.empty()) return; // No need if no delayed messages.
    }
    // FIXME aconway 2012-06-15: optimize, only messages in delayed set.
    queue.eachMessage(boost::bind(&QueueGuard::complete, this, _1));
}

void QueueGuard::attach(ReplicatingSubscription& rs) {
    Mutex::ScopedLock l(lock);
     subscription = &rs;
}

namespace {
void completeBefore(QueueGuard* guard, SequenceNumber position, const QueuedMessage& qm) {
    if (qm.position <= position) guard->complete(qm);
}
}

bool QueueGuard::subscriptionStart(SequenceNumber position) {
   // Complete any messages before or at the ReplicatingSubscription start position.
    if (!delayed.empty() && delayed.front() <= position) {
        // FIXME aconway 2012-06-15: queue iteration, only messages in delayed
        queue.eachMessage(boost::bind(&completeBefore, this, position, _1));
    }
    return position >= range.back;
}

void QueueGuard::complete(const QueuedMessage& qm) {
    assert(qm.queue == &queue);
    {
        Mutex::ScopedLock l(lock);
        // The same message can be completed twice, by
        // ReplicatingSubscription::acknowledged and dequeued. Remove it
        // from the set so we only call finishCompleter() once
        if (delayed.contains(qm.position))
            delayed -= qm.position;
        else
            return;
    }
    QPID_LOG(trace, logPrefix << "Completed " << qm);
    qm.payload->getIngressCompletion().finishCompleter();
}

// FIXME aconway 2012-06-04: TODO support for timeout.

}} // namespaces qpid::ha
