/*
 Copyright (C) 2014 Erik Ogenvik

 This program is free software; you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
 the Free Software Foundation; either version 2 of the License, or
 (at your option) any later version.

 This program 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 for more details.

 You should have received a copy of the GNU General Public License
 along with this program; if not, write to the Free Software
 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "OperationsDispatcher.h"
#include "rulesets/LocatedEntity.h"
#include "BaseWorld.h"
#include "const.h"
#include "debug.h"
#include "Monitors.h"

#include <iostream>

static const bool debug_flag = false;

OpQueEntry::OpQueEntry(const Operation & o, LocatedEntity & f) : op(o),
                                                                        from(&f)
{
    from->incRef();
}

OpQueEntry::OpQueEntry(const OpQueEntry & o) : op(o.op), from(o.from)
{
    from->incRef();
}

OpQueEntry::~OpQueEntry()
{
    from->decRef();
}


OperationsDispatcher::OperationsDispatcher(const std::function<void(const Operation&, LocatedEntity&)>& operationProcessor, const std::function<double()>& timeProviderFn)
: m_operationProcessor(operationProcessor), m_timeProviderFn(timeProviderFn), m_operation_queues_dirty(false)
{
}

OperationsDispatcher::~OperationsDispatcher()
{
    clearQueues();
}

void OperationsDispatcher::clearQueues()
{
    m_immediateQueue = OpQueue();
    m_operationQueue = OpPriorityQueue();
}

void OperationsDispatcher::dispatchOperation(const OpQueEntry& oqe)
{
    try {
        m_operationProcessor(oqe.op, *oqe.from);
    }
    catch (const std::exception& ex) {
        log(ERROR, String::compose("Exception caught in WorldRouter::idle() "
                                   "thrown while processing operation "
                                   "sent to \"%1\" from \"%2\": %3",
                                   oqe->getTo(), oqe->getFrom(), ex.what()));
    }
    catch (...) {
        log(ERROR, String::compose("Unspecified exception caught in WorldRouter::idle() "
                                   "thrown while processing operation "
                                   "sent to \"%1\" from \"%2\"",
                                   oqe->getTo(), oqe->getFrom()));
    }
}

/// \brief Add an operation to the ordered op queue.
///
/// Any time adjustment required is made to the operation, and it
/// is added to the apropriate place in the chronologically ordered
/// queue. The From attribute of the operation is set to the id of
/// the entity that is responsible for adding the operation to the
/// queue.
void OperationsDispatcher::addOperationToQueue(const Operation & op, LocatedEntity & ent)
{
    assert(op.isValid());
    assert(op->getFrom() != "cheat");

    m_operation_queues_dirty = true;
    op->setFrom(ent.getId());
    if (!op->hasAttrFlag(Atlas::Objects::Operation::FUTURE_SECONDS_FLAG)) {
        op->setSeconds(getTime());
        m_immediateQueue.push(OpQueEntry(op, ent));
        return;
    }
    double t = getTime() + (op->getFutureSeconds() * consts::time_multiplier);
    op->setSeconds(t);
    op->setFutureSeconds(0.);
    m_operationQueue.push(OpQueEntry(op, ent));
    if (debug_flag) {
        std::cout << "WorldRouter::addOperationToQueue {" << std::endl;
        debug_dump(op, std::cout);
        std::cout << "}" << std::endl << std::flush;
    }
}

bool OperationsDispatcher::idle()
{
    unsigned int op_count = 0;

    double realtime = getTime();
    bool result = false;

    while (true) {
        if (!m_immediateQueue.empty()) {
            ++op_count;
            auto opQueueEntry = std::move(m_immediateQueue.front());
            m_immediateQueue.pop();
            dispatchOperation(opQueueEntry);
        } else if (!m_operationQueue.empty() && m_operationQueue.top()->getSeconds() <= realtime) {
            ++op_count;
            auto opQueueEntry = m_operationQueue.top();
            //Pop it before we dispatch it, since dispatching might alter the queue.
            m_operationQueue.pop();
            dispatchOperation(opQueueEntry);
        } else {
            //There were neither any immediate ops to dispatch, or any regular ops that were ready for dispatch.
            //We should return and signal that it's ok to sleep until any op is ready for dispatch.
            result = false;
            break;
        }

        if (op_count >= 10) {
            //we've processed 10 ops, we should return to allow for IO to interleave. Check if there are more
            //ops that should be processed now.

            // If there are still immediate or regular ops to deliver return true
            // to tell the server not to sleep when polling clients. This ensures
            // that we keep processing ops at a the maximum rate without leaving
            // clients unattended.
            if (!m_immediateQueue.empty() || (!m_operationQueue.empty() && m_operationQueue.top()->getSeconds() <= realtime)) {
                result = true;
                break;
            } else {
                result = false;
                break;
            }
        }
    }
    Monitors::instance()->insert("immediate_operations_queue", (Atlas::Message::IntType) m_immediateQueue.size());
    Monitors::instance()->insert("operations_queue", (Atlas::Message::IntType) m_operationQueue.size());
    return result;
}


bool OperationsDispatcher::isQueueDirty() const
{
    return m_operation_queues_dirty;
}

void OperationsDispatcher::markQueueAsClean()
{
    m_operation_queues_dirty = false;
}

double OperationsDispatcher::getTime() const
{
    return m_timeProviderFn();
    //TODO: remove this tangle somehow
//    return BaseWorld::instance().getTime();
}

double OperationsDispatcher::secondsUntilNextOp() const {
    if (m_operationQueue.empty()) {
        //600 is a fairly large number of seconds
        return 600.0;
    }
    return m_operationQueue.top()->getSeconds() - getTime();
}