/*MT*

    MediaTomb - http://www.mediatomb.cc/

    update_manager.cc - this file is part of MediaTomb.

    Copyright (C) 2005 Gena Batyan <bgeradz@mediatomb.cc>,
                       Sergey 'Jin' Bostandzhyan <jin@mediatomb.cc>

    Copyright (C) 2006-2010 Gena Batyan <bgeradz@mediatomb.cc>,
                            Sergey 'Jin' Bostandzhyan <jin@mediatomb.cc>,
                            Leonhard Wimmer <leo@mediatomb.cc>

    Copyright (C) 2016-2024 Gerbera Contributors

    MediaTomb is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License version 2
    as published by the Free Software Foundation.

    MediaTomb 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
    version 2 along with MediaTomb; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.

    $Id$
*/

/// \file update_manager.cc
#define GRB_LOG_FAC GrbLogFacility::update

#include "update_manager.h" // API

#include <csignal>

#include "database/database.h"
#include "server.h"
#include "util/grb_net.h"
#include "util/grb_time.h"
#include "util/tools.h"

static constexpr auto specInterval = std::chrono::seconds(2);
static constexpr auto minSleep = std::chrono::milliseconds(1);

#define MAX_OBJECT_IDS 1000
#define MAX_OBJECT_IDS_OVERLOAD 30

UpdateManager::UpdateManager(std::shared_ptr<Config> config, std::shared_ptr<Database> database, std::shared_ptr<Server> server)
    : config(std::move(config))
    , database(std::move(database))
    , server(std::move(server))
{
}

void UpdateManager::run()
{
    threadRunner = std::make_unique<StdThreadRunner>(
        "UpdateThread", [](void* arg) {
            auto inst = static_cast<UpdateManager*>(arg);
            inst->threadProc();
        },
        this);
    // wait for thread to become ready
    threadRunner->waitForReady();
}

UpdateManager::~UpdateManager() { log_debug("UpdateManager destroyed"); }

void UpdateManager::shutdown()
{
    log_debug("start");
    auto lock = threadRunner->uniqueLock();
    shutdownFlag = true;

    log_debug("signalling...");
    threadRunner->notify();
    lock.unlock();

    threadRunner->join();
    log_debug("end");
}

void UpdateManager::containersChanged(const std::vector<int>& objectIDs, int flushPolicy)
{
    auto lock = threadRunner->uniqueLock();
    // signalling thread if it could have been idle, because
    // there were no unprocessed updates
    bool signal = (!haveUpdates());
    // signalling if the flushPolicy changes, so the thread recalculates
    // the sleep time
    if (flushPolicy > this->flushPolicy) {
        this->flushPolicy = flushPolicy;
        signal = true;
    }
    auto size = objectIDs.size();
    auto hashSize = objectIDHash.size();

    bool split = (hashSize + size >= MAX_OBJECT_IDS + MAX_OBJECT_IDS_OVERLOAD);
    for (int objectID : objectIDs) {
        if (objectID != lastContainerChanged) {
            // log_debug("containerChanged. id: {}, signal: {}", objectID, signal);
            objectIDHash.insert(objectID);
            if (split && objectIDHash.size() > MAX_OBJECT_IDS) {
                while (objectIDHash.size() > MAX_OBJECT_IDS) {
                    log_debug("in-between signalling...");
                    threadRunner->notify();
                    lock.unlock();
                    lock.lock();
                }
            }
        }
    }
    if (objectIDHash.size() >= MAX_OBJECT_IDS)
        signal = true;
    if (signal) {
        log_debug("signalling...");
        threadRunner->notify();
    }
}

void UpdateManager::containerChanged(int objectID, int flushPolicy)
{
    if (objectID == INVALID_OBJECT_ID)
        return;

    auto lock = threadRunner->lockGuard();

    if (objectID != lastContainerChanged || flushPolicy > this->flushPolicy) {
        // signalling thread if it could have been idle, because
        // there were no unprocessed updates
        bool signal = (!haveUpdates());
        log_debug("containerChanged. id: {}, signal: {}", objectID, signal);
        objectIDHash.insert(objectID);

        // signalling if the hash gets too full
        if (objectIDHash.size() >= MAX_OBJECT_IDS)
            signal = true;

        // very simple caching, but it gets a lot of hits
        lastContainerChanged = objectID;

        // signalling if the flushPolicy changes, so the thread recalculates
        // the sleep time
        if (flushPolicy > this->flushPolicy) {
            this->flushPolicy = flushPolicy;
            signal = true;
        }
        if (signal) {
            log_debug("signalling...");
            threadRunner->notify();
        }
    } else {
        log_debug("last container changed!");
    }
}

/* private stuff */

void UpdateManager::threadProc()
{
    StdThreadRunner::waitFor("UpdateManager", [this] { return threadRunner != nullptr; });

    auto lock = threadRunner->uniqueLockS("threadProc");
    // tell run() that we are ready
    threadRunner->setReady();

    auto lastUpdate = currentTimeMS();
    while (!shutdownFlag) {
        if (haveUpdates()) {
            std::chrono::milliseconds sleepMillis {};
            auto now = currentTimeMS();
            auto timeDiff = getDeltaMillis(lastUpdate, now);
            switch (flushPolicy) {
            case FLUSH_SPEC:
                sleepMillis = specInterval - timeDiff;
                break;
            case FLUSH_ASAP:
                sleepMillis = {};
                break;
            }
            bool sendUpdates = true;
            if (sleepMillis >= minSleep && objectIDHash.size() < MAX_OBJECT_IDS) {
                log_debug("threadProc: sleeping for {} millis", sleepMillis.count());
                auto ret = threadRunner->waitFor(lock, sleepMillis);

                if (!shutdownFlag) {
                    if (ret == std::cv_status::timeout)
                        sendUpdates = false;
                } else
                    sendUpdates = false;
            }

            if (sendUpdates) {
                log_debug("sending updates...");
                lastContainerChanged = INVALID_OBJECT_ID;
                flushPolicy = FLUSH_SPEC;
                std::string updateString;

                try {
                    updateString = database->incrementUpdateIDs(objectIDHash);
                    objectIDHash.clear(); // hash_data_array will be invalid after clear()
                } catch (const std::runtime_error& e) {
                    log_error("Fatal error when sending updates: {}", e.what());
                    log_error("Forcing Gerbera shutdown.");
                    kill(0, SIGINT);
                }
                lock.unlock(); // we don't need to hold the lock during the sending of the updates
                if (!updateString.empty()) {
                    try {
                        log_debug("updates sent: \"{}\"", updateString);
                        server->sendCDSSubscriptionUpdate(updateString);
                        lastUpdate = currentTimeMS();
                    } catch (const std::runtime_error& e) {
                        log_error("Fatal error when sending updates: {}", e.what());
                        log_error("Forcing Gerbera shutdown.");
                        kill(0, SIGINT);
                    }
                } else {
                    log_debug("NOT sending updates (string empty or invalid).");
                }
                lock.lock();
            }
        } else {
            // nothing to do
            threadRunner->wait(lock);
        }
    }

    database->threadCleanup();
}
