/*
 *  This file is part of RawTherapee.
 *
 *  Copyright (c) 2004-2010 Gabor Horvath <hgabor@rawtherapee.com>
 *
 *  RawTherapee 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 3 of the License, or
 *  (at your option) any later version.
 *
 *  RawTherapee 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 RawTherapee.  If not, see <https://www.gnu.org/licenses/>.
 */

#include <atomic>
#include <memory>
#include <set>

#include <gtkmm.h>

#include "thumbimageupdater.h"
#include "thumbbrowserentrybase.h"

#include "guiutils.h"
#include "threadutils.h"
#include "thumbnail.h"

#include "rtengine/procparams.h"

#ifdef _OPENMP
#include <omp.h>
#endif

#define DEBUG(format,args...)
//#define DEBUG(format,args...) printf("ThumbImageUpdate::%s: " format "\n", __FUNCTION__, ## args)

class ThumbImageUpdater::Impl :
    public rtengine::NonCopyable
{
public:

    struct Job {
        Job(ThumbBrowserEntryBase* tbe, bool* priority, bool upgrade,
            bool forceUpgrade, ThumbImageUpdateListener* listener):
            tbe_(tbe),
            /*pparams_(pparams),
            height_(height), */
            priority_(priority),
            upgrade_(upgrade),
            force_upgrade_(forceUpgrade),
            listener_(listener)
        {}

        Job():
            tbe_(nullptr),
            priority_(nullptr),
            upgrade_(false),
            force_upgrade_(false),
            listener_(nullptr)
        {}

        ThumbBrowserEntryBase* tbe_;
        /*rtengine::procparams::ProcParams pparams_;
        int height_;*/
        bool* priority_;
        bool upgrade_;
        bool force_upgrade_;
        ThumbImageUpdateListener* listener_;
    };

    typedef std::list<Job> JobList;

    Impl():
        active_(0),
        inactive_waiting_(false)
    {
        int threadCount = 1;
#ifdef _OPENMP
        threadCount = omp_get_num_procs();
#endif

        threadPool_.reset(new Glib::ThreadPool(threadCount, 0));
    }

    std::unique_ptr<Glib::ThreadPool> threadPool_;

    // Need to be a std::mutex because used in a std::condition_variable object...
    // This is the only exceptions along with GThreadMutex (guiutils.cc), MyMutex is used everywhere else
    std::mutex mutex_;

    JobList jobs_;

    std::atomic<unsigned int> active_;

    bool inactive_waiting_;

    std::condition_variable inactive_;

    void
    processNextJob()
    {
        Job j;

        {
            std::lock_guard<std::mutex> lock(mutex_);

            // nothing to do; could be jobs have been removed
            if ( jobs_.empty() ) {
                DEBUG("processing: nothing to do (%d)", jobs_.empty());
                return;
            }

            JobList::iterator i;

            // see if any priority jobs exist
            for ( i = jobs_.begin(); i != jobs_.end(); ++i) {
                if ( *(i->priority_) ) {
                    DEBUG("processing(priority) %s", i->tbe_->thumbnail->getFileName().c_str());
                    break;
                }
            }

            // see if any none upgrade jobs exist
            if ( i == jobs_.end() ) {
                for ( i = jobs_.begin(); i != jobs_.end(); ++i) {
                    if ( !i->upgrade_ ) {
                        DEBUG("processing(not-upgrade) %s", i->tbe_->thumbnail->getFileName().c_str());
                        break;
                    }
                }
            }

            // if none, then use first
            if ( i == jobs_.end() ) {
                i = jobs_.begin();
                DEBUG("processing(first) %s", i->tbe_->thumbnail->getFileName().c_str());
            }

            // copy found job
            j = *i;

            // remove so not run again
            jobs_.erase(i);
            DEBUG("%d job(s) remaining", int(jobs_.size()) );

            ++active_;
        }

        // unlock and do processing; will relock on block exit, then call listener
        double scale = 1.0;
        rtengine::IImage8* img = nullptr;
        Thumbnail* thm = j.tbe_->thumbnail;

        if ( j.upgrade_ ) {
            if ( thm->isQuick() || j.force_upgrade_ ) {
                img = thm->upgradeThumbImage(thm->getProcParams(), j.tbe_->getPreviewHeight(), scale, j.force_upgrade_);
            }
        } else {
            img = thm->processThumbImage(thm->getProcParams(), j.tbe_->getPreviewHeight(), scale);
        }

        if (img) {
            DEBUG("pushing image %s", thm->getFileName().c_str());
            j.listener_->updateImage(img, scale, thm->getProcParams().crop);
        }

        if ( --active_ == 0 ) {
            std::lock_guard<std::mutex> lock(mutex_);
            if (inactive_waiting_) {
                inactive_waiting_ = false;
                inactive_.notify_all();
            }
        }
    }
};

ThumbImageUpdater*
ThumbImageUpdater::getInstance()
{
    static ThumbImageUpdater instance_;
    return &instance_;
}

ThumbImageUpdater::ThumbImageUpdater():
    impl_(new Impl())
{
}

ThumbImageUpdater::~ThumbImageUpdater() {
    delete impl_;
}

void ThumbImageUpdater::add(ThumbBrowserEntryBase* tbe, bool* priority, bool upgrade, bool forceUpgrade, ThumbImageUpdateListener* l)
{
    // nobody listening?
    if ( l == nullptr ) {
        return;
    }

    std::lock_guard<std::mutex> lock(impl_->mutex_);

    // look up if an older version is in the queue
    Impl::JobList::iterator i(impl_->jobs_.begin());

    for ( ; i != impl_->jobs_.end(); ++i ) {
        if ( i->tbe_ == tbe &&
                i->listener_ == l &&
                i->upgrade_ == upgrade &&
                i->force_upgrade_ == forceUpgrade) {
            DEBUG("updating job %s", tbe->shortname.c_str());
            // we have one, update queue entry, will be picked up by thread when processed
            /*i->pparams_ = params;
            i->height_ = height; */
            i->priority_ = priority;
            return;
        }
    }

    // create a new job and append to queue
    DEBUG("queueing job %s", tbe->shortname.c_str());
    impl_->jobs_.push_back(Impl::Job(tbe, priority, upgrade, forceUpgrade, l));

    DEBUG("adding run request %s", tbe->shortname.c_str());
    impl_->threadPool_->push(sigc::mem_fun(*impl_, &ThumbImageUpdater::Impl::processNextJob));
}


void ThumbImageUpdater::removeJobs(ThumbImageUpdateListener* listener)
{
    DEBUG("removeJobs(%p)", listener);

    {
        std::lock_guard<std::mutex> lock(impl_->mutex_);

        for( Impl::JobList::iterator i(impl_->jobs_.begin()); i != impl_->jobs_.end(); ) {
            if (i->listener_ == listener) {
                DEBUG("erasing specific job");
                Impl::JobList::iterator e(i++);
                impl_->jobs_.erase(e);
            } else {
                ++i;
            }
        }
    }

    while ( impl_->active_ != 0 ) {
        DEBUG("waiting for running jobs1");
        {
            std::unique_lock<std::mutex> lock(impl_->mutex_);
            impl_->inactive_waiting_ = true;
            impl_->inactive_.wait(lock);
        }
    }
}

void ThumbImageUpdater::removeAllJobs()
{
    DEBUG("stop");

    {
        std::lock_guard<std::mutex> lock(impl_->mutex_);

        impl_->jobs_.clear();
    }

    while ( impl_->active_ != 0 ) {
        DEBUG("waiting for running jobs2");
        {
            std::unique_lock<std::mutex> lock(impl_->mutex_);
            impl_->inactive_waiting_ = true;
            impl_->inactive_.wait(lock);
        }
    }
}