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/*! \internal \file
 * \brief Defines the force element for the modular simulator
 *
 * \author Pascal Merz <pascal.merz@me.com>
 * \ingroup module_modularsimulator
 */

#include "gmxpre.h"

#include "forceelement.h"

#include "gromacs/domdec/mdsetup.h"
#include "gromacs/math/vectypes.h"
#include "gromacs/mdlib/constr.h"
#include "gromacs/mdlib/force.h"
#include "gromacs/mdlib/force_flags.h"
#include "gromacs/mdlib/mdatoms.h"
#include "gromacs/mdrun/shellfc.h"
#include "gromacs/mdtypes/forcebuffers.h"
#include "gromacs/mdtypes/inputrec.h"
#include "gromacs/mdtypes/mdatom.h"
#include "gromacs/mdtypes/mdrunoptions.h"
#include "gromacs/mdtypes/simulation_workload.h"
#include "gromacs/pbcutil/pbc.h"

#include "energydata.h"
#include "freeenergyperturbationdata.h"
#include "modularsimulator.h"
#include "simulatoralgorithm.h"
#include "statepropagatordata.h"

struct gmx_edsam;
struct gmx_enfrot;
struct gmx_multisim_t;
class history_t;

namespace gmx
{
ForceElement::ForceElement(StatePropagatorData*        statePropagatorData,
                           EnergyData*                 energyData,
                           FreeEnergyPerturbationData* freeEnergyPerturbationData,
                           bool                        isVerbose,
                           bool                        isDynamicBox,
                           FILE*                       fplog,
                           const t_commrec*            cr,
                           const t_inputrec*           inputrec,
                           const MDAtoms*              mdAtoms,
                           t_nrnb*                     nrnb,
                           t_forcerec*                 fr,

                           gmx_wallcycle*         wcycle,
                           MdrunScheduleWorkload* runScheduleWork,
                           VirtualSitesHandler*   vsite,
                           ImdSession*            imdSession,
                           pull_t*                pull_work,
                           Constraints*           constr,
                           const gmx_mtop_t*      globalTopology,
                           gmx_enfrot*            enforcedRotation) :
    shellfc_(init_shell_flexcon(fplog,
                                globalTopology,
                                constr ? constr->numFlexibleConstraints() : 0,
                                inputrec->nstcalcenergy,
                                DOMAINDECOMP(cr),
                                runScheduleWork->simulationWork.useGpuPme)),
    doShellFC_(shellfc_ != nullptr),
    nextNSStep_(-1),
    nextEnergyCalculationStep_(-1),
    nextVirialCalculationStep_(-1),
    nextFreeEnergyCalculationStep_(-1),
    statePropagatorData_(statePropagatorData),
    energyData_(energyData),
    freeEnergyPerturbationData_(freeEnergyPerturbationData),
    localTopology_(nullptr),
    isDynamicBox_(isDynamicBox),
    isVerbose_(isVerbose),
    nShellRelaxationSteps_(0),
    ddBalanceRegionHandler_(cr),
    lambda_(),
    fplog_(fplog),
    cr_(cr),
    inputrec_(inputrec),
    mdAtoms_(mdAtoms),
    nrnb_(nrnb),
    wcycle_(wcycle),
    fr_(fr),
    vsite_(vsite),
    imdSession_(imdSession),
    pull_work_(pull_work),
    runScheduleWork_(runScheduleWork),
    constr_(constr),
    enforcedRotation_(enforcedRotation)
{
    lambda_.fill(0);

    if (doShellFC_ && !DOMAINDECOMP(cr))
    {
        // This was done in mdAlgorithmsSetupAtomData(), but shellfc
        // won't be available outside this element.
        make_local_shells(cr, mdAtoms->mdatoms(), shellfc_);
    }
}

void ForceElement::scheduleTask(Step step, Time time, const RegisterRunFunction& registerRunFunction)
{
    unsigned int flags =
            (GMX_FORCE_STATECHANGED | GMX_FORCE_ALLFORCES | (isDynamicBox_ ? GMX_FORCE_DYNAMICBOX : 0)
             | (nextVirialCalculationStep_ == step ? GMX_FORCE_VIRIAL : 0)
             | (nextEnergyCalculationStep_ == step ? GMX_FORCE_ENERGY : 0)
             | (nextFreeEnergyCalculationStep_ == step ? GMX_FORCE_DHDL : 0)
             | (!doShellFC_ && nextNSStep_ == step ? GMX_FORCE_NS : 0));

    registerRunFunction([this, step, time, flags]() {
        if (doShellFC_)
        {
            run<true>(step, time, flags);
        }
        else
        {
            run<false>(step, time, flags);
        }
    });
}

void ForceElement::elementSetup()
{
    GMX_ASSERT(localTopology_, "Setup called before local topology was set.");
}

template<bool doShellFC>
void ForceElement::run(Step step, Time time, unsigned int flags)
{
    // Disabled functionality
    gmx_multisim_t* ms = nullptr;


    if (!DOMAINDECOMP(cr_) && (flags & GMX_FORCE_NS) && inputrecDynamicBox(inputrec_))
    {
        // TODO: Correcting the box is done in DomDecHelper (if using DD) or here (non-DD simulations).
        //       Think about unifying this responsibility, could this be done in one place?
        auto box = statePropagatorData_->box();
        correct_box(fplog_, step, box);
    }

    /* The coordinates (x) are shifted (to get whole molecules)
     * in do_force.
     * This is parallelized as well, and does communication too.
     * Check comments in sim_util.c
     */
    auto       x      = statePropagatorData_->positionsView();
    auto&      forces = statePropagatorData_->forcesView();
    auto       box    = statePropagatorData_->constBox();
    history_t* hist   = nullptr; // disabled

    tensor force_vir = { { 0 } };
    // TODO: Make lambda const (needs some adjustments in lower force routines)
    ArrayRef<real> lambda =
            freeEnergyPerturbationData_ ? freeEnergyPerturbationData_->lambdaView() : lambda_;

    if (doShellFC)
    {
        auto v = statePropagatorData_->velocitiesView();

        relax_shell_flexcon(
                fplog_, cr_, ms, isVerbose_, enforcedRotation_, step, inputrec_, imdSession_,
                pull_work_, step == nextNSStep_, static_cast<int>(flags), localTopology_, constr_,
                energyData_->enerdata(), statePropagatorData_->localNumAtoms(), x, v, box, lambda,
                hist, &forces, force_vir, mdAtoms_->mdatoms(), nrnb_, wcycle_, shellfc_, fr_,
                runScheduleWork_, time, energyData_->muTot(), vsite_, ddBalanceRegionHandler_);
        nShellRelaxationSteps_++;
    }
    else
    {
        // Disabled functionality
        Awh*       awh = nullptr;
        gmx_edsam* ed  = nullptr;

        do_force(fplog_, cr_, ms, inputrec_, awh, enforcedRotation_, imdSession_, pull_work_, step,
                 nrnb_, wcycle_, localTopology_, box, x, hist, &forces, force_vir,
                 mdAtoms_->mdatoms(), energyData_->enerdata(), lambda, fr_, runScheduleWork_, vsite_,
                 energyData_->muTot(), time, ed, static_cast<int>(flags), ddBalanceRegionHandler_);
    }
    energyData_->addToForceVirial(force_vir, step);
}

void ForceElement::elementTeardown()
{
    if (doShellFC_)
    {
        done_shellfc(fplog_, shellfc_, nShellRelaxationSteps_);
    }
}

void ForceElement::setTopology(const gmx_localtop_t* top)
{
    localTopology_ = top;
}

std::optional<SignallerCallback> ForceElement::registerNSCallback()
{
    return [this](Step step, Time gmx_unused time) { this->nextNSStep_ = step; };
}

std::optional<SignallerCallback> ForceElement::registerEnergyCallback(EnergySignallerEvent event)
{
    if (event == EnergySignallerEvent::EnergyCalculationStep)
    {
        return [this](Step step, Time /*unused*/) { nextEnergyCalculationStep_ = step; };
    }
    if (event == EnergySignallerEvent::VirialCalculationStep)
    {
        return [this](Step step, Time /*unused*/) { nextVirialCalculationStep_ = step; };
    }
    if (event == EnergySignallerEvent::FreeEnergyCalculationStep)
    {
        return [this](Step step, Time /*unused*/) { nextFreeEnergyCalculationStep_ = step; };
    }
    return std::nullopt;
}

ISimulatorElement*
ForceElement::getElementPointerImpl(LegacySimulatorData*                    legacySimulatorData,
                                    ModularSimulatorAlgorithmBuilderHelper* builderHelper,
                                    StatePropagatorData*                    statePropagatorData,
                                    EnergyData*                             energyData,
                                    FreeEnergyPerturbationData* freeEnergyPerturbationData,
                                    GlobalCommunicationHelper gmx_unused* globalCommunicationHelper)
{
    const bool isVerbose    = legacySimulatorData->mdrunOptions.verbose;
    const bool isDynamicBox = inputrecDynamicBox(legacySimulatorData->inputrec);
    return builderHelper->storeElement(std::make_unique<ForceElement>(
            statePropagatorData, energyData, freeEnergyPerturbationData, isVerbose, isDynamicBox,
            legacySimulatorData->fplog, legacySimulatorData->cr, legacySimulatorData->inputrec,
            legacySimulatorData->mdAtoms, legacySimulatorData->nrnb, legacySimulatorData->fr,
            legacySimulatorData->wcycle, legacySimulatorData->runScheduleWork, legacySimulatorData->vsite,
            legacySimulatorData->imdSession, legacySimulatorData->pull_work, legacySimulatorData->constr,
            legacySimulatorData->top_global, legacySimulatorData->enforcedRotation));
}
} // namespace gmx
