/* -------------------------------------------------------------------------- *
 *                                   OpenMM                                   *
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 * This is part of the OpenMM molecular simulation toolkit.                   *
 * See https://openmm.org/development.                                        *
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 * Authors: Peter Eastman                                                     *
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#include "openmm/OpenMMException.h"
#include "openmm/internal/ContextImpl.h"
#include "openmm/internal/PeriodicTorsionForceImpl.h"
#include "openmm/kernels.h"
#include <sstream>

using namespace OpenMM;
using namespace std;

PeriodicTorsionForceImpl::PeriodicTorsionForceImpl(const PeriodicTorsionForce& owner) : owner(owner) {
    forceGroup = owner.getForceGroup();
}

PeriodicTorsionForceImpl::~PeriodicTorsionForceImpl() {
}

void PeriodicTorsionForceImpl::initialize(ContextImpl& context) {
    const System& system = context.getSystem();
    for (int i = 0; i < owner.getNumTorsions(); i++) {
        int particle[4], periodicity;
        double phase, k;
        owner.getTorsionParameters(i, particle[0], particle[1], particle[2], particle[3], periodicity, phase, k);
        for (int j = 0; j < 4; j++) {
            if (particle[j] < 0 || particle[j] >= system.getNumParticles()) {
                stringstream msg;
                msg << "PeriodicTorsionForce: Illegal particle index for a torsion: ";
                msg << particle[j];
                throw OpenMMException(msg.str());
            }
        }
        if (periodicity < 1)
            throw OpenMMException("PeriodicTorsionForce: periodicity must be positive");
    }
    kernel = context.getPlatform().createKernel(CalcPeriodicTorsionForceKernel::Name(), context);
    kernel.getAs<CalcPeriodicTorsionForceKernel>().initialize(context.getSystem(), owner);
}

double PeriodicTorsionForceImpl::calcForcesAndEnergy(ContextImpl& context, bool includeForces, bool includeEnergy, int groups) {
    if ((groups&(1<<forceGroup)) != 0)
        return kernel.getAs<CalcPeriodicTorsionForceKernel>().execute(context, includeForces, includeEnergy);
    return 0.0;
}

std::vector<std::string> PeriodicTorsionForceImpl::getKernelNames() {
    return {CalcPeriodicTorsionForceKernel::Name()};
}

void PeriodicTorsionForceImpl::updateParametersInContext(ContextImpl& context, int firstTorsion, int lastTorsion) {
    kernel.getAs<CalcPeriodicTorsionForceKernel>().copyParametersToContext(context, owner, firstTorsion, lastTorsion);
    context.systemChanged();
}
