/* -------------------------------------------------------------------------- *
 *                                   OpenMM                                   *
 * -------------------------------------------------------------------------- *
 * 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/DrudeSCFIntegrator.h"
#include "openmm/DrudeKernels.h"
#include "openmm/Context.h"
#include "openmm/OpenMMException.h"
#include "openmm/internal/ContextImpl.h"
#include "openmm/internal/DrudeHelpers.h"
#include <cmath>
#include <ctime>
#include <string>

using namespace OpenMM;
using std::string;
using std::vector;

DrudeSCFIntegrator::DrudeSCFIntegrator(double stepSize) : DrudeIntegrator(stepSize)
{
    setDrudeTemperature(0.0);  // This is only used to initialize velocities for this integrator
    setStepSize(stepSize);
    setMinimizationErrorTolerance(1.0);
    setConstraintTolerance(1e-5);
    setMaxDrudeDistance(0.0);
}

void DrudeSCFIntegrator::initialize(ContextImpl& contextRef) {
    if (owner != NULL && &contextRef.getOwner() != owner)
        throw OpenMMException("This Integrator is already bound to a context");
    const DrudeForce* force = getDrudeForce(contextRef);
    if (getMaxDrudeDistance() != 0.0)
        throw OpenMMException("DrudeSCFIntegrator does not currently support setting max Drude distance");
    context = &contextRef;
    owner = &contextRef.getOwner();
    kernel = context->getPlatform().createKernel(IntegrateDrudeSCFStepKernel::Name(), contextRef);
    kernel.getAs<IntegrateDrudeSCFStepKernel>().initialize(contextRef.getSystem(), *this, *force);
}

void DrudeSCFIntegrator::setMinimizationErrorTolerance(double tol) {
    if (tol <= 0)
        throw OpenMMException("Minimization error tolerance must be positive");
    tolerance = tol;
}

void DrudeSCFIntegrator::cleanup() {
    kernel = Kernel();
}

vector<string> DrudeSCFIntegrator::getKernelNames() {
    return {IntegrateDrudeSCFStepKernel::Name()};
}

double DrudeSCFIntegrator::computeKineticEnergy() {
    return kernel.getAs<IntegrateDrudeSCFStepKernel>().computeKineticEnergy(*context, *this);
}

void DrudeSCFIntegrator::step(int steps) {
    if (context == NULL)
        throw OpenMMException("This Integrator is not bound to a context!");    
    for (int i = 0; i < steps; ++i) {
        context->updateContextState();
        context->calcForcesAndEnergy(true, false);
        kernel.getAs<IntegrateDrudeSCFStepKernel>().execute(*context, *this);
    }
}
