/* -------------------------------------------------------------------------- *
 *                                   OpenMM                                   *
 * -------------------------------------------------------------------------- *
 * This is part of the OpenMM molecular simulation toolkit originating from   *
 * Simbios, the NIH National Center for Physics-Based Simulation of           *
 * Biological Structures at Stanford, funded under the NIH Roadmap for        *
 * Medical Research, grant U54 GM072970. See https://simtk.org.               *
 *                                                                            *
 * Portions copyright (c) 2008-2024 Stanford University and the Authors.      *
 * Authors: Peter Eastman                                                     *
 * Contributors:                                                              *
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#include "openmm/Force.h"
#include "openmm/OpenMMException.h"
#include "openmm/HarmonicBondForce.h"
#include "openmm/internal/AssertionUtilities.h"
#include "openmm/internal/HarmonicBondForceImpl.h"

using namespace OpenMM;
using namespace std;

HarmonicBondForce::HarmonicBondForce() : usePeriodic(false), numContexts(0) {
}

int HarmonicBondForce::addBond(int particle1, int particle2, double length, double k) {
    bonds.push_back(BondInfo(particle1, particle2, length, k));
    return bonds.size()-1;
}

void HarmonicBondForce::getBondParameters(int index, int& particle1, int& particle2, double& length, double& k) const {
    ASSERT_VALID_INDEX(index, bonds);
    particle1 = bonds[index].particle1;
    particle2 = bonds[index].particle2;
    length = bonds[index].length;
    k = bonds[index].k;
}

void HarmonicBondForce::setBondParameters(int index, int particle1, int particle2, double length, double k) {
    ASSERT_VALID_INDEX(index, bonds);
    bonds[index].particle1 = particle1;
    bonds[index].particle2 = particle2;
    bonds[index].length = length;
    bonds[index].k = k;
    if (numContexts > 0) {
        firstChangedBond = min(index, firstChangedBond);
        lastChangedBond = max(index, lastChangedBond);
    }
}

ForceImpl* HarmonicBondForce::createImpl() const {
    if (numContexts == 0) {
        // Begin tracking changes to bonds.
        firstChangedBond = bonds.size();
        lastChangedBond = -1;
    }
    numContexts++;
    return new HarmonicBondForceImpl(*this);
}

void HarmonicBondForce::updateParametersInContext(Context& context) {
    dynamic_cast<HarmonicBondForceImpl&>(getImplInContext(context)).updateParametersInContext(getContextImpl(context), firstChangedBond, lastChangedBond);
    if (numContexts == 1) {
        // We just updated the only existing context for this force, so we can reset
        // the tracking of changed bonds.
        firstChangedBond = bonds.size();
        lastChangedBond = -1;
    }
}

void HarmonicBondForce::setUsesPeriodicBoundaryConditions(bool periodic) {
    usePeriodic = periodic;
}

bool HarmonicBondForce::usesPeriodicBoundaryConditions() const {
    return usePeriodic;
}

int HarmonicBondForce::getNumBonds() const {
    return bonds.size();
}
