/* -------------------------------------------------------------------------- *
 *                                   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.               *
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 * Portions copyright (c) 2008-2009 Stanford University and the Authors.      *
 * Authors: Peter Eastman                                                     *
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/**
 * This tests the OpenCL implementation of CustomExternalForce.
 */

#include "openmm/internal/AssertionUtilities.h"
#include "openmm/Context.h"
#include "OpenCLPlatform.h"
#include "openmm/CustomExternalForce.h"
#include "openmm/System.h"
#include "openmm/VerletIntegrator.h"
#include "SimTKOpenMMRealType.h"
#include "sfmt/SFMT.h"
#include <iostream>
#include <vector>

using namespace OpenMM;
using namespace std;

static OpenCLPlatform platform;

const double TOL = 1e-5;

void testForce() {
    System system;
    system.addParticle(1.0);
    system.addParticle(1.0);
    system.addParticle(1.0);
    VerletIntegrator integrator(0.01);
    CustomExternalForce* forceField = new CustomExternalForce("scale*(x+yscale*(y-y0)^2)");
    forceField->addPerParticleParameter("y0");
    forceField->addPerParticleParameter("yscale");
    forceField->addGlobalParameter("scale", 0.5);
    vector<double> parameters(2);
    parameters[0] = 0.5;
    parameters[1] = 2.0;
    forceField->addParticle(0, parameters);
    parameters[0] = 1.5;
    parameters[1] = 3.0;
    forceField->addParticle(2, parameters);
    system.addForce(forceField);
    Context context(system, integrator, platform);
    vector<Vec3> positions(3);
    positions[0] = Vec3(0, 2, 0);
    positions[1] = Vec3(0, 0, 1);
    positions[2] = Vec3(1, 0, 1);
    context.setPositions(positions);
    State state = context.getState(State::Forces | State::Energy);
    {
        const vector<Vec3>& forces = state.getForces();
        ASSERT_EQUAL_VEC(Vec3(-0.5, -0.5*2.0*2.0*1.5, 0), forces[0], TOL);
        ASSERT_EQUAL_VEC(Vec3(0, 0, 0), forces[1], TOL);
        ASSERT_EQUAL_VEC(Vec3(-0.5, 0.5*3.0*2.0*1.5, 0), forces[2], TOL);
        ASSERT_EQUAL_TOL(0.5*(1.0 + 2.0*1.5*1.5 + 3.0*1.5*1.5), state.getPotentialEnergy(), TOL);
    }
    
    // Try changing the parameters and make sure it's still correct.
    
    parameters[0] = 1.4;
    parameters[1] = 3.5;
    forceField->setParticleParameters(1, 2, parameters);
    forceField->updateParametersInContext(context);
    state = context.getState(State::Forces | State::Energy);
    {
        const vector<Vec3>& forces = state.getForces();
        ASSERT_EQUAL_VEC(Vec3(-0.5, -0.5*2.0*2.0*1.5, 0), forces[0], TOL);
        ASSERT_EQUAL_VEC(Vec3(0, 0, 0), forces[1], TOL);
        ASSERT_EQUAL_VEC(Vec3(-0.5, 0.5*3.5*2.0*1.4, 0), forces[2], TOL);
        ASSERT_EQUAL_TOL(0.5*(1.0 + 2.0*1.5*1.5 + 3.5*1.4*1.4), state.getPotentialEnergy(), TOL);
    }
}

void testManyParameters() {
    System system;
    system.addParticle(1.0);
    VerletIntegrator integrator(0.01);
    CustomExternalForce* forceField = new CustomExternalForce("xscale*(x-x0)^2+yscale*(y-y0)^2+zscale*(z-z0)^2");
    forceField->addPerParticleParameter("x0");
    forceField->addPerParticleParameter("y0");
    forceField->addPerParticleParameter("z0");
    forceField->addPerParticleParameter("xscale");
    forceField->addPerParticleParameter("yscale");
    forceField->addPerParticleParameter("zscale");
    vector<double> parameters(6);
    parameters[0] = 1.0;
    parameters[1] = 2.0;
    parameters[2] = 3.0;
    parameters[3] = 0.1;
    parameters[4] = 0.2;
    parameters[5] = 0.3;
    forceField->addParticle(0, parameters);
    system.addForce(forceField);
    Context context(system, integrator, platform);
    vector<Vec3> positions(1);
    positions[0] = Vec3(0, -1, 0);
    context.setPositions(positions);
    State state = context.getState(State::Forces | State::Energy);
    const vector<Vec3>& forces = state.getForces();
    ASSERT_EQUAL_VEC(Vec3(2*0.1*1.0, 2*0.2*3.0, 2*0.3*3.0), forces[0], TOL);
    ASSERT_EQUAL_TOL(0.1*1*1 + 0.2*3*3 + 0.3*3*3, state.getPotentialEnergy(), TOL);
}

void testParallelComputation() {
    System system;
    const int numParticles = 200;
    for (int i = 0; i < numParticles; i++)
        system.addParticle(1.0);
    CustomExternalForce* force = new CustomExternalForce("x^2+y^2+z^2");
    vector<double> params;
    for (int i = 0; i < numParticles; i++)
        force->addParticle(i, params);
    system.addForce(force);
    OpenMM_SFMT::SFMT sfmt;
    init_gen_rand(0, sfmt);
    vector<Vec3> positions(numParticles);
    for (int i = 0; i < numParticles; i++)
        positions[i] = Vec3(5*genrand_real2(sfmt), 5*genrand_real2(sfmt), 5*genrand_real2(sfmt));
    VerletIntegrator integrator1(0.01);
    Context context1(system, integrator1, platform);
    context1.setPositions(positions);
    State state1 = context1.getState(State::Forces | State::Energy);
    VerletIntegrator integrator2(0.01);
    string deviceIndex = platform.getPropertyValue(context1, OpenCLPlatform::OpenCLDeviceIndex());
    map<string, string> props;
    props[OpenCLPlatform::OpenCLDeviceIndex()] = deviceIndex+","+deviceIndex;
    Context context2(system, integrator2, platform, props);
    context2.setPositions(positions);
    State state2 = context2.getState(State::Forces | State::Energy);
    ASSERT_EQUAL_TOL(state1.getPotentialEnergy(), state2.getPotentialEnergy(), 1e-5);
    for (int i = 0; i < numParticles; i++)
        ASSERT_EQUAL_VEC(state1.getForces()[i], state2.getForces()[i], 1e-5);
}

int main(int argc, char* argv[]) {
    try {
        if (argc > 1)
            platform.setPropertyDefaultValue("OpenCLPrecision", string(argv[1]));
        testForce();
        testManyParameters();
        testParallelComputation();
    }
    catch(const exception& e) {
        cout << "exception: " << e.what() << endl;
        return 1;
    }
    cout << "Done" << endl;
    return 0;
}