/* -------------------------------------------------------------------------- *
 *                                   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/internal/AssertionUtilities.h"
#include "openmm/Context.h"
#include "openmm/NonbondedForce.h"
#include "openmm/PythonForce.h"
#include "openmm/Platform.h"
#include "openmm/VerletIntegrator.h"
#include "sfmt/SFMT.h"
#include <iostream>

using namespace OpenMM;
using namespace std;

void testForce(bool subsetParticles) {
    class Computation : public PythonForceComputation {
        void compute(const State& state, double& energy, void* forces, bool forcesAreDouble) const {
            ASSERT_EQUAL(5.0, state.getParameters().at("a"));
            ASSERT_EQUAL(10.0, state.getParameters().at("b"));
            Vec3 a, b, c;
            state.getPeriodicBoxVectors(a, b, c);
            ASSERT_EQUAL(Vec3(2, 0, 0), a);
            ASSERT_EQUAL(Vec3(0.1, 2, 0), b);
            ASSERT_EQUAL(Vec3(0.1, 0.1, 2), c);
            energy = 25.0;
            int numParticles = state.getPositions().size();
            for (int i = 0; i < numParticles; i++) {
                Vec3 f = state.getPositions()[i]*2;
                if (forcesAreDouble)
                    ((Vec3*) forces)[i] = f;
                else {
                    ((float*) forces)[3*i] = (float) f[0];
                    ((float*) forces)[3*i+1] = (float) f[1];
                    ((float*) forces)[3*i+2] = (float) f[2];
                }
            }
        }
    };
    int numParticles = 5;
    int totalParticles = (subsetParticles ? numParticles+10 : numParticles);
    System system;
    Vec3 a(2, 0, 0);
    Vec3 b(0.1, 2, 0);
    Vec3 c(0.1, 0.1, 2);
    system.setDefaultPeriodicBoxVectors(a, b, c);
    NonbondedForce* nonbonded = new NonbondedForce(); // To trigger reordering
    nonbonded->setNonbondedMethod(NonbondedForce::PME);
    system.addForce(nonbonded);
    vector<Vec3> positions;
    OpenMM_SFMT::SFMT sfmt;
    init_gen_rand(0, sfmt);
    for (int i = 0; i < totalParticles; i++) {
        system.addParticle(1.0);
        positions.push_back(Vec3(genrand_real2(sfmt), genrand_real2(sfmt), genrand_real2(sfmt)));
        nonbonded->addParticle(0.0, 1.0, 0.0);
    }
    map<string, double> params;
    params["a"] = 5.0;
    params["b"] = 10.0;
    vector<int> particles;
    if (subsetParticles)
        for (int i = 0; i < numParticles; i++)
            particles.push_back(i+5);
    PythonForce* force = new PythonForce(new Computation(), params, particles);
    ASSERT(!force->usesPeriodicBoundaryConditions());
    force->setUsesPeriodicBoundaryConditions(true);
    ASSERT(force->usesPeriodicBoundaryConditions());
    system.addForce(force);
    VerletIntegrator integrator(0.01);
    Context context(system, integrator, platform);
    context.setPositions(positions);
    State state = context.getState(State::Energy | State::Forces);
    ASSERT_EQUAL_TOL(25.0, state.getPotentialEnergy(), 1e-6);
    if (subsetParticles) {
        for (int i : particles)
            ASSERT_EQUAL_VEC(2*positions[i], state.getForces()[i], 1e-6)
        Vec3 zero;
        for (int i = 0; i < 5; i++)
            ASSERT_EQUAL_VEC(zero, state.getForces()[i], 1e-6);
    }
    else {
        for (int i = 0; i < numParticles; i++)
            ASSERT_EQUAL_VEC(2*positions[i], state.getForces()[i], 1e-6)
    }

    // Check that force groups are handled correctly.

    ASSERT_EQUAL_TOL(25.0, context.getState(State::Energy, false, 1).getPotentialEnergy(), 1e-6);
    ASSERT_EQUAL_TOL(0.0, context.getState(State::Energy, false, 2).getPotentialEnergy(), 1e-6);
}

void runPlatformTests();

int main(int argc, char* argv[]) {
    try {
        initializeTests(argc, argv);
        testForce(false);
        testForce(true);
        runPlatformTests();
    }
    catch(const exception& e) {
        cout << "exception: " << e.what() << endl;
        return 1;
    }
    cout << "Done" << endl;
    return 0;
}