/*************************************************************************
*  Copyright (C) 2005 by Bruno Chareyre   bruno.chareyre@grenoble-inp.fr     *
*                                                                        *
*  This program is free software; it is licensed under the terms of the  *
*  GNU General Public License v2 or later. See file LICENSE for details. *
*************************************************************************/

#include "ElasticContactLaw.hpp"
#include <core/Omega.hpp>
#include <core/Scene.hpp>
#include <pkg/dem/DemXDofGeom.hpp>
#include <pkg/dem/FrictPhys.hpp>
#include <pkg/dem/ScGeom.hpp>

namespace yade { // Cannot have #include directive inside.

YADE_PLUGIN((Law2_ScGeom_FrictPhys_CundallStrack)(Law2_ScGeom_ViscoFrictPhys_CundallStrack)(ElasticContactLaw));

#if 1
Real Law2_ScGeom_FrictPhys_CundallStrack::getPlasticDissipation() const { return (Real)plasticDissipation; }
void Law2_ScGeom_FrictPhys_CundallStrack::initPlasticDissipation(Real initVal)
{
	plasticDissipation.reset();
	plasticDissipation += initVal;
}
Real Law2_ScGeom_FrictPhys_CundallStrack::elasticEnergy()
{
	Real energy = 0;
	FOREACH(const shared_ptr<Interaction>& I, *scene->interactions)
	{
		if (!I->isReal()) continue;
		FrictPhys* phys = dynamic_cast<FrictPhys*>(I->phys.get());
		if (phys) { energy += 0.5 * (phys->normalForce.squaredNorm() / phys->kn + phys->shearForce.squaredNorm() / phys->ks); }
	}
	return energy;
}
#endif

void ElasticContactLaw::action()
{
	if (!functor) functor = shared_ptr<Law2_ScGeom_FrictPhys_CundallStrack>(new Law2_ScGeom_FrictPhys_CundallStrack);
	functor->neverErase = neverErase;
	functor->scene      = scene;
	FOREACH(const shared_ptr<Interaction>& I, *scene->interactions)
	{
		if (!I->isReal()) continue;
#ifdef YADE_DEBUG
		// these checks would be redundant in the functor (LawDispatcher does that already)
		if (!dynamic_cast<ScGeom*>(I->geom.get()) || !dynamic_cast<FrictPhys*>(I->phys.get())) continue;
#endif
		functor->go(I->geom, I->phys, I.get());
	}
}

CREATE_LOGGER(Law2_ScGeom_FrictPhys_CundallStrack);
bool Law2_ScGeom_FrictPhys_CundallStrack::go(shared_ptr<IGeom>& ig, shared_ptr<IPhys>& ip, Interaction* contact)
{
	int id1 = contact->getId1(), id2 = contact->getId2();

	ScGeom*    geom = static_cast<ScGeom*>(ig.get());
	FrictPhys* phys = static_cast<FrictPhys*>(ip.get());
	if (geom->penetrationDepth < 0) {
		if (neverErase) {
			phys->shearForce  = Vector3r::Zero();
			phys->normalForce = Vector3r::Zero();
		} else
			return false;
	}
	Real& un          = geom->penetrationDepth;
	phys->normalForce = phys->kn * math::max(un, (Real)0) * geom->normal;

	Vector3r&       shearForce = geom->rotate(phys->shearForce);
	const Vector3r& shearDisp  = geom->shearIncrement();
	shearForce -= phys->ks * shearDisp;
	Real maxFs = phys->normalForce.squaredNorm() * math::pow(phys->tangensOfFrictionAngle, 2);

	if (!scene->trackEnergy && !traceEnergy) { //Update force but don't compute energy terms (see below))
		// PFC3d SlipModel, is using friction angle. CoulombCriterion
		if (shearForce.squaredNorm() > maxFs) {
			Real ratio = sqrt(maxFs) / shearForce.norm();
			shearForce *= ratio;
		}
	} else {
		//almost the same with additional Vector3r instatinated for energy tracing,
		//duplicated block to make sure there is no cost for the instanciation of the vector when traceEnergy==false
		if (shearForce.squaredNorm() > maxFs) {
			Real     ratio      = sqrt(maxFs) / shearForce.norm();
			Vector3r trialForce = shearForce; //store prev force for definition of plastic slip
			//define the plastic work input and increment the total plastic energy dissipated
			shearForce *= ratio;
			Real dissip = ((1 / phys->ks) * (trialForce - shearForce)) /*plastic disp*/.dot(shearForce) /*active force*/;
			if (traceEnergy) plasticDissipation += dissip;
			else if (dissip > 0)
				scene->energy->add(dissip, "plastDissip", plastDissipIx, /*reset*/ false);
		}
		// compute elastic energy as well
		scene->energy->add(
		        0.5 * (phys->normalForce.squaredNorm() / phys->kn + phys->shearForce.squaredNorm() / phys->ks),
		        "elastPotential",
		        elastPotentialIx,
		        /*reset at every timestep*/ true);
	}
	if (!scene->isPeriodic && !sphericalBodies) { // For non-periodic simulations only
		State* de1 = Body::byId(id1, scene)->state.get();
		State* de2 = Body::byId(id2, scene)->state.get();
		applyForceAtContactPoint(-phys->normalForce - shearForce, geom->contactPoint, id1, de1->se3.position, id2, de2->se3.position);
	} else if (sphericalBodies) { // For spheres only
		Vector3r force = -phys->normalForce - shearForce;
		scene->forces.addForce(id1, force);
		scene->forces.addForce(id2, -force);
		scene->forces.addTorque(id1, (geom->radius1 - 0.5 * geom->penetrationDepth) * geom->normal.cross(force));
		scene->forces.addTorque(id2, (geom->radius2 - 0.5 * geom->penetrationDepth) * geom->normal.cross(force));
	} else { // The general case
		Vector3r shift2 = scene->cell->hSize * contact->cellDist.cast<Real>();
		State*   de1    = Body::byId(id1, scene)->state.get();
		State*   de2    = Body::byId(id2, scene)->state.get();
		applyForceAtContactPoint(-phys->normalForce - shearForce, geom->contactPoint, id1, de1->se3.position, id2, de2->se3.position + shift2);
	}
	return true;
}

bool Law2_ScGeom_ViscoFrictPhys_CundallStrack::go(shared_ptr<IGeom>& ig, shared_ptr<IPhys>& ip, Interaction* contact)
{
	ScGeom*         geom = static_cast<ScGeom*>(ig.get());
	ViscoFrictPhys* phys = static_cast<ViscoFrictPhys*>(ip.get());
	if (shearCreep) {
		const Real& dt = scene->dt;
		geom->rotate(phys->creepedShear);
		phys->creepedShear += creepStiffness * phys->ks * (phys->shearForce - phys->creepedShear) * dt / viscosity;
		phys->shearForce -= phys->ks * ((phys->shearForce - phys->creepedShear) * dt / viscosity);
	}
	return Law2_ScGeom_FrictPhys_CundallStrack::go(ig, ip, contact);
}

} // namespace yade
