/*=========================================================================

   Library: iMSTK

   Copyright (c) Kitware, Inc. & Center for Modeling, Simulation,
   & Imaging in Medicine, Rensselaer Polytechnic Institute.

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

      http://www.apache.org/licenses/LICENSE-2.0.txt

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   See the License for the specific language governing permissions and
   limitations under the License.

=========================================================================*/

#include "imstkRigidBodyCH.h"
#include "imstkCollisionData.h"
#include "imstkLineMesh.h"
#include "imstkRbdContactConstraint.h"
#include "imstkRbdFrictionConstraint.h"
#include "imstkRigidBodyModel2.h"
#include "imstkRigidObject2.h"
#include "imstkSurfaceMesh.h"

#include "imstkCollisionUtils.h"

namespace imstk
{
void
RigidBodyCH::setInputRigidObjectA(std::shared_ptr<RigidObject2> rbdObjA)
{
    setInputObjectA(rbdObjA);
}

void
RigidBodyCH::setInputRigidObjectB(std::shared_ptr<RigidObject2> rbdObjB)
{
    setInputObjectB(rbdObjB);
}

void
RigidBodyCH::setInputCollidingObjectB(std::shared_ptr<CollidingObject> colObjB)
{
    setInputObjectB(colObjB);
}

std::shared_ptr<RigidObject2>
RigidBodyCH::getRigidObjA()
{
    return std::dynamic_pointer_cast<RigidObject2>(getInputObjectA());
}

std::shared_ptr<RigidObject2>
RigidBodyCH::getRigidObjB()
{
    return std::dynamic_pointer_cast<RigidObject2>(getInputObjectB());
}

void
RigidBodyCH::handle(
    const std::vector<CollisionElement>& elementsA,
    const std::vector<CollisionElement>& elementsB)
{
    std::shared_ptr<RigidObject2>    rbdObjA = getRigidObjA();
    std::shared_ptr<RigidObject2>    rbdObjB = getRigidObjB();
    std::shared_ptr<CollidingObject> colObjB = getInputObjectB();

    // If both objects are rigid objects
    if (rbdObjA != nullptr && rbdObjB != nullptr)
    {
        // If we only have elements of A, process one-sided rigid
        if (elementsB.size() == 0 && elementsA.size() != 0)
        {
            handleRbdStaticOneWay(rbdObjA, colObjB, elementsA, elementsB);
        }
        // If we have both elements
        else
        {
            std::shared_ptr<RigidBodyModel2> rbdModelA = rbdObjA->getRigidBodyModel2();
            std::shared_ptr<RigidBodyModel2> rbdModelB = rbdObjB->getRigidBodyModel2();

            // If the two bodies exist in separate rbd models, add two one-way constraints
            // to each system
            if (rbdModelA != rbdModelB)
            {
                if (rbdModelA != nullptr)
                {
                    handleRbdStaticOneWay(rbdObjA, nullptr, elementsA, elementsB);
                }
                if (rbdModelB != nullptr)
                {
                    handleRbdStaticOneWay(rbdObjB, nullptr, elementsB, elementsA);
                }
            }
            // If in the same model use one two-way constraint
            else
            {
                handleRbdRbdTwoWay(rbdObjA, rbdObjB, elementsA, elementsB);
            }
        }
    }
    // If objA is rigid and b is colliding
    else if (rbdObjA != nullptr && colObjB != nullptr)
    {
        // Process one sided with both
        handleRbdStaticOneWay(rbdObjA, colObjB, elementsA, elementsB);
    }
}

void
RigidBodyCH::handleRbdRbdTwoWay(
    std::shared_ptr<RigidObject2>        rbdObjA,
    std::shared_ptr<RigidObject2>        rbdObjB,
    const std::vector<CollisionElement>& elementsA,
    const std::vector<CollisionElement>& elementsB)
{
    if (elementsA.size() != elementsB.size())
    {
        return;
    }

    auto geom = std::dynamic_pointer_cast<PointSet>(rbdObjA->getCollidingGeometry());

    // Generate one two-way constraint
    std::shared_ptr<RigidBodyModel2> rbdModelAB = rbdObjA->getRigidBodyModel2();
    for (size_t i = 0; i < elementsA.size(); i++)
    {
        const CollisionElement& colElemA = elementsA[i];
        if (colElemA.m_type == CollisionElementType::PointDirection)
        {
            const Vec3d& dir       = colElemA.m_element.m_PointDirectionElement.dir;
            const double depth     = colElemA.m_element.m_PointDirectionElement.penetrationDepth;
            const Vec3d& contactPt = colElemA.m_element.m_PointDirectionElement.pt + dir * depth;

            addConstraint(rbdObjA, rbdObjB, contactPt, dir, depth);
        }
        else if (colElemA.m_type == CollisionElementType::PointIndexDirection)
        {
            // Doesn't support mapping yet
            const Vec3d& dir       = colElemA.m_element.m_PointIndexDirectionElement.dir;
            const double depth     = colElemA.m_element.m_PointIndexDirectionElement.penetrationDepth;
            const Vec3d& contactPt = (*geom->getVertexPositions())[colElemA.m_element.m_PointIndexDirectionElement.ptIndex] + dir * depth;

            addConstraint(rbdObjA, rbdObjB, contactPt, dir, depth);
        }
    }
}

void
RigidBodyCH::handleRbdStaticOneWay(
    std::shared_ptr<RigidObject2>        rbdObj,
    std::shared_ptr<CollidingObject>     colObj,
    const std::vector<CollisionElement>& elementsA,
    const std::vector<CollisionElement>& elementsB)
{
    // First handle one-way point-direction constraints
    for (size_t i = 0; i < elementsA.size(); i++)
    {
        const CollisionElement& colElem = elementsA[i];
        if (colElem.m_type == CollisionElementType::PointDirection)
        {
            const Vec3d& dir       = colElem.m_element.m_PointDirectionElement.dir;
            const double depth     = colElem.m_element.m_PointDirectionElement.penetrationDepth;
            const Vec3d& contactPt = colElem.m_element.m_PointDirectionElement.pt + dir * depth;

            addConstraint(rbdObj, contactPt, dir, depth);
        }
        else if (colElem.m_type == CollisionElementType::PointIndexDirection)
        {
            // Doesn't support mapping yet
            auto         geom      = std::dynamic_pointer_cast<PointSet>(rbdObj->getCollidingGeometry());
            const Vec3d& dir       = colElem.m_element.m_PointIndexDirectionElement.dir;
            const double depth     = colElem.m_element.m_PointIndexDirectionElement.penetrationDepth;
            const Vec3d& contactPt = (*geom->getVertexPositions())[colElem.m_element.m_PointIndexDirectionElement.ptIndex] + dir * depth;

            addConstraint(rbdObj, contactPt, dir, depth);
        }
    }

    // So long as both sides were filled we may have two-way
    if (elementsA.size() != elementsB.size() || colObj == nullptr)
    {
        return;
    }

    // Two-way is only supported through mesh-mesh
    auto geomA = std::dynamic_pointer_cast<PointSet>(rbdObj->getCollidingGeometry());
    auto geomB = std::dynamic_pointer_cast<PointSet>(colObj->getCollidingGeometry());
    if (geomA == nullptr || geomB == nullptr)
    {
        return;
    }

    std::shared_ptr<VecDataArray<double, 3>> verticesAPtr = geomA->getVertexPositions();
    const VecDataArray<double, 3>&           verticesA    = *verticesAPtr;
    std::shared_ptr<VecDataArray<double, 3>> verticesBPtr = geomB->getVertexPositions();
    const VecDataArray<double, 3>&           verticesB    = *verticesBPtr;

    // Generate one two-way constraint
    std::shared_ptr<RigidBodyModel2> rbdModelA = rbdObj->getRigidBodyModel2();
    for (size_t i = 0; i < elementsA.size(); i++)
    {
        const CollisionElement& colElemA = elementsA[i];
        const CollisionElement& colElemB = elementsB[i];

        // Only handle mesh-mesh constraints here
        if (colElemA.m_type != CollisionElementType::CellIndex || colElemB.m_type != CollisionElementType::CellIndex)
        {
            continue;
        }

        const CellIndexElement& elemA = colElemA.m_element.m_CellIndexElement;
        const CellIndexElement& elemB = colElemB.m_element.m_CellIndexElement;

        // Vertex vs Triangle
        if (elemA.cellType == IMSTK_VERTEX && elemB.cellType == IMSTK_TRIANGLE)
        {
            const Vec3d& p = verticesA[elemA.ids[0]];

            Vec3i tri;
            if (elemB.idCount == 1)
            {
                tri = (*dynamic_cast<SurfaceMesh*>(geomB.get())->getTriangleIndices().get())[elemB.ids[0]];
            }
            else if (elemB.idCount == 3)
            {
                tri = Vec3i(elemB.ids[0], elemB.ids[1], elemB.ids[2]);
            }
            const Vec3d& a = verticesB[tri[0]];
            const Vec3d& b = verticesB[tri[1]];
            const Vec3d& c = verticesB[tri[2]];

            // Project the vertex onto the triangle
            Vec3d  n;
            double depth;
            {
                const Vec3d v0 = b - a;
                const Vec3d v1 = c - a;
                const Vec3d v2 = p - a;
                n     = v0.cross(v1).normalized();
                depth = v2.dot(n);
            }
            Vec3d contactPt = p + n * depth; // Point n triangle

            addConstraint(rbdObj, contactPt, n, depth);
        }
        // Edge vs Edge
        else if (elemA.cellType == IMSTK_EDGE && elemB.cellType == IMSTK_EDGE)
        {
            Vec2i edgeA;
            if (elemA.idCount == 1)
            {
                edgeA = (*dynamic_cast<LineMesh*>(geomA.get())->getLinesIndices().get())[elemA.ids[0]];
            }
            else if (elemA.idCount == 2)
            {
                edgeA = Vec2i(elemA.ids[0], elemA.ids[1]);
            }
            Vec2i edgeB;
            if (elemB.idCount == 1)
            {
                edgeB = (*dynamic_cast<LineMesh*>(geomB.get())->getLinesIndices().get())[elemB.ids[0]];
            }
            else if (elemB.idCount == 2)
            {
                edgeB = Vec2i(elemB.ids[0], elemB.ids[1]);
            }

            // Measure closest distances
            Vec3d pA, pB;
            CollisionUtils::edgeToEdgeClosestPoints(
                verticesA[edgeA[0]], verticesA[edgeA[1]],
                verticesB[edgeB[0]], verticesB[edgeB[1]], pA, pB);

            const Vec3d  diff = pB - pA;
            const double l    = diff.norm();
            if (l > 0.0)
            {
                // If A is within/behind edge B, then pB-pA gives direction to move A out of B
                const Vec3d n = diff / l;

                // pA is point of contact on objA which is rigid body
                addConstraint(rbdObj, pA, n, l);
            }
        }
        // Edge vs Vertex
        else if (elemA.cellType == IMSTK_EDGE && elemB.cellType == IMSTK_VERTEX)
        {
            Vec2i edge;
            if (elemA.idCount == 1)
            {
                edge = (*dynamic_cast<LineMesh*>(geomA.get())->getLinesIndices().get())[elemA.ids[0]];
            }
            else if (elemA.idCount == 2)
            {
                edge = Vec2i(elemA.ids[0], elemA.ids[1]);
            }
            const Vec3d& a = verticesA[edge[0]];
            const Vec3d& b = verticesA[edge[1]];

            const Vec3d& pt = verticesB[elemB.ids[0]];

            const Vec3d  ab     = b - a;
            const double length = ab.norm();
            const Vec3d  dir1   = ab / length;

            // Project onto the line
            const Vec3d  diff = pt - a;
            const double p    = dir1.dot(diff);

            // Remove tangent component to get normal
            const Vec3d  diff1 = diff - p * dir1;
            const double l     = diff1.norm();
            if (l > 0.0)
            {
                const Vec3d  n = diff1 / l;
                const double u = p / length;

                const Vec3d contactPt = pt - n * l;

                addConstraint(rbdObj, contactPt, n, l);
            }
        }
        else if (elemA.cellType == IMSTK_VERTEX && elemB.cellType == IMSTK_EDGE)
        {
            const Vec3d& pt = verticesA[elemA.ids[0]];

            Vec2i edge;
            if (elemB.idCount == 1)
            {
                edge = (*dynamic_cast<LineMesh*>(geomB.get())->getLinesIndices().get())[elemB.ids[0]];
            }
            else if (elemB.idCount == 2)
            {
                edge = Vec2i(elemB.ids[0], elemB.ids[1]);
            }
            const Vec3d& a = verticesB[edge[0]];
            const Vec3d& b = verticesB[edge[1]];

            const Vec3d  ab     = b - a;
            const double length = ab.norm();
            const Vec3d  dir1   = ab / length;

            // Project onto the line
            const Vec3d  diff = pt - a;
            const double p    = dir1.dot(diff);

            // Remove tangent component to get normal
            const Vec3d  diff1 = diff - p * dir1;
            const double l     = diff1.norm();
            if (l > 0.0)
            {
                const Vec3d  n = diff1 / l;
                const double u = p / length;

                const Vec3d contactPt = pt + n * l;
                //std::cout << "n: " << n[0] << ", " << n[1] << ", " << n[2] << std::endl;

                addConstraint(rbdObj, contactPt, -n, l);
            }
        }
        else if (elemA.cellType == IMSTK_VERTEX && elemB.cellType == IMSTK_VERTEX)
        {
            const Vec3d& a = verticesA[elemA.ids[0]];  // Vertex to resolve
            const Vec3d& b = verticesB[elemB.ids[0]];

            const Vec3d  diff = b - a;
            const double l    = diff.norm();
            if (l > 0.0)
            {
                addConstraint(rbdObj, a, diff / l, l);
            }
        }
    }
}

void
RigidBodyCH::addConstraint(
    std::shared_ptr<RigidObject2> rbdObj,
    const Vec3d& contactPt, const Vec3d& contactNormal,
    const double contactDepth)
{
    auto contactConstraint = std::make_shared<RbdContactConstraint>(
            rbdObj->getRigidBody(), nullptr,
            contactNormal.normalized(), contactPt, contactDepth,
            m_beta,
            RbdConstraint::Side::A);
    contactConstraint->compute(rbdObj->getRigidBodyModel2()->getTimeStep());
    rbdObj->getRigidBodyModel2()->addConstraint(contactConstraint);

    if (m_useFriction)
    {
        std::shared_ptr<RbdFrictionConstraint> frictionConstraint =
            std::make_shared<RbdFrictionConstraint>(
                rbdObj->getRigidBody(), nullptr,
                contactPt, contactNormal.normalized(), contactDepth,
                m_frictionalCoefficient,
                RbdConstraint::Side::A);
        frictionConstraint->compute(rbdObj->getRigidBodyModel2()->getTimeStep());
        rbdObj->getRigidBodyModel2()->addConstraint(frictionConstraint);
    }
}

void
RigidBodyCH::addConstraint(
    std::shared_ptr<RigidObject2> rbdObjA,
    std::shared_ptr<RigidObject2> rbdObjB,
    const Vec3d& contactPt, const Vec3d& contactNormal,
    const double contactDepth)
{
    // Add a two-way constraint to solve both with one constraint
    if (rbdObjA->getRigidBodyModel2() == rbdObjB->getRigidBodyModel2())
    {
        auto contactConstraint = std::make_shared<RbdContactConstraint>(
            rbdObjA->getRigidBody(), rbdObjB->getRigidBody(),
            contactNormal.normalized(), contactPt, contactDepth,
            m_beta);
        contactConstraint->compute(rbdObjA->getRigidBodyModel2()->getTimeStep());
        rbdObjA->getRigidBodyModel2()->addConstraint(contactConstraint);

        if (m_useFriction)
        {
            auto frictionConstraint = std::make_shared<RbdFrictionConstraint>(
                    rbdObjA->getRigidBody(), rbdObjB->getRigidBody(),
                    contactPt, contactNormal.normalized(), contactDepth,
                    m_frictionalCoefficient,
                    RbdConstraint::Side::AB);
            frictionConstraint->compute(rbdObjA->getRigidBodyModel2()->getTimeStep());
            rbdObjA->getRigidBodyModel2()->addConstraint(frictionConstraint);
        }
    }
    // If both belong to differing systems then use two one-way constraints
    else
    {
        addConstraint(rbdObjA, contactPt, contactNormal, contactDepth);
        addConstraint(rbdObjB, contactPt, -contactNormal, contactDepth);
    }
}
}