/*
 * Copyright (c) 2011-2019, The DART development contributors
 * All rights reserved.
 *
 * The list of contributors can be found at:
 *   https://github.com/dartsim/dart/blob/master/LICENSE
 *
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 *   without modification, are permitted provided that the following
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 *   * Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *   * Redistributions in binary form must reproduce the above
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 *     disclaimer in the documentation and/or other materials provided
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#include "dart/planning/PathShortener.hpp"

#include <cstdio>
#include <ctime>

#include "dart/collision/CollisionDetector.hpp"
#include "dart/dynamics/Skeleton.hpp"
#include "dart/planning/RRT.hpp"
#include "dart/simulation/World.hpp"

using namespace std;
using namespace Eigen;
using namespace dart;
using namespace simulation;

#define RAND12(N1, N2)                                                         \
  N1                                                                           \
      + ((N2 - N1)                                                             \
         * ((double)rand() / ((double)RAND_MAX + 1))) // random # between N&M

namespace dart {
namespace planning {

PathShortener::PathShortener()
{
}

PathShortener::PathShortener(
    WorldPtr world,
    dynamics::SkeletonPtr robot,
    const vector<std::size_t>& dofs,
    double stepSize)
  : world(world), robot(robot), dofs(dofs), stepSize(stepSize)
{
}

PathShortener::~PathShortener()
{
}

void PathShortener::shortenPath(list<VectorXd>& path)
{
  printf("--> Start Brute Force Shortener \n");
  srand(time(nullptr));

  VectorXd savedDofs = robot->getPositions(dofs);

  const int numShortcuts = path.size() * 5;

  // Number of checks
  for (int count = 0; count < numShortcuts; count++)
  {
    if (path.size() < 3)
    { //-- No way we can reduce something leaving out the extremes
      return;
    }

    int node1Index;
    int node2Index;
    do
    {
      node1Index = (int)RAND12(0, path.size());
      node2Index = (int)RAND12(0, path.size());
    } while (node2Index <= node1Index + 1);

    list<VectorXd>::iterator node1Iter = path.begin();
    advance(node1Iter, node1Index);
    list<VectorXd>::iterator node2Iter = node1Iter;
    advance(node2Iter, node2Index - node1Index);

    list<VectorXd> intermediatePoints;
    if (localPlanner(intermediatePoints, node1Iter, node2Iter))
    {
      list<VectorXd>::iterator node1NextIter = node1Iter;
      ++node1NextIter;
      path.erase(node1NextIter, node2Iter);
      path.splice(node2Iter, intermediatePoints);
    }
  }
  // TODO(JS): What kinematic values should be updated here?
  robot->setPositions(dofs, savedDofs);

  printf("End Brute Force Shortener \n");
}

bool PathShortener::localPlanner(
    list<VectorXd>& intermediatePoints,
    list<VectorXd>::const_iterator it1,
    list<VectorXd>::const_iterator it2)
{
  return segmentCollisionFree(intermediatePoints, *it1, *it2);
}

// true iff collision-free
// does not check endpoints
// interemdiatePoints are only touched if collision-free
bool PathShortener::segmentCollisionFree(
    list<VectorXd>& intermediatePoints,
    const VectorXd& config1,
    const VectorXd& config2)
{
  const double length = (config1 - config2).norm();
  if (length <= stepSize)
  {
    return true;
  }

  const int n = (int)(length / stepSize) + 1; // number of intermediate segments
  int n1 = n / 2;
  int n2 = n / 2;
  if (n % 2 == 1)
  {
    n2 += 1;
  }

  VectorXd midpoint
      = (double)n2 / (double)n * config1 + (double)n1 / (double)n * config2;
  list<VectorXd> intermediatePoints1, intermediatePoints2;
  // TODO(JS): What kinematic values should be updated here?
  robot->setPositions(dofs, midpoint);
  if (!world->checkCollision()
      && segmentCollisionFree(intermediatePoints1, config1, midpoint)
      && segmentCollisionFree(intermediatePoints2, midpoint, config2))
  {
    intermediatePoints.clear();
    intermediatePoints.splice(intermediatePoints.end(), intermediatePoints1);
    intermediatePoints.push_back(midpoint);
    intermediatePoints.splice(intermediatePoints.end(), intermediatePoints2);
    return true;
  }
  else
  {
    return false;
  }
}

} // namespace planning
} // namespace dart
