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/* Author: Ioan Sucan */

#include "ompl/geometric/planners/kpiece/LBKPIECE1.h"
#include "ompl/base/goals/GoalSampleableRegion.h"
#include "ompl/tools/config/SelfConfig.h"
#include <cassert>

ompl::geometric::LBKPIECE1::LBKPIECE1(const base::SpaceInformationPtr &si)
  : base::Planner(si, "LBKPIECE1")
  , dStart_([this](Motion *m) { freeMotion(m); })
  , dGoal_([this](Motion *m) { freeMotion(m); })
{
    specs_.recognizedGoal = base::GOAL_SAMPLEABLE_REGION;

    Planner::declareParam<double>("range", this, &LBKPIECE1::setRange, &LBKPIECE1::getRange, "0.:1.:10000");
    Planner::declareParam<double>("border_fraction", this, &LBKPIECE1::setBorderFraction, &LBKPIECE1::getBorderFraction,
                                  "0.:.05:1.");
    Planner::declareParam<double>("min_valid_path_fraction", this, &LBKPIECE1::setMinValidPathFraction,
                                  &LBKPIECE1::getMinValidPathFraction);
}

ompl::geometric::LBKPIECE1::~LBKPIECE1() = default;

void ompl::geometric::LBKPIECE1::setup()
{
    Planner::setup();
    tools::SelfConfig sc(si_, getName());
    sc.configureProjectionEvaluator(projectionEvaluator_);
    sc.configurePlannerRange(maxDistance_);

    if (minValidPathFraction_ < std::numeric_limits<double>::epsilon() || minValidPathFraction_ > 1.0)
        throw Exception("The minimum valid path fraction must be in the range (0,1]");

    dStart_.setDimension(projectionEvaluator_->getDimension());
    dGoal_.setDimension(projectionEvaluator_->getDimension());
}

ompl::base::PlannerStatus ompl::geometric::LBKPIECE1::solve(const base::PlannerTerminationCondition &ptc)
{
    checkValidity();
    auto *goal = dynamic_cast<base::GoalSampleableRegion *>(pdef_->getGoal().get());

    if (goal == nullptr)
    {
        OMPL_ERROR("%s: Unknown type of goal", getName().c_str());
        return base::PlannerStatus::UNRECOGNIZED_GOAL_TYPE;
    }

    Discretization<Motion>::Coord xcoord(projectionEvaluator_->getDimension());

    while (const base::State *st = pis_.nextStart())
    {
        auto *motion = new Motion(si_);
        si_->copyState(motion->state, st);
        motion->root = st;
        motion->valid = true;
        projectionEvaluator_->computeCoordinates(motion->state, xcoord);
        dStart_.addMotion(motion, xcoord);
    }

    if (dStart_.getMotionCount() == 0)
    {
        OMPL_ERROR("%s: Motion planning start tree could not be initialized!", getName().c_str());
        return base::PlannerStatus::INVALID_START;
    }

    if (!goal->couldSample())
    {
        OMPL_ERROR("%s: Insufficient states in sampleable goal region", getName().c_str());
        return base::PlannerStatus::INVALID_GOAL;
    }

    if (!sampler_)
        sampler_ = si_->allocStateSampler();

    OMPL_INFORM("%s: Starting planning with %d states already in datastructure", getName().c_str(),
                (int)(dStart_.getMotionCount() + dGoal_.getMotionCount()));

    base::State *xstate = si_->allocState();
    bool startTree = true;
    bool solved = false;
    base::PlannerStatus::StatusType status = base::PlannerStatus::TIMEOUT;

    while (!ptc)
    {
        Discretization<Motion> &disc = startTree ? dStart_ : dGoal_;
        startTree = !startTree;
        Discretization<Motion> &otherDisc = startTree ? dStart_ : dGoal_;
        disc.countIteration();

        // if we have not sampled too many goals already
        if (dGoal_.getMotionCount() == 0 || pis_.getSampledGoalsCount() < dGoal_.getMotionCount() / 2)
        {
            const base::State *st = dGoal_.getMotionCount() == 0 ? pis_.nextGoal(ptc) : pis_.nextGoal();
            if (st != nullptr)
            {
                auto *motion = new Motion(si_);
                si_->copyState(motion->state, st);
                motion->root = motion->state;
                motion->valid = true;
                projectionEvaluator_->computeCoordinates(motion->state, xcoord);
                dGoal_.addMotion(motion, xcoord);
            }
            if (dGoal_.getMotionCount() == 0)
            {
                OMPL_ERROR("%s: Unable to sample any valid states for goal tree", getName().c_str());
                status = base::PlannerStatus::INVALID_GOAL;
                break;
            }
        }

        Discretization<Motion>::Cell *ecell = nullptr;
        Motion *existing = nullptr;
        disc.selectMotion(existing, ecell);
        assert(existing);
        sampler_->sampleUniformNear(xstate, existing->state, maxDistance_);

        /* create a motion */
        auto *motion = new Motion(si_);
        si_->copyState(motion->state, xstate);
        motion->parent = existing;
        motion->root = existing->root;
        existing->children.push_back(motion);
        projectionEvaluator_->computeCoordinates(motion->state, xcoord);
        disc.addMotion(motion, xcoord);

        /* attempt to connect trees */
        Discretization<Motion>::Cell *ocell = otherDisc.getGrid().getCell(xcoord);
        if ((ocell != nullptr) && !ocell->data->motions.empty())
        {
            Motion *connectOther = ocell->data->motions[rng_.uniformInt(0, ocell->data->motions.size() - 1)];

            if (goal->isStartGoalPairValid(startTree ? connectOther->root : motion->root,
                                           startTree ? motion->root : connectOther->root))
            {
                auto *connect = new Motion(si_);
                si_->copyState(connect->state, connectOther->state);
                connect->parent = motion;
                connect->root = motion->root;
                motion->children.push_back(connect);
                projectionEvaluator_->computeCoordinates(connect->state, xcoord);
                disc.addMotion(connect, xcoord);

                if (isPathValid(disc, connect, xstate) && isPathValid(otherDisc, connectOther, xstate))
                {
                    if (startTree)
                        connectionPoint_ = std::make_pair(connectOther->state, motion->state);
                    else
                        connectionPoint_ = std::make_pair(motion->state, connectOther->state);

                    /* extract the motions and put them in solution vector */

                    std::vector<Motion *> mpath1;
                    while (motion != nullptr)
                    {
                        mpath1.push_back(motion);
                        motion = motion->parent;
                    }

                    std::vector<Motion *> mpath2;
                    while (connectOther != nullptr)
                    {
                        mpath2.push_back(connectOther);
                        connectOther = connectOther->parent;
                    }

                    if (startTree)
                        mpath1.swap(mpath2);

                    auto path(std::make_shared<PathGeometric>(si_));
                    path->getStates().reserve(mpath1.size() + mpath2.size());
                    for (int i = mpath1.size() - 1; i >= 0; --i)
                        path->append(mpath1[i]->state);
                    for (auto &i : mpath2)
                        path->append(i->state);

                    pdef_->addSolutionPath(path, false, 0.0, getName());
                    solved = true;
                    break;
                }
            }
        }
    }

    si_->freeState(xstate);

    OMPL_INFORM("%s: Created %u (%u start + %u goal) states in %u cells (%u start (%u on boundary) + %u goal (%u on "
                "boundary))",
                getName().c_str(), dStart_.getMotionCount() + dGoal_.getMotionCount(), dStart_.getMotionCount(),
                dGoal_.getMotionCount(), dStart_.getCellCount() + dGoal_.getCellCount(), dStart_.getCellCount(),
                dStart_.getGrid().countExternal(), dGoal_.getCellCount(), dGoal_.getGrid().countExternal());

    return solved ? base::PlannerStatus::EXACT_SOLUTION : status;
}

bool ompl::geometric::LBKPIECE1::isPathValid(Discretization<Motion> &disc, Motion *motion, base::State *temp)
{
    std::vector<Motion *> mpath;

    /* construct the solution path */
    while (motion != nullptr)
    {
        mpath.push_back(motion);
        motion = motion->parent;
    }

    std::pair<base::State *, double> lastValid;
    lastValid.first = temp;

    /* check the path */
    for (int i = mpath.size() - 1; i >= 0; --i)
        if (!mpath[i]->valid)
        {
            if (si_->checkMotion(mpath[i]->parent->state, mpath[i]->state, lastValid))
                mpath[i]->valid = true;
            else
            {
                Motion *parent = mpath[i]->parent;
                removeMotion(disc, mpath[i]);

                // add the valid part of the path, if sufficiently long
                if (lastValid.second > minValidPathFraction_)
                {
                    auto *reAdd = new Motion(si_);
                    si_->copyState(reAdd->state, lastValid.first);
                    reAdd->parent = parent;
                    reAdd->root = parent->root;
                    parent->children.push_back(reAdd);
                    reAdd->valid = true;
                    Discretization<Motion>::Coord coord(projectionEvaluator_->getDimension());
                    projectionEvaluator_->computeCoordinates(reAdd->state, coord);
                    disc.addMotion(reAdd, coord);
                }

                return false;
            }
        }
    return true;
}

void ompl::geometric::LBKPIECE1::removeMotion(Discretization<Motion> &disc, Motion *motion)
{
    /* remove from grid */

    Discretization<Motion>::Coord coord(projectionEvaluator_->getDimension());
    projectionEvaluator_->computeCoordinates(motion->state, coord);
    disc.removeMotion(motion, coord);

    /* remove self from parent list */

    if (motion->parent != nullptr)
    {
        for (unsigned int i = 0; i < motion->parent->children.size(); ++i)
            if (motion->parent->children[i] == motion)
            {
                motion->parent->children.erase(motion->parent->children.begin() + i);
                break;
            }
    }

    /* remove children */
    for (auto &i : motion->children)
    {
        i->parent = nullptr;
        removeMotion(disc, i);
    }

    freeMotion(motion);
}

void ompl::geometric::LBKPIECE1::freeMotion(Motion *motion)
{
    if (motion->state != nullptr)
        si_->freeState(motion->state);
    delete motion;
}

void ompl::geometric::LBKPIECE1::clear()
{
    Planner::clear();

    sampler_.reset();
    dStart_.clear();
    dGoal_.clear();
    connectionPoint_ = std::make_pair<base::State *, base::State *>(nullptr, nullptr);
}

void ompl::geometric::LBKPIECE1::getPlannerData(base::PlannerData &data) const
{
    Planner::getPlannerData(data);
    dStart_.getPlannerData(data, 1, true, nullptr);
    dGoal_.getPlannerData(data, 2, false, nullptr);

    // Insert the edge connecting the two trees
    data.addEdge(data.vertexIndex(connectionPoint_.first), data.vertexIndex(connectionPoint_.second));
}
