/*****************************************************************************************
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 * OpenSpace                                                                             *
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 * Copyright (c) 2014-2019                                                               *
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#include <modules/autonavigation/pathsegment.h>

#include <modules/autonavigation/pathcurves.h>
#include <modules/autonavigation/rotationinterpolator.h>
#include <modules/autonavigation/speedfunction.h>
#include <openspace/engine/globals.h>
#include <openspace/scene/scenegraphnode.h>
#include <ghoul/logging/logmanager.h>

namespace {
    constexpr const char* _loggerCat = "PathSegment";
} // namespace

namespace openspace::autonavigation {

PathSegment::PathSegment(Waypoint start, Waypoint end, CurveType type, 
						 std::optional<double> duration = std::nullopt)
    : _start(start), _end(end), _curveType(type)
{
    initCurve();

    // TODO: handle duration better
    if (duration.has_value()) {
        _duration = duration.value();
    }
    else {
        // TODO: compute default duration based on curve length 
        // Also, when compensatng for simulation time later we need to make a guess for 
        // the duration, based on the current position of the target. 
        _duration = 5;
    }
}

void PathSegment::setStart(Waypoint cs) {
    _start = std::move(cs);
    initCurve();
    // TODO later: maybe recompute duration as well...
}

const Waypoint PathSegment::start() const { return _start; }

const Waypoint PathSegment::end() const { return _end; }

const double PathSegment::duration() const { return _duration; }

const double PathSegment::pathLength() const { return _curve->length(); }

// TODO: remove function for debugging
const std::vector<glm::dvec3> PathSegment::getControlPoints() const {
    return _curve->getPoints();
}

CameraPose PathSegment::traversePath(double dt) {
    if (!_curve || !_rotationInterpolator || !_speedFunction) {
        // TODO: handle better (abort path somehow)
        return _start.pose;
    }

    // compute displacement along the path during this frame
    double displacement = 0.0;
    int steps = 2; // TODO: should possibly increase with larger risk of error
    double h = dt / steps;
    for (int i = 0; i < steps; ++i) {
        double t = _progressedTime + i * h;
        double speed = 0.5 * (speedAtTime(t - 0.5*h) + speedAtTime(t + 0.5*h)); // midpoint method
        displacement += h * speed;
    }

    _traveledDistance += displacement;

    double relativeDisplacement = _traveledDistance / pathLength();
    relativeDisplacement = std::max(0.0, std::min(relativeDisplacement, 1.0));

    // TEST: 
    //LINFO("-----------------------------------");
    //LINFO(fmt::format("u = {}", relativeDisplacement));
    //LINFO(fmt::format("progressedTime = {}", _progressedTime));

    _progressedTime += dt;

    return interpolatedPose(relativeDisplacement);
}

std::string PathSegment::getCurrentAnchor() const {
    bool pastHalfway = (_traveledDistance / pathLength()) > 0.5;
    return (pastHalfway) ? _end.nodeDetails.identifier : _start.nodeDetails.identifier;
}

bool PathSegment::hasReachedEnd() const {
    return (_traveledDistance / pathLength()) >= 1.0;
}

double PathSegment::speedAtTime(double time) const {
    return _speedFunction->scaledValue(time, _duration, pathLength());
}

CameraPose PathSegment::interpolatedPose(double u) const {
    CameraPose cs;
    cs.position = _curve->positionAt(u);
    cs.rotation = _rotationInterpolator->interpolate(u);
    return cs;
}

void PathSegment::initCurve() {
    _curve.reset();

    switch (_curveType) 
    {
    case CurveType::Bezier3:
        _curve = std::make_unique<Bezier3Curve>(_start, _end);
        _rotationInterpolator = std::make_unique<LookAtInterpolator>(
            _start.rotation(),
            _end.rotation(),
            _start.node()->worldPosition(),
            _end.node()->worldPosition(),
            _curve.get()
        );
        _speedFunction = std::make_unique<CubicDampenedSpeed>(); 
        break;

    case CurveType::Linear:
        _curve = std::make_unique<LinearCurve>(_start, _end);
        _rotationInterpolator = std::make_unique<EasedSlerpInterpolator>(
            _start.rotation(), 
            _end.rotation()
        );
        _speedFunction = std::make_unique<CubicDampenedSpeed>();
        break;

    default:
        LERROR("Could not create curve. Type does not exist!");
        return;
    }

    if (!_curve || !_rotationInterpolator || !_speedFunction) {
        LERROR("Curve type has not been properly initialized.");
        return;
    }
}

} // namespace openspace::autonavigation