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

#include <modules/autonavigation/helperfunctions.h>
#include <openspace/engine/globals.h>
#include <openspace/engine/windowdelegate.h>
#include <openspace/interaction/navigationhandler.h>
#include <openspace/scene/scenegraphnode.h>
#include <openspace/util/camera.h>
#include <openspace/query/query.h>
#include <ghoul/logging/logmanager.h>
#include <glm/gtx/vector_angle.hpp>
#include <glm/gtx/quaternion.hpp>

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

namespace openspace::autonavigation {

AutoNavigationHandler::AutoNavigationHandler()
    : properties::PropertyOwner({ "AutoNavigationHandler" })
{
    // Add the properties
    // TODO
}

AutoNavigationHandler::~AutoNavigationHandler() {} // NOLINT

Camera* AutoNavigationHandler::camera() const {
    return global::navigationHandler.camera();
}

const double AutoNavigationHandler::pathDuration() const {
    double sum = 0.0;
    for (auto ps : _pathSegments) {
        sum += ps.duration();
    }
    return sum;
}

const bool AutoNavigationHandler::hasFinished() const {
    return _currentTime > pathDuration();
}


const int AutoNavigationHandler::currentPathSegmentIndex() const {
    for (int i = 0; i < _pathSegments.size(); ++i) {
        const PathSegment& ps = _pathSegments[i];
        double endTime = ps.startTime() + ps.duration();
        if (endTime > _currentTime) {
            return i;
        }
    }
}

CameraState AutoNavigationHandler::currentCameraState() {
    CameraState cs;
    cs.position = camera()->positionVec3();
    cs.rotation = camera()->rotationQuaternion();
    cs.referenceNode = global::navigationHandler.anchorNode()->identifier();
    return cs;
}

void AutoNavigationHandler::updateCamera(double deltaTime) {
    ghoul_assert(camera() != nullptr, "Camera must not be nullptr");

    if (!_isPlaying || _pathSegments.empty()) return;

    const int currentIndex = currentPathSegmentIndex();

    if (_stopAtTargets && (currentIndex != _activeSegmentIndex)) {
        _activeSegmentIndex = currentIndex; 
        pausePath();
        return;
    }

    const PathSegment& cps = _pathSegments[currentIndex];

    // Interpolation variable
    double t = (_currentTime - cps.startTime()) / cps.duration();
    t = std::max(0.0, std::min(t, 1.0));

    // TODO: don't set every frame
    // Set anchor node in orbitalNavigator, to render visible nodes and 
    // add possibility to navigate when we reach the end.
    CameraState cs = (t < 0.5) ? cps.start() : cps.end();
    global::navigationHandler.orbitalNavigator().setAnchorNode(cs.referenceNode);

    glm::dvec3 cameraPosition = cps.getPositionAt(t);
    glm::dquat cameraRotation = cps.getRotationAt(t);

    camera()->setPositionVec3(cameraPosition); 
    camera()->setRotation(cameraRotation);

    _currentTime += deltaTime;

    _activeSegmentIndex = currentIndex;

    if (hasFinished()) {
        LINFO("Reached end of path.");
        _isPlaying = false;
    }
}

void AutoNavigationHandler::createPath(PathSpecification& spec) {
    clearPath();
    bool success = true;
    for (int i = 0; i < spec.instructions()->size(); i++) {
        const Instruction& ins = spec.instructions()->at(i);
        success = handleInstruction(ins, i);

        if (!success)
            break;
    }

    // OBS! Would it be better to save the spec in the handler class? 
    _stopAtTargets = spec.stopAtTargets();

    if (success) {
        LINFO("Succefully generated camera path.");
        startPath();
    }
    else
        LERROR("Could not create path.");
}

void AutoNavigationHandler::clearPath() {
    LINFO("Clearing path...");
    _pathSegments.clear();
    _currentTime = 0.0;
    _activeSegmentIndex = 0;
}

void AutoNavigationHandler::startPath() {
    ghoul_assert(!_pathSegments.empty(), "Cannot start an empty path");
    LINFO("Starting path...");
    _currentTime = 0.0;
    _isPlaying = true;
}

void AutoNavigationHandler::pausePath() {
    ghoul_assert(!_isPlaying, "Cannot pause a path that isn't playing");
    LINFO(fmt::format("Paused path at target {} / {}", _activeSegmentIndex, _pathSegments.size()));
    _isPlaying = false;
}

void AutoNavigationHandler::continuePath() {
    ghoul_assert(_isPlaying, "Cannot start a path that is already playing");
    ghoul_assert(!_pathSegments.empty(), "No path to continue on");

    if (hasFinished()) {
        LERROR("Path has ended, cannot continue.");
        return;
    }

    LINFO("Continuing path...");

    // Recompute start camera state for the upcoming path segment, to avoid clipping to
    // the old camera state.
    _pathSegments[_activeSegmentIndex].setStart(currentCameraState());

    _isPlaying = true;
}

bool AutoNavigationHandler::handleInstruction(const Instruction& instruction, int index)
{
    // compute startTime 
    double startTime = 0.0;
    if (!_pathSegments.empty()) {
        PathSegment& last = _pathSegments.back();
        startTime = last.startTime() + last.duration();
    }

    bool success = true;

    switch (instruction.type)
    {
    case InstructionType::TargetNode:
        success = handleTargetNodeInstruction(instruction, index, startTime);
        break;

    case InstructionType::NavigationState:
        success = handleNavigationStateInstruction(instruction, index, startTime);
        break;

    case InstructionType::Pause:
        success = handlePauseInstruction(instruction, index, startTime);
        break;

    default:
        LERROR(fmt::format("Non-implemented instruction type: {}.", instruction.type));
        success = false;
        break;
    }

    if (!success) return false;

    return true;
}

bool AutoNavigationHandler::handleTargetNodeInstruction(
    const Instruction& instruction, int index, double startTime)
{
    // Verify instruction type
    TargetNodeInstructionProps* props = 
        dynamic_cast<TargetNodeInstructionProps*>(instruction.props.get());

    if (!props) {
        LERROR(fmt::format("Could not handle target node instruction (number {}).", index + 1));
        return false;
    }

    CameraState startState = 
        _pathSegments.empty() ? currentCameraState() : _pathSegments.back().end();

    // Compute end state 
    std::string& identifier = props->targetNode;
    const SceneGraphNode* targetNode = sceneGraphNode(identifier);
    if (!targetNode) {
        LERROR(fmt::format(
            "Failed handling instruction number {}. Could not find node '{}' to target", 
            index + 1, 
            identifier)
        );
        return false;
    }

    glm::dvec3 targetPos;
    if (props->position.has_value()) {
        // note that the anchor and reference frame is our targetnode. 
        // The position in instruction is given is relative coordinates.
        targetPos = targetNode->worldPosition() + 
            targetNode->worldRotationMatrix() * props->position.value();
    }
    else {
        bool hasHeight = props->height.has_value();

        // TODO: compute defualt height in a better way
        double defaultHeight = 2 * targetNode->boundingSphere();
        double height = hasHeight? props->height.value() : defaultHeight;

        targetPos = computeTargetPositionAtNode(
            targetNode, 
            startState.position,
            height
        );
    }

    glm::dmat4 lookAtMat = glm::lookAt(
        targetPos,
        targetNode->worldPosition(),
        camera()->lookUpVectorWorldSpace()
    );

    glm::dquat targetRot = glm::normalize(glm::inverse(glm::quat_cast(lookAtMat)));

    CameraState endState = CameraState{ targetPos, targetRot, identifier };

    // TODO: Handle duration better
    PathSegment newSegment{ startState, endState, startTime };
    if (instruction.props->duration.has_value()) {
        newSegment.setDuration(instruction.props->duration.value());
    }
    _pathSegments.push_back(newSegment);

    return true;
}

bool AutoNavigationHandler::handleNavigationStateInstruction(
    const Instruction& instruction, int index, double startTime)
{
    // Verify instruction type
    NavigationStateInstructionProps* props =
        dynamic_cast<NavigationStateInstructionProps*>(instruction.props.get());

    if (!props) {
        LERROR(fmt::format(
            "Could not handle navigation state instruction (number {}).", 
            index + 1)
        );
        return false;
    }

    CameraState startState =
        _pathSegments.empty() ? currentCameraState() : _pathSegments.back().end();

    interaction::NavigationHandler::NavigationState ns = props->navState;

    // OBS! The following code is exactly the same as used in 
    // NavigationHandler::applyNavigationState. Should probably be made into a function.
    const SceneGraphNode* referenceFrame = sceneGraphNode(ns.referenceFrame);
    const SceneGraphNode* anchorNode = sceneGraphNode(ns.anchor); // The anchor is also the target

    if (!anchorNode) {
        LERROR(fmt::format(
            "Failed handling instruction number {}. Could not find node '{}' to target", 
            index + 1, 
            ns.anchor)
        );
        return false;
    }

    const glm::dvec3 anchorWorldPosition = anchorNode->worldPosition();
    const glm::dmat3 referenceFrameTransform = referenceFrame->worldRotationMatrix();

    const glm::dvec3 targetPositionWorld = anchorWorldPosition +
        glm::dvec3(referenceFrameTransform * glm::dvec4(ns.position, 1.0));

    glm::dvec3 up = ns.up.has_value() ?
        glm::normalize(referenceFrameTransform * ns.up.value()) :
        glm::dvec3(0.0, 1.0, 0.0);

    // Construct vectors of a "neutral" view, i.e. when the aim is centered in view.
    glm::dvec3 neutralView =
        glm::normalize(anchorWorldPosition - targetPositionWorld);

    glm::dquat neutralCameraRotation = glm::inverse(glm::quat_cast(glm::lookAt(
        glm::dvec3(0.0),
        neutralView,
        up
    )));

    glm::dquat pitchRotation = glm::angleAxis(ns.pitch, glm::dvec3(1.f, 0.f, 0.f));
    glm::dquat yawRotation = glm::angleAxis(ns.yaw, glm::dvec3(0.f, -1.f, 0.f));

    glm::quat targetRotation = neutralCameraRotation * yawRotation * pitchRotation;

    CameraState endState = CameraState{ targetPositionWorld, targetRotation, ns.anchor };

    // TODO: Handle duration better
    PathSegment newSegment{ startState, endState, startTime };
    if (instruction.props->duration.has_value()) {
        newSegment.setDuration(instruction.props->duration.value());
    }
    _pathSegments.push_back(newSegment);

    return true;
}

bool AutoNavigationHandler::handlePauseInstruction(
    const Instruction& instruction, int index, double startTime)
{
    // Verify instruction type
    PauseInstructionProps* props =
        dynamic_cast<PauseInstructionProps*>(instruction.props.get());

    if (!props) {
        LERROR(fmt::format("Could not handle pause instruction (number {}).", index + 1));
        return false;
    }

    CameraState startState =
        _pathSegments.empty() ? currentCameraState() : _pathSegments.back().end();

    CameraState endState = startState;

    // TODO: implement more complex behavior later

    // TODO: Handle duration better
    PathSegment newSegment{ startState, endState, startTime };
    if (instruction.props->duration.has_value()) {
        newSegment.setDuration(instruction.props->duration.value());
    }
    _pathSegments.push_back(newSegment);

    return true;
}

glm::dvec3 AutoNavigationHandler::computeTargetPositionAtNode(
    const SceneGraphNode* node, glm::dvec3 prevPos, double height)
{
    // TODO: compute actual distance above surface and validate negative values

    glm::dvec3 targetPos = node->worldPosition();
    glm::dvec3 targetToPrevVector = prevPos - targetPos;

    double radius = static_cast<double>(node->boundingSphere());

    // move target position out from surface, along vector to camera
    targetPos += glm::normalize(targetToPrevVector) * (radius + height);

    return targetPos;
}

} // namespace openspace::autonavigation