#include "aiwander.hpp"

#include <algorithm>

#include <components/debug/debuglog.hpp>
#include <components/misc/rng.hpp>
#include <components/esm/aisequence.hpp>
#include <components/detournavigator/navigator.hpp>

#include "../mwbase/world.hpp"
#include "../mwbase/environment.hpp"
#include "../mwbase/mechanicsmanager.hpp"
#include "../mwbase/dialoguemanager.hpp"

#include "../mwworld/class.hpp"
#include "../mwworld/esmstore.hpp"
#include "../mwworld/cellstore.hpp"

#include "../mwphysics/collisiontype.hpp"

#include "pathgrid.hpp"
#include "creaturestats.hpp"
#include "movement.hpp"
#include "coordinateconverter.hpp"
#include "actorutil.hpp"

namespace MWMechanics
{
    static const int COUNT_BEFORE_RESET = 10;
    static const float DOOR_CHECK_INTERVAL = 1.5f;

    // to prevent overcrowding
    static const int DESTINATION_TOLERANCE = 64;

    // distance must be long enough that NPC will need to move to get there.
    static const int MINIMUM_WANDER_DISTANCE = DESTINATION_TOLERANCE * 2;

    static const std::size_t MAX_IDLE_SIZE = 8;

    const std::string AiWander::sIdleSelectToGroupName[GroupIndex_MaxIdle - GroupIndex_MinIdle + 1] =
    {
        std::string("idle2"),
        std::string("idle3"),
        std::string("idle4"),
        std::string("idle5"),
        std::string("idle6"),
        std::string("idle7"),
        std::string("idle8"),
        std::string("idle9"),
    };

    namespace
    {
        inline int getCountBeforeReset(const MWWorld::ConstPtr& actor)
        {
            if (actor.getClass().isPureWaterCreature(actor) || actor.getClass().isPureFlyingCreature(actor))
                return 1;
            return COUNT_BEFORE_RESET;
        }

        osg::Vec3f getRandomPointAround(const osg::Vec3f& position, const float distance)
        {
            const float randomDirection = Misc::Rng::rollClosedProbability() * 2.0f * osg::PI;
            osg::Matrixf rotation;
            rotation.makeRotate(randomDirection, osg::Vec3f(0.0, 0.0, 1.0));
            return position + osg::Vec3f(distance, 0.0, 0.0) * rotation;
        }

        bool isDestinationHidden(const MWWorld::ConstPtr &actor, const osg::Vec3f& destination)
        {
            const auto position = actor.getRefData().getPosition().asVec3();
            const bool isWaterCreature = actor.getClass().isPureWaterCreature(actor);
            const bool isFlyingCreature = actor.getClass().isPureFlyingCreature(actor);
            const osg::Vec3f halfExtents = MWBase::Environment::get().getWorld()->getPathfindingHalfExtents(actor);
            osg::Vec3f direction = destination - position;
            direction.normalize();
            const auto visibleDestination = (
                    isWaterCreature || isFlyingCreature
                    ? destination
                    : destination + osg::Vec3f(0, 0, halfExtents.z())
                ) + direction * std::max(halfExtents.x(), std::max(halfExtents.y(), halfExtents.z()));
            const int mask = MWPhysics::CollisionType_World
                | MWPhysics::CollisionType_HeightMap
                | MWPhysics::CollisionType_Door
                | MWPhysics::CollisionType_Actor;
            return MWBase::Environment::get().getWorld()->castRay(position, visibleDestination, mask, actor);
        }

        bool isAreaOccupiedByOtherActor(const MWWorld::ConstPtr &actor, const osg::Vec3f& destination)
        {
            const auto world = MWBase::Environment::get().getWorld();
            const osg::Vec3f halfExtents = world->getPathfindingHalfExtents(actor);
            const auto maxHalfExtent = std::max(halfExtents.x(), std::max(halfExtents.y(), halfExtents.z()));
            return world->isAreaOccupiedByOtherActor(destination, 2 * maxHalfExtent, actor);
        }

        void stopMovement(const MWWorld::Ptr& actor)
        {
            actor.getClass().getMovementSettings(actor).mPosition[1] = 0;
        }

        std::vector<unsigned char> getInitialIdle(const std::vector<unsigned char>& idle)
        {
            std::vector<unsigned char> result(MAX_IDLE_SIZE, 0);
            std::copy_n(idle.begin(), std::min(MAX_IDLE_SIZE, idle.size()), result.begin());
            return result;
        }

        std::vector<unsigned char> getInitialIdle(const unsigned char (&idle)[MAX_IDLE_SIZE])
        {
            return std::vector<unsigned char>(std::begin(idle), std::end(idle));
        }
    }

    AiWander::AiWander(int distance, int duration, int timeOfDay, const std::vector<unsigned char>& idle, bool repeat):
        mDistance(std::max(0, distance)),
        mDuration(std::max(0, duration)),
        mRemainingDuration(duration), mTimeOfDay(timeOfDay),
        mIdle(getInitialIdle(idle)),
        mRepeat(repeat), mStoredInitialActorPosition(false), mInitialActorPosition(osg::Vec3f(0, 0, 0)),
        mHasDestination(false), mDestination(osg::Vec3f(0, 0, 0)), mUsePathgrid(false)
    {
    }

    /*
     * AiWander high level states (0.29.0). Not entirely accurate in some cases
     * e.g. non-NPC actors do not greet and some creatures may be moving even in
     * the IdleNow state.
     *
     *                          [select node,
     *                           build path]
     *                 +---------->MoveNow----------->Walking
     *                 |                                 |
     * [allowed        |                                 |
     *  nodes]         |        [hello if near]          |
     *  start--->ChooseAction----->IdleNow               |
     *                ^ ^           |                    |
     *                | |           |                    |
     *                | +-----------+                    |
     *                |                                  |
     *                +----------------------------------+
     *
     *
     * New high level states.  Not exactly as per vanilla (e.g. door stuff)
     * but the differences are required because our physics does not work like
     * vanilla and therefore have to compensate/work around.
     *
     *                         [select node,     [if stuck evade
     *                          build path]       or remove nodes if near door]
     *                 +---------->MoveNow<---------->Walking
     *                 |              ^                | |
     *                 |              |(near door)     | |
     * [allowed        |              |                | |
     *  nodes]         |        [hello if near]        | |
     *  start--->ChooseAction----->IdleNow             | |
     *                ^ ^           |  ^               | |
     *                | |           |  | (stuck near   | |
     *                | +-----------+  +---------------+ |
     *                |                    player)       |
     *                +----------------------------------+
     *
     * NOTE: non-time critical operations are run once every 250ms or so.
     *
     * TODO: It would be great if door opening/closing can be detected and pathgrid
     * links dynamically updated.  Currently (0.29.0) AiWander allows choosing a
     * destination beyond closed doors which sometimes makes the actors stuck at the
     * door and impossible for the player to open the door.
     *
     * For now detect being stuck at the door and simply delete the nodes from the
     * allowed set.  The issue is when the door opens the allowed set is not
     * re-calculated.  However this would not be an issue in most cases since hostile
     * actors will enter combat (i.e. no longer wandering) and different pathfinding
     * will kick in.
     */
    bool AiWander::execute (const MWWorld::Ptr& actor, CharacterController& /*characterController*/, AiState& state, float duration)
    {
        MWMechanics::CreatureStats& cStats = actor.getClass().getCreatureStats(actor);
        if (cStats.isDead() || cStats.getHealth().getCurrent() <= 0)
            return true; // Don't bother with dead actors

        // get or create temporary storage
        AiWanderStorage& storage = state.get<AiWanderStorage>();

        mRemainingDuration -= ((duration*MWBase::Environment::get().getWorld()->getTimeScaleFactor()) / 3600);

        cStats.setDrawState(DrawState_Nothing);
        cStats.setMovementFlag(CreatureStats::Flag_Run, false);

        ESM::Position pos = actor.getRefData().getPosition();

        // If there is already a destination due to the package having been interrupted by a combat or pursue package,
        // rebuild a path to it
        if (!mPathFinder.isPathConstructed() && mHasDestination)
        {
            if (mUsePathgrid)
            {
                mPathFinder.buildPathByPathgrid(pos.asVec3(), mDestination, actor.getCell(),
                    getPathGridGraph(actor.getCell()));
            }
            else
            {
                const osg::Vec3f halfExtents = MWBase::Environment::get().getWorld()->getPathfindingHalfExtents(actor);
                mPathFinder.buildPath(actor, pos.asVec3(), mDestination, actor.getCell(),
                    getPathGridGraph(actor.getCell()), halfExtents, getNavigatorFlags(actor));
            }

            if (mPathFinder.isPathConstructed())
                storage.setState(AiWanderStorage::Wander_Walking);
        }

        GreetingState greetingState = MWBase::Environment::get().getMechanicsManager()->getGreetingState(actor);
        if (greetingState == Greet_InProgress)
        {
            if (storage.mState == AiWanderStorage::Wander_Walking)
            {
                stopMovement(actor);
                mObstacleCheck.clear();
                storage.setState(AiWanderStorage::Wander_IdleNow);
            }
        }

        doPerFrameActionsForState(actor, duration, storage);

        float& lastReaction = storage.mReaction;
        lastReaction += duration;
        if (AI_REACTION_TIME <= lastReaction)
        {
            lastReaction = 0;
            return reactionTimeActions(actor, storage, pos);
        }
        else
            return false;
    }

    bool AiWander::reactionTimeActions(const MWWorld::Ptr& actor, AiWanderStorage& storage, ESM::Position& pos)
    {
        if (mDistance <= 0)
            storage.mCanWanderAlongPathGrid = false;

        if (isPackageCompleted())
        {
            stopWalking(actor);
            // Reset package so it can be used again
            mRemainingDuration=mDuration;
            return true;
        }

        if (!mStoredInitialActorPosition)
        {
            mInitialActorPosition = actor.getRefData().getPosition().asVec3();
            mStoredInitialActorPosition = true;
        }

        // Initialization to discover & store allowed node points for this actor.
        if (storage.mPopulateAvailableNodes)
        {
            getAllowedNodes(actor, actor.getCell()->getCell(), storage);
        }

        if (canActorMoveByZAxis(actor) && mDistance > 0) {
            // Typically want to idle for a short time before the next wander
            if (Misc::Rng::rollDice(100) >= 92 && storage.mState != AiWanderStorage::Wander_Walking) {
                wanderNearStart(actor, storage, mDistance);
            }

            storage.mCanWanderAlongPathGrid = false;
        }
        // If the package has a wander distance but no pathgrid is available,
        // randomly idle or wander near spawn point
        else if(storage.mAllowedNodes.empty() && mDistance > 0 && !storage.mIsWanderingManually) {
            // Typically want to idle for a short time before the next wander
            if (Misc::Rng::rollDice(100) >= 96) {
                wanderNearStart(actor, storage, mDistance);
            } else {
                storage.setState(AiWanderStorage::Wander_IdleNow);
            }
        } else if (storage.mAllowedNodes.empty() && !storage.mIsWanderingManually) {
            storage.mCanWanderAlongPathGrid = false;
        }

        // If Wandering manually and hit an obstacle, stop
        if (storage.mIsWanderingManually && mObstacleCheck.isEvading()) {
            completeManualWalking(actor, storage);
        }

        if (storage.mState == AiWanderStorage::Wander_MoveNow && storage.mCanWanderAlongPathGrid)
        {
            // Construct a new path if there isn't one
            if(!mPathFinder.isPathConstructed())
            {
                if (!storage.mAllowedNodes.empty())
                {
                    setPathToAnAllowedNode(actor, storage, pos);
                }
            }
        }
        else if (storage.mIsWanderingManually && mPathFinder.checkPathCompleted())
        {
            completeManualWalking(actor, storage);
        }

        if (storage.mIsWanderingManually
            && storage.mState == AiWanderStorage::Wander_Walking
            && (mPathFinder.getPathSize() == 0
                || isDestinationHidden(actor, mPathFinder.getPath().back())
                || isAreaOccupiedByOtherActor(actor, mPathFinder.getPath().back())))
            completeManualWalking(actor, storage);

        return false; // AiWander package not yet completed
    }

    bool AiWander::getRepeat() const
    {
        return mRepeat;
    }

    osg::Vec3f AiWander::getDestination(const MWWorld::Ptr& actor) const
    {
        if (mHasDestination)
            return mDestination;

        return actor.getRefData().getPosition().asVec3();
    }

    bool AiWander::isPackageCompleted() const
    {
        // End package if duration is complete
        return mDuration && mRemainingDuration <= 0;
    }

    /*
     * Commands actor to walk to a random location near original spawn location.
     */
    void AiWander::wanderNearStart(const MWWorld::Ptr &actor, AiWanderStorage &storage, int wanderDistance) {
        const auto currentPosition = actor.getRefData().getPosition().asVec3();

        std::size_t attempts = 10; // If a unit can't wander out of water, don't want to hang here
        const bool isWaterCreature = actor.getClass().isPureWaterCreature(actor);
        const bool isFlyingCreature = actor.getClass().isPureFlyingCreature(actor);
        const auto world = MWBase::Environment::get().getWorld();
        const auto halfExtents = world->getPathfindingHalfExtents(actor);
        const auto navigator = world->getNavigator();
        const auto navigatorFlags = getNavigatorFlags(actor);

        do {
            // Determine a random location within radius of original position
            const float wanderRadius = (0.2f + Misc::Rng::rollClosedProbability() * 0.8f) * wanderDistance;
            if (!isWaterCreature && !isFlyingCreature)
            {
                // findRandomPointAroundCircle uses wanderDistance as limit for random and not as exact distance
                if (const auto destination = navigator->findRandomPointAroundCircle(halfExtents, mInitialActorPosition, wanderDistance, navigatorFlags))
                    mDestination = *destination;
                else
                    mDestination = getRandomPointAround(mInitialActorPosition, wanderRadius);
            }
            else
                mDestination = getRandomPointAround(mInitialActorPosition, wanderRadius);

            // Check if land creature will walk onto water or if water creature will swim onto land
            if (!isWaterCreature && destinationIsAtWater(actor, mDestination))
                continue;

            if (isDestinationHidden(actor, mDestination))
                continue;

            if (isAreaOccupiedByOtherActor(actor, mDestination))
                continue;

            if (isWaterCreature || isFlyingCreature)
                mPathFinder.buildStraightPath(mDestination);
            else
                mPathFinder.buildPathByNavMesh(actor, currentPosition, mDestination, halfExtents, navigatorFlags);

            if (mPathFinder.isPathConstructed())
            {
                storage.setState(AiWanderStorage::Wander_Walking, true);
                mHasDestination = true;
                mUsePathgrid = false;
            }

            break;
        } while (--attempts);
    }

    /*
     * Returns true if the position provided is above water.
     */
    bool AiWander::destinationIsAtWater(const MWWorld::Ptr &actor, const osg::Vec3f& destination) {
        float heightToGroundOrWater = MWBase::Environment::get().getWorld()->getDistToNearestRayHit(destination, osg::Vec3f(0,0,-1), 1000.0, true);
        osg::Vec3f positionBelowSurface = destination;
        positionBelowSurface[2] = positionBelowSurface[2] - heightToGroundOrWater - 1.0f;
        return MWBase::Environment::get().getWorld()->isUnderwater(actor.getCell(), positionBelowSurface);
    }

    void AiWander::completeManualWalking(const MWWorld::Ptr &actor, AiWanderStorage &storage) {
        stopWalking(actor);
        mObstacleCheck.clear();
        storage.setState(AiWanderStorage::Wander_IdleNow);
    }

    void AiWander::doPerFrameActionsForState(const MWWorld::Ptr& actor, float duration, AiWanderStorage& storage)
    {
        switch (storage.mState)
        {
            case AiWanderStorage::Wander_IdleNow:
                onIdleStatePerFrameActions(actor, duration, storage);
                break;

            case AiWanderStorage::Wander_Walking:
                onWalkingStatePerFrameActions(actor, duration, storage);
                break;

            case AiWanderStorage::Wander_ChooseAction:
                onChooseActionStatePerFrameActions(actor, storage);
                break;

            case AiWanderStorage::Wander_MoveNow:
                break;  // nothing to do

            default:
                // should never get here
                assert(false);
                break;
        }
    }

    void AiWander::onIdleStatePerFrameActions(const MWWorld::Ptr& actor, float duration, AiWanderStorage& storage)
    {
        // Check if an idle actor is  too close to a door - if so start walking
        storage.mDoorCheckDuration += duration;

        if (storage.mDoorCheckDuration >= DOOR_CHECK_INTERVAL)
        {
            storage.mDoorCheckDuration = 0;    // restart timer
            static float distance = MWBase::Environment::get().getWorld()->getMaxActivationDistance();
            if (mDistance &&            // actor is not intended to be stationary
                proximityToDoor(actor, distance*1.6f))
            {
                storage.setState(AiWanderStorage::Wander_MoveNow);
                storage.mTrimCurrentNode = false; // just in case
                return;
            }
        }

        // Check if idle animation finished
        GreetingState greetingState = MWBase::Environment::get().getMechanicsManager()->getGreetingState(actor);
        if (!checkIdle(actor, storage.mIdleAnimation) && (greetingState == Greet_Done || greetingState == Greet_None))
        {
            if (mPathFinder.isPathConstructed())
                storage.setState(AiWanderStorage::Wander_Walking);
            else
                storage.setState(AiWanderStorage::Wander_ChooseAction);
        }
    }

    void AiWander::onWalkingStatePerFrameActions(const MWWorld::Ptr& actor, float duration, AiWanderStorage& storage)
    {
        // Is there no destination or are we there yet?
        if ((!mPathFinder.isPathConstructed()) || pathTo(actor, osg::Vec3f(mPathFinder.getPath().back()), duration, DESTINATION_TOLERANCE))
        {
            stopWalking(actor);
            storage.setState(AiWanderStorage::Wander_ChooseAction);
        }
        else
        {
            // have not yet reached the destination
            evadeObstacles(actor, storage);
        }
    }

    void AiWander::onChooseActionStatePerFrameActions(const MWWorld::Ptr& actor, AiWanderStorage& storage)
    {

        unsigned short idleAnimation = getRandomIdle();
        storage.mIdleAnimation = idleAnimation;

        if (!idleAnimation && mDistance)
        {
            storage.setState(AiWanderStorage::Wander_MoveNow);
            return;
        }
        if(idleAnimation)
        {
            if(std::find(storage.mBadIdles.begin(), storage.mBadIdles.end(), idleAnimation)==storage.mBadIdles.end())
            {
                if(!playIdle(actor, idleAnimation))
                {
                    storage.mBadIdles.push_back(idleAnimation);
                    storage.setState(AiWanderStorage::Wander_ChooseAction);
                    return;
                }
            }
        }

        storage.setState(AiWanderStorage::Wander_IdleNow);
    }

    void AiWander::evadeObstacles(const MWWorld::Ptr& actor, AiWanderStorage& storage)
    {
        if (mUsePathgrid)
        {
            const auto halfExtents = MWBase::Environment::get().getWorld()->getHalfExtents(actor);
            mPathFinder.buildPathByNavMeshToNextPoint(actor, halfExtents, getNavigatorFlags(actor));
        }

        if (mObstacleCheck.isEvading())
        {
            // first check if we're walking into a door
            static float distance = MWBase::Environment::get().getWorld()->getMaxActivationDistance();
            if (proximityToDoor(actor, distance))
            {
                // remove allowed points then select another random destination
                storage.mTrimCurrentNode = true;
                trimAllowedNodes(storage.mAllowedNodes, mPathFinder);
                mObstacleCheck.clear();
                stopWalking(actor);
                storage.setState(AiWanderStorage::Wander_MoveNow);
            }

           storage.mStuckCount++;  // TODO: maybe no longer needed
        }

        // if stuck for sufficiently long, act like current location was the destination
        if (storage.mStuckCount >= getCountBeforeReset(actor)) // something has gone wrong, reset
        {
            mObstacleCheck.clear();
            stopWalking(actor);
            storage.setState(AiWanderStorage::Wander_ChooseAction);
            storage.mStuckCount = 0;
        }
    }



    void AiWander::setPathToAnAllowedNode(const MWWorld::Ptr& actor, AiWanderStorage& storage, const ESM::Position& actorPos)
    {
        unsigned int randNode = Misc::Rng::rollDice(storage.mAllowedNodes.size());
        ESM::Pathgrid::Point dest(storage.mAllowedNodes[randNode]);

        ToWorldCoordinates(dest, actor.getCell()->getCell());

        // actor position is already in world coordinates
        const osg::Vec3f start = actorPos.asVec3();

        // don't take shortcuts for wandering
        const osg::Vec3f destVec3f = PathFinder::makeOsgVec3(dest);
        mPathFinder.buildPathByPathgrid(start, destVec3f, actor.getCell(), getPathGridGraph(actor.getCell()));

        if (mPathFinder.isPathConstructed())
        {
            mDestination = destVec3f;
            mHasDestination = true;
            mUsePathgrid = true;
            // Remove this node as an option and add back the previously used node (stops NPC from picking the same node):
            ESM::Pathgrid::Point temp = storage.mAllowedNodes[randNode];
            storage.mAllowedNodes.erase(storage.mAllowedNodes.begin() + randNode);
            // check if mCurrentNode was taken out of mAllowedNodes
            if (storage.mTrimCurrentNode && storage.mAllowedNodes.size() > 1)
                storage.mTrimCurrentNode = false;
            else
                storage.mAllowedNodes.push_back(storage.mCurrentNode);
            storage.mCurrentNode = temp;

            storage.setState(AiWanderStorage::Wander_Walking);
        }
        // Choose a different node and delete this one from possible nodes because it is uncreachable:
        else
            storage.mAllowedNodes.erase(storage.mAllowedNodes.begin() + randNode);
    }

    void AiWander::ToWorldCoordinates(ESM::Pathgrid::Point& point, const ESM::Cell * cell)
    {
        CoordinateConverter(cell).toWorld(point);
    }

    void AiWander::trimAllowedNodes(std::vector<ESM::Pathgrid::Point>& nodes,
                                    const PathFinder& pathfinder)
    {
        // TODO: how to add these back in once the door opens?
        // Idea: keep a list of detected closed doors (see aicombat.cpp)
        // Every now and then check whether one of the doors is opened. (maybe
        // at the end of playing idle?) If the door is opened then re-calculate
        // allowed nodes starting from the spawn point.
        auto paths = pathfinder.getPath();
        while(paths.size() >= 2)
        {
            const auto pt = paths.back();
            for(unsigned int j = 0; j < nodes.size(); j++)
            {
                // FIXME: doesn't handle a door with the same X/Y
                //        coordinates but with a different Z
                if (std::abs(nodes[j].mX - pt.x()) <= 0.5 && std::abs(nodes[j].mY - pt.y()) <= 0.5)
                {
                    nodes.erase(nodes.begin() + j);
                    break;
                }
            }
            paths.pop_back();
        }
    }

    int AiWander::getTypeId() const
    {
        return TypeIdWander;
    }

    void AiWander::stopWalking(const MWWorld::Ptr& actor)
    {
        mPathFinder.clearPath();
        mHasDestination = false;
        stopMovement(actor);
    }

    bool AiWander::playIdle(const MWWorld::Ptr& actor, unsigned short idleSelect)
    {
        if ((GroupIndex_MinIdle <= idleSelect) && (idleSelect <= GroupIndex_MaxIdle))
        {
            const std::string& groupName = sIdleSelectToGroupName[idleSelect - GroupIndex_MinIdle];
            return MWBase::Environment::get().getMechanicsManager()->playAnimationGroup(actor, groupName, 0, 1);
        }
        else
        {
            Log(Debug::Verbose) << "Attempted to play out of range idle animation \"" << idleSelect << "\" for " << actor.getCellRef().getRefId();
            return false;
        }
    }

    bool AiWander::checkIdle(const MWWorld::Ptr& actor, unsigned short idleSelect)
    {
        if ((GroupIndex_MinIdle <= idleSelect) && (idleSelect <= GroupIndex_MaxIdle))
        {
            const std::string& groupName = sIdleSelectToGroupName[idleSelect - GroupIndex_MinIdle];
            return MWBase::Environment::get().getMechanicsManager()->checkAnimationPlaying(actor, groupName);
        }
        else
        {
            return false;
        }
    }

    short unsigned AiWander::getRandomIdle()
    {
        unsigned short idleRoll = 0;
        short unsigned selectedAnimation = 0;

        for(unsigned int counter = 0; counter < mIdle.size(); counter++)
        {
            static float fIdleChanceMultiplier = MWBase::Environment::get().getWorld()->getStore()
                .get<ESM::GameSetting>().find("fIdleChanceMultiplier")->mValue.getFloat();

            unsigned short idleChance = static_cast<unsigned short>(fIdleChanceMultiplier * mIdle[counter]);
            unsigned short randSelect = (int)(Misc::Rng::rollProbability() * int(100 / fIdleChanceMultiplier));
            if(randSelect < idleChance && randSelect > idleRoll)
            {
                selectedAnimation = counter + GroupIndex_MinIdle;
                idleRoll = randSelect;
            }
        }
        return selectedAnimation;
    }

    void AiWander::fastForward(const MWWorld::Ptr& actor, AiState &state)
    {
        // Update duration counter
        mRemainingDuration--;
        if (mDistance == 0)
            return;

        AiWanderStorage& storage = state.get<AiWanderStorage>();
        if (storage.mPopulateAvailableNodes)
            getAllowedNodes(actor, actor.getCell()->getCell(), storage);

        if (storage.mAllowedNodes.empty())
            return;

        int index = Misc::Rng::rollDice(storage.mAllowedNodes.size());
        ESM::Pathgrid::Point dest = storage.mAllowedNodes[index];
        ESM::Pathgrid::Point worldDest = dest;
        ToWorldCoordinates(worldDest, actor.getCell()->getCell());

        bool isPathGridOccupied = MWBase::Environment::get().getMechanicsManager()->isAnyActorInRange(PathFinder::makeOsgVec3(worldDest), 60);

        // add offset only if the selected pathgrid is occupied by another actor
        if (isPathGridOccupied)
        {
            ESM::Pathgrid::PointList points;
            getNeighbouringNodes(dest, actor.getCell(), points);

            // there are no neighbouring nodes, nowhere to move
            if (points.empty())
                return;

            int initialSize = points.size();
            bool isOccupied = false;
            // AI will try to move the NPC towards every neighboring node until suitable place will be found
            for (int i = 0; i < initialSize; i++)
            {
                int randomIndex = Misc::Rng::rollDice(points.size());
                ESM::Pathgrid::Point connDest = points[randomIndex];

                // add an offset towards random neighboring node
                osg::Vec3f dir = PathFinder::makeOsgVec3(connDest) - PathFinder::makeOsgVec3(dest);
                float length = dir.length();
                dir.normalize();

                for (int j = 1; j <= 3; j++)
                {
                    // move for 5-15% towards random neighboring node
                    dest = PathFinder::makePathgridPoint(PathFinder::makeOsgVec3(dest) + dir * (j * 5 * length / 100.f));
                    worldDest = dest;
                    ToWorldCoordinates(worldDest, actor.getCell()->getCell());

                    isOccupied = MWBase::Environment::get().getMechanicsManager()->isAnyActorInRange(PathFinder::makeOsgVec3(worldDest), 60);

                    if (!isOccupied)
                        break;
                }

                if (!isOccupied)
                    break;

                // Will try an another neighboring node
                points.erase(points.begin()+randomIndex);
            }

            // there is no free space, nowhere to move
            if (isOccupied)
                return;
        }

        // place above to prevent moving inside objects, e.g. stairs, because a vector between pathgrids can be underground.
        // Adding 20 in adjustPosition() is not enough.
        dest.mZ += 60;

        ToWorldCoordinates(dest, actor.getCell()->getCell());

        state.moveIn(new AiWanderStorage());

        MWBase::Environment::get().getWorld()->moveObject(actor, static_cast<float>(dest.mX),
            static_cast<float>(dest.mY), static_cast<float>(dest.mZ));
        actor.getClass().adjustPosition(actor, false);
    }

    void AiWander::getNeighbouringNodes(ESM::Pathgrid::Point dest, const MWWorld::CellStore* currentCell, ESM::Pathgrid::PointList& points)
    {
        const ESM::Pathgrid *pathgrid =
            MWBase::Environment::get().getWorld()->getStore().get<ESM::Pathgrid>().search(*currentCell->getCell());

        int index = PathFinder::getClosestPoint(pathgrid, PathFinder::makeOsgVec3(dest));

        getPathGridGraph(currentCell).getNeighbouringPoints(index, points);
    }

    void AiWander::getAllowedNodes(const MWWorld::Ptr& actor, const ESM::Cell* cell, AiWanderStorage& storage)
    {
        // infrequently used, therefore no benefit in caching it as a member
        const ESM::Pathgrid *
            pathgrid = MWBase::Environment::get().getWorld()->getStore().get<ESM::Pathgrid>().search(*cell);
        const MWWorld::CellStore* cellStore = actor.getCell();

        storage.mAllowedNodes.clear();

        // If there is no path this actor doesn't go anywhere. See:
        // https://forum.openmw.org/viewtopic.php?t=1556
        // http://www.fliggerty.com/phpBB3/viewtopic.php?f=30&t=5833
        // Note: In order to wander, need at least two points.
        if(!pathgrid || (pathgrid->mPoints.size() < 2))
            storage.mCanWanderAlongPathGrid = false;

        // A distance value passed into the constructor indicates how far the
        // actor can  wander from the spawn position.  AiWander assumes that
        // pathgrid points are available, and uses them to randomly select wander
        // destinations within the allowed set of pathgrid points (nodes).
        // ... pathgrids don't usually include water, so swimmers ignore them
        if (mDistance && storage.mCanWanderAlongPathGrid && !actor.getClass().isPureWaterCreature(actor))
        {
            // get NPC's position in local (i.e. cell) coordinates
            osg::Vec3f npcPos(mInitialActorPosition);
            CoordinateConverter(cell).toLocal(npcPos);

            // Find closest pathgrid point
            int closestPointIndex = PathFinder::getClosestPoint(pathgrid, npcPos);

            // mAllowedNodes for this actor with pathgrid point indexes based on mDistance
            // and if the point is connected to the closest current point
            // NOTE: mPoints and mAllowedNodes are in local coordinates
            int pointIndex = 0;
            for(unsigned int counter = 0; counter < pathgrid->mPoints.size(); counter++)
            {
                osg::Vec3f nodePos(PathFinder::makeOsgVec3(pathgrid->mPoints[counter]));
                if((npcPos - nodePos).length2() <= mDistance * mDistance &&
                   getPathGridGraph(cellStore).isPointConnected(closestPointIndex, counter))
                {
                    storage.mAllowedNodes.push_back(pathgrid->mPoints[counter]);
                    pointIndex = counter;
                }
            }
            if (storage.mAllowedNodes.size() == 1)
            {
                AddNonPathGridAllowedPoints(npcPos, pathgrid, pointIndex, storage);
            }
            if(!storage.mAllowedNodes.empty())
            {
                SetCurrentNodeToClosestAllowedNode(npcPos, storage);
            }
        }

        storage.mPopulateAvailableNodes = false;
    }

    // When only one path grid point in wander distance,
    // additional points for NPC to wander to are:
    // 1. NPC's initial location
    // 2. Partway along the path between the point and its connected points.
    void AiWander::AddNonPathGridAllowedPoints(osg::Vec3f npcPos, const ESM::Pathgrid * pathGrid, int pointIndex, AiWanderStorage& storage)
    {
        storage.mAllowedNodes.push_back(PathFinder::makePathgridPoint(npcPos));
        for (std::vector<ESM::Pathgrid::Edge>::const_iterator it = pathGrid->mEdges.begin(); it != pathGrid->mEdges.end(); ++it)
        {
            if (it->mV0 == pointIndex)
            {
                AddPointBetweenPathGridPoints(pathGrid->mPoints[it->mV0], pathGrid->mPoints[it->mV1], storage);
            }
        }
    }

    void AiWander::AddPointBetweenPathGridPoints(const ESM::Pathgrid::Point& start, const ESM::Pathgrid::Point& end, AiWanderStorage& storage)
    {
        osg::Vec3f vectorStart = PathFinder::makeOsgVec3(start);
        osg::Vec3f delta = PathFinder::makeOsgVec3(end) - vectorStart;
        float length = delta.length();
        delta.normalize();

        int distance = std::max(mDistance / 2, MINIMUM_WANDER_DISTANCE);

        // must not travel longer than distance between waypoints or NPC goes past waypoint
        distance = std::min(distance, static_cast<int>(length));
        delta *= distance;
        storage.mAllowedNodes.push_back(PathFinder::makePathgridPoint(vectorStart + delta));
    }

    void AiWander::SetCurrentNodeToClosestAllowedNode(const osg::Vec3f& npcPos, AiWanderStorage& storage)
    {
        float distanceToClosestNode = std::numeric_limits<float>::max();
        unsigned int index = 0;
        for (unsigned int counterThree = 0; counterThree < storage.mAllowedNodes.size(); counterThree++)
        {
            osg::Vec3f nodePos(PathFinder::makeOsgVec3(storage.mAllowedNodes[counterThree]));
            float tempDist = (npcPos - nodePos).length2();
            if (tempDist < distanceToClosestNode)
            {
                index = counterThree;
                distanceToClosestNode = tempDist;
            }
        }
        storage.mCurrentNode = storage.mAllowedNodes[index];
        storage.mAllowedNodes.erase(storage.mAllowedNodes.begin() + index);
    }

    void AiWander::writeState(ESM::AiSequence::AiSequence &sequence) const
    {
        float remainingDuration;
        if (mRemainingDuration > 0 && mRemainingDuration < 24)
            remainingDuration = mRemainingDuration;
        else
            remainingDuration = mDuration;

        std::unique_ptr<ESM::AiSequence::AiWander> wander(new ESM::AiSequence::AiWander());
        wander->mData.mDistance = mDistance;
        wander->mData.mDuration = mDuration;
        wander->mData.mTimeOfDay = mTimeOfDay;
        wander->mDurationData.mRemainingDuration = remainingDuration;
        assert (mIdle.size() == 8);
        for (int i=0; i<8; ++i)
            wander->mData.mIdle[i] = mIdle[i];
        wander->mData.mShouldRepeat = mRepeat;
        wander->mStoredInitialActorPosition = mStoredInitialActorPosition;
        if (mStoredInitialActorPosition)
            wander->mInitialActorPosition = mInitialActorPosition;

        ESM::AiSequence::AiPackageContainer package;
        package.mType = ESM::AiSequence::Ai_Wander;
        package.mPackage = wander.release();
        sequence.mPackages.push_back(package);
    }

    AiWander::AiWander (const ESM::AiSequence::AiWander* wander)
        : mDistance(std::max(static_cast<short>(0), wander->mData.mDistance))
        , mDuration(std::max(static_cast<short>(0), wander->mData.mDuration))
        , mRemainingDuration(wander->mDurationData.mRemainingDuration)
        , mTimeOfDay(wander->mData.mTimeOfDay)
        , mIdle(getInitialIdle(wander->mData.mIdle))
        , mRepeat(wander->mData.mShouldRepeat != 0)
        , mStoredInitialActorPosition(wander->mStoredInitialActorPosition)
        , mHasDestination(false)
        , mDestination(osg::Vec3f(0, 0, 0))
        , mUsePathgrid(false)
    {
        if (mStoredInitialActorPosition)
            mInitialActorPosition = wander->mInitialActorPosition;
        if (mRemainingDuration <= 0 || mRemainingDuration >= 24)
            mRemainingDuration = mDuration;
    }
}