#ifndef GAME_MWMECHANICS_PATHFINDING_H
#define GAME_MWMECHANICS_PATHFINDING_H

#include <components/esm/defs.hpp>
#include <components/esm/loadpgrd.hpp>
#include <list>

#include <OgreMath.h>
#include <OgreVector3.h>

namespace MWWorld
{
    class CellStore;
}

namespace MWMechanics
{
    float distance(ESM::Pathgrid::Point point, float x, float y, float z);
    float distance(ESM::Pathgrid::Point a, ESM::Pathgrid::Point b);
    float getZAngleToDir(const Ogre::Vector3& dir);
    float getXAngleToDir(const Ogre::Vector3& dir, float dirLen = 0.0f);
    float getZAngleToPoint(const ESM::Pathgrid::Point &origin, const ESM::Pathgrid::Point &dest);
    float getXAngleToPoint(const ESM::Pathgrid::Point &origin, const ESM::Pathgrid::Point &dest);

     const float PATHFIND_Z_REACH = 50.0f;
    //static const float sMaxSlope = 49.0f; // duplicate as in physicssystem
    // distance at which actor pays more attention to decide whether to shortcut or stick to pathgrid
    const float PATHFIND_CAUTION_DIST = 500.0f;
    // distance after which actor (failed previously to shortcut) will try again
    const float PATHFIND_SHORTCUT_RETRY_DIST = 300.0f;

    // cast up-down ray with some offset from actor position to check for pits/obstacles on the way to target;
    // magnitude of pits/obstacles is defined by PATHFIND_Z_REACH
    bool checkWayIsClear(const Ogre::Vector3& from, const Ogre::Vector3& to, float offsetXY);

    class PathFinder
    {
        public:
            PathFinder();

            static float sgn(Ogre::Radian a)
            {
                if(a.valueRadians() > 0)
                    return 1.0;
                return -1.0;
            }

            static int sgn(int a)
            {
                if(a > 0)
                    return 1;
                return -1;
            }

            void clearPath();

            void buildPath(const ESM::Pathgrid::Point &startPoint, const ESM::Pathgrid::Point &endPoint,
                           const MWWorld::CellStore* cell);

            bool checkPathCompleted(float x, float y, float tolerance=32.f);
            ///< \Returns true if we are within \a tolerance units of the last path point.

            float getZAngleToNext(float x, float y) const;

            float getXAngleToNext(float x, float y, float z) const;

            bool isPathConstructed() const
            {
                return !mPath.empty();
            }

            int getPathSize() const
            {
                return mPath.size();
            }

            const std::list<ESM::Pathgrid::Point>& getPath() const
            {
                return mPath;
            }

            /** Synchronize new path with old one to avoid visiting 1 waypoint 2 times
            @note
                BuildPath() takes closest PathGrid point to NPC as first point of path.
                This is undesireable if NPC has just passed a Pathgrid point, as this
                makes the 2nd point of the new path == the 1st point of old path.
                Which results in NPC "running in a circle" back to the just passed waypoint.
             */
            void buildSyncedPath(const ESM::Pathgrid::Point &startPoint, const ESM::Pathgrid::Point &endPoint,
                const MWWorld::CellStore* cell);

            void addPointToPath(const ESM::Pathgrid::Point &point)
            {
                mPath.push_back(point);
            }

            /// utility function to convert a Ogre::Vector3 to a Pathgrid::Point
            static ESM::Pathgrid::Point MakePathgridPoint(const Ogre::Vector3& v)
            {
                return ESM::Pathgrid::Point(static_cast<int>(v[0]), static_cast<int>(v[1]), static_cast<int>(v[2]));
            }

            /// utility function to convert an ESM::Position to a Pathgrid::Point
            static ESM::Pathgrid::Point MakePathgridPoint(const ESM::Position& p)
            {
                return ESM::Pathgrid::Point(static_cast<int>(p.pos[0]), static_cast<int>(p.pos[1]), static_cast<int>(p.pos[2]));
            }

            /// utility function to convert a Pathgrid::Point to a Ogre::Vector3
            static Ogre::Vector3 MakeOgreVector3(const ESM::Pathgrid::Point& p)
            {
                return Ogre::Vector3(static_cast<Ogre::Real>(p.mX), static_cast<Ogre::Real>(p.mY), static_cast<Ogre::Real>(p.mZ));
            }

        private:

            std::list<ESM::Pathgrid::Point> mPath;

            const ESM::Pathgrid *mPathgrid;
            const MWWorld::CellStore* mCell;
    };
}

#endif