//
// Lol Engine
//
// Copyright: (c) 2010-2012 Sam Hocevar <sam@hocevar.net>
//            (c) 2009-2012 Cédric Lecacheur <jordx@free.fr>
//            (c) 2009-2012 Benjamin Huet <huet.benjamin@gmail.com>
//   This program is free software; you can redistribute it and/or
//   modify it under the terms of the Do What The Fuck You Want To
//   Public License, Version 2, as published by Sam Hocevar. See
//   http://www.wtfpl.net/ for more details.
//

#if defined HAVE_CONFIG_H
#   include "config.h"
#endif

#define USE_LOL_CTRLR_CHARAC

#ifdef HAVE_PHYS_USE_BULLET
#include "core.h"
#include <stdio.h>
#include "../Include/LolBtPhysicsIntegration.h"
#include "../Include/LolPhysics.h"
#include "../Include/EasyCharacterController.h"
#include "../Include/BulletCharacterController.h"
//#include "LinearMath/btIDebugDraw.h"
//#include "BulletCollision/CollisionDispatch/btGhostObject.h"
//#include "BulletCollision/CollisionShapes/btMultiSphereShape.h"
//#include "BulletCollision/BroadphaseCollision/btOverlappingPairCache.h"
//#include "BulletCollision/BroadphaseCollision/btCollisionAlgorithm.h"
//#include "BulletCollision/CollisionDispatch/btCollisionWorld.h"
//#include "LinearMath/btDefaultMotionState.h"
#endif //HAVE_PHYS_USE_BULLET


namespace lol
{

namespace phys
{

#ifdef USE_LOL_CTRLR_CHARAC
#ifdef HAVE_PHYS_USE_BULLET

//When called, will try to remove Character controller from its collision.
bool BulletKinematicCharacterController::RecoverFromPenetration(btCollisionWorld* CollisionWorld)
{
    bool HasPenetration = false;

    //Retrieve all pair with us colliding.
    CollisionWorld->getDispatcher()->dispatchAllCollisionPairs(m_ghost_object->getOverlappingPairCache(), CollisionWorld->getDispatchInfo(), CollisionWorld->getDispatcher());
    m_current_position = BT2LOLU_VEC3(m_ghost_object->getWorldTransform().getOrigin());

    float MaxPen = .0f;
    for (int i = 0; i < m_ghost_object->getOverlappingPairCache()->getNumOverlappingPairs(); i++)
    {
        m_manifold_array.resize(0);

        //this is the equivalent of the "Touch algorithm". Maybe refactor ?
        btBroadphasePair* CollisionPair = &m_ghost_object->getOverlappingPairCache()->getOverlappingPairArray()[i];
        if (CollisionPair->m_algorithm)
            CollisionPair->m_algorithm->getAllContactManifolds(m_manifold_array);

        for (int j = 0; j < m_manifold_array.size(); ++j)
        {
            btPersistentManifold* CurMfold = m_manifold_array[j];
            //Normal direction differs if we're Body0
            float DirSign = CurMfold->getBody0() == m_ghost_object ? -1.f : 1.f;

            for (int k = 0; k < CurMfold->getNumContacts(); k++)
            {
                const btManifoldPoint& MfPoint = CurMfold->getContactPoint(k);
                float Dist = MfPoint.getDistance();
                if (Dist < .0f)
                {
                    if (Dist < MaxPen)
                    {
                        MaxPen = Dist;
                        m_touching_normal = BT2LOL_VEC3(MfPoint.m_normalWorldOnB) * DirSign;
                    }
                    m_current_position += BT2LOL_VEC3(MfPoint.m_normalWorldOnB) * DirSign * Dist * .2f;
                    HasPenetration = true;
                }
            }
        }
    }

    btTransform GObjMx = m_ghost_object->getWorldTransform();
    GObjMx.setOrigin(LOL2BTU_VEC3(m_current_position));
    m_ghost_object->setWorldTransform(GObjMx);

    return HasPenetration;
}

//When the Controller hits a wall, we modify the target so the controller will MoveStep along the wall.
void BulletKinematicCharacterController::UpdateTargetOnHit(const vec3& HitNormal, float TangentMag, float NormalMag)
{
    vec3 Movedir = m_target_position - m_current_position;
    float MoveLength = (float)length(Movedir);

    if (MoveLength > SIMD_EPSILON)
    {
        Movedir = normalize(Movedir);

        vec3 ReflectDir = normalize(GetReflectedDir(Movedir, HitNormal));
        vec3 ParallelDir = ProjectDirOnNorm(ReflectDir, HitNormal);
        vec3 PerpindicularDir = ProjectDirOnNormPerpindicular(ReflectDir, HitNormal);

        m_target_position = m_current_position;

        if (NormalMag != .0f)
            m_target_position += PerpindicularDir * NormalMag * MoveLength;
    }
}

//Handles the actual Movement. It actually moves in the 3 dimensions, function name is confusing.
void BulletKinematicCharacterController::DoMove(btCollisionWorld* CollisionWorld, const vec3& MoveStep, float DeltaTime)
{
    // phase 2: forward and strafe
    m_target_position = m_current_position + MoveStep;
    btTransform SweepStart, SweepEnd;
    SweepStart.setIdentity();
    SweepEnd.setIdentity();

    float Fraction = 1.f;
    float SqDist = .0f;

    if (m_touching_contact && dot(m_normalized_direction, m_touching_normal) > .0f)
        UpdateTargetOnHit(m_touching_normal);

    //Let's loop on movement, until Movement fraction if below 0.01, which means we've reached our destination.
    //Or until we'tried 10 times.
    int MaxMoveLoop = 10;
    while (Fraction > .01f && MaxMoveLoop-- > 0)
    {
        SweepStart.setOrigin(LOL2BTU_VEC3(m_current_position));
        SweepEnd.setOrigin(LOL2BTU_VEC3(m_target_position));
        vec3 SweepDirNeg(m_current_position - m_target_position);

        ClosestNotMeConvexResultCallback SweepCallback(m_ghost_object, SweepDirNeg, .0f);
        SweepCallback.m_collisionFilterGroup = GetGhostObject()->getBroadphaseHandle()->m_collisionFilterGroup;
        SweepCallback.m_collisionFilterMask = GetGhostObject()->getBroadphaseHandle()->m_collisionFilterMask;

        //The sweep test is done with an added margin, so we use it and then discard it
        float SavedMargin = m_convex_shape->getMargin();
        m_convex_shape->setMargin(SavedMargin + m_added_margin); //Apply Added Margin
        if (m_do_gobject_sweep_test)
            m_ghost_object->convexSweepTest (m_convex_shape, SweepStart, SweepEnd, SweepCallback, CollisionWorld->getDispatchInfo().m_allowedCcdPenetration);
        else
            CollisionWorld->convexSweepTest (m_convex_shape, SweepStart, SweepEnd, SweepCallback, CollisionWorld->getDispatchInfo().m_allowedCcdPenetration);
        m_convex_shape->setMargin(SavedMargin); //Restore saved margin

        Fraction -= SweepCallback.m_closestHitFraction;

        if (SweepCallback.hasHit())
        {
            //We moved only a Fraction
            float HitDist = (float)length(BT2LOLU_VEC3(SweepCallback.m_hitPointWorld) - m_current_position);

            UpdateTargetOnHit(BT2LOL_VEC3(SweepCallback.m_hitNormalWorld));
            vec3 NewDir = m_target_position - m_current_position;
            SqDist = sqlength(NewDir);
            if (SqDist > SIMD_EPSILON)
            {
                NewDir = normalize(NewDir);
                //See Quake2: "If velocity is against original velocity, stop ead to avoid tiny oscilations in sloping corners."
                if (dot(NewDir, m_normalized_direction) <= .0f)
                    break;
            }
            else
                break;
        }
        else //We moved whole way
            m_current_position = m_target_position;
    }
}

//The PreStep is done in order to recover from any HasPenetration.
void BulletKinematicCharacterController::PreStep(btCollisionWorld* CollisionWorld)
{
    int MaxPenetrationLoop = 0;
    m_touching_contact = false;

    while (RecoverFromPenetration(CollisionWorld))
    {
        MaxPenetrationLoop++;
        m_touching_contact = true;
        if (MaxPenetrationLoop > 4)
            break;
    }

    m_current_position = BT2LOLU_VEC3(m_ghost_object->getWorldTransform().getOrigin());
    m_target_position = m_current_position;
}

//And so we step :
//StepUpfirst, then movement, then StepDownon the ground.
void BulletKinematicCharacterController::PlayerStep(btCollisionWorld* CollisionWorld, float DeltaTime)
{
    // quick check...
    if (!m_use_walk_direction && m_velocity_time_interval <= .0f)
        return;        // no motion

    // Update fall velocity.
    //m_velocity -= m_gravity * DeltaTime;

    btTransform NewTransform;
    NewTransform = m_ghost_object->getWorldTransform();

    vec3 MoveStep(.0f);
    if (m_use_walk_direction)
        MoveStep = m_walk_direction;
    else
    {
        //Still have some time left for moving!
        float dtMoving = (DeltaTime < m_velocity_time_interval) ? DeltaTime : m_velocity_time_interval;
        m_velocity_time_interval -= DeltaTime;

        // how far will we MoveStep while we are moving?
        MoveStep = m_walk_direction * dtMoving;
    }

    //Okay, step !
    DoMove(CollisionWorld, MoveStep, DeltaTime);

    //Movement finished, update World transform
    NewTransform.setOrigin(LOL2BTU_VEC3(m_current_position));
    m_ghost_object->setWorldTransform(NewTransform);
}

//should MoveStep Jump logic in EasyCC
void BulletKinematicCharacterController::Jump()
{
    if (!CanJump())
        return;

    m_vertical_velocity = m_jump_speed;
    m_was_jumping = true;
}

#endif // HAVE_PHYS_USE_BULLET
#endif // USE_LOL_CTRLR_CHARAC

    } /* namespace phys */

} /* namespace lol */