#include <algorithm>
#include <functional>
#include "libs.h"
#include "space.h"
#include "body.h"
#include "frame.h"
#include "star.h"
#include "planet.h"
#include "l3d.h"
#include "player.h"
#include "star_system.h"
#include "sbre/sbre.h"

dWorldID Space::world;
std::list<Body*> Space::bodies;
Frame* Space::rootFrame;
static dJointGroupID _contactgroup;
std::list<Body*> Space::corpses;

void Space::Init(void) {
  world = dWorldCreate();
  rootFrame = new Frame(NULL, "System");
  rootFrame->SetRadius(FLT_MAX);
  _contactgroup = dJointGroupCreate(0);
  //dWorldSetGravity(world, 0, -9.81, 0);
}

void Space::Clear(void) {
  for(std::list<Body*>::iterator i = bodies.begin(); i != bodies.end(); ++i) {
    (*i)->SetFrame(NULL);
    if((*i) != (Body*)L3D::player) {
      KillBody(*i);
    }
  }
  PruneCorpses();

  for(std::list<Frame*>::iterator i = rootFrame->m_children.begin();
      i != rootFrame->m_children.end(); ++i) delete *i;
  rootFrame->m_children.clear();

  L3D::player->SetFrame(rootFrame);
}

void Space::MoveOrbitingObjectFrames(Frame* f) {
  if(f->m_sbody) {
    /* Not too efficient. */
    vector3d pos = f->m_sbody->orbit.CartesianPosAtTime(L3D::GetGameTime());
    vector3d pos2 = f->m_sbody->orbit.CartesianPosAtTime(L3D::GetGameTime()+1.0);
    vector3d vel = pos2 - pos;
    f->SetPosition(pos);
    f->SetVelocity(vel);
  }
  f->RotateInTimestep(L3D::GetTimeStep());

  for(std::list<Frame*>::iterator i = f->m_children.begin(); i != f->m_children.end(); ++i) {
    MoveOrbitingObjectFrames(*i);
  }
}

static Frame* MakeFrameFor(StarSystem::SBody* sbody, Body* b, Frame* f) {
  Frame* orbFrame, *rotFrame;
  double frameRadius;

  if(!sbody->parent) {
    if(b) b->SetFrame(f);
    f->m_sbody = sbody;
    f->m_astroBody = b;
    return f;
  }

  if(sbody->type == StarSystem::TYPE_GRAVPOINT) {
    orbFrame = new Frame(f, sbody->name.c_str());
    orbFrame->m_sbody = sbody;
    orbFrame->m_astroBody = b;
    orbFrame->SetRadius(sbody->GetMaxChildOrbitalDistance()*1.1);
    return orbFrame;
  }  

  StarSystem::BodySuperType supertype = sbody->GetSuperType();

  if((supertype == StarSystem::SUPERTYPE_GAS_GIANT) ||
      (supertype == StarSystem::SUPERTYPE_ROCKY_PLANET)) {
    /*
     * For planets we want a non-rotating frame for a few radii
     * and a rotating frame in the same position but with maybe 1.1*radius,
     * which actually contains the object.
     */
    frameRadius = sbody->GetMaxChildOrbitalDistance()*1.1;
    orbFrame = new Frame(f, sbody->name.c_str());
    orbFrame->m_sbody = sbody;
    orbFrame->SetRadius(frameRadius ? frameRadius : 10*sbody->GetRadius());

    assert(sbody->GetRotationPeriod() != 0);
    rotFrame = new Frame(orbFrame, sbody->name.c_str());
    rotFrame->SetRadius(1.1*sbody->GetRadius());
    rotFrame->SetAngVelocity(vector3d(0,2*M_PI/sbody->GetRotationPeriod(), 0));
    rotFrame->m_astroBody = b;
    b->SetFrame(rotFrame);
    return orbFrame;
  } else {
    /* Stars want a single small non-rotating frame. */
    orbFrame = new Frame(f, sbody->name.c_str());
    orbFrame->m_sbody = sbody;
    orbFrame->m_astroBody = b;
    orbFrame->SetRadius(sbody->GetMaxChildOrbitalDistance()*1.1);
    b->SetFrame(orbFrame);
    return orbFrame;
  }
}

void Space::GenBody(StarSystem::SBody* sbody, Frame* f) {
  Body* b = 0;

  if(sbody->type != StarSystem::TYPE_GRAVPOINT) {
    if(sbody->GetSuperType() == StarSystem::SUPERTYPE_STAR) {
      Star* star = new Star(sbody);
      b = star;
    } else {
      Planet* planet = new Planet(sbody);
      b = planet;
    }
    b->SetLabel(sbody->name.c_str());
    b->SetPosition(vector3d(0,0,0));
    AddBody(b);
  }
  f = MakeFrameFor(sbody, b, f);

  for(std::vector<StarSystem::SBody*>::iterator i = sbody->children.begin();
      i != sbody->children.end(); ++i) {
    GenBody(*i, f);
  }
}

void Space::BuildSystem(void) {
  GenBody(L3D::currentSystem->rootBody, rootFrame);
  MoveOrbitingObjectFrames(rootFrame);
}

void Space::AddBody(Body* b) {
  bodies.push_back(b);
}

void Space::KillBody(Body* const b) {
  b->MarkDead();
  corpses.push_back(b);
}

void Space::UpdateFramesOfReference(void) {
  for(std::list<Body*>::iterator i = bodies.begin(); i != bodies.end(); ++i) {
    Body* b = *i;

    if(!b->GetFlags() & Body::FLAG_CAN_MOVE_FRAME) continue;

    /* Falling out of frames. */
    if(!b->GetFrame()->IsLocalPosInFrame(b->GetPosition())) {
      printf("%s leaves frame %s\n", b->GetLabel().c_str(), b->GetFrame()->GetLabel());

      vector3d oldFrameVel = b->GetFrame()->GetVelocity();

      Frame* new_frame = b->GetFrame()->m_parent;
      if(new_frame) { /* Don't fall out of root frame. */
        matrix4x4d m = matrix4x4d::Identity();
        b->GetFrame()->ApplyLeavingTransform(m);

        vector3d new_pos = m * b->GetPosition();

        matrix4x4d rot;
        b->GetRotMatrix(rot);
        b->SetRotMatrix(m * rot);

        b->SetFrame(new_frame);
        b->SetPosition(new_pos);

        /* Get rid of transforms. */
        m.ClearToRotOnly();
        b->SetVelocity(m*b->GetVelocity() + oldFrameVel);
      } else {
        b->SetVelocity(b->GetVelocity() + oldFrameVel);
      }
    }

    /* Entering into frames. */
    for(std::list<Frame*>::iterator j = b->GetFrame()->m_children.begin();
        j != b->GetFrame()->m_children.end(); ++j) {
      Frame* child = *j;
      matrix4x4d m;
      Frame::GetFrameTransform(b->GetFrame(), child, m);
      vector3d pos = m * b->GetPosition();
      if(child->IsLocalPosInFrame(pos)) {
        printf("%s enters frame %s\n", b->GetLabel().c_str(), child->GetLabel());
        b->SetPosition(pos);
        b->SetFrame(child);

        matrix4x4d rot;
        b->GetRotMatrix(rot);
        b->SetRotMatrix(m * rot);

        /* Get rid of transforms. */
        m.ClearToRotOnly();
        b->SetVelocity(m*b->GetVelocity()-child->GetVelocity());
        break;
      }
    }
  }
}

static bool _OnCollision(dGeomID g1, dGeomID g2, Object* o1, Object* o2,
                         int numContacts, dContact contacts[]) {
  if((o1->GetType() == Object::LASER) || (o2->GetType() == Object::LASER)) {
    if(o1->GetType() == Object::LASER) {
      std::swap<Object*>(o1, o2);
      std::swap<dGeomID>(g1, g2);
    }
    Ship::LaserObj* lobj = static_cast<Ship::LaserObj*>(o2);
    if(o1 == lobj->owner) return false;
    printf("%s (geom flag %x) was shot by %s\n", ((ModelBody::Geom*)o1)->parent->GetLabel().c_str(),
        ((ModelBody::Geom*)o1)->flags, lobj->owner->GetLabel().c_str());

    if(o1->GetType() == Object::SHIP) {
      DynamicBody* rb = (DynamicBody*)o1;
      dVector3 start, dir;
      dGeomRayGet(g2, start, dir);
      dBodyAddForceAtPos(rb->m_body,
                         100*dir[0],
                         100*dir[1],
                         100*dir[2],
                         contacts[0].geom.pos[0],
                         contacts[0].geom.pos[1],
                         contacts[0].geom.pos[2]);
    }
    return false;
  } else {
    Body* pb1, *pb2;
    int flags = 0;
    /* Geom bodies point to their parents. */
    if(o1->GetType() == Object::GEOM) {
      pb1 = static_cast<ModelBody::Geom*>(o1)->parent;
      flags |= static_cast<ModelBody::Geom*>(o1)->flags;
    } else pb1 = static_cast<Body*>(o1);
    if(o2->GetType() == Object::GEOM) {
      pb2 = static_cast<ModelBody::Geom*>(o2)->parent;
      flags |= static_cast<ModelBody::Geom*>(o2)->flags;
    } else pb2 = static_cast<Body*>(o2);

    if((pb1 && !pb1->OnCollision(pb2, flags)) || (pb2 && !pb2->OnCollision(pb1, flags))) return false;
  }
  return true;
}

static void nearCallback(void* data, dGeomID oO, dGeomID o1) {
  /* Create an array of dContact objects to hold the contact joints. */
  static const int MAX_CONTACTS = 100;
  dContact contact[MAX_CONTACTS];

  for(int i = 0; i < MAX_CONTACTS; i++) {
    contact[i].surface.mode       = dContactBounce;
    contact[i].surface.mu         = 0.8;
    contact[i].surface.mu2        = 0;
    contact[i].surface.bounce     = 0.1;
    contact[i].surface.bounce_vel = 0.1;
  }
  if(int numc = dCollide(oO, o1, MAX_CONTACTS, &contact[0].geom, sizeof(dContact))) {
    Object* po1 = static_cast<Object*>(dGeomGetData(oO));
    Object* po2 = static_cast<Object*>(dGeomGetData(o1));
    if(!_OnCollision(oO, o1, po1, po2, numc, contact)) return;
    /* Get the dynamics body for each geom. */
    dBodyID b1 = dGeomGetBody(oO);
    dBodyID b2 = dGeomGetBody(o1);
    /* 
     * To add contact point found to our joint group we call dJointCreateContact
     * which is just one of the many different types available.
     */
    for(int i = 0; i < numc; i++) {
      /*
       * dJointCreateContact needs to know which world and joint group to work
       * with as well as the dContact object itself.
       * It returns a new dJointID which we then use with dJointAttach to
       * finally create the temp contact joint between the two geom bodies.
       */
      dJointID c = dJointCreateContact(Space::world, _contactgroup, contact + i);
#if 0
      struct dContactGeom {
        dVector3  pos;    /* Constact position. */
        dVector3  normal; /* Normal vector. */
        dReal     depth;  /* Penetration depth. */
        dGeomId g1, g2;   /* The colliding geoms. */
      };
#endif

      dJointAttach(c, b1, b2);
    }
  }
}

void Space::CollideFrame(Frame* f) {
  dSpaceCollide(f->GetSpaceID(), NULL, &nearCallback);
  for(std::list<Frame*>::iterator i = f->m_children.begin(); i != f->m_children.end(); ++i) {
    CollideFrame(*i);
  }
}

void Space::ApplyGravity(void) {
  Body* lump = 0;
  /*
   * Gravity is applied when our frame contains an 'astroBody', ie a star or planet,
   * or when our frame contains a rotating frame which contains this body.
   */
  if(L3D::player->GetFrame()->m_astroBody) {
    lump = L3D::player->GetFrame()->m_astroBody;
  } else if(L3D::player->GetFrame()->m_sbody &&
      (L3D::player->GetFrame()->m_children.begin() !=
       L3D::player->GetFrame()->m_children.end())) {

    lump = (*L3D::player->GetFrame()->m_children.begin())->m_astroBody;
  }
  /* Just to the player and only in the most stupid way for the moment. */
  if(lump) {
    vector3d b1b2 = lump->GetPosition() - L3D::player->GetPosition();
    const double m1m2 = L3D::player->GetMass() * lump->GetMass();
    const double r = b1b2.Length();
    const double force = G*m1m2 / (r*r);
    b1b2.Normalize();
    b1b2 = b1b2 * force;
    dBodyAddForce(L3D::player->m_body, b1b2.x, b1b2.y, b1b2.z);
  }
}

void Space::TimeStep(float step) {
  ApplyGravity();

  CollideFrame(rootFrame);
  dWorldQuickStep(world, step);
  dJointGroupEmpty(_contactgroup);

  /* TODO: Does not need to be done this often. */
  UpdateFramesOfReference();
  MoveOrbitingObjectFrames(rootFrame);

  for(bodiesIter_t i = bodies.begin(); i != bodies.end(); ++i) {
    (*i)->TimeStepUpdate(step);
  }
  PruneCorpses();
}

void Space::PruneCorpses(void) {
  for(bodiesIter_t corpse = corpses.begin(); corpse != corpses.end(); ++corpse) {
    for(bodiesIter_t i = bodies.begin(); i != bodies.end(); i++)
      (*i)->NotifyDeath(*corpse);
    bodies.remove(*corpse);
    delete *corpse;
  }
  corpses.clear();
}

struct body_zsort_t {
  double dist;
  Body* b;
};

struct body_zsort_compare : public std::binary_function<body_zsort_t, body_zsort_t, bool> {
  bool operator()(body_zsort_t a, body_zsort_t b) { return a.dist > b.dist; }
};

void Space::Render(const Frame* cam_frame) {
  /* Simple z-sort. */
  body_zsort_t* bz = new body_zsort_t[bodies.size()];
  int idx = 0;
  for(std::list<Body*>::iterator i = bodies.begin(); i != bodies.end(); ++i) {
    vector3d toBody = (*i)->GetPositionRelTo(cam_frame);
    bz[idx].dist = toBody.Length();
    bz[idx].b = *i;
    idx++;
  }
  sort(bz, bz+bodies.size(), body_zsort_compare());
  
  /* Probably the right place for this when partitioning is done. */
  sbreSetDepthRange(L3D::GetScrWidth()*0.5f, 0.0f, 1.0f);
  
  for(unsigned int i = 0; i < bodies.size(); i++) {
    bz[i].b->Render(cam_frame);
  }
  delete [] bz;
}