/*************************************************************************
 *                                                                       *
 * Open Dynamics Engine, Copyright (C) 2001-2003 Russell L. Smith.       *
 * All rights reserved.  Email: russ@q12.org   Web: www.q12.org          *
 *                                                                       *
 * This library is free software; you can redistribute it and/or         *
 * modify it under the terms of EITHER:                                  *
 *   (1) The GNU Lesser General Public License as published by the Free  *
 *       Software Foundation; either version 2.1 of the License, or (at  *
 *       your option) any later version. The text of the GNU Lesser      *
 *       General Public License is included with this library in the     *
 *       file LICENSE.TXT.                                               *
 *   (2) The BSD-style license that is included with this library in     *
 *       the file LICENSE-BSD.TXT.                                       *
 *                                                                       *
 * This library is distributed in the hope that it will be useful,       *
 * but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the files    *
 * LICENSE.TXT and LICENSE-BSD.TXT for more details.                     *
 *                                                                       *
 *************************************************************************/

/*

spaces

*/

#include <ode/common.h>
#include <ode/matrix.h>
#include <ode/collision_space.h>
#include <ode/collision.h>
#include "collision_kernel.h"

#include "collision_space_internal.h"

//****************************************************************************
// make the geom dirty by setting the GEOM_DIRTY and GEOM_BAD_AABB flags
// and moving it to the front of the space's list. all the parents of a
// dirty geom also become dirty.

void dGeomMoved (dxGeom *geom)
{
  dAASSERT (geom);
  
  // from the bottom of the space heirarchy up, process all clean geoms
  // turning them into dirty geoms.
  dxSpace *parent = geom->parent_space;

  while (parent && (geom->gflags & GEOM_DIRTY)==0) {
    CHECK_NOT_LOCKED (parent);
    geom->gflags |= GEOM_DIRTY | GEOM_AABB_BAD;
    parent->dirty (geom);
    geom = parent;
    parent = parent->parent_space;
  }

  // all the remaining dirty geoms must have their AABB_BAD flags set, to
  // ensure that their AABBs get recomputed
  while (geom) {
    geom->gflags |= GEOM_DIRTY | GEOM_AABB_BAD;
    CHECK_NOT_LOCKED (geom->parent_space);
    geom = geom->parent_space;
  }
}

#define GEOM_ENABLED(g) ((g)->gflags & GEOM_ENABLED)

//****************************************************************************
// dxSpace

dxSpace::dxSpace (dSpaceID _space) : dxGeom (_space,0)
{
  count = 0;
  first = 0;
  cleanup = 1;
  current_index = 0;
  current_geom = 0;
  lock_count = 0;
}


dxSpace::~dxSpace()
{
  CHECK_NOT_LOCKED (this);
  if (cleanup) {
    // note that destroying each geom will call remove()
    dxGeom *g,*n;
    for (g = first; g; g=n) {
      n = g->next;
      dGeomDestroy (g);
    }
  }
  else {
    dxGeom *g,*n;
    for (g = first; g; g=n) {
      n = g->next;
      remove (g);
    }
  }
}


void dxSpace::computeAABB()
{
  if (first) {
    int i;
    dReal a[6];
    a[0] = dInfinity;
    a[1] = -dInfinity;
    a[2] = dInfinity;
    a[3] = -dInfinity;
    a[4] = dInfinity;
    a[5] = -dInfinity;
    for (dxGeom *g=first; g; g=g->next) {
      g->recomputeAABB();
      for (i=0; i<6; i += 2) if (g->aabb[i] < a[i]) a[i] = g->aabb[i];
      for (i=1; i<6; i += 2) if (g->aabb[i] > a[i]) a[i] = g->aabb[i];
    }
    memcpy(aabb,a,6*sizeof(dReal));
  }
  else {
    dSetZero (aabb,6);
  }
}


void dxSpace::setCleanup (int mode)
{
  cleanup = (mode != 0);
}


int dxSpace::getCleanup()
{
  return cleanup;
}


int dxSpace::query (dxGeom *geom)
{
  dAASSERT (geom);
  return (geom->parent_space == this);
}


int dxSpace::getNumGeoms()
{
  return count;
}


// the dirty geoms are numbered 0..k, the clean geoms are numbered k+1..count-1

dxGeom *dxSpace::getGeom (int i)
{
  dUASSERT (i >= 0 && i < count,"index out of range");
  if (current_geom && current_index == i-1) {
    current_geom = current_geom->next;
    current_index = i;
    return current_geom;
  }
  else {
    dxGeom *g=first;
    for (int j=0; j<i; j++) {
      if (g) g = g->next; else return 0;
    }
    current_geom = g;
    current_index = i;
    return g;
  }
}


void dxSpace::add (dxGeom *geom)
{
  CHECK_NOT_LOCKED (this);
  dAASSERT (geom);
  dUASSERT (geom->parent_space == 0 && geom->next == 0,
	    "geom is already in a space");

  // add
  geom->parent_space = this;
  geom->spaceAdd (&first);
  count++;

  // enumerator has been invalidated
  current_geom = 0;

  // new geoms are added to the front of the list and are always
  // considered to be dirty. as a consequence, this space and all its
  // parents are dirty too.
  geom->gflags |= GEOM_DIRTY | GEOM_AABB_BAD;
  dGeomMoved (this);
}


void dxSpace::remove (dxGeom *geom)
{
  CHECK_NOT_LOCKED (this);
  dAASSERT (geom);
  dUASSERT (geom->parent_space == this,"object is not in this space");

  // remove
  geom->spaceRemove();
  count--;

  // safeguard
  geom->next = 0;
  geom->tome = 0;
  geom->parent_space = 0;

  // enumerator has been invalidated
  current_geom = 0;

  // the bounding box of this space (and that of all the parents) may have
  // changed as a consequence of the removal.
  dGeomMoved (this);
}


void dxSpace::dirty (dxGeom *geom)
{
  geom->spaceRemove();
  geom->spaceAdd (&first);
}

//****************************************************************************
// simple space - reports all n^2 object intersections

struct dxSimpleSpace : public dxSpace {
  dxSimpleSpace (dSpaceID _space);
  void cleanGeoms();
  void collide (void *data, dNearCallback *callback);
  void collide2 (void *data, dxGeom *geom, dNearCallback *callback);
};


dxSimpleSpace::dxSimpleSpace (dSpaceID _space) : dxSpace (_space)
{
  type = dSimpleSpaceClass;
}


void dxSimpleSpace::cleanGeoms()
{
  // compute the AABBs of all dirty geoms, and clear the dirty flags
  lock_count++;
  for (dxGeom *g=first; g && (g->gflags & GEOM_DIRTY); g=g->next) {
    if (IS_SPACE(g)) {
      ((dxSpace*)g)->cleanGeoms();
    }
    g->recomputeAABB();
    g->gflags &= (~(GEOM_DIRTY|GEOM_AABB_BAD));
  }
  lock_count--;
}


void dxSimpleSpace::collide (void *data, dNearCallback *callback)
{
  dAASSERT (callback);

  lock_count++;
  cleanGeoms();

  // intersect all bounding boxes
  for (dxGeom *g1=first; g1; g1=g1->next) {
    if (GEOM_ENABLED(g1)){
      for (dxGeom *g2=g1->next; g2; g2=g2->next) {
	if (GEOM_ENABLED(g2)){
	  collideAABBs (g1,g2,data,callback);
	}
      }
    }
  }

  lock_count--;
}


void dxSimpleSpace::collide2 (void *data, dxGeom *geom,
			      dNearCallback *callback)
{
  dAASSERT (geom && callback);

  lock_count++;
  cleanGeoms();
  geom->recomputeAABB();

  // intersect bounding boxes
  for (dxGeom *g=first; g; g=g->next) {
    if (GEOM_ENABLED(g)){
      collideAABBs (g,geom,data,callback);
    }
  }

  lock_count--;
}

//****************************************************************************
// utility stuff for hash table space

// kind of silly, but oh well...
#define MAXINT ((int)((((unsigned int)(-1)) << 1) >> 1))


// prime[i] is the largest prime smaller than 2^i
#define NUM_PRIMES 31
static long int prime[NUM_PRIMES] = {1L,2L,3L,7L,13L,31L,61L,127L,251L,509L,
  1021L,2039L,4093L,8191L,16381L,32749L,65521L,131071L,262139L,
  524287L,1048573L,2097143L,4194301L,8388593L,16777213L,33554393L,
  67108859L,134217689L,268435399L,536870909L,1073741789L};


// an axis aligned bounding box in the hash table
struct dxAABB {
  dxAABB *next;		// next in the list of all AABBs
  int level;		// the level this is stored in (cell size = 2^level)
  int dbounds[6];	// AABB bounds, discretized to cell size
  dxGeom *geom;		// corresponding geometry object (AABB stored here)
  int index;		// index of this AABB, starting from 0
};


// a hash table node that represents an AABB that intersects a particular cell
// at a particular level
struct Node {
  Node *next;		// next node in hash table collision list, 0 if none
  int x,y,z;		// cell position in space, discretized to cell size
  dxAABB *aabb;		// axis aligned bounding box that intersects this cell
};


// return the `level' of an AABB. the AABB will be put into cells at this
// level - the cell size will be 2^level. the level is chosen to be the
// smallest value such that the AABB occupies no more than 8 cells, regardless
// of its placement. this means that:
//	size/2 < q <= size
// where q is the maximum AABB dimension.

static int findLevel (dReal bounds[6])
{
  // compute q
  dReal q,q2;
  q = bounds[1] - bounds[0];	// x bounds
  q2 = bounds[3] - bounds[2];	// y bounds
  if (q2 > q) q = q2;
  q2 = bounds[5] - bounds[4];	// z bounds
  if (q2 > q) q = q2;

  if (q == dInfinity || q == -dInfinity) return MAXINT;

  // find level such that 0.5 * 2^level < q <= 2^level
  int level;
  frexp (q,&level);	// q = (0.5 .. 1.0) * 2^level (definition of frexp)
  return level;
}


// find a virtual memory address for a cell at the given level and x,y,z
// position.
// @@@ currently this is not very sophisticated, e.g. the scaling
// factors could be better designed to avoid collisions, and they should
// probably depend on the hash table physical size.

static unsigned long getVirtualAddress (int level, int x, int y, int z)
{
  return level*1000 + x*100 + y*10 + z;
}

//****************************************************************************
// hash space

struct dxHashSpace : public dxSpace {
  int global_minlevel;	// smallest hash table level to put AABBs in
  int global_maxlevel;	// objects that need a level larger than this will be
			// put in a "big objects" list instead of a hash table

  dxHashSpace (dSpaceID _space);
  void setLevels (int minlevel, int maxlevel);
  void cleanGeoms();
  void collide (void *data, dNearCallback *callback);
  void collide2 (void *data, dxGeom *geom, dNearCallback *callback);
};


dxHashSpace::dxHashSpace (dSpaceID _space) : dxSpace (_space)
{
  type = dHashSpaceClass;
  global_minlevel = -3;
  global_maxlevel = 10;
}


void dxHashSpace::setLevels (int minlevel, int maxlevel)
{
  dAASSERT (minlevel <= maxlevel);
  global_minlevel = minlevel;
  global_maxlevel = maxlevel;
}


void dxHashSpace::cleanGeoms()
{
  // compute the AABBs of all dirty geoms, and clear the dirty flags
  lock_count++;
  for (dxGeom *g=first; g && (g->gflags & GEOM_DIRTY); g=g->next) {
    if (IS_SPACE(g)) {
      ((dxSpace*)g)->cleanGeoms();
    }
    g->recomputeAABB();
    g->gflags &= (~(GEOM_DIRTY|GEOM_AABB_BAD));
  }
  lock_count--;
}


void dxHashSpace::collide (void *data, dNearCallback *callback)
{
  dAASSERT(this && callback);
  dxGeom *geom;
  dxAABB *aabb;
  int i,maxlevel;

  // 0 or 1 geoms can't collide with anything
  if (count < 2) return;

  lock_count++;
  cleanGeoms();

  // create a list of auxiliary information for all geom axis aligned bounding
  // boxes. set the level for all AABBs. put AABBs larger than the space's
  // global_maxlevel in the big_boxes list, check everything else against
  // that list at the end. for AABBs that are not too big, record the maximum
  // level that we need.

  int n = 0;			// number of AABBs in main list
  dxAABB *first_aabb = 0;	// list of AABBs in hash table
  dxAABB *big_boxes = 0;	// list of AABBs too big for hash table
  maxlevel = global_minlevel - 1;
  for (geom = first; geom; geom=geom->next) {
    if (!GEOM_ENABLED(geom)){
      continue;
    }
    dxAABB *aabb = (dxAABB*) ALLOCA (sizeof(dxAABB));
    aabb->geom = geom;
    // compute level, but prevent cells from getting too small
    int level = findLevel (geom->aabb);
    if (level < global_minlevel) level = global_minlevel;
    if (level <= global_maxlevel) {
      // aabb goes in main list
      aabb->next = first_aabb;
      first_aabb = aabb;
      aabb->level = level;
      if (level > maxlevel) maxlevel = level;
      // cellsize = 2^level
      dReal cellsize = (dReal) ldexp (1.0,level);
      // discretize AABB position to cell size
      for (i=0; i < 6; i++) aabb->dbounds[i] = (int)
			      floor (geom->aabb[i]/cellsize);
      // set AABB index
      aabb->index = n;
      n++;
    }
    else {
      // aabb is too big, put it in the big_boxes list. we don't care about
      // setting level, dbounds, index, or the maxlevel
      aabb->next = big_boxes;
      big_boxes = aabb;
    }
  }

  // for `n' objects, an n*n array of bits is used to record if those objects
  // have been intersection-tested against each other yet. this array can
  // grow large with high n, but oh well...
  int tested_rowsize = (n+7) >> 3;	// number of bytes needed for n bits
  unsigned char *tested = (unsigned char *) alloca (n * tested_rowsize);
  memset (tested,0,n * tested_rowsize);

  // create a hash table to store all AABBs. each AABB may take up to 8 cells.
  // we use chaining to resolve collisions, but we use a relatively large table
  // to reduce the chance of collisions.

  // compute hash table size sz to be a prime > 8*n
  for (i=0; i<NUM_PRIMES; i++) {
    if (prime[i] >= (8*n)) break;
  }
  if (i >= NUM_PRIMES) i = NUM_PRIMES-1;	// probably pointless
  int sz = prime[i];

  // allocate and initialize hash table node pointers
  Node **table = (Node **) ALLOCA (sizeof(Node*) * sz);
  for (i=0; i<sz; i++) table[i] = 0;

  // add each AABB to the hash table (may need to add it to up to 8 cells)
  for (aabb=first_aabb; aabb; aabb=aabb->next) {
    int *dbounds = aabb->dbounds;
    for (int xi = dbounds[0]; xi <= dbounds[1]; xi++) {
      for (int yi = dbounds[2]; yi <= dbounds[3]; yi++) {
	for (int zi = dbounds[4]; zi <= dbounds[5]; zi++) {
	  // get the hash index
	  unsigned long hi = getVirtualAddress (aabb->level,xi,yi,zi) % sz;
	  // add a new node to the hash table
	  Node *node = (Node*) alloca (sizeof (Node));
	  node->x = xi;
	  node->y = yi;
	  node->z = zi;
	  node->aabb = aabb;
	  node->next = table[hi];
	  table[hi] = node;
	}
      }
    }
  }

  // now that all AABBs are loaded into the hash table, we do the actual
  // collision detection. for all AABBs, check for other AABBs in the
  // same cells for collisions, and then check for other AABBs in all
  // intersecting higher level cells.

  int db[6];			// discrete bounds at current level
  for (aabb=first_aabb; aabb; aabb=aabb->next) {
    // we are searching for collisions with aabb
    for (i=0; i<6; i++) db[i] = aabb->dbounds[i];
    for (int level = aabb->level; level <= maxlevel; level++) {
      for (int xi = db[0]; xi <= db[1]; xi++) {
	for (int yi = db[2]; yi <= db[3]; yi++) {
	  for (int zi = db[4]; zi <= db[5]; zi++) {
	    // get the hash index
	    unsigned long hi = getVirtualAddress (level,xi,yi,zi) % sz;
	    // search all nodes at this index
	    Node *node;
	    for (node = table[hi]; node; node=node->next) {
	      // node points to an AABB that may intersect aabb
	      if (node->aabb == aabb) continue;
	      if (node->aabb->level == level &&
		  node->x == xi && node->y == yi && node->z == zi) {
		// see if aabb and node->aabb have already been tested
		// against each other
		unsigned char mask;
		if (aabb->index <= node->aabb->index) {
		  i = (aabb->index * tested_rowsize)+(node->aabb->index >> 3);
		  mask = 1 << (node->aabb->index & 7);
		}
		else {
		  i = (node->aabb->index * tested_rowsize)+(aabb->index >> 3);
		  mask = 1 << (aabb->index & 7);
		}
		dIASSERT (i >= 0 && i < (tested_rowsize*n));
		if ((tested[i] & mask)==0) {
		  collideAABBs (aabb->geom,node->aabb->geom,data,callback);
		}
		tested[i] |= mask;
	      }
	    }
	  }
	}
      }
      // get the discrete bounds for the next level up
      for (i=0; i<6; i++) db[i] >>= 1;
    }
  }

  // every AABB in the normal list must now be intersected against every
  // AABB in the big_boxes list. so let's hope there are not too many objects
  // in the big_boxes list.
  for (aabb=first_aabb; aabb; aabb=aabb->next) {
    for (dxAABB *aabb2=big_boxes; aabb2; aabb2=aabb2->next) {
      collideAABBs (aabb->geom,aabb2->geom,data,callback);
    }
  }

  // intersected all AABBs in the big_boxes list together
  for (aabb=big_boxes; aabb; aabb=aabb->next) {
    for (dxAABB *aabb2=aabb->next; aabb2; aabb2=aabb2->next) {
      collideAABBs (aabb->geom,aabb2->geom,data,callback);
    }
  }

  lock_count--;
}


void dxHashSpace::collide2 (void *data, dxGeom *geom,
			    dNearCallback *callback)
{
  //@@@
  dDebug (0,"dxHashSpace::collide2() not yet implemented");
}

//****************************************************************************
// space functions

dxSpace *dSimpleSpaceCreate (dxSpace *space)
{
  return new dxSimpleSpace (space);
}


dxSpace *dHashSpaceCreate (dxSpace *space)
{
  return new dxHashSpace (space);
}


void dHashSpaceSetLevels (dxSpace *space, int minlevel, int maxlevel)
{
  dAASSERT (space);
  dUASSERT (minlevel <= maxlevel,"must have minlevel <= maxlevel");
  dUASSERT (space->type == dHashSpaceClass,"argument must be a hash space");
  dxHashSpace *hspace = (dxHashSpace*) space;
  hspace->setLevels (minlevel,maxlevel);
}


void dSpaceDestroy (dxSpace *space)
{
  dAASSERT (space);
  dUASSERT (dGeomIsSpace(space),"argument not a space");
  dGeomDestroy (space);
}


void dSpaceSetCleanup (dxSpace *space, int mode)
{
  dAASSERT (space);
  dUASSERT (dGeomIsSpace(space),"argument not a space");
  space->setCleanup (mode);
}


int dSpaceGetCleanup (dxSpace *space)
{
  dAASSERT (space);
  dUASSERT (dGeomIsSpace(space),"argument not a space");
  return space->getCleanup();
}


void dSpaceAdd (dxSpace *space, dxGeom *g)
{
  dAASSERT (space);
  dUASSERT (dGeomIsSpace(space),"argument not a space");
  CHECK_NOT_LOCKED (space);
  space->add (g);
}


void dSpaceRemove (dxSpace *space, dxGeom *g)
{
  dAASSERT (space);
  dUASSERT (dGeomIsSpace(space),"argument not a space");
  CHECK_NOT_LOCKED (space);
  space->remove (g);
}


int dSpaceQuery (dxSpace *space, dxGeom *g)
{
  dAASSERT (space);
  dUASSERT (dGeomIsSpace(space),"argument not a space");
  return space->query (g);
}


int dSpaceGetNumGeoms (dxSpace *space)
{
  dAASSERT (space);
  dUASSERT (dGeomIsSpace(space),"argument not a space");
  return space->getNumGeoms();
}


dGeomID dSpaceGetGeom (dxSpace *space, int i)
{
  dAASSERT (space);
  dUASSERT (dGeomIsSpace(space),"argument not a space");
  return space->getGeom (i);
}


void dSpaceCollide (dxSpace *space, void *data, dNearCallback *callback)
{
  dAASSERT (space && callback);
  dUASSERT (dGeomIsSpace(space),"argument not a space");
  space->collide (data,callback);
}


void dSpaceCollide2 (dxGeom *g1, dxGeom *g2, void *data,
		     dNearCallback *callback)
{
  dAASSERT (g1 && g2 && callback);
  dxSpace *s1,*s2;

  // see if either geom is a space
  if (IS_SPACE(g1)) s1 = (dxSpace*) g1; else s1 = 0;
  if (IS_SPACE(g2)) s2 = (dxSpace*) g2; else s2 = 0;

  // handle the four space/geom cases
  if (s1) {
    if (s2) {
      // g1 and g2 are spaces.
      if (s1==s2) {
	// collide a space with itself --> interior collision
	s1->collide (data,callback);
      }
      else {
	// iterate through the space that has the fewest geoms, calling
	// collide2 in the other space for each one.
	if (s1->count < s2->count) {
	  for (dxGeom *g = s1->first; g; g=g->next) {
	    s2->collide2 (data,g,callback);
	  }
	}
	else {
	  for (dxGeom *g = s2->first; g; g=g->next) {
	    s1->collide2 (data,g,callback);
	  }
	}
      }
    }
    else {
      // g1 is a space, g2 is a geom
      s1->collide2 (data,g2,callback);
    }
  }
  else {
    if (s2) {
      // g1 is a geom, g2 is a space
      s2->collide2 (data,g1,callback);
    }
    else {
      // g1 and g2 are geoms, call the callback directly
      callback (data,g1,g2);
    }
  }
}
