#include <cstdlib>

#include <vector>

using namespace std;

#define GL_GLEXT_PROTOTYPES
#include <GL/gl.h>

#include "oct.h"
#include "view.h"
#include "entity.h"

vector<GLuint> occ_query_objects;

static GLuint begin_occ_query ()
{
  GLuint id;

  if (occ_query_objects.size ())
    {
      id = *(occ_query_objects.end () - 1);
      occ_query_objects.pop_back ();
    }
  else
    glGenQueries (1, &id);

  glBeginQuery (GL_SAMPLES_PASSED, id);
  return id;
}

#define end_occ_query() glEndQuery (GL_SAMPLES_PASSED);

static GLuint occ_query_result (GLuint id)
{
  GLuint count;

  glGetQueryObjectuiv (id, GL_QUERY_RESULT, &count);
  occ_query_objects.push_back (id);

  return count;
}

octant world(0, sector (SOFFS_MIN, SOFFS_MIN, SOFFS_MIN), MAXEXTENT);

octant::octant (octant *parent, const sector &orig, uoffs extent)
: parent(parent), orig(orig), extent(extent)
{
  for (fill = 8; fill--; )
    sub[fill] = 0;
}

octant::~octant ()
{
  for (fill = 8; fill--; )
    delete sub[fill];
}

static bool overlap (const sector &o1, uoffs ea, const box &bbox)
{
  sector a2, b2;

  ea /= 2;

  a2.x = o1.x + ea;
  a2.y = o1.y + ea;
  a2.z = o1.z + ea;
  
  b2.x = (bbox.a.x + bbox.b.x) / 2;
  b2.y = (bbox.a.y + bbox.b.y) / 2;
  b2.z = (bbox.a.z + bbox.b.z) / 2;

  return abs (a2.x - b2.x) <= ea + (bbox.b.x - bbox.a.x)
      && abs (a2.y - b2.y) <= ea + (bbox.b.y - bbox.a.y)
      && abs (a2.z - b2.z) <= ea + (bbox.b.z - bbox.a.z);
}

void octant::add (entity_base *e)
{
  box bbox = translate (e->bbox, e->orig, sector (0, 0, 0));

  uoffs size = max (abs (bbox.b.x - bbox.a.x),
               max (abs (bbox.b.y - bbox.a.y),
                    abs (bbox.b.z - bbox.a.z)));

  if (overlap (orig, extent, bbox))
    {
      uoffs extent2 = extent / 2;

      if (size > extent2 || !extent2)
        {
          push_back (e);
          e->o.push_back (this);
          return;
        }

      for (int i = 8; i--; )
        {
          sector s = orig;
          s.offset (i, extent2);
          if (overlap (s, extent2, bbox))
            {
              if (!sub[i])
                sub[i] = new octant (this, s, extent2);

              sub[i]->add (e);
            }
        }
    }
}

void octant::remove (entity_base *e)
{
}

void octant::draw (draw_context &ctx)
{
  visibility_state &vs = ctx.vismap[this];

  if (vs.generation != ctx.generation)
    vs.visibility = visibility_state::UNKNOWN;

  const sector &cam = ctx.v.orig;
#if 0
  if (cam.x >= orig.x && cam.x <= orig.x + extent
      && cam.y >= orig.y && cam.y <= orig.y + extent
      && cam.z >= orig.z && cam.z <= orig.z + extent)
    {
      vs.visibility = visibility_state::PARTIAL;
      vs.generation = ctx.generation;
    }
  else
#endif
    {
      //printf ("OCTANT %d,%d,%d+%d\n", orig.x, orig.y, orig.z, extent);
      point center (
        orig.x + (soffs)extent / 2 - cam.x ,
        orig.y + (soffs)extent / 2 - cam.y ,
        orig.z + (soffs)extent / 2 - cam.z 
      );

      GLfloat dia = (0.5 * sqrtf (3))*(GLfloat)extent;

#if 0
      printf ("DISTANCE %f,%f,%f TO near: %f\n",
          center.x, center.y, center.z,
          ctx.frustum.n.distance (center)
          );
#endif
#if 0
      printf ("DISTANCE %f,%f,%f TO far: %f\n",
          center.x, center.y, center.z,
          ctx.frustum.f.distance (center)
          );
#endif
#if 1
      if (ctx.frustum.t.distance (center) < -dia) return;
      if (ctx.frustum.b.distance (center) < -dia) return;
      if (ctx.frustum.l.distance (center) < -dia) return;
      if (ctx.frustum.r.distance (center) < -dia) return;
      if (ctx.frustum.n.distance (center) < -dia) return;
      if (ctx.frustum.f.distance (center) < -dia) return;
#endif

    }

#if 1
  glBegin (GL_LINES);
  sector s = orig;
  s.x -= ctx.v.orig.x;
  s.y -= ctx.v.orig.y;
  s.z -= ctx.v.orig.z;
  vec3 clr(0, 0.8, 0);
  glMaterialfv (GL_FRONT_AND_BACK, GL_DIFFUSE, (const GLfloat*)&clr);

  for (int i = 8; i--; )
    for (int ji = 3; ji--; )
      {
        int j = i | (1 << ji);
        if (i != j)
          {
            glVertex3i (s.x + !!(i & 1) * extent,
                        s.y + !!(i & 2) * extent,
                        s.z + !!(i & 4) * extent);
            glVertex3i (s.x + !!(j & 1) * extent,
                        s.y + !!(j & 2) * extent,
                        s.z + !!(j & 4) * extent);
          }
      }
  
  glEnd ();
  glDisable(GL_COLOR_MATERIAL);
#endif

#if 0
  if (vs.visibility == visibility_state::PARTIAL
      && vs.generation == ctx.generation)
#endif
    {
      for (iterator i = end (); i-- != begin (); )
#if 0
        printf ("draw %p %d,%d,%d     (%d,%d,%d - %d,%d,%d)\n", *i,
            (*i)->orig.x,
            (*i)->orig.y,
            (*i)->orig.z,
            (*i)->bbox.a.x,
            (*i)->bbox.a.y,
            (*i)->bbox.a.z,
            (*i)->bbox.b.x,
            (*i)->bbox.b.y,
            (*i)->bbox.b.z
            ),
#endif
        (*i)->display (ctx);

      // node to start with
      unsigned char si = ctx.v.d.x < 0 ? 1 : 0
                       | ctx.v.d.y < 0 ? 2 : 0
                       | ctx.v.d.z < 0 ? 4 : 0;

      // bit-toggle to find next child for front-to-back order
      static unsigned char next[8]
        = { 0,  0^1, 1^2, 2^4,  4^3, 3^5, 5^6,  6^7 };

      for (int i = 0; i < 8; i++)
        {
          si ^= next[i];

          if (sub[si])
            sub[si]->draw (ctx);
        }
    }

  vs.generation = ctx.generation;
}