#include <cmath>

#include "opengl.h"

#include "view.h"
#include "oct.h"
#include "material.h"

using namespace gl;

pass_data pass_depth     (0, DEPTH);
pass_data pass_postdepth (0, POSTDEPTH);

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;
}

inline void 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;
}

view::view ()
: gamma(1.0), nz_near (1.F), nz_far (2.F)
{
}

view::~view ()
{
}

void view::begin_occ_query (recv_occ_query &recv, void *id)
{
  occ_queries.push_back (oq_data (&recv, ::begin_occ_query (), id));
}

void view::end_occ_query ()
{
  ::end_occ_query ();
}

struct occ_query_material : material
{
  void vsh (view &ctx);
  void fsh (view &ctx);
};

static struct occ_query_material occ_query_material;

void occ_query_material::vsh (view &ctx)
{
  std_vsh ();
}

void occ_query_material::fsh (view &ctx)
{
  // nop
}

bool view::may_draw (const entity *e)
{
  if (drawn.find (e) != drawn.end ())
    return false;

  drawn.insert (e);
  return true;
}

visibility_base *visible::get_visibility (view &ctx)
{
  view::visibility_map::iterator i = ctx.vismap.find (this);
  visibility_base *vs;

  if (i == ctx.vismap.end ())
    {
      vs = new_visibility ();
      ctx.vismap.insert (view::visibility_map::value_type (this, vs));
    }
  else
    {
      vs = i->second;

      if (vs->generation != ctx.generation)
        {
          if (vs->generation + 1 != ctx.generation)
            clear_visibility (vs);

          vs->generation = ctx.generation;
        }
    }

  return vs;
}

void view::reset_projection ()
{
  renormalize (orig, p);

  glViewport (0, 0, w, h);

  glMatrixMode (GL_PROJECTION);

  GLdouble aspect = (GLdouble)w/h;
  GLdouble ftan = tanf (fov * GLfloat (.5 * M_PI / 180.));
  GLdouble ymax = ftan;
  GLdouble xmax = ymax * aspect;

  matrix perspective;
  {
    matrix &m = perspective;

    m(0,0) = 1.F / xmax; m(0,1) =          0; m(0,2) =               0; m(0,3) = 0;
    m(1,0) =          0; m(1,1) = 1.F / ymax; m(1,2) =               0; m(1,3) = 0;
    m(2,0) =          0; m(2,1) =          0; m(2,2) =  -1e10F / z_far; m(2,3) = 1;
    m(3,0) =          0; m(3,1) =          0; m(3,2) =              -1; m(3,3) = 0;

    glLoadMatrixf (perspective);
  }
  //glFrustum (-xmax, xmax, -ymax, ymax, z_near, z_far);

  glGetFloatv (GL_PROJECTION_MATRIX, perspective);

  perspfact = z_near / ymax * 0.5F * h;

  glMatrixMode (GL_MODELVIEW);
  glLoadIdentity ();
  matrix &m = projection;

  d = normalize (d);//D
  u = normalize (u);//D

  vec3 rz = -d;
  vec3 rx = cross (u, rz);
  vec3 ry = cross (rz, rx);

  m(0,0) = rx.x; m(0,1) = rx.y; m(0,2) = rx.z; m(0,3) = 0;
  m(1,0) = ry.x; m(1,1) = ry.y; m(1,2) = ry.z; m(1,3) = 0;
  m(2,0) = rz.x; m(2,1) = rz.y; m(2,2) = rz.z; m(2,3) = 0;
  m(3,0) =    0; m(3,1) =    0; m(3,2) =    0; m(3,3) = 1;

  diagfact = abs (rz.x) + abs (rz.y) + abs (rz.z);
  //printf ("diagfact = %f\n", diagfact);
  diagfact = sqrtf (3.);//D WHY???

  glMultMatrixf (m);
  
  glTranslatef (-p.x, -p.y, -p.z);

  glGetFloatv (GL_MODELVIEW_MATRIX, m);

  m = perspective * m;

  frustum.l = plane ( m(3,0) + m(0,0), m(3,1) + m(0,1), m(3,2) + m(0,2), m(3,3) + m(0,3) );
  frustum.r = plane ( m(3,0) - m(0,0), m(3,1) - m(0,1), m(3,2) - m(0,2), m(3,3) - m(0,3) );
  frustum.b = plane ( m(3,0) + m(1,0), m(3,1) + m(1,1), m(3,2) + m(1,2), m(3,3) + m(1,3) );
  frustum.t = plane ( m(3,0) - m(1,0), m(3,1) - m(1,1), m(3,2) - m(1,2), m(3,3) - m(1,3) );
  frustum.n = plane ( m(3,0) + m(2,0), m(3,1) + m(2,1), m(3,2) + m(2,2), m(3,3) + m(2,3) );
  frustum.f = plane ( m(3,0) - m(2,0), m(3,1) - m(2,1), m(3,2) - m(2,2), m(3,3) - m(2,3) );

#if 0
  {
    GLdouble frustlen = z_far - z_near;
    GLdouble fheight  = frustlen * ftan;
    GLdouble fwidth   = fheight * w / h;
    point half (0, 0, z_near + frustlen * .5);
    point corner (fwidth, fheight, frustlen);
    
    frustum.s = sphere (p + d * (.5 * frustlen), length (corner - half));
  }
#endif

  {
    GLdouble depth = h / ftan;

    frustum.c = cone (p, d, atan (sqrt (GLdouble (w * w + h * h)) * ftan / h));
  }
}

void view::begin ()
{
  generation++;

  vislist.clear ();

  z_near = max (nz_near, 1.F);
  z_far = max (nz_far, z_near * 2.F);
  c_far = nc_far;

  reset_projection ();

  nz_near = 100.;
  nc_far = nz_far = 1.F;

  first_lighted = false;
}

void view::end ()
{
  vislist.clear ();
}

#define DEPTH_OFFSET (1. / (GLdouble)(1L << 16))

void view::render (pass_data &pass)
{
  this->pass = &pass;

  stat1 = stat2 = 0; //D

  switch (pass.type)
    {
      case DEPTH:
        glColorMask (1, 1, 1, 1);
        glDepthMask (1);
        glDisable (GL_BLEND);

        //glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
        glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

        //glEnable (GL_STENCIL_TEST); // for depth-passes
        //glStencilOp (GL_KEEP, GL_KEEP, GL_REPLACE);
        //glStencilFunc (GL_LESS, 1, 255);

        //glEnable (GL_POLYGON_OFFSET_FILL);
        //glPolygonOffset (0, 5);
        glEnable (GL_CULL_FACE);
        glDisable (GL_MINMAX);
        glDepthRange (DEPTH_OFFSET, 1.);
        glDepthFunc (GL_LESS);
        glEnable (GL_DEPTH_TEST);
        glColorMask (0, 0, 0, 0);
        glDisable (GL_DEPTH_CLAMP_NV);

        world.detect_visibility (*this);

        for (vector<octant *>::iterator i = vislist.begin (); i != vislist.end (); ++i)
          (*i)->draw_depth (*this);

        if (pass.type == DEPTH)
          printf ("fps %f NF %f:%f vis %d,%d (%d,%d) CAM (%ld,%ld,%ld)\n",
                  timer.fps, z_near, z_far, vislist.size (), drawn.size (), stat1, stat2, orig.x, orig.y, orig.z);//D

        break;

      case POSTDEPTH:
        glDepthRange (0., 1. - DEPTH_OFFSET);
        glDepthFunc (GL_LESS);
        glColorMask (0, 0, 0, 0);
        glDepthMask (0);
        glEnable (GL_DEPTH_CLAMP_NV);
        glDisable (GL_STENCIL_TEST);
        glDisable (GL_CULL_FACE);
       
        occ_query_material.enable (*this);

        // check occlusion queries
        for (vector<oq_data>::iterator i = occ_queries.begin (); i != occ_queries.end (); ++i)
          {
            occ_query oq(*this, i->data, ::occ_query_result (i->id));
            i->recv->event (oq);
          }

        occ_query_material.disable (*this);

        occ_queries.clear ();

        for (vector<octant *>::iterator i = vislist.begin (); i != vislist.end (); ++i)
          (*i)->draw_postdepth (*this);

        first_lighted = true;

        break;

      case LIGHTED:
        if (first_lighted)
          glDisable (GL_BLEND);
        else
          {
            glBlendFunc (GL_ONE, GL_ONE);
            glEnable (GL_BLEND);
          }

        //glClear (GL_STENCIL_BUFFER_BIT);
        //glEnable (GL_STENCIL_TEST);
        glEnable (GL_CULL_FACE);
        glEnable (GL_MINMAX);
        glDepthRange (0., 1. - DEPTH_OFFSET);
        glDepthFunc (GL_LESS);
        glColorMask (1, 1, 1, 1);
        glDepthMask (0);
        glDisable (GL_DEPTH_CLAMP_NV);

        for (vector<octant *>::iterator i = vislist.begin (); i != vislist.end (); ++i)
          (*i)->draw_lighted (*this);

        first_lighted = false;

        break;
    }
  
  drawn.clear ();
}

void light::enable ()
{
  lightpos->set (p);
}

void light::disable ()
{
}

static shader::varying_1f camdist;
static shader::varying_3f lightvec;

void linear_light::vsh ()
{
  using namespace shader::compile;

  lightvec = xyz (lightpos - model_view_matrix * vin.vertex);
  camdist = max (1 - length (lightvec) / radius, 0);

  fsh ();
}

void linear_light::fsh ()
{
  using namespace shader::compile;

  sh_lightvec = lightvec;
  sh_colour = float3 (c.r / 255.F, c.g / 255.F, c.b / 255.F) * (min (intensity * camdist * 100.F + 0.9F, 1.F));
}