#ifndef UTIL_H
#define UTIL_H

#include <cmath>
#include <cfloat>
#include <cstdlib>
#include <vector>
#include <string>

#include "opengl.h"

#include <SDL/SDL_image.h>

using namespace std;

extern CGcontext cgc;
extern CGprogram vsh;
extern CGprogram fsh;
extern CGparameter mv, mvp, lightpos;
extern CGprofile vsh_profile, fsh_profile;

typedef long long soffs; // 32 bit
typedef unsigned long long uoffs;
#define OFFS_BITS 63
#define SOFFS_MIN (soffs)-(1LL << (OFFS_BITS - 2))
#define SOFFS_MAX (soffs)+(1LL << (OFFS_BITS - 2))
#define MAXEXTENT (1ULL << (OFFS_BITS - 1))

#define ABS(n) ((n) < 0 ? -(n) : (n))

struct sector
{
  soffs x, y, z;

  sector (soffs x, soffs y, soffs z) : x(x), y(y), z(z) { };
  sector (soffs xyz = 0) : x(xyz), y(xyz), z(xyz) { };

  void offset (int subindex, uoffs extent)
  {
    if (subindex & 1) x += extent;
    if (subindex & 2) y += extent;
    if (subindex & 4) z += extent;
  }
};

inline sector operator +(const sector &a, const sector &b)
{
  return sector (a.x + b.x, a.y + b.y, a.z + b.z);
}

inline sector operator -(const sector &a, const sector &b)
{
  return sector (a.x - b.x, a.y - b.y, a.z - b.z);
}

inline sector operator /(const sector &a, soffs b)
{
  return sector (a.x / b, a.y / b, a.z / b);
}

inline sector operator >>(const sector &a, unsigned int b)
{
  return sector (a.x >> b, a.y >> b, a.z >> b);
}

inline bool operator <=(const sector &a, const sector &b)
{
  return a.x <= b.x && a.y <= b.y && a.z <= b.z;
}

inline soffs max (const sector &a)
{
  return max (a.x, max (a.y, a.z));
}

inline sector translate (const sector &p, const sector &src, const sector &dst)
{
  return p + (dst - src);
}

inline sector abs (const sector &s)
{
  return sector (ABS (s.x), ABS (s.y), ABS (s.z));
}

struct vec3
{
  GLfloat x, y, z;
  vec3 () { };
  vec3 (GLfloat s) : x(s), y(s), z(s) { };
  vec3 (GLfloat x, GLfloat y, GLfloat z) : x(x), y(y), z(z) { };
  vec3 (const sector &s) : x(s.x), y(s.y), z(s.z) { };

  const vec3 operator -() const
  { return vec3 (-x, -y, -z); }
};

const vec3 normalize (const vec3 &v);
const vec3 cross (const vec3 &a, const vec3 &b);

inline const vec3 operator *(const vec3 &a, GLfloat s)
{
  return vec3 (a.x * s, a.y * s, a.z * s);
}

inline const vec3 operator +(const vec3 &a, const vec3 &b)
{
  return vec3 (a.x + b.x, a.y + b.y, a.z + b.z);
}

inline const vec3 operator -(const vec3 &a, const vec3 &b)
{
  return vec3 (a.x - b.x, a.y - b.y, a.z - b.z);
}

inline GLfloat dot (const vec3 &a, const vec3 &b)
{
  return a.x * b.x + a.y * b.y + a.z * b.z;
}

// squared length
inline const GLfloat length2 (const vec3 &v)
{
  return dot (v, v);
}

inline const GLfloat length (const vec3 &v)
{
  return sqrtf (length2 (v));
}

typedef vec3 point;

// a generic plane
struct plane
{
  vec3 n;
  GLfloat d;

  plane () { };
  plane (GLfloat a, GLfloat b, GLfloat c, GLfloat d);
};

inline GLfloat distance (const plane &a, const point &p)
{
  return dot (a.n, p) + a.d;
}

struct sphere {
  point p;
  GLfloat r;

  sphere () { };
  sphere (const point &p, GLfloat r) : p(p), r(r) { };
};

inline bool overlap (const sphere &a, const sphere &b)
{
  GLfloat d = a.r + b.r;

  return length2 (a.p - b.p) <= d * d;
}

struct cone {
  point p;
  vec3 a; // axis
  GLfloat f, fs, fc; // angle

  cone () { };
  cone (const point &p, const vec3 &a, GLfloat f)
  : p(p), a(a), f(f)
  {
    fs = sinf (f);
    fc = cosf (f);
  };
};

inline bool overlap (const cone &c, const sphere &s)
{
  vec3 u = c.p - c.a * (s.r / c.fs);
  vec3 d = s.p - u;
  return dot (c.a, d) >= length (d) * c.fc;
}

void renormalize (sector &s, point &p);

struct colour
{
  GLubyte r, g, b, a;
  colour (GLfloat r = 1., GLfloat g = 1., GLfloat b = 1., GLfloat a = 1.)
  : r(GLubyte (r * 255.F + .5F))
  , g(GLubyte (g * 255.F + .5F))
  , b(GLubyte (b * 255.F + .5F))
  , a(GLubyte (a * 255.F + .5F))
  {
  }
};

struct tex2
{
  GLfloat s, t;
  tex2 () { };
  tex2 (GLfloat s, GLfloat t) : s(s), t(t) { };
};

struct box
{
  point a, b;

  box() { };

  void reset ()
  {
    a = point ( FLT_MAX,  FLT_MAX,  FLT_MAX);
    b = point (-FLT_MAX, -FLT_MAX, -FLT_MAX);
  }

  void add (const box &o);
  void add (const point &p);
};

struct entity;
struct geometry;
struct view;
struct octant;

extern struct timer
{
  static double now;
  static double diff;
  static double fps;

  static void frame ();
  timer ();
} timer;

/*
#define MAX_EVENT_TYPES 10
enum event_type { TIMER_EV };
struct event
{
   event_type type;
};

typedef callback1<void, event&> event_cb;

class skedjuhlar
{
   public:
// only 10 types for now
   private:
      vector <list<event_cb> > event_lists;
   
   public:
      skedjuhlar () {
         event_lists.resize (MAX_EVENT_TYPES, list<event_cb>());
      }
      
      void register_event_cb (const event_type &t, const event_cb &e) {
         event_lists[t].push_back (e);
      };
      void send_event (event &e) {
         list<event_cb> &l = event_lists[e.type];
         for (list<event_cb>::iterator it = l.begin (); it != l.end (); it++) {
            (*it)(e);
         }
      };
      void check_events () {
         while (!events.empty ()) {
            event &e = events.pop_front ();
            list<event_cb> &l = event_lists[e->name];
            for (list<event_cb>::iterator it = l.begin (); it !+ l.end (); it++) {
               (*it)(e);
            }
            delete e; // ugly slow? hai hai..... 183G
         }
      }
};

extern skedjuhlar main_scheduler;
*/

namespace gl
{
#ifdef DEBUG
  extern int nesting;
  void errchk (const char *name, const char *args, const char *file, int line);
#endif

  struct vertex_v3f
  {
    point p; // vertex

    vertex_v3f () { };
    vertex_v3f (point p) : p(p) { };

    GLenum gl_format () const { return GL_V3F; }
  };

  struct vertex_t2f_n3f_v3f
  {
    tex2  t; // texture
    vec3  n; // normal
    point p; // vertex

    vertex_t2f_n3f_v3f () { };
    vertex_t2f_n3f_v3f (point p, vec3 n, tex2 t = tex2()) : p(p), n(n), t(t) { };

    GLenum gl_format () const { return GL_T2F_N3F_V3F; }
  };

  struct matrix
  {
    GLfloat data[4][4];

    const GLfloat operator ()(int i, int j) const { return data[j][i]; };
    GLfloat &operator ()(int i, int j) { return data[j][i]; };

    operator GLfloat *() { return &data[0][0]; }

    void diagonal (GLfloat v);
    void clear () { diagonal (0.F); };
    void identity () { diagonal (1.F); };

    void print (); // ugly

    static const matrix translation (const vec3 &v);
    static const matrix rotation (GLfloat degrees, const vec3 &axis);

    matrix () { };
    matrix (GLfloat diag) { diagonal (diag); };
  };

  const matrix operator *(const matrix &a, const matrix &b);
  const vec3 operator *(const matrix &a, const vec3 &v);

  struct vertex_buffer_object {
    GLuint buffer;
    GLenum format;

    void alloc ()
    {
      if (!buffer)
        glGenBuffersARB (1, &buffer);
    }

    void bind (GLenum target = GL_ARRAY_BUFFER_ARB)
    {
      glBindBufferARB (target, buffer);
      glInterleavedArrays (format, 0, 0);
    }

    void draw (GLenum mode, GLint first, GLsizei count)
    {
      bind ();
      glDrawArrays (mode, first, count);
    }

    template<class vertex>
    void set (const vertex *v, GLsizei count, GLenum usage = GL_STATIC_DRAW_ARB, GLenum target = GL_ARRAY_BUFFER_ARB)
    {
      alloc ();
      format = v->gl_format ();
      glBindBufferARB (target, buffer);
      glBufferDataARB (target, count * sizeof (vertex), v, usage);
    }

    template<class vertex>
    void set (const vector<vertex> &v, GLenum usage = GL_STATIC_DRAW_ARB, GLenum target = GL_ARRAY_BUFFER_ARB)
    {
      set (&v[0], v.size (), usage, target);
    }

    vertex_buffer_object ()
    : buffer(0)
    {
    }
    
    ~vertex_buffer_object ()
    {
      glDeleteBuffersARB (1, &buffer);
    }

    operator GLint ()
    {
      return buffer;
    }
  };

  void draw_bbox (vertex_buffer_object &vb, const sector &a, const sector &b);
}

GLuint SDL_GL_LoadTexture (SDL_Surface *surface, GLfloat *texcoord);

#endif