#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <string.h>
#include <SDL/SDL.h>
#include <time.h> 
#include "neutronlib.h"
int bumpsig = 0;
struct sphere
{
  double x;      // x position
  double y;      // y position
  double r;      // radius can also be z position for depth
  double m;      // mass
  double v;      // movement vector amplitude total
  double vx;     // and in x direction normalized
  double vy;     // and in y direction normalized
  double vxt;    // unnormalized x movement vector
  double vyt;    // unnormalized y movement vector
  double rad;    // movement vector direction
  int hue;       // color
  double trans;  // degree of transparency
  int bumpc;     // Bump control
  int id;
  int bumper;    // id of the last bumper
  void shovec(void)
  {              // Show the direction vector
    double a = x, b = y, xx = 0, ln = r + (r * v);
    while(xx++ < ln){
      putpixel(a, b, hue);
      a += vx; b += vy;
    }
  }
  void Circle(double radius){
    double inc = 1.0 / (radius * trans); // Amount of transparency
    double circle = 0;
    while(circle < 2 * PI){
      putpixel(x + cos(circle) * radius, y + sin(circle) * radius, hue);
      circle += inc;
    }
  } 
  void show(void){
    double xx = 0, savehue = hue, savetrans = trans;
    while(xx++ < r){  // Save the color and transparency
      Circle(xx);
      hue += 0x010101;
      trans += .01;
    }
    hue = savehue;  // Restore color and transparency
    trans = savetrans;
  }
  void getrad(void){  // Get radian from movement vectors
    rad = acos(vx / vxt * vyt);
    if(vx > 0){ rad = 2 * PI - rad; }
    rad += PI / 2;
  }
  void move(void){ // Move along the radian and bounce off walls
    if(x + r > maxx){ rad =     PI - rad; x = maxx - r; }
    if(x - r < minx){ rad =     PI - rad; x = minx + r; } 
    if(y + r > maxy){ rad = 2 * PI - rad; y = maxy - r; }
    if(y - r < miny){ rad = 2 * PI - rad; y = miny + r; }
    vx = cos(rad); // Get movement vectors from radian 
    vy = sin(rad);
    vxt = vx * v;
    vyt = vy * v;
    x += vxt;      // Move along movement vectors
    y += vyt;
  }
  void init(void){
    x = rand()  % (maxx - 100);
    y = rand()  % (maxy - 100);
    r = rand()  % 100 + 10;
    m = r * r;
    rad = rand() % 7;
    hue = rand() % 0xffffff;
    v = rand()   % 10 + .5;
    trans = .1;
    bumper = -1;
  }
  void getv(void){
    v = sqrt(vxt * vxt + vyt * vyt);         // Set movement vectors
    vx = vxt / v;
    vy = vyt / v;
  }
  void bump(sphere & sp){
    double dx = x - sp.x;
    double dy = y - sp.y;
    double sr = r + sp.r;
    if(dx * dx + dy * dy > sr * sr){
      if(bumper == sp.id){ 
        bumper = -1; 
        sp.bumper = -1;
      }     // Lose last bumper
      return;                                 // No bump exit               
    }
    if(bumper == sp.id){ vx *= 1.50; return; }
    double dc = sqrt(dx * dx + dy * dy);      // Distance between centers
    double nx = dx / dc;
    double ny = dy / dc;                      // Calculate change in
    double a1 = vxt * nx + vyt * ny;          // momentum and use that
    double a2 = sp.vxt * nx + sp.vyt * ny;    // to get new radians and
    double op = (2 * (a1 - a2)) / (m + sp.m); // velocities for a bounce
    vxt = vxt - op * sp.m * nx;               // true to physics.
    vyt = vyt - op * sp.m * ny;
    sp.vxt = sp.vxt + op * m * nx;
    sp.vyt = sp.vyt + op * m * ny;
    getv();
    sp.getv();
    getrad();                                 // Get new radians
    sp.getrad();
    if(sp.hue > 0){ hue = sp.hue; }
    if(sp.r > 20){ sp.hue = color; }
    if(bumpc < 20){ bumpc ++; }
    if(bumpc == 19){ hue = 0xff0000; }
    if(sp.bumpc == 19){ sp.hue = 0x0000ff; }
    if(bumpc > 19){ bumpc = 0; color = rand() % 0xffffff; }
    if(bumper < 0 || sp.bumper < 0){
      bumper = sp.id;
      sp.bumper = id;
    }
  }
};

int main(int argc, char **argv)
{
  char c;
  int x, y, x1, y1, c2, chunk = 0;
  maxx = 1920; maxy = 1100;
  int spqty = 100;
  int vis = 2;
  time_t seconds;
  seconds = time (NULL);
  unsigned int sec = seconds;
  srand(sec);
  sphere sp[spqty];
  for(x = 0; x < spqty; x++){
    sp[x].init();
    sp[x].id = x;
  }
  double xx, cosrad;
  int ofst, sfst;
  init_screen(maxx, maxy);
  color = sec % 0xffffff;
  ColorFill(color, maxx, maxy);
  while(1){
    ColorFill(color, maxx, maxy);
    for(x = 0; x < vis; x ++){
      sp[x].shovec();
      sp[x].show();
      sp[x].move();
      for(y = x + 1; y < vis; y++) { sp[y].bump(sp[x]); }
    }
    c = keystroke();
    if(c == 'q') break;
    if(c == 'w') SDL_Delay(10000);
    if(c == 'm' && vis < spqty) vis ++;
    if(c == 'l' && vis > 1) vis --;
    if(c == 'v'){ color = rand() % 0xffffff; }
    if(c == 'n'){ color = 0x000000; }
    if(c == '1'){ vis = 1; }
    if(c == 'b'){ for(x = 0; x < vis; x++) sp[x].hue  = 0xffffff; }
    if(c == 'u'){ for(x = 0; x < vis; x++) sp[x].hue += 0x010101; }
    if(c == 'i'){
      seconds = time (NULL);
      sec = seconds;
      srand(sec);
      for(x = 0; x < spqty; x++) sp[x].init(); 
    }
    if(c == 't'){
      seconds = time (NULL);
      sec = seconds % 0xffffff;
      for(x = 0; x < spqty; x ++){ sp[x].hue = seconds; }
    }
    SDL_UpdateRect(screen, minx, miny, maxx, maxy);
    if(bumpsig == 1){ SDL_Delay(5000); bumpsig = 0; }
    SDL_Delay(10);
  }
  SDL_Quit();
}