//
// 「ビルゲイツの入社試験」に出てきた問題をProcessingで作ってみたもの。
//

int MARGIN = 50;
int RADIUS = 200;
float centerx,centery;
float oposx, oposy; // 鬼の位置
float posx, posy;   // 人の位置
float ospeed = 4.0; // 鬼の速度
float speed =  1.0; // 人の速度

int targetidx = 0;
int step = 0;
int end = 0;
float [] pathx = new float[7];
float [] pathy = new float[7];

void setup(){
  float sradius = RADIUS / 4.0;
  float sx = sradius / 2.0 * sqrt(3.0);
  float sy = sradius / 2.0;

  pathx[0] = 0.0;  pathy[0] = -sradius;
  pathx[1] = -sx;  pathy[1] = -sy;
  pathx[2] = -sx;  pathy[2] = sy;
  pathx[3] = 0.0;  pathy[3] = sradius;
  pathx[4] = sx;   pathy[4] = sy;
  pathx[5] = sx;   pathy[5] = -sy;

  size((RADIUS+MARGIN)*2,(RADIUS+MARGIN)*2);
  centerx = RADIUS + MARGIN;
  centery = RADIUS + MARGIN;
  oposx = 0.0;
  oposy = RADIUS;
  posx = 0.0;
  posy = 0.0;
}

void loop(){
  if (end == 1) { return; }

  float oangle,odelta;
  float angle,delta;
  float mangle;
  float mx, my; 
  background(200,140,255);
  fill(200,200,200);
  ellipse(centerx-RADIUS,centery-RADIUS,RADIUS*2,RADIUS*2);

  // 鬼の角度
  oangle = atan2(oposy,oposx);
  // ヒトの角度
  angle = atan2(posy,posx);
  delta = angle - oangle;
  if(delta < 0) delta += PI * 2;
  odelta = ospeed / RADIUS;
  if(delta > PI) odelta = -odelta;

  oangle += odelta;
  oposx = cos(oangle) * RADIUS;
  oposy = sin(oangle) * RADIUS;
  fill(255,255,0);
  rect(centerx+oposx-5,centerx+oposy-5,10,10);

  mx = pathx[targetidx];
  my = pathy[targetidx];
  mangle = atan2(my-posy,mx-posx);
  posx += cos(mangle) * speed;
  posy += sin(mangle) * speed;
  fill(0,0,255);
  rect(centerx+posx-5,centery+posy-5,10,10);
  point(centerx, centery);
  line(centerx+posx, centery+posy, centerx+oposx, centery+oposy);

  float dx = abs(posx - pathx[targetidx]);
  float dy = abs(posy - pathy[targetidx]);
  if (dx < 0.1 && dy < 0.1) {
    if (targetidx != 6) {
      targetidx = (targetidx + 1) % 6;
      step += 1;
      if (abs(posy / (oposy - posy) - posx / (oposx - posx)) < 0.02 && 0 < step && targetidx != 6) {
        pathx[6] = -oposx;
        pathy[6] = -oposy;
        targetidx = 6;
      }
    } else {
      end = 1;
    }
  }
}