// OOP EXample: Robots is a visual robot that moves forward facing
// the directions dictated by its theta. When it runs into a wall
// it turns right
class Robot {
   // Attributes
   float x, y;    // location
   float sz;      // size
   float theta;   // direction.orientation
   float speed = 1;

   // Constructor(s)
   Robot (float s) {
      float[] dir = {0, 90, 180, 270};
      theta = dir[int(random(4))];
      sz = s;
      x = random(2*sz, width-2*sz);
      y = random(2*sz, height-2*sz);
  } // Robot()

   void display() {
      // Display the robot
      push();
      translate(x, y);
      rotate(radians(theta));
      rectMode(CENTER);
      fill(255, 126, 126);
      rect(0, 0, sz, sz);
      fill(0);
      // eyes
      circle(sz/2, -sz/5, sz/10);
      circle(sz/2, sz/5, sz/10);
      line(0, 0, sz/2, 0); // rib
      // tail
      line(-sz/2, 0, -sz/2-10, -5);
      line(-sz/2, 0, -sz/2-10, 5);
      pop();
   } // display()

   void move() {
      push();
      translate(x, y);
      rotate(radians(theta));
   
      // Move the robot at speed in the direction it is headed, based on theta
      if (theta == 90) {
         y = y + speed;
      }
      else if (theta == 180) {
         x = x - speed;
      }
      else if (theta == 270) {
         y = y - speed;
      }
      else {
         x = x + speed;
   }

   // Check which wall it is colliding against and turn right
   if ((theta == 90) && (distance(x, y, x, height) < sz)) {
      turnRight(90);
   }
   else if ((theta == 180) && (distance(x, y, 0, y) < sz)) {
      turnRight(90);
   }
      else if ((theta == 270) && (distance(x, y, x, 0) < sz)) {
      turnRight(90);
   }
      else if ((theta == 0) && (distance(x, y, width, y) < sz)) {
      turnRight(90);
   }
      pop();
   }
   
   void turnLeft(float deg) {
      theta = (theta - deg) % 360;
   }
   
   void turnRight(float deg) {
      theta = (theta + deg)%360;
   }
 

   float distance(float x1, float y1, float x2, float y2) {
      return sqrt(((x1 - x2) * (x1 - x2)) + ((y1 - y2) * (y1 - y2)));
   } // distance()
   
   String toString() {
      return "<Robot of size " + sz + " at <"+x+","+y+"> facing "+theta+" degrees>";
   } // toString()
} // class Robot