/**
   \symmetries all
*/
element Herbivore {
  typedef Unsigned(8) Channel;
  typedef Channel ARGB[4];
  typedef Channel RGB[3];
  typedef Unsigned(7) Hunger;

  EventWindow ew;
  Random random;

  Once once;
  RGB color;
  Hunger hunger;

  constant Hunger cEAT_PER_ENERGY = 6;
  constant Int cMUTATION_DISTANCE = 10;

  Channel mutate(Channel cur) {
    Int mutOdds = cMUTATION_DISTANCE;
    return (Channel) (cur + random.between(-mutOdds,mutOdds));
  }

  Bool isEdible(RGB us, RGB them) {
    Unsigned sad;
    for (Int i = 0; i < 3; ++i) {
      Int diff = (Int) us[i] - (Int) them[i];
      if (diff < 0) diff = -diff;
      sad += (Unsigned) diff;
    }
    return random.oneIn(sad/50u);
  }

  Void behave() {
    if (once.new()) {
      hunger = hunger.maxof / 2 + 1;
      for (Int i = 0; i < 3; ++i) 
        color[i] = (Channel) random.between(Channel.minof,Channel.maxof);
    }
    if (++hunger == hunger.maxof) {
      Empty e;
      ew[0] = e;
      return;
    }
    if (!ew.isLive(1)) return;
    if (ew[1] is Plant) {
      Plant p = (Plant) ew[1];
      if (isEdible(color, p.color)) {
        hunger -= (Hunger) (p.energy * cEAT_PER_ENERGY);
        if (hunger == hunger.minof) {
          Hunger give = (Hunger) (3 * hunger.maxof / 4 + 1);
          hunger = give;
          Self kid = self;
          hunger = (Hunger) (Hunger.maxof - give);
          for (Int i = 0; i < 3; ++i) {
            kid.color[i] = mutate(kid.color[i]);
          }
          ew[0] = kid;
        }
      } else {
        Empty e;
        ew[0] = e;
      }
      ew[1] = self;
    } else if (ew[1] is Empty || ew[1] is Self) {
      ew.swap(0,1);
    }
  }


  ARGB getColor(Unsigned selector) {
    ARGB ret;
    ret[0] = 0xff;
    if (selector==2u) {
      ret[1] = color[0]; 
      ret[2] = color[1]; 
      ret[3] = color[2]; 
    } else {
      ret[1] = 0;
      ret[2] = 0;
      ret[3] = 0;
    }
    return ret;
  }
  
}