/* L-System.js */
/* Author: Daniel Gray */
/* daniel@technigami.com */

addV = function(start, angle, length) {
     /* Adds a polar vector to the start position */
  
    return [start[0] + Math.cos(angle)*length,
           start[1] + Math.sin(angle)*length];
}

G_ = function(v,w,P) {
  /* L-System Interpreter */
  
  ret = "";
  for(ch in w) {     
    if(v.indexOf(w[ch]) >= 0) {
      ret = ret.concat(P[w[ch]]);
    }
    else {
      ret = ret.concat(w[ch]);
    }
  }
  return ret;
}
G = function(v, w, P, levels) {
  /* L-System Iterator */
  
  ret = w;
  for(i=0;i<levels;i++){
    ret = G_(v,ret,P);
  }
  return ret;
}

drawToPath = function(position,w ,L, initial_angle, t_left, t_right) {
  /* Iterate through the string & draw */
  
  var angle = initial_angle;
  if(t_right === undefined) {
    t_right = t_left;
  }
  if(t_left === undefined && t_right === undefined) {
    t_left = initial_angle;
    t_right = initial_angle;
    angle =-Math.PI/2;
  }
  position_stack = [];
  forward_strings = ["1","0","F","G","A","B"]
  // Move in angle direction with length L,

  path = "M "+position[0]+" "+position[1];

  for(ch in w) {
    if(forward_strings.indexOf(w[ch]) > -1 ){
      position = addV(position,angle,L);
      path = path + "L " + position[0] + " " + position[1];
    }
    if(w[ch] === "+") {
      angle -= t_left;
    }
      if(w[ch] === "-") {
        angle += t_right;
      }
      if(w[ch] === "[") {
        angle += t_right;
        position_stack.push([position, angle]);
      }
      if(w[ch] === "]") {

        last_pos_ = position_stack.pop();
        last_pos = last_pos_[0];
        angle = last_pos_[1];

        angle += t_left;
        path = path + " L " + last_pos[0] + " " + last_pos[1];
      }
  	}
    return path;
  }