var evader = function(spec) {
  var that = {};

  that.element = document.getElementById(spec.element);
  that.over = spec.over;
  that.out = spec.out;

  that.origin = vector({elements: [Math.ceil(Math.random()*600)+200, Math.ceil(Math.random()*400)+200]});
  that.threshhold = 100;
  that.spriteliness = 2000.0;
  that.intervalFactor = 100;
  that.approachFactor = 1000;

  that.now = vector({elements: [0, 0]});
  that.before = vector({elements: [0, 0]});
  that.motion = vector({elements: [0, 0]});
  that.offset = vector({elements: [-25, -20]});
  that.approached = false;
  that.accepted = false;
  that.rejected = false;

  that.evading = vector({elements: [0, 0]});

  that.applyVector = function(v) {
    that.element.style.left = '' + v.elements[0] + 'px';
    that.element.style.top = '' + v.elements[1] + 'px';

    return that;
  };

  that.applyMotion = function() {
    that.orient();
    that.evade();

    that.applyVector(that.origin);
  };

  that.orient = function() {
    that.direction = that.origin.subtract(that.now);
    that.distance = that.origin.distance(that.now);
    that.motion = that.now.subtract(that.before);
  };

  that.track = function(event) {
    that.before = that.now;
    that.now = vector({elements: [event.pageX, event.pageY]}).add(that.offset);
    that.applyMotion();
  };

  that.accept = function(event) {
    if (!that.rejected) {
      that.over();
      that.accepted = true;
    }
  };

  that.reject = function(event) {
    that.out();
    that.rejected = true;
    that.element.addClassName('nothingness');
  };

  that.decide = function() {
    that.decided = true;
    var self = that;
    that.interval = setInterval(function(){self.approach();}, self.intervalFactor);
  };

  that.approach = function() {
    if(that.distance > 7 && !that.accepted) {
      var factor = that.approachFactor * (8.0 / (that.distance + 8.0));
      var new_origin = that.origin.add(that.direction.invert().normalize().scale(factor));

      that.origin.set(new_origin);
      that.applyVector(that.origin);
      that.orient();
    } else if (that.distance <= 7) {
      that.over(that.element);
    }
  };

  that.clear = function() {
    if(that.decided) {that.decided = false;};
    if(that.timeout != null) {
      clearTimeout(that.timeout);
      that.timeout = null;
    }
    if(that.interval != null) {
      clearInterval(that.interval);
      that.interval = null;
    }
  };

  that.evade = function() {
    that.clear();

    if(!that.rejected) {
      if (that.distance < that.threshhold) {
        if(that.approached == false) {
          that.approached = true;
        }

        //        that.factor = (that.distance == 0) ? 1 : (that.spriteliness / that.distance)
        that.factor = ((that.spriteliness * 100) / that.distance.square());
        that.force = that.direction.normalize().scale(that.factor);
        that.origin.set(that.origin.add(that.force));
      }

      if(that.approached) {
        self = that;
        that.timeout = setTimeout(function(){self.decide();}, 5000);
      }
    }
  };

  that.applyMotion();

  document.onmousemove = that.track;
  that.element.onmouseover = that.accept;
  that.element.onmouseout = that.reject;
  //     document.observe('mousemove', that.track.bindAsEventListener(that));
  //     that.element.observe('mouseover', that.accept.bindAsEventListener(that));
  //     that.element.observe('mouseout', that.reject.bindAsEventListener(that));

  return that;
};