var ai = {
  race(list) {
    return function(dt) {
      var good = false;
      for (var i = 0; i < list.length; i++)
        if (list[i].call(this,dt)) good=true;
        
      return good;
    };
  },

  sequence(list) {
    var i = 0;
    var fn = function(dt) {
      while (i !== list.length) {
        if (list[i].call(this,dt))
	       i++;
	      else
	       return false;
      }
      if (fn.done) fn.done();
      return true;
    };
    
    fn.restart = function() { i = 0; };
    return fn;
  },

  parallel(list) {
    return function(dt) {
      var good = true;
      list.forEach(function(x){ if (!x.call(this,dt)) good = false; },this);
      return good;
    };
  },
  
  dofor(secs, fn) {
    return ai.race([
      ai.wait(secs),
      fn
    ]);
  },

  wait(secs = 1) {
    var accum = 0;
    return function(dt) {
      accum += dt;
      if (accum >= secs) {
        accum = 0;
        return true;
      }
	
      return false;
    };
  },
};

return {ai};