(function(undefined) {
  
  /* local var and method */
  var version = '0.0';
  var debugLevel = 0; // 0: no message; higher means more message
  var canlog = true; // enable log
  
  /* object prototype */
  
  /* public method and attribute */
  
  /**
  * debug function
  */
  $$.debug = {};
  
  /**
   * set debug level
   *
   * @param level int  0=>no message; higher for more message
   */
  $$.debug.logLevel = function(level) {
    debugLevel = level;
  }
  
  /**
   * log a message
   *
   * @param mode string  dir|log|info|...native log mode
   */
  $$.debug.log = function(mode, msg) {
    if (!canlog) return;
    if (debugLevel == 0) return;

  	// Remove first argument
  	var args = Array.prototype.slice.apply(arguments, [1]);
  	// Prepend timestamp
  	var dt = new Date();
  	var tag = dt.getHours()+":"+dt.getMinutes()+":"+dt.getSeconds()+"."+dt.getMilliseconds();
  	var args = Array.prototype.slice.apply(arguments, [0]);
  	args[0] = tag + " - ";
  	
  	if (mode == 'dir' && typeof args[1] == 'object') {
  	  window.console.log(args[0]);
  	  window.console.dir(args[1]);
  	  return;
  	}
  	if(typeof window.console[mode] == 'function') {
  	  window.console[mode].apply(window.console, args);
  	}
  }
  
  /* init code */
  // check browser console
  if( !window.console ) {
    canlog = false; // disable log when console not present
  }

  // debug test message
  //$$.debug.logLevel(1);
  //$$.debug.log('table', $$);
  
  
  
})();