var debug = (function(){
  var window = this,
    
    // Some convenient shortcuts.
    aps = Array.prototype.slice,
    con = window.console,
    
    // Public object to be returned.
    that = {},
    
    callback_func,
    callback_force,
    
    // Default logging level, show everything.
    log_level = 9,
    
    // Logging methods, in "priority order". Not all console implementations
    // will utilize these, but they will be used in the callback passed to
    // setCallback.
    log_methods = [ 'error', 'warn', 'info', 'debug', 'log' ],
    
    // Pass these methods through to the console if they exist, otherwise just
    // fail gracefully. These methods are provided for convenience.
    pass_methods = 'assert clear count dir dirxml exception group groupCollapsed groupEnd profile profileEnd table time timeEnd trace'.split(' '),
    idx = pass_methods.length,
    
    // Logs are stored here so that they can be recalled as necessary.
    logs = [];
  
  while ( --idx >= 0 ) {
    (function( method ){
      
      // Generate pass-through methods. These methods will be called, if they
      // exist, as long as the logging level is non-zero.
      that[ method ] = function() {
        log_level !== 0 && con && con[ method ]
          && con[ method ].apply( con, arguments );
      }
      
    })( pass_methods[idx] );
  }
  
  idx = log_methods.length;
  while ( --idx >= 0 ) {
    (function( idx, level ){
      
      // Method: debug.log
      // 
      // Call the console.log method if available. Adds an entry into the logs
      // array for a callback specified via <debug.setCallback>.
      // 
      // Usage:
      // 
      //  debug.log( object [, object, ...] );                               - -
      // 
      // Arguments:
      // 
      //  object - (Object) Any valid JavaScript object.
      
      // Method: debug.debug
      // 
      // Call the console.debug method if available, otherwise call console.log.
      // Adds an entry into the logs array for a callback specified via
      // <debug.setCallback>.
      // 
      // Usage:
      // 
      //  debug.debug( object [, object, ...] );                             - -
      // 
      // Arguments:
      // 
      //  object - (Object) Any valid JavaScript object.
      
      // Method: debug.info
      // 
      // Call the console.info method if available, otherwise call console.log.
      // Adds an entry into the logs array for a callback specified via
      // <debug.setCallback>.
      // 
      // Usage:
      // 
      //  debug.info( object [, object, ...] );                              - -
      // 
      // Arguments:
      // 
      //  object - (Object) Any valid JavaScript object.
      
      // Method: debug.warn
      // 
      // Call the console.warn method if available, otherwise call console.log.
      // Adds an entry into the logs array for a callback specified via
      // <debug.setCallback>.
      // 
      // Usage:
      // 
      //  debug.warn( object [, object, ...] );                              - -
      // 
      // Arguments:
      // 
      //  object - (Object) Any valid JavaScript object.
      
      // Method: debug.error
      // 
      // Call the console.error method if available, otherwise call console.log.
      // Adds an entry into the logs array for a callback specified via
      // <debug.setCallback>.
      // 
      // Usage:
      // 
      //  debug.error( object [, object, ...] );                             - -
      // 
      // Arguments:
      // 
      //  object - (Object) Any valid JavaScript object.
      
      that[ level ] = function() {
        var args = aps.call( arguments ),
          log_arr = [ level ].concat( args );
        
        logs.push( log_arr );
        exec_callback( log_arr );
        
        if ( !con || !is_level( idx ) ) { return; }
        
        con.firebug ? con[ level ].apply( window, args )
          : con[ level ] ? con[ level ]( args )
          : con.log( args );
      };
      
    })( idx, log_methods[idx] );
  }
  
  // Execute the callback function if set.
  function exec_callback( args ) {
    if ( callback_func && (callback_force || !con || !con.log) ) {
      callback_func.apply( window, args );
    }
  };
  
  // Method: debug.setLevel
  // 
  // Set a minimum or maximum logging level for the console. Doesn't affect
  // the <debug.setCallback> callback function, but if set to 0 to disable
  // logging, <Pass-through console methods> will be disabled as well.
  // 
  // Usage:
  // 
  //  debug.setLevel( [ level ] )                                            - -
  // 
  // Arguments:
  // 
  //  level - (Number) If 0, disables logging. If negative, shows N lowest
  //    priority levels of log messages. If positive, shows N highest priority
  //    levels of log messages.
  //
  // Priority levels:
  // 
  //   log (1) < debug (2) < info (3) < warn (4) < error (5)
  
  that.setLevel = function( level ) {
    log_level = typeof level === 'number' ? level : 9;
  };
  
  // Determine if the level is visible given the current log_level.
  function is_level( level ) {
    return log_level > 0
      ? log_level > level
      : log_methods.length + log_level <= level;
  };
  
  // Method: debug.setCallback
  // 
  // Set a callback to be used if logging isn't possible due to console.log
  // not existing. If unlogged logs exist when callback is set, they will all
  // be logged immediately unless a limit is specified.
  // 
  // Usage:
  // 
  //  debug.setCallback( callback [, force ] [, limit ] )
  // 
  // Arguments:
  // 
  //  callback - (Function) The aforementioned callback function. The first
  //    argument is the logging level, and all subsequent arguments are those
  //    passed to the initial debug logging method.
  //  force - (Boolean) If false, log to console.log if available, otherwise
  //    callback. If true, log to both console.log and callback.
  //  limit - (Number) If specified, number of lines to limit initial scrollback
  //    to.
  
  that.setCallback = function() {
    var args = aps.call( arguments ),
      max = logs.length,
      i = max;
    
    callback_func = args.shift() || null;
    callback_force = typeof args[0] === 'boolean' ? args.shift() : false;
    
    i -= typeof args[0] === 'number' ? args.shift() : max;
    
    while ( i < max ) {
      exec_callback( logs[i++] );
    }
  };
  
  return that;
})();

if(window.$) {
  $.debug = debug.debug;
  $.warn = debug.warn;
  $.error = debug.error;
  
  $.fn.debug = function() {
    var args = Array.prototype.slice.call(arguments);
    args.unshift(this)
    $.debug.apply(args,args);
    return this;
  }
}