(function($){
  $.strength = function(username, password, options, callback) {
    if (typeof(options) == "function") {
      callback = options;
      options = {};
    } else if (!options) {
      options = {};
    }

    var usernameField = $(username);
    var passwordField = $(password);
    var strength = new PasswordStrength();

    strength.exclude = options["exclude"];

    callback = callback || $.strength.callback;

    var handler = function(){
      strength.username = $(usernameField).val();

      if ($(usernameField).length == 0) {
        strength.username = username;
      }

      strength.password = $(passwordField).val();

      if ($(passwordField).length == 0) {
        strength.password = password;
      }

      strength.test();
      callback(usernameField, passwordField, strength);
    };

    $(usernameField).keydown(handler);
    $(usernameField).keyup(handler);

    $(passwordField).keydown(handler);
    $(passwordField).keyup(handler);
  };

  $.extend($.strength, {
    callback: function(username, password, strength){
      var img = $(password).next("img.strength");

      if (!img.length) {
        $(password).after("<img class='strength'>");
        img = $("img.strength");
      }

      $(img)
        .removeClass("weak")
        .removeClass("good")
        .removeClass("strong")
        .addClass(strength.status)
        .attr("src", $.strength[strength.status + "Image"]);
    },
    weakImage: "/images/weak.png",
    goodImage: "/images/good.png",
    strongImage: "/images/strong.png"
  });
})(jQuery);