(function($) {

  $.InFieldLabels = function(label, field, options) {
    // To avoid scope issues, use 'base' instead of 'this'
    // to reference this class from internal events and functions.
    var base = this;

    // Access to jQuery and DOM versions of each element
    base.$label = $(label);
    base.label = label;

    base.$field = $(field);
    base.field = field;

    base.$label.data("InFieldLabels", base);
    base.showing = true;

    base.init = function() {
      var initialSet;

      // Merge supplied options with default options
      base.options = $.extend({}, $.InFieldLabels.defaultOptions, options);

      // Add provided class name to the label, if set
      if (base.options.className) {
        base.$label.addClass(base.options.className);
      }

      // Check if the field is already filled in
      // add a short delay to handle autocomplete
      setTimeout(function() {
        if (base.$field.val() !== "") {
          base.$label.hide();
          base.showing = false;
        } else {
          base.$label.show();
          base.showing = true;
        }
      }, 200);

      base.$field.focus(function() {
        base.fadeOnFocus();
      }).blur(function() {
        base.checkForEmpty(true);
      }).bind('keydown.infieldlabel', function(e) {
        // Use of a namespace (.infieldlabel) allows us to
        // unbind just this method later
        base.hideOnChange(e);
      }).bind('paste', function() {
        // Since you can not paste an empty string we can assume
        // that the field is not empty and the label can be cleared.
        base.setOpacity(0.0);
      }).change(function() {
        base.checkForEmpty();
      }).bind('onPropertyChange', function() {
        base.checkForEmpty();
      }).bind('keyup.infieldlabel', function() {
        base.checkForEmpty();
      });

      if (base.options.pollDuration > 0) {
        initialSet = setInterval(function() {
          if (base.$field.val() !== "") {
            base.$label.hide();
            base.showing = false;
            clearInterval(initialSet);
          }
        }, base.options.pollDuration);

      }
    };

    // If the label is currently showing
    // then fade it down to the amount
    // specified in the settings
    base.fadeOnFocus = function() {
      if (base.showing) {
        base.setOpacity(base.options.fadeOpacity);
      }
    };

    base.setOpacity = function(opacity) {
      base.$label.stop().animate({opacity: opacity}, base.options.fadeDuration, function() {
        if (opacity === 0.0) {
          base.$label.hide();
        }
      });
      base.showing = (opacity > 0.0);
    };

    // Checks for empty as a fail safe
    // set blur to true when passing from
    // the blur event
    base.checkForEmpty = function(blur) {
      if (base.$field.val() === "") {
        base.prepForShow();
        base.setOpacity(blur ? 1.0 : base.options.fadeOpacity);
      } else {
        base.setOpacity(0.0);
      }
    };

    base.prepForShow = function() {
      if (!base.showing) {
        // Prepare for a animate in...
        base.$label.css({opacity: 0.0}).show();

        // Reattach the keydown event
        base.$field.bind('keydown.infieldlabel', function(e) {
          base.hideOnChange(e);
        });
      }
    };

    base.hideOnChange = function(e) {
      if (
              (e.keyCode === 16) || // Skip Shift
              (e.keyCode === 9) // Skip Tab
              ) {
        return;
      }

      if (base.showing) {
        base.$label.hide();
        base.showing = false;
      }

      // Remove keydown event to save on CPU processing
      base.$field.unbind('keydown.infieldlabel');
    };

    // Run the initialization method
    base.init();
  };

  $.InFieldLabels.defaultOptions = {
    fadeOpacity: 0.5, // Once a field has focus, how transparent should the label be
    fadeDuration: 300, // How long should it take to animate from 1.0 opacity to the fadeOpacity
    pollDuration: 0, // If set to a number greater than zero, this will poll until content is detected in a field
    enabledInputTypes: ["text", "search", "tel", "url", "email", "password", "number", "textarea"],
    className: false // Class assigned to enhanced labels
  };


  $.fn.inFieldLabels = function(options) {
    var allowed_types = options && options.enabledInputTypes || $.InFieldLabels.defaultOptions.enabledInputTypes;

    return this.each(function() {
      // Find input or textarea based on for= attribute
      // The for attribute on the label must contain the ID
      // of the input or textarea element
      var for_attr = $(this).attr('for'), field, restrict_type;
      if (!for_attr) {
        return; // Nothing to attach, since the for field wasn't used
      }

      // Find the referenced input or textarea element
      field = document.getElementById(for_attr);
      if (!field) {
        return; // No element found
      }

      // Restrict input type
      restrict_type = $.inArray(field.type, allowed_types);

      if (restrict_type === -1 && field.nodeName !== "TEXTAREA") {
        return; // Again, nothing to attach
      }

      // Only create object for matched input types and textarea
      (new $.InFieldLabels(this, field, options));
    });
  };

}(jQuery));