/*
* In-Field Label jQuery Plugin
* http://fuelyourcoding.com/scripts/infield.html
*
* Copyright (c) 2009 Doug Neiner
* Dual licensed under the MIT and GPL licenses.
* Uses the same license as jQuery, see:
* http://docs.jquery.com/License
*
* @version 0.1
*/
(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(){
      // Merge supplied options with default options
      base.options = $.extend({},$.InFieldLabels.defaultOptions, options);

      // Check if the field is already filled in
      if(base.$field.val() != ""){
        base.$label.hide();
        base.showing = false;
      };

      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);
      }).change(function(e){
        base.checkForEmpty();
      }).bind('onPropertyChange', function(){
        base.checkForEmpty();
      });
    };

    // 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);
      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(e){
      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: 0.8, // Once a field has focus, how transparent should the label be
      fadeDuration: 100 // How long should it take to animate from 1.0 opacity to the fadeOpacity
    };


    $.fn.inFieldLabels = function(options){
      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');
        if( !for_attr ) return; // Nothing to attach, since the for field wasn't used


        // Find the referenced input or textarea element
        var $field = $(
          "input#" + for_attr + "[type='text']," +
          "input#" + for_attr + "[type='password']," +
          "textarea#" + for_attr
        );

        if( $field.length == 0) return; // Again, nothing to attach

        // Only create object for input[text], input[password], or textarea
        (new $.InFieldLabels(this, $field[0], options));
      });
    };

    })(jQuery);