/*
 * jQuery Form Example Plugin 1.4.1
 * Populate form inputs with example text that disappears on focus.
 *
 * e.g.
 *  jQuery('input#name').example('Bob Smith');
 *  jQuery('input[@title]').example(function() {
 *    return jQuery(this).attr('title');
 *  });
 *  jQuery('textarea#message').example('Type your message here', {
 *    className: 'example_text'
 *  });
 *
 * Copyright (c) Paul Mucur (http://mucur.name), 2007-2008.
 * Dual-licensed under the BSD (BSD-LICENSE.txt) and GPL (GPL-LICENSE.txt)
 * licenses.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */
(function(jQuery) {
  
  jQuery.fn.example = function(text, args) {
    
    /* Only calculate once whether a callback has been used. */
    var isCallback = jQuery.isFunction(text);
    
    /* Merge the arguments and given example text into one options object. */
    var options = jQuery.extend({}, args, {example: text});
    
    return this.each(function() {
      
      /* Reduce method calls by saving the current jQuery object. */
      var jQuerythis = jQuery(this);
      
      /* Merge the plugin defaults with the given options and, if present,
       * any metadata.
       */
      if (jQuery.metadata) {        
        var o = jQuery.extend({}, jQuery.fn.example.defaults, jQuerythis.metadata(), options);
      } else {
        var o = jQuery.extend({}, jQuery.fn.example.defaults, options);
      }
      
      jQuerythis.attr('placeholder', isCallback ? o.example.call(this) : o.example);
      
      /* The following event handlers only need to be bound once
       * per class name. In order to do this, an array of used
       * class names is stored and checked on each use of the plugin.
       * If the class name is in the array then this whole section 
       * is skipped. If not, the events are bound and the class name 
       * added to the array.
       *
       * As of 1.3.2, the class names are stored as keys in the
       * array, rather than as elements. This removes the need for
       * jQuery.inArray().
       */
      if (!jQuery.fn.example.boundClassNames[o.className]) {
      
        /* Because Gecko-based browsers cache form values
         * but ignore all other attributes such as class, all example
         * values must be cleared on page unload to prevent them from
         * being saved.
         */
        jQuery(window).unload(function() {
          jQuery('.' + o.className).val('');
        });
      
        /* Clear fields that are still examples before any form is submitted
         * otherwise those examples will be sent along as well.
         * 
         * Prior to 1.3, this would only be bound to forms that were
         * parents of example fields but this meant that a page with
         * multiple forms would not work correctly.
         */
        jQuery('form').submit(function() {
        
          /* Clear only the fields inside this particular form. */
          jQuery(this).find('.' + o.className).val('');
        });
      
        /* Add the class name to the array. */
        jQuery.fn.example.boundClassNames[o.className] = true;
      }
    
      /* Internet Explorer will cache form values even if they are cleared
       * on unload, so this will clear any value that matches the example
       * text and hasn't been specified in the value attribute.
       *
       * If a callback is used, it is not possible or safe to predict
       * what the example text is going to be so all non-default values
       * are cleared. This means that caching is effectively disabled for
       * that field.
       *
       * Many thanks to Klaus Hartl for helping resolve this issue.
       */
      if (jQuery.browser.msie && !jQuerythis.attr('defaultValue') && (isCallback || jQuerythis.val() == o.example))
        jQuerythis.val('');
      
      /* Initially place the example text in the field if it is empty
       * and doesn't have focus yet.
       */
      if (jQuerythis.val() == '' && this != document.activeElement) {
        jQuerythis.addClass(o.className);
        
        /* The text argument can now be a function; if this is the case,
         * call it, passing the current element as `this`.
         */
        jQuerythis.val(isCallback ? o.example.call(this) : o.example);
      }
      
      /* Make the example text disappear when someone focuses.
       *
       * To determine whether the value of the field is an example or not,
       * check for the example class name only; comparing the actual value
       * seems wasteful and can stop people from using example values as real 
       * input.
       */
      jQuerythis.focus(function() {
        
        /* jQuery 1.1 has no hasClass(), so is() must be used instead. */
        if (jQuery(this).is('.' + o.className)) {
          jQuery(this).val('');
          jQuery(this).removeClass(o.className);
        }
      });
    
      /* Make the example text reappear if the input is blank on blurring. */
      jQuerythis.blur(function() {
        if (jQuery(this).val() == '') {
          jQuery(this).addClass(o.className);
          
          /* Re-evaluate the callback function every time the user
           * blurs the field without entering anything. While this
           * is not as efficient as caching the value, it allows for
           * more dynamic applications of the plugin.
           */
          jQuery(this).val(isCallback ? o.example.call(this) : o.example);
        }
      });
    });
  };
  
  /* Users can override the defaults for the plugin like so:
   *
   *   jQuery.fn.example.defaults.className = 'not_example';
   */
  jQuery.fn.example.defaults = {
    className: 'example'
  };
  
  /* All the class names used are stored as keys in the following array. */
  jQuery.fn.example.boundClassNames = [];
  
})(jQuery);