(function($){
 if ( ! $) return;

 $.ajax_upload = function(button, options){
  button = $(button);

  if (button.size() != 1 ){
   console.error('You passed ', button.size(),' elements to ajax_upload at once');
   return false;
  }
  return new Ajax_upload(button, options);
 };

 var get_uid = function(){
  var uid = 0;
  return function(){
   return uid++;
  }
 }();

 var Ajax_upload = function(button, options){
  this.button = button;

  this.wrapper = null;
  this.form = null;
  this.input = null;
  this.iframe = null;

  this.disabled = false;
  this.submitting = false;

  this.settings = {
   // Location of the server-side upload script
   action: '',
   // File upload name
   name: 'file',
   // Additional data to send
   data: {},
   // Fired when user selects file
   // You can return false to cancel upload
   onSubmit: function(file, extension) {},
   // Fired when file upload is completed
   onComplete: function(file, response) {},
   // Fired when server returns the "success" string
   onSuccess: function(file){},
   // Fired when server return something else
   onError: function(file, response){}
  };

  // Merge the users options with our defaults
  $.extend(this.settings, options);

  this.create_wrapper();
  this.create_input();

  if (jQuery.browser.msie){
   // fix ie transparent background bug
   this.make_parent_opaque();
  }

  this.create_iframe();
 }
 // assigning methods to our class
 Ajax_upload.prototype = {
  set_data : function(data){
   this.settings.data = data;
  },
  disable : function(){
   this.disabled = true;
   if ( ! this.submitting){
    this.input.attr('disabled', true);
   }
  },
  enable : function(){
   this.disabled = false;
   this.input.attr('disabled', false);
  },
  /**
  * Creates wrapper for button and invisible file input
  */
  create_wrapper : function(){
   // Shorten names
   var button = this.button, wrapper;

   wrapper = this.wrapper = $('<div></div>')
   .insertAfter(button)
   .append(button);

   // wait a bit because of FF bug
   // it can't properly calculate the outerHeight
    setTimeout(function(){
    wrapper.css({
      position: 'relative'
     ,cursor: 'pointer'
     ,display: 'block'
     ,overflow: 'hidden'
     ,height: button.outerHeight(true)
     ,width: button.outerWidth(true)
    });
   }, 1);

   var self = this;
   wrapper.mousemove(function(e){
    // Move the input with the mouse, so the user can't misclick it
    if (!self.input) {
     return;
    }
    self.input.css({
      top: e.pageY - wrapper.offset().top - 5 + 'px'
     ,left: e.pageX - wrapper.offset().left - 170 + 'px'
    });
   });
  },
  /**
  * Creates invisible file input above the button
  */
  create_input : function(){
   var self = this;

   this.input =
   $('<input type="file" />')
   .attr('name', this.settings.name)
   .css({
     'position' : 'absolute'
    ,'margin': 0
    ,'padding': 0
    ,'width': '220px'
    ,'heigth': '10px'
    ,'opacity': 0
   })
   .change(function(){
    if ($(this).val() == ''){
     // there is no file
     return;
    }
    // we need to lock "disable" method
    self.submitting = true;
    // Submit form when value is changed
    self.submit();
    // unlock "disable" method
    self.submitting = false;
   })
   .appendTo(this.wrapper)
   .hover(
     function(){self.button.addClass('hover');}
    ,function(){self.button.removeClass('hover');}
   );
 
   if (this.disabled){
    this.input.attr('disabled', true);
   }
  },

  create_iframe : function(){
   var name = 'iframe_au' + get_uid();
   this.iframe =
   $('<iframe name="' + name + '"></iframe>')
   .css('display', 'none')
   .appendTo('body');
  },

  submit : function(){
   var self = this, settings = this.settings;
   var file = this.file_from_path(this.input.val());
 
   if (settings.onSubmit.call(this, file, this.get_ext(file)) === false){
    // Do not continue if user function returns false
    if (self.disabled){
     this.input.attr('disabled', true);
    }
    return;
   }

   this.create_form();
   this.input.appendTo(this.form);
   this.form.submit();

   this.input.remove();
   this.input = null;
   this.form.remove();
   this.form = null;

   this.submitting = false;

   this.create_input();

   var iframe = this.iframe;

   iframe.load(function(){
    var response = iframe.contents().find('body').html();
    settings.onComplete.call(self, file, response);
    if (response == 'success'){
     settings.onSuccess.call(self, file);
    } else {
     settings.onError.call(self, file, response);
    }

    // CLEAR ( ,   FF2 )
    setTimeout(function(){
     iframe.remove();
    }, 1);
   });

   this.create_iframe();
  },

  create_form : function(){
   // Enctype
   //    ATTR " "
   this.form =
   $('<form method="post" enctype="multipart/form-data"></form>')
   .appendTo('body')
   .attr({
     "action" : this.settings.action
    ,"target" : this.iframe.attr('name')
   });

   for (var i in this.settings.data){
    $('<input type="hidden" />')
    .appendTo(this.form)
    .attr({
      'name': i
     ,'value': this.settings.data[i]
    });
   }
  },

  file_from_path : function(file){
   var i = file.lastIndexOf('\\');
   if (i !== -1 ){
    return file.slice(i+1);
   }
   return file;
  },
  get_ext : function(file){
   var i = file.lastIndexOf('.');
   if (i !== -1 ){
    return file.slice(i+1);
   }
   return '';
  },
  make_parent_opaque : function(){
   // ie
   this.button.add(this.button.parents()).each(function(){
    var color = $(this).css('backgroundColor');
    var image = $(this).css('backgroundImage');

    if ( color != 'transparent' ||  image != 'none'){
     $(this).css('opacity', 1);
     return false;
    }
   });
  }
 };

})(jQuery);