/**
 * JQuery shiftcheckbox plugin
 *
 * shiftcheckbox provides a simpler and faster way to select/unselect multiple checkboxes within a given range with just two clicks.
 * Inspired from GMail checkbox functionality
 *
 * Just call $('.<class-name>').shiftcheckbox() in $(document).ready
 *
 * @name shiftcheckbox
 * @type jquery
 * @cat Plugin/Form
 * @return JQuery
 *
 * Copyright (c) 2009 Aditya Mooley <adityamooley@sanisoft.com>
 * Dual licensed under the MIT (MIT-LICENSE.txt) and GPL (GPL-LICENSE.txt) licenses
 */

(function ($) {
  $.fn.shiftcheckbox = function()
  {
	prevChecked = null;

	selectorStr = this;

	$(selectorStr).bind("click", handleClick);
  };

  function handleClick(event)
  {
	var val = this.value;
	var checkStatus = this.checked;
	//get the checkbox number which the user has checked

	//check whether user has pressed shift
	if (event.shiftKey && prevChecked != null) {
	  //get the current checkbox number
	  var ind = 0, found = 0, currentChecked;
	  currentChecked = getSelected(val);

	  ind = 0;
	  if (currentChecked < prevChecked) {
		$(selectorStr).each(function(i) {
		  if (ind >= currentChecked && ind <= prevChecked) {
			this.checked = checkStatus;
		  }
		  ind++;
		});
	  } else {
		$(selectorStr).each(function(i) {
		  if (ind >= prevChecked && ind <= currentChecked) {
			this.checked = checkStatus;
		  }
		  ind++;
		});
	  }

	  prevChecked = currentChecked;
	} else if (checkStatus) {
	  prevChecked = getSelected(val);
	}
  };

  function getSelected(val)
  {
	var ind = 0, found = 0, checkedIndex;

	$(selectorStr).each(function(i) {
	  if (val == this.value && found != 1) {
		checkedIndex = ind;
		found = 1;
	  }
	  ind++;
	});

	return checkedIndex;
  };
})(jQuery);