/**
* 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 () {
        var 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) {
            if (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);