/**
 * jquery select2 sortable
 * - enable select2 to be sortable via normal select element
 *
 * author : vafour
 * inspired by : jquery chosen sortable (https://github.com/mrhenry/jquery-chosen-sortable)
 * license : gpl
 */
(function($){
    $.fn.extend({
        select2sortableorder: function(){
            var $this = this.filter('[multiple]');
            $this.each(function(){
                var $select = $(this);
// skip elements not select2-ed
                if(typeof($select.data('select2')) !== 'object'){
                    return false;
                }
                var $select2 = $select.siblings('.select2-container'),
                    unselected = [],
                    sorted;
                $select.find('option').each(function(){
                    !this.selected && unselected.push(this);
                });
                sorted = $($select2.find('.select2-choices li[class!="select2-search-field"]').map( function() {
                    if (!this) {
                        return undefined;
                    }
                    var id = $(this).data('select2data').id;
                    return $select.find('option[value="' + id + '"]')[0];
                }));
                sorted.push.apply(sorted, unselected);
                $select.children().remove();
                $select.append(sorted);
            });
            return $this;
        },
        select2sortable: function(){
            var args = array.prototype.slice.call(arguments, 0);
            $this = this.filter('[multiple]'),
                validmethods = ['destroy'];
            if(args.length === 0 || typeof(args[0]) === 'object')
            {
                var defaultoptions = {
                    bindorder : 'formsubmit', // or sortablestop
                    sortableoptions : {
                        placeholder : 'ui-state-highlight',
                        items : 'li:not(.select2-search-field)',
                        tolerance : 'pointer'
                    }
                };
                var options = $.extend(defaultoptions, args[0]);
// init select2 only if not already initialized to prevent select2 configuration loss
                if(typeof($this.data('select2')) !== 'object'){
                    $this.select2();
                }
                $this.each(function(){
                    var $select = $(this),
                        $select2choices = $select.siblings('.select2-container').find('.select2-choices');
// init jquery ui sortable
                    $select2choices.sortable(options.sortableoptions);
                    switch(options.bindorder){
                        case 'sortablestop':
// apply options ordering in sortstop event
                            $select2choices.on("sortstop.select2sortable", function( event, ui ) {
                                $select.select2sortableorder();
                            });
                            $select.on('change', function(e){
                                $(this).select2sortableorder();
                            });
                            break;
                        default:
// apply options ordering in form submit
                            $select.closest('form').unbind('submit.select2sortable').on('submit.select2sortable', function(){
                                $select.select2sortableorder();
                            });
                    }
                });
            }
            else if(typeof(args[0] === 'string'))
            {
                if($.inarray(args[0], validmethods) == -1)
                {
                    throw "unknown method: " + args[0];
                }
                if(args[0] === 'destroy')
                {
                    $this.select2sortabledestroy();
                }
            }
            return $this;
        },
        select2sortabledestroy: function(){
            var $this = this.filter('[multiple]');
            $this.each(function(){
                var $select = $(this),
                    $select2choices = $select.parent().find('.select2-choices');
// unbind form submit event
                $select.closest('form').unbind('submit.select2sortable');
// unbind sortstop event
                $select2choices.unbind("sortstop.select2sortable");
// destroy select2sortable
                $select2choices.sortable('destroy');
            });
            return $this;
        }
    });
}(jquery));