(function($) {

    $.fn.prepopulate = function(dependencies, maxLength) {

        /*

            Depends on urlify.js

            Populates a selected field with the values of the dependent fields,

            URLifies and shortens the string. 

            dependencies - selected jQuery object of dependent fields

            maxLength - maximum length of the URLify'd string 

        */

        return this.each(function() {

            var field = $(this);

            field.data('_changed', false);

            field.change(function() {

                field.data('_changed', true);

            });

            var populate = function () {

                // Bail if the fields value has changed

                if (field.data('_changed') == true) return;

                var values = [];

                dependencies.each(function() {

                    if ($(this).val().length > 0) {

                        values.push($(this).val());

                    }

                });

                field.val(URLify(values.join(' '), maxLength));

            };

            dependencies.keyup(populate).change(populate).focus(populate);

        });

    };

})(django.jQuery);