(function() {
    "use strict";

    angular.module("raz")
        .service("correlationGradeFilterService", ["$window", function ($window) {
            var defaultGrade = 'K';
            var curGrade = null;
            var storageKey = 'ss-grade-filter';

            function fromStorage() {
                return $window.sessionStorage.getItem(storageKey);
            }

            function toStorage() {
                $window.sessionStorage.setItem(storageKey, curGrade);
            }

            function getDefaultGrade() {
                return fromStorage() || defaultGrade;
            }

            function selectGrade(grade) {
                curGrade = grade;
                toStorage();
            }

            function getSelectedGrade() {
                return curGrade;
            }

            selectGrade(getDefaultGrade());

            return {
                selectGrade: selectGrade,
                getSelectedGrade: getSelectedGrade
            };

        }]);
})();