(function(){
    "use strict";
    angular.module('shared')
        .factory('ChunkStudents', ['_', function ChunkStudentsFactory(_) {
            var thresholds = [30, 40];
            var minCols = 3;
            return {
                chunk: chunk
            };

            function chunk(students) {
                var studentsPerChunk = Math.ceil(students.length / numCols(students.length));
                return _.chain(students)
                    .groupBy(function (item, index) {
                        return Math.floor(index / studentsPerChunk)
                    })
                    .toArray()
                    .value();
            }

            function numCols(numStudents) {
                return _.reduce(thresholds, function (memo, threshold) {
                    return numStudents > threshold
                        ? memo + 1 : memo;
                }, minCols);
            }
        }])

})();