/**
 *
 */
var ShellSort = function() {
    this.instructions = [];
};

ShellSort.prototype = Object.create(Sorter.prototype);

/**
 *
 */
ShellSort.prototype.sort = function(arr) {
    var len = arr.length;
    var gap = Math.floor(len / 3);
    var i, j;

    for (i = 0; i < gap; i++) {
        this.gapSort(arr, i, gap);
    }

    var IS = new InsertionSort();
    IS.sort(arr);

    return arr;
};

/**
 *
 */
ShellSort.prototype.gapSort = function(arr, start, gap) {
    var i, j;
    var len = arr.length;

    // console.log(`start ${start}, gap ${gap}`)

    for (i = start; i < len; i += gap) {
        // console.log(`i: ${i}`)
        for (j = i; j > start; j -= gap) {
            // console.log(`j: ${j}`)
            // console.log(`checking if ${arr[j - gap].value} > ${arr[j].value}`)

            if (arr[j - gap].value > arr[j].value) {
                // console.log(`swapping ${arr[j - gap].value} and ${arr[j].value}`)
                tmp = arr[j - gap];
                arr[j - gap] = arr[j];
                arr[j] = tmp;
                // console.log(dump(arr));
            }
            else {
                break;
            }
        }
    }

    // console.log(dump(arr));
};