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

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

/**
 *
 */
Mergesort.prototype.addInstruction = function(operation, left, right, mid) {
    console.log({
        operation: operation,
        left: left,
        right: right,
        mid: mid
    });

    this.instructions.push({
        operation: operation,
        left: left,
        right: right
    });
};

/**
 *
 */
Mergesort.prototype.sort = function(arr, start, end) {
    if (arr.length === 0) {
        return arr;
    }

    if (start === end) {
        this.addInstruction('single', start);
        return new Array(arr[start]);
    }

    var mid = start + Math.floor((end - start) / 2);

    var arr1 = this.sort(arr, start, mid);
    var arr2 = this.sort(arr, mid + 1, end);

    var result = this.merge(arr1, arr2);

    return result;
};

/**
 *
 */
Mergesort.prototype.merge = function(arr1, arr2) {
    var result = [];

    while (arr1.length > 0 || arr2.length > 0) {
        if (arr1.length === 0) {
            result.push(arr2.shift());
        }
        else if (arr2.length === 0) {
            result.push(arr1.shift());
        }
        else if (arr1[0].value <= arr2[0].value) {
            result.push(arr1.shift());
        }
        else {
            result.push(arr2.shift());
        }
    }

    return result;
};