timer

function Timer() {
    this.timer = 0;
    this.time = null;
    this.lvl = 0;
    this.initialValue = 0;
    this.currentValue = 0;
    this.periodCallback = null;
    this.endCallback = null;
    this.o = this;

    this.formatTime = function () {
        var currentValueTmp = this.currentValue;
        var seconds, minutes, hours, days;
        var seconds1 = '';
        var minutes1 = '';
        var hours1 = '';
        var days1 = '';
        switch (this.lvl) {
            case 4:
                days = Math.floor(currentValueTmp / 86400);
                currentValueTmp = currentValueTmp - days * 86400;
                days1 = days + '';
                if (days1.length < 2) days1 = '0' + days1;
            case 3:
                hours = Math.floor(currentValueTmp / 3600);
                currentValueTmp = currentValueTmp - hours * 3600;
                hours1 = hours + '';
                if (hours1.length < 2) hours1 = '0' + hours1;
            case 2:
                minutes = Math.floor(currentValueTmp / 60);
                currentValueTmp = currentValueTmp - minutes * 60;
                minutes1 = minutes + '';
                if (minutes1.length < 2) minutes1 = '0' + minutes1;
            case 1:
                seconds = currentValueTmp;
                seconds1 = seconds + '';
                if (seconds1.length < 2) seconds1 = '0' + seconds1;
        }

        this.time = {
            days: days1,
            hours: hours1,
            minutes: minutes1,
            seconds: seconds1
        };
    };

    this.subtractTimer = function () {
        if (this.currentValue > 0) {
            this.formatTime();
            if (typeof this.periodCallback === 'function') {
                this.periodCallback(this.time);
            }
        } else {
            if (typeof this.endCallback === 'function') {
                this.endCallback();
            }
            this.time = {
                days: '00',
                hours: '00',
                minutes: '00',
                seconds: '00'
            };
        }
        this.currentValue--;
    };

    this.kill = function () {
        clearInterval(this.timer);
    };

    this.setPeriodCallback = function (callback) {
        this.periodCallback = callback;
        return this;
    };

    this.setEndCallback = function (callback) {
        this.endCallback = callback;
        return this;
    };

    this.setDisplay = function (lvl) {
        this.lvl = lvl;
        return this;
    };

    this.start = function (value) {
        this.initialValue = parseInt(value);
        var ob = this.o;
        clearInterval(this.timer);
        if (parseInt(this.lvl) === 0) {
            this.lvl = 1;
            if (this.initialValue > 60)
                this.lvl = 2;
            if (this.initialValue > 3600)
                this.lvl = 3;
            if (this.initialValue > 86400)
                this.lvl = 4;
        }
        this.currentValue = this.initialValue;
        this.timer = setInterval(function () {
            if (ob.currentValue >= 0) {
                ob.subtractTimer();
            }
            else {
                ob.kill();
            }
        }, 1000);
    }
}