shop2.queue.amount = function() {

    var $document = $(document);

    function validate(input) {
        var kind = input.data('kind'),
            max = input.data('max'),
            val = Number(input.val()),
            amount = 0,
            available,
            amount_min = parseFloat(input.data('min')),
            multiplicity = parseFloat(input.data('multiplicity'));

        if (kind && max > 0) {
            amount = Number(input.val());

            if (amount > max) {
                available = max - amount + val;
                input.val(available);

                available = available.toFixed(4) - 0;

                shop2.msg(_s3Lang.JS_AVAILABLE_ONLY + ' ' + available, input);
            }
        }

        if (amount_min || multiplicity) {

            if (multiplicity) {
                var x = (val - amount_min) % multiplicity;

                if (x < (multiplicity / 2)) {
                    val -= x;
                } else {
                    val += multiplicity - x;
                }

                if (amount_min === 1 && multiplicity > 1) {
                    val--;
                }

                val = val.toFixed(4) - 0;

                input.val(val);
            }

            if (amount_min > 0) {
                if (amount_min && val <= amount_min) {
                    input.val(amount_min);
                }
            } else {
                if (val <= shop2.options.amountDefaultValue) {
                    input.val(amountDefaultValue);
                }
            }

        }


    }

    $document.on('click', '.amount-minus', function() {
        var $this = $(this),
            text = $this.siblings('input:text'),
            value = text.getVal(),
            amount_min = parseFloat(text.data('min')),
            multiplicity = parseFloat(text.data('multiplicity'));

        if (value) {
            value = value[0];
        }

        if (amount_min && value <= amount_min) {
            return;
        }

        value = checkAmount(value, amount_min, multiplicity, -1);

        if (amount_min > 0) {
            if (value <= amount_min) {
                value = amount_min;
            }
        } else {
            if (value <= shop2.options.amountDefaultValue) {
                value = shop2.options.amountDefaultValue;
            }
        }



        text.val(value);
        text.trigger('change');
    });
    $document.on('click', '.amount-plus', function() {
        var $this = $(this),
            text = $this.siblings('input:text'),
            value = text.getVal(),
            amount_min = parseFloat(text.data('min')),
            multiplicity = parseFloat(text.data('multiplicity'));

        if (value) {
            value = value[0];
        }

        value = checkAmount(value, amount_min, multiplicity, 1);
        text.val(value);
        text.trigger('change');
    });

    function checkAmount(amount, amount_min, multiplicity, sign) {

        if (multiplicity > 0) {
            amount += multiplicity * sign;
        } else {
            amount += shop2.options.amountDefaultInc * sign;
        }

        amount = amount.toFixed(4) - 0;

        return amount
    }

    $document.on('change', '.shop2-product-amount input:text', function() {
        var $this = $(this);
        validate($this);
    });

    $document.keyFilter('.shop2-product-amount input:text', {
        type: shop2.options.amountType
    });

};