function changeAmount(objid,action)
{
    if ($(objid))
    {
        var currentValue = parseInt($(objid).value);
        if ( isNaN(currentValue) )
            $(objid).value = 1;
        else
        {
            if ( action == '+' )
                $(objid).value = currentValue + 1;
            else
                $(objid).value = Math.max(1, currentValue - 1);
        }
    }
    calculateTotal();
}

function checkNumeric(obj)
{
    if ( isNaN(obj.value) )
        obj.value = obj.value.replace(/[^0-9]/, '');
    calculateTotal();
}

function changeCountry(obj)
{
    if (!isNaN(obj.value))
    {
        var country = parseInt(obj.value);
        if ( country >= 4 && country <= 49 )
            $('p1price').innerHTML = '49.99 €';
        else
            $('p1price').innerHTML = '79.99 USD';
    }
    calculateTotal();
}

function calculateTotal()
{
    if (isNaN($('p1amount').value) || parseInt($('p1amount').value) < 1)
        $('p1amount').value = '1';
    var amountOfLicenses = parseInt($('p1amount').value);
    var country = parseInt($('countryselect').value);

    var currency = 'USD';
    var unitPrice = 79.99;

    if ( country >= 4 && country <= 49 )
    {
        currency = '€';
        unitPrice = 49.99;
    }
    
    var totalPrice = Math.round( (unitPrice * amountOfLicenses) * 100 ) / 100 ;
    $('grandtotal').innerHTML = totalPrice + ' ' + currency;
}

function validatePurchaseForm()
{
    var emptyFieldPresent = false;
    var fields = ['firstname','lastname','address1','zip','city','email'];
    if ( $('gift').checked )
    {
        fields.push('giftgiverfirstname');
        fields.push('giftgiverlastname');
        fields.push('giftgiveremail');
    }
    fields.each(function(field) {
                                    if ( $(field).value == '' )
                                    {
                                        $(field + '-warning').style.display = 'block';
                                        emptyFieldPresent = true;
                                    }
                                    else
                                        $(field + '-warning').style.display = 'none';
                                } )
    if ( emptyFieldPresent )
    {
        if ( $('warning').style.display == 'none' )
            Effect.BlindDown('warning', { duration:.2 });
    }
    else
        Effect.BlindUp('warning', { duration:.2 });
    return !emptyFieldPresent;
}

function validateContactForm()
{
    if ( $('contact-name').value == '' )
    {
        alert('Please enter your name.');
        return false;
    }
    if ( $('contact-email').value == '' )
    {
        alert('Please enter your email.');
        return false;
    }
    if ( $('contact-message').value == '' )
    {
        alert('Please enter a message.');
        return false;
    }
    return true;
}

function toggleGift()
{
    var checked = $('gift').checked;
    if ( checked )
        Effect.SlideDown('gifttable');
    else
        Effect.SlideUp('gifttable');
}