function getSelectedValue(select) {
    var index = select.selectedIndex;
    if ((index >= 0) && (index < select.length)) {
      return select.options[index].value;
    }
    return '';
}

function id(id) {
    return document.getElementById(id);
}

function operator_guess(number) {
    number = '^' + number;
    number = number.replace(' ', '');
    number = number.replace('^+420', '^');
    number = number.replace('^00420', '^');
    number = number.replace('^', '');
    var pre = number.substring(0, 3);
    
    var vodafone = new Array(608, 771, 772, 773, 774, 775, 776, 777, 778, 779);
    var o2 = new Array(601, 602, 606, 607, 720, 721, 722, 723, 724, 725, 726, 727, 728, 729);

    if (getSelectedValue(id('smsOperatorSelect'))) {
        operator = getSelectedValue(id('smsOperatorSelect'));
        }

    else {
        var operator = 't-mobile';
        for (i = 0; i<vodafone.length; i++){
            if (vodafone[i] == pre) {
                operator = 'vodafone';
                break;
            }
        }
        for (i = 0; i<o2.length; i++){
            if (o2[i] == pre) {
                operator = 'o2';
                break;
            }
        }
    }

    if (operator == 'vodafone') {
        id('maxChars').innerHTML = 760;
        if (id('captchaO2')) id('captchaO2').style.display = 'none';
        else id('captchas').style.display = 'none';
        id('captchaTmobile').style.display = 'none';
        id('captchaVodafone').style.display = 'block';
        id('odesilatel').style.display = 'block';
    }
    else {
        if(operator == 'o2') {
            if (id('captchaO2')) id('maxChars').innerHTML = 60;
            else id('maxChars').innerHTML = 160;
            id('captchaVodafone').style.display = 'none';
            id('captchaTmobile').style.display = 'none';
            id('odesilatel').style.display = 'none';
            if (id('captchaO2')) id('captchaO2').style.display = 'block';
            else {
                id('captchas').style.display = 'block';
                return false;
            }
        }
        else {
            id('maxChars').innerHTML = 160;
            id('captchaVodafone').style.display = 'none';
            if (id('captchaO2')) id('captchaO2').style.display = 'none';
            else id('captchas').style.display = 'none';
            id('captchaTmobile').style.display = 'block';
            id('odesilatel').style.display = 'none';
        }
    }
    return true
}

function captcha_change() {
    var number = id('smsNumber').value;
    if (number.length >= 3 || getSelectedValue(id('smsOperatorSelect'))) {
        show = operator_guess(number);
        if(show) id('captchas').style.display = 'block';
        else id('captchas').style.display = 'none';
    }
    else {
        id('captchas').style.display = 'none';
        id('odesilatel').style.display = 'none';
    }
    if (id('moved').value && !getSelectedValue(id('smsOperatorSelect'))) {
        id('captchas').style.display = 'none';
        id('odesilatel').style.display = 'none';
    }
}

function check_length(element) {
    var text = id('smsText');
    var maxchars = id('maxChars').innerHTML;
    if(text.value.length > maxchars) {
        text.value = text.value.substring(0, maxchars);
    }
    id('usedChars').innerHTML = text.value.length;

}

function inicialize() {
    captcha_change();
    check_length();
    id('smsVodafoneCaptcha').value = '';
    id('smsTmobileCaptcha').value = '';
    if (id("smsO2Captcha")) id('smsO2Captcha').value = '';
}