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

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, 773, 774, 775, 776, 777);
    var o2 = new Array(601, 602, 606, 607, 720, 721, 722, 723, 724, 725, 726, 727, 728, 729);

    if (document.getElementById('moved').value) {
        operator = getSelectedValue(document.getElementById('smsOperatorSelect'));
        document.getElementById('smsOperators').style.display='block';
        }

    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') {
        document.getElementById('maxChars').innerHTML = 760;
        document.getElementById('operator').innerHTML = 'Vodafone';
        document.getElementById('captchaO2').style.display = 'none';
        document.getElementById('captchaTmobile').style.display = 'none';
        document.getElementById('captchaVodafone').style.display = 'block';
        document.getElementById('odesilatel').style.display = 'block';
    }
    else {
        if(operator == 'o2') {
            document.getElementById('maxChars').innerHTML = 60;
            document.getElementById('operator').innerHTML = 'O2';
            document.getElementById('captchaVodafone').style.display = 'none';
            document.getElementById('captchaTmobile').style.display = 'none';
            document.getElementById('captchaO2').style.display = 'block';
            document.getElementById('odesilatel').style.display = 'none';
        }
        else {
            document.getElementById('maxChars').innerHTML = 160;
            document.getElementById('operator').innerHTML = 'Tmobile';
            document.getElementById('captchaVodafone').style.display = 'none';
            document.getElementById('captchaO2').style.display = 'none';
            document.getElementById('captchaTmobile').style.display = 'block';
            document.getElementById('odesilatel').style.display = 'none';
        }
    }
}

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

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

}

function inicialize() {
    captcha_change();
    check_length();
    document.getElementById('smsVodafoneCaptcha').value = '';
    document.getElementById('smsTmobileCaptcha').value = '';
    document.getElementById('smsO2Captcha').value = '';
}