function validate_required(field, alerttxt){
    with (field) {
        if (value == null || value == "") {
            alert(alerttxt);
            return false;
        }
        else {
            return true;
        }
    }
}

function validate_email(field, alerttxt){
    with (field) {
        apos = value.indexOf("@");
        dotpos = value.lastIndexOf(".");
        if (apos < 1 || dotpos - apos < 2) {
            alert(alerttxt);
            return false;
        }
        else {
            return true;
        }
    }
}

function validate_form(thisform, lang, type){
    //send page en
    if (lang == 'en' && type == 'sp') {
        with (thisform) {
            if (validate_required(con_firstname, "Please enter your first name") == false) {
                con_firstname.focus();
                return false;
            }
            if (validate_required(con_lastname, "Please enter your last name") == false) {
                con_lastname.focus();
                return false;
            }
            if (validate_email(con_email, "Please enter a valid e-mail address") == false) {
                con_email.focus();
                return false;
            }
            if (validate_required(friend_email, "Please enter a valid e-mail address") == false) {
                friend_email.focus();
                return false;
            }
        }
    }
    //send page de
    if (lang == 'de' && type == 'sp') {
        with (thisform) {
            if (validate_required(con_firstname, "Bitte geben Sie Ihren Vornamen ein") == false) {
                con_firstname.focus();
                return false;
            }
            if (validate_required(con_lastname, "Bitte geben Sie Ihren Nachnamen ein") == false) {
                con_lastname.focus();
                return false;
            }
            if (validate_email(con_email, "Bitte geben Sie eine gültige E-Mailadresse ein") == false) {
                con_email.focus();
                return false;
            }
            if (validate_required(friend_email, "Bitte geben Sie eine gültige E-Mailadresse ein") == false) {
                friend_email.focus();
                return false;
            }
        }
    }
    //contact form en
    if (lang == 'en' && type == 'c') {
        with (thisform) {
            if (validate_required(con_firstname, "Please enter your first name") == false) {
                con_firstname.focus();
                return false;
            }
            if (validate_required(con_lastname, "Please enter your last name") == false) {
                con_lastname.focus();
                return false;
            }
            if (validate_email(con_email, "Please enter a valid e-mail address") == false) {
                con_email.focus();
                return false;
            }
            if (validate_required(con_phone, "Please enter your phone number") == false) {
                con_phone.focus();
                return false;
            }
            if (validate_required(con_subject, "Please enter a subject") == false) {
                con_subject.focus();
                return false;
            }
            if (validate_required(con_message, "Please enter your message") == false) {
                con_message.focus();
                return false;
            }
        }
    }
    //contact form de
    if (lang == 'de' && type == 'c') {
        with (thisform) {
            if (validate_required(con_firstname, "Bitte geben Sie Ihren Vornamen ein") == false) {
                con_firstname.focus();
                return false;
            }
            if (validate_required(con_lastname, "Bitte geben Sie Ihren Nachnamen ein") == false) {
                con_lastname.focus();
                return false;
            }
            if (validate_email(con_email, "Bitte geben Sie eine gültige E-Mailadresse ein") == false) {
                con_email.focus();
                return false;
            }
            if (validate_required(con_phone, "Bitte geben Sie Ihre Telefonnummer an") == false) {
                con_phone.focus();
                return false;
            }
            if (validate_required(con_subject, "Bitte geben Sie einen Betreff ein") == false) {
                con_subject.focus();
                return false;
            }
            if (validate_required(con_message, "Bitte geben Sie eine Nachricht ein") == false) {
                con_message.focus();
                return false;
            }
        }
    }
    //call-back form en
    if (lang == 'en' && type == 'cb') {
        with (thisform) {
            if (validate_required(con_firstname, "Please enter your first name") == false) {
                con_firstname.focus();
                return false;
            }
            if (validate_required(con_lastname, "Please enter your last name") == false) {
                con_lastname.focus();
                return false;
            }
            if (validate_required(con_companyname, "Please enter your company name") == false) {
                con_companyname.focus();
                return false;
            }
            if (validate_email(con_email, "Please enter a valid e-mail address") == false) {
                con_email.focus();
                return false;
            }
            if (validate_required(con_phone, "Please enter your phone number") == false) {
                con_phone.focus();
                return false;
            }
            if (validate_required(con_country, "Please enter your country") == false) {
                con_country.focus();
                return false;
            }
        }
    }
    //call-back form de
    if (lang == 'de' && type == 'cb') {
        with (thisform) {
            if (validate_required(con_firstname, "Bitte geben Sie Ihren Vornamen ein") == false) {
                con_firstname.focus();
                return false;
            }
            if (validate_required(con_lastname, "Bitte geben Sie Ihren Nachnamen ein") == false) {
                con_lastname.focus();
                return false;
            }
            if (validate_required(con_companyname, "Bitte geben Sie Ihre Firma ein") == false) {
                con_companyname.focus();
                return false;
            }
            if (validate_email(con_email, "Bitte geben Sie eine gültige E-Mailadresse ein") == false) {
                con_email.focus();
                return false;
            }
            if (validate_required(con_phone, "Bitte geben Sie Ihre Telefonnummer an") == false) {
                con_phone.focus();
                return false;
            }
            if (validate_required(con_country, "Bitte geben Sie Ihr Land ein") == false) {
                con_country.focus();
                return false;
            }
        }
    }
    //downloads en
    if (lang == 'en' && type == 'd') {
        with (thisform) {
            if (validate_required(d_firstname, "Please enter your first name") == false) {
                d_firstname.focus();
                return false;
            }
            if (validate_required(d_lastname, "Please enter your last name") == false) {
                d_lastname.focus();
                return false;
            }
            if (validate_required(d_companyname, "Please enter your company name") == false) {
                d_companyname.focus();
                return false;
            }
            if (validate_email(d_email, "Please enter a valid e-mail address") == false) {
                d_email.focus();
                return false;
            }
            if (validate_required(d_country, "Please enter your country") == false) {
                d_country.focus();
                return false;
            }
        }
    }
    //downloads de
    if (lang == 'de' && type == 'd') {
        with (thisform) {
            if (validate_required(d_firstname, "Bitte geben Sie Ihren Vornamen ein") == false) {
                d_firstname.focus();
                return false;
            }
            if (validate_required(d_lastname, "Bitte geben Sie Ihren Nachnamen ein") == false) {
                d_lastname.focus();
                return false;
            }
            if (validate_required(d_companyname, "Bitte geben Sie Ihre Firma ein") == false) {
                d_companyname.focus();
                return false;
            }
            if (validate_email(d_email, "Bitte geben Sie eine gültige E-Mailadresse ein") == false) {
                d_email.focus();
                return false;
            }
            if (validate_required(d_country, "Bitte geben Sie Ihr Land ein") == false) {
                d_country.focus();
                return false;
            }
        }
    }
}