var createXHR = function() {
    if('all' in document && !('atob' in window) && 'XDomainRequest' in window)
        return new XDomainRequest;

    if('XMLHttpRequest' in window)
        return new XMLHttpRequest;

    if('ActiveXObject' in window)
        try {
            return new ActiveXObject('Msxml2.XMLHTTP');
        } catch(e) {
            try {
                return new ActiveXObject('Microsoft.XMLHTTP');
            } catch(e) {}
        }

    return null;
}

var getRemoteString = function(url, callback) {
    var xhr = createXHR();
    xhr.onload = function(ev) {
        callback({ success: true, info: ev, text: xhr.responseText });
    };
    xhr.onerror = function(ev) {
        callback({ success: false, info: ev });
    };
    xhr.open('GET', url);
    xhr.send();
};

var selectTextInElement = function(target) {
    // MSIE
    if(document.body.createTextRange) {
        var range = document.body.createTextRange();
        range.moveToElementText(target);
        range.select();
        return;
    }

    // Mozilla
    if(window.getSelection) {
        var select = window.getSelection(),
            range = document.createRange();
        range.selectNodeContents(target);
        select.removeAllRanges();
        select.addRange(range);
        return;
    }
};

var copySelectedText = function() {
    if(document.execCommand) {
        document.execCommand('copy');
        return;
    }
};

(function() {
    var fields = [
        { target: 'ipv4', ext: 'v4', clickTarget: 'ipv4-click' },
        { target: 'ipv6', ext: 'v6', clickTarget: 'ipv6-click' },
    ];

    for(var i in fields)
        (function(field) {
            var host = location.host.split('.');
            host[0] += field.ext;
            var url = location.protocol + '//' + host.join('.') + '/';

            getRemoteString(url, function(info) {
                var target = document.getElementById(field.target),
                    prop = 'textContent' in target ? 'textContent' : 'innerText';

                if(info.success) {
                    target[prop] = info.text;

                    if(field.clickTarget) {
                        var clickTarget = document.getElementById(field.clickTarget);
                        if(clickTarget)
                            clickTarget.onclick = function() {
                                selectTextInElement(target);
                                copySelectedText();
                            };
                    }
                } else
                    target[prop] = 'not available';
            });
        })(fields[i]);
})();