(function() {
    const activeElement = document.activeElement;
    var inputs = ["input", "select", "textarea"];
    var pageUrl = window.location.href;
    var tagName = activeElement.tagName.toLowerCase();

    if (pageUrl === "https://mail.qq.com/" && activeElement) {
        // QQ mail have some security mechanism that we can't fetch value of activeElement.
        // So we just return empty string make is_focus method works well in browser.py
        return "";
    } else if (activeElement && inputs.indexOf(tagName) !== -1) {
        return activeElement.value;
    } else {
        if (pageUrl.startsWith("https://web.telegram.org/") && activeElement.hasAttribute("placeholder")) {
            return activeElement.textContent;
        } else if ((pageUrl.startsWith("https://console.cloud.google.com/") || pageUrl.startsWith("https://ssh.cloud.google.com/")) && tagName == "iframe") {
            // Make user can type text in Terminal of Google Cloud.
            return "";
        } else {
            return undefined;
        }
    }
})();