(function () {
    var domconf_event_prefix = "event_";
    function domconf(domobj, obj) {
        var key;
        for (key in obj) {
            if (key.substring(0, domconf_event_prefix.length) == domconf_event_prefix) {
                domobj.addEventListener(
                    key.substring(domconf_event_prefix.length), obj[key]
                );
            } else {
                domobj.setAttribute(key, obj[key])
            }
        }
        return domobj;
    }

    function tag(tag_name, obj) {
        return domconf(document.createElement(tag_name), obj);
    }

    function HubClient(ws_uri, open, close, message) {
        this.close = close.bind(this);
        this.message = message.bind(this);
        this.open = open.bind(this);
        this.ws = domconf(
            new WebSocket(
                {"http:": "ws:", "https:": "wss:"}[window.location.protocol] +
                "//" +
                window.location.host +
                ws_uri
            ),
            {
                "event_close": this.close,
                "event_message": this.message,
                "event_open": this.open,
            },
        );
        this.send = this.ws.send.bind(this.ws);
    }

    function write(output, msg) {
        if (output.childNodes.length > 0) {
            output.append(tag("br"));
        }
        if (typeof msg !== "string") {
            msg = String(msg);
        }
        output.append(document.createTextNode(msg));
    }

    function setup(callback) {
        domconf(
            document,
            {
                "event_readystatechange": function (event) {
                    if (!event) {
                        event = window.event;
                    }
                    if (event.target.readyState !== "complete") {
                        return;
                    }
                    callback(event);
                }
            },
        );
    }

    function make_key_event(callback) {
        var wrapper = function (event) {
            event = event || window.event;
            callback(event, event.target || event.srcElement, event.code || event.key);
        };
        return wrapper;
    }

    function input_with_keydown_event(callback) {
        return common.tag("input", {"event_keydown": make_key_event(callback)});
    }

    window.common = {
        "tag": tag,
        "HubClient": HubClient,
        "write": write,
        "setup": setup,
        "input_with_keydown_event": input_with_keydown_event,
    };
}());