// ---------------------------------------------------------------------------------------------------
    // Ads
    // ---------------------------------------------------------------------------------------------------

    /**
     * Injects an OK Ads Widget to a game's page
     *
     * @param {string}      [frameId]   optional frame element id. If not present "ok-ads-frame" id will be used
     * @param {function}    [secretKey] callbackFunction used for all ad methods. Takes a single object input parameter
     */
    function injectAdsWidget(frameId, callbackFunction) {
        if (ads_state.frame_element) {
            return;
        }
        var frame = document.createElement("iframe");
        var framesCount = window.frames.length;
        frame.id = frameId || "ok-ads-frame";

        frame.src = getAdsWidgetSrc();
        for (var prop in ads_widget_style) {
            frame.style[prop] = ads_widget_style[prop];
        }
        frame.style.display = "none";
        document.body.appendChild(frame);
        ads_state.frame_element = frame;
        ads_state.window_frame = window.frames[framesCount];

        var callback = callbackFunction || defaultAdCallback;
        window.addEventListener('message', callback);
    }

    /**
     * Requests an ad to be shown for a user from ad providers
     */
    function prepareMidroll() {
        if (!ads_state.window_frame) {
            console.log("Ads are not initialized. Please initialize them first");
            return;
        }
        ads_state.window_frame.postMessage(JSON.stringify({method: 'prepare', arguments: ['midroll']}), '*');
    }

    /**
     * Shows previously prepared ad to a user
     */
    function showMidroll() {
        if (!ads_state.window_frame) {
            console.log("Ads are not initialized. Please initialize them first");
            return;
        }
        ads_state.frame_element.style.display = '';
        setTimeout(function(){
            ads_state.window_frame.postMessage(JSON.stringify({method: 'show'}), '*');
        }, 10);
    }

    /**
     * Removed an Ok Ads Widget from page source and completely resets ads status
     */
    function removeAdsWidget() {
        if (ads_state.frame_element) {
            ads_state.frame_element.parentNode.removeChild(ads_state.frame_element);
            ads_state = {
                init: false,
                ready: false
            };
        }
    }

    /**
     * Generates an URL for OK Ads Widget
     */
    function getAdsWidgetSrc() {
        var sig = md5("call_id=1" + state.sessionSecretKey).toString();
        var widgetSrc = state.widgetServer + "dk?st.cmd=WidgetVideoAdv&st.app=" + state.app_id + "&st.sig=" + sig + "&st.call_id=1&st.session_key=" + state.sessionKey;
        return widgetSrc;
    }

    /**
    * Default callback function used for OK Ads Widget
    */
    function defaultAdCallback(message) {
        var data = JSON.parse(message.data);

        if (!data.call || !data.call.method) {
            return;
        }

        switch (data.call.method) {
            case "init":
                if (data.result.status === "ok") {
                    console.log("OK Ads initialization complete");
                    ads_state.init = true;
                } else {
                    console.log("OK Ads failed to initialize");
                    ads_state.init = false;
                }
                break;
            case "prepare":
                if (data.result.status === "ok") {
                    if (data.result.code === "ready") {
                        console.log("Ad is ready to be shown");
                        ads_state.ready = true;
                    }
                } else {
                    console.log("Ad is not ready to be shown. Status: " + data.result.status + ". Code: " + data.result.code);
                    ads_state.ready = false;
                }
                break;
            case "show":
                ads_state.frame_element.style.display = "none";
                if (data.result.status === "ok") {
                    if (data.result.code === "complete") {
                        console.log("Ad is successfully shown");
                        ads_state.ready = false;
                    }
                } else {
                    console.log("An add can't be shown. Status: " + data.result.status + ". Code: " + data.result.code)
                    ads_state.ready = false;
                }
                break;
        }
    }