(function () {
    "use strict";

    var API_URL_ROOT = "/expo-b/get-banners/";

    var getUrl = function () {
        var data = window.sendData;

        if (data instanceof Object) {
            var search = [];

            for (var key in data) {
                if (data.hasOwnProperty(key)) {
                    var value = data[key];

                    if (value instanceof Array) {
                        for (var i = 0, l = value.length; i < l; i++) {
                            search.push(encodeURIComponent(key) + "=" + encodeURIComponent(value[i]));
                        }
                    } else {
                        search.push(encodeURIComponent(key) + "=" + encodeURIComponent(value));
                    }
                }
            }

            if (search.length) {
                return API_URL_ROOT + "?" + search.join("&");
            }
        }

        return API_URL_ROOT;
    };

    var getBanners = function (url, callback) {
        var xhr = new XMLHttpRequest();
        xhr.open("GET", url, true);

        xhr.onreadystatechange = function (event) {
            if (event.target.readyState === 4) {
                if (event.target.status === 200) {
                    try {
                        callback(JSON.parse(event.target.responseText));
                    } catch (error) {
                        // do nothing
                    }
                }
            }
        };

        xhr.send();
    };

    var addBanner = function (banner) {
        var parent = document.getElementById(banner.id);

        if (parent) {
            if (banner.is_img) {
                var a = document.createElement("a");
                a.href = banner.url;

                var img = document.createElement("img");
                img.src = banner.img;
                img.alt = banner.alt;

                a.appendChild(img);
                parent.appendChild(a);
            } else if (banner.is_html) {
                parent.innerHTML = banner.text;
            }
        }

    };

    var insertBanners = function (data) {
        if (data instanceof Array) {
            for (var i = 0, l = data.length; i < l; i++) {
                addBanner(data[i]);
            }
        }
    };

    var main = function () {
        getBanners(getUrl(), insertBanners);
    };

    window.addEventListener("load", main);
})();