vkUser = {};
APP_CLIENT_ID = '2692017';
APP_CLIENT_SECRET = 'rqIkXYBauPjqE2EVxB2j';
APP_SCOPE = 'notify,friends,photos,audio,video,docs,notes,wall,groups,messages,notifications,activity,status,pages,stats';
APP_API_VERSION = '5.3';

function showCaptcha(url, sid, cb, params) {
    var img = g('captcha-image');
    img.src = url;
    img.onload = function () {
        var wrapper = g('captcha-wrapper');
        var field = g('captcha-key');
        wrapper.classList.remove('hidden');
        field.focus();
        g('captcha-form').onsubmit = function () {
            params.captcha_key = val(field);
            params.captcha_sid = sid;
            wrapper.classList.add('hidden');
            this.reset();
            cb(params);
            return false;
        }
    }
}

function rawApi(method, cb, data) {
    if (isObject(data)) {
        data = QueryString.stringify(data);
    }
    var xhr = new CrossXHR;
    xhr.open('POST', 'https://api.vk.com/method/' + method);
    xhr.onreadystatechange = function() {
        if (xhr.readyState == 4) {
            if (xhr.status == 200) {
                cb();
            }
        }
    }
    xhr.send(data);
}

function api(method, cb, data) {
    data = data || {};
    if (data instanceof FormData) {
        data.append('v', APP_API_VERSION);
        data.append('access_token', vkUser.access_token);
    }
    else {
        data.v = APP_API_VERSION;
        data.access_token = vkUser.access_token;
    }
}

function login(params) {
    console.log(params);
    var xhr = new XMLHttpRequest;
    xhr.open('GET', 'ajax/vk_login.php?' + QueryString.stringify(params));
    xhr.onload = function () {
        if (xhr.status == 200) {
            r = JSON.parse(xhr.responseText);
            console.log(r);
            if (r.error) {
                if (r.error == 'need_captcha') {
                    showCaptcha(r.captcha_img, r.captcha_sid, login, params);
                }
                else {
                    alert('Error ' + r.error + ': ' + r.error_description);
                }
            }
            else {
                vkUser.access_token = r.access_token;
                vkUser.user_id = r.user_id;
                // тут получаем еще данные
            }
        }
    }
    xhr.send();
}

addEventListener('load', function () {
    if (localStorage.vkUser) {
        vkUser = JSON.parse(localStorage.vkUser);
        g('main-screen').classList.remove('hidden');
        // обновить информацию об пользователе
    }
    else {
        g('login-screen').classList.remove('hidden');
    }
    g('login-form').onsubmit = function () {
        var params = {
            username: val(this.login),
            password: val(this.password),
            grant_type: 'password',
            client_id: APP_CLIENT_ID,
            client_secret: APP_CLIENT_SECRET,
            scope: APP_SCOPE,
            v: APP_API_VERSION
        };
        login(params);
        return false;
    }
});