var permissions = ['create_event' , 'manage_pages'];
var loggedIn;

document.addEvent('domready',function(){
        FB.Event.subscribe('auth.logout', function(response) {
            loggedIn = false; // get, if the user logs off on facebook to prohibit posts
        });
        FB.Event.subscribe('auth.login', function(response) {
            loggedIn = true; // get, if the user logs off on facebook to prohibit posts
        });

        FB.getLoginStatus(function(response) {
            if (response.session) { // facebook session was found
                checkPerms(response.perms);
                FB.api('/me', function(response) {
                    createSessionStatus(response); // set the session status and generate a logou butom
                    loggedIn = true;
                });
            } else {
                createLoginElement(); // no session was found so generate a login button
            }
        });

        myFacebookBackend = new FacebookBackend();
    });

/*
    Function: checkPerms

    Function checks if the user has granted sufficient permissions

*/
function checkPerms(perms){
    var extendedPermissions = JSON.decode(perms).extended; // get the granted permissions and check if we need more
    permissions.each(function(item){
        if(!extendedPermissions.contains(item))
            facebook_login(); // we need more permissions so call login
    });
}

/*
    Function: getPermsAndCheck

    Function gets the granted permissions and then checks wheter they are sufficient

*/
function getPermsAndCheck(){
        FB.getLoginStatus(function(response) {
            if (response.session) { // facebook session was found
                checkPerms(perms);
            };
        });
}

/*
   Function: facebook_logout

   Logs the current user out and creates an login-Element.

*/
function facebook_logout(){
    FB.logout(function(response) {
        createLoginElement();
    });
}


/*
   Function: facebook_login

   Logs the user in to facebook and trys to get oermissions granted.

*/
function facebook_login(){
    FB.login(function(response){
        if (response.session){
            if (response.perms){
                FB.api('/me', function(response){
                    createSessionStatus(response);
                });
            } else {
                createLoginElement(); // logged in but not all permissions
                return;
            }
        } else {
            createLoginElement(); // not logged in
            return;
        }
    },{perms: permissions.toString()});
}


/*
   Function: createLoginElement

   Ccreates a link for loggin in to facebook.

*/
function createLoginElement(){
    var element = $('facebook_session');
    var loginElement = new Element('a', {'onClick' : 'facebook_login()', 'html' : 'Login to facebook'}).inject(element);
}


/*
   Function: createSessionStatus

   Creates a overview of the actual sessions and an logout button.

   Parameters:

      response - The facebook API response.
*/
function createSessionStatus(response){
    var element = $('facebook_session');
    element.empty();
    var loginStatus = new Element('span.text', {'html' : 'Logged in to facebook as ' + response.name + ' // '}).inject(element);
    var logout = new Element('a', {'onClick' : 'facebook_logout()', 'html' : 'Logout'}).inject(loginStatus);
}

/**
 * Class FacebookBackend
 */

var FacebookBackend = new Class({
    Implements: [Options],

    //Properties

    /**
     * Initialize
     */
    initialize: function(options){
        this.setOptions(options);
    },

    // posts the selected event to facebook
    // TODO: correct the timestamps!!
    postToFacebook: function(event, eventId, el){
        FB.api('/events', 'post',{ name: event[0].title, start_time:1272718027, location:"Beirut", page_id : event[0].fbId},
                function(response) {
                    console.log(response);
                    new Request.JSON(
                    {
                        url: window.location.href,
                        data: 'isAjax=1&action=fillFacebookEventId&id=' + eventId + '&facebookEventId=' + response.id,
                        onComplete: function()
                        {
                            AjaxRequest.hideBox();
                        },
                        onFailure: function()
                        {
                            alert('failed to post facebookEventId');
                        },
                        onSuccess: function(result)
                        {
                            el.getChildren().set( {src: 'system/modules/calendar/html/fb_on.gif'});
                        }
                    }).send();
                });
    },

    // gets the selected event as JSON
    getEvent2: function(el, eventId){
        var self = this;
        new Request.JSON(
        {
            url: window.location.href,
            data: 'isAjax=1&action=getEvent&id=' + eventId,
            onRequest: function()
            {
                AjaxRequest.displayBox('Loading data …');
            },
            onFailure: function()
            {
                alert('failed to get event');
            },
            onSuccess: function(event)
            {
                if(loggedIn){ // check if the user is logged in on facebook
                    if(!event[0].facebookEid)
                        self.postToFacebook(event, eventId, el);
                } else {
                    AjaxRequest.hideBox();
                    alert('You need to be logged in to facebook. Use the \'Login-Buttont\'in the right top corner to login');
                }
            }
        }).send();
        return false;
    },

    getEvent: function(eventId){
        var self = this;
        var result;
        new Request.JSON({
            async: false,
            url: window.location.href,
            data: 'isAjax=1&action=getEvent&id=' + eventId,
            onRequest: function()
            {
                AjaxRequest.displayBox('Loading data …');
            },
            onFailure: function()
            {
                alert('failed to get event');
            },
            onSuccess: function(event)
            {
                result = event;
            }
        }).send();
        return result;
    },

    publishEventOnFacebook: function(el, eventId){
        var self = this;
        var event = this.getEvent(eventId);
            FB.api('/events', 'post',{ name: event[0].title, start_time:1272718027, location:"Beirut", page_id : event[0].fbId},
                function(response) {
                    new Request.JSON(
                    {
                        url: window.location.href,
                        data: 'isAjax=1&action=fillFacebookEventId&id=' + eventId + '&facebookEventId=' + response.id,
                        onComplete: function()
                        {
                            AjaxRequest.hideBox();
                        },
                        onFailure: function()
                        {
                            alert('failed to post facebookEventId');
                        },
                        onSuccess: function(result)
                        {
                            el.set( {onclick: 'Backend.getScrollOffset(); return myFacebookBackend.deleteEventOnFacebook(this, ' + eventId + ')'})
                            el.getChildren().set( {src: 'system/modules/calendar/html/fb_on.gif'});
                        }
                    }).send();
            });
        return false;
    },

    deleteEventOnFacebook: function(el,eventId){
        var self = this;
        var event = this.getEvent(eventId);
            FB.api('/' + event[0].facebookEid, 'delete', { },
                function(response) {
                    new Request.JSON(
                    {
                        url: window.location.href,
                        data: 'isAjax=1&action=deleteFacebookEventId&id=' + eventId,
                        onComplete: function()
                        {
                            AjaxRequest.hideBox();
                        },
                        onFailure: function()
                        {
                            alert('failed to post facebookEventId');
                        },
                        onSuccess: function(result)
                        {
                            el.set( {onclick: 'Backend.getScrollOffset(); return myFacebookBackend.publishEventOnFacebook(this, ' + eventId + ')'});
                            el.getChildren().set( {src: 'system/modules/calendar/html/fb_off.gif'});
                            console.log(result);
                        }
                    }).send();
            });
        return false;
    }

    // TODO: $a = $this->api->api("/{$this->id}", "DELETE" , '');
    // delete event on facebook
})