define([
    "./session",
    "dojo/Deferred",
    "dojo/on",
    "dojo/request"
], function(session, Deferred, on, request) {

    var user = session.get();
    var queue = [];
    
    on(session, 'change', function(newUser) {
        user = newUser;
        if ( user ) {
            retry();
        }
    });
    
    function retry() {
        if (queue.length > 0) {
            var item = queue.shift();
            console.log("Retry",item.url);
            real_request(item);
        }
    }
    
    function real_request(item) {
        var req = request(item.url,item.options);

        // forward successfull response
        req.then(function(body){
            item.dfd.resolve(body);
        });

        // handle unauthenticated and queued requests
        req.response.then(function(response){
            retry();
        }, function(error) {
            if ( error.response.status === 401 ) {
                queue.unshift(item);
                session.restore();
            } else {
                item.dfd.reject(error); // this should be error body
                                        // not, the request?
                retry();
            }
        });
    }
    
    var _request = function(url, options) {
        var item = {
            url: url,
            options: options,
            dfd: new Deferred()
        };
        // only do the request directly if we are authenticated and
        // there are no earlier requests queued.
        if ( user && queue.length === 0 ) {
            console.log("Request",url);
            real_request(item);
        } else {
            console.log("Push",url);
            queue.push(item);
        }
        return item.dfd.promise;
    };

    return _request;
});