public Task <string> FetchBalances()
{
var callbackUrl = Request.Url.ToString();
// retrieve CSRF token from browser cookie
var csrfToken = Request.Cookies["csrf_token"];
return(GetPfmMember()
// check CSRF token and retrieve state and token ID from callback parameters
.FlatMap(mem => tokenClient.ParseTokenRequestCallbackUrl(callbackUrl, csrfToken.Value)
// use access token's permissions from now on
.Map(callback => mem.ForAccessToken(callback.TokenId)))
.FlatMap(representable => representable.GetAccounts())
.FlatMap(async accounts =>
{
// for each account, get its balance
var balanceTasks = accounts.Select(account => account.GetBalance(Key.Types.Level.Standard));
var balances = await Task.WhenAll(balanceTasks);
// respond to script.js with JSON
return "{\"balances\":["
+ string.Join(",", balances.Select(bal => JsonConvert.SerializeObject(bal.Current)))
+ "]}";
}));
}