protected Uri GetUrl(HttpContextBase context)
{
Contract.Requires(context != null);
Contract.Requires(context.Request != null);
Contract.Ensures(Contract.Result <Uri>() != null);
// TODO: need unit tests for this method, might as well need to refactor this method.
UriBuilder redirectUriBuilder;
if (!context.Request.QueryString.AllKeys.Contains("state"))
{
// todo: better to redirect to the default canvas page.
return(new Uri("http://www.facebook.com"));
}
// if state is present.
var state = Encoding.UTF8.GetString(FacebookUtils.Base64UrlDecode(context.Request.QueryString["state"]));
var json = (IDictionary <string, object>)JsonSerializer.Current.DeserializeObject(state);
// make it one letter character so more info can fit in.
// r -> return_url_path (full uri)
// c -> cancel_url_path (full uri)
// s -> user_state
FacebookOAuthResult oauthResult;
if (!FacebookOAuthResult.TryParse(context.Request.Url, out oauthResult))
{
// todo: better to redirect to the default canvas page.
return(new Uri("http://www.facebook.com"));
}
if (oauthResult.IsSuccess)
{
var returnUrl = json["r"].ToString();
redirectUriBuilder = new UriBuilder(returnUrl);
if (returnUrl.Contains("?"))
{
// incase return url path contains querystrings.
var returnUrlParts = returnUrl.Split('?');
if (returnUrlParts.Length == 2 && !string.IsNullOrEmpty(returnUrlParts[1]))
{
var queryStrings = FacebookUtils.ParseUrlQueryString(returnUrlParts[1]);
if (queryStrings.ContainsKey("error_reason"))
{
// remove oauth stuffs.
if (queryStrings.ContainsKey("error_reason"))
{
queryStrings.Remove("error_reason");
}
if (queryStrings.ContainsKey("error"))
{
queryStrings.Remove("error");
}
if (queryStrings.ContainsKey("error_description"))
{
queryStrings.Remove("error_description");
}
redirectUriBuilder.Query = FacebookUtils.ToJsonQueryString(queryStrings);
}
}
}
}
else
{
if (!json.ContainsKey("c"))
{
// there is no cancel url path
redirectUriBuilder = new UriBuilder("http://facebook.com");
}
else
{
var cancelUrl = json["c"].ToString();
IDictionary <string, object> cancelUrlQueryStrings = new Dictionary <string, object>
{
{ "error_reason", context.Request.QueryString["error_reason"] },
{ "error", context.Request.QueryString["error"] },
{ "error_description", context.Request.QueryString["error_description"] }
};
if (cancelUrl.Contains("?"))
{
// incase cancel url path contains querystrings.
var cancelUrlParts = cancelUrl.Split('?');
if (cancelUrlParts.Length == 2 && !string.IsNullOrEmpty(cancelUrlParts[1]))
{
var queryStrings = FacebookUtils.ParseUrlQueryString(cancelUrlParts[1]);
cancelUrlQueryStrings = FacebookUtils.Merge(cancelUrlQueryStrings, queryStrings);
}
}
redirectUriBuilder = new UriBuilder(cancelUrl)
{
Query = FacebookUtils.ToJsonQueryString(cancelUrlQueryStrings)
};
}
}
return(redirectUriBuilder.Uri);
}