/// <summary>
/// Checks that an access token is available.
/// </summary>
/// <returns>The access token.</returns>
internal static async Task <string> EnsureAccessTokenAvailableAsync(string serviceResourceId)
{
try
{
// First, look for the authority used during the last authentication.
// If that value is not populated, use _commonAuthority.
string authority = null;
if (String.IsNullOrEmpty(_lastAuthority))
{
authority = _commonAuthority;
}
else
{
authority = _lastAuthority;
}
// Create an AuthenticationContext using this authority.
_authenticationContext = new AuthenticationContext(authority);
// Set the value of _authenticationContext.UseCorporateNetwork to true so that you
// can use this app inside a corporate intranet. If the value of UseCorporateNetwork
// is true, you also need to add the Enterprise Authentication, Private Networks, and
// Shared User Certificates capabilities in the Package.appxmanifest file.
//_authenticationContext.UseCorporateNetwork = true;
//Get the current app object, which exposes the ClientId and ReturnUri properties
// that we need in the following call to AcquireTokenAsync
App currentApp = (App)App.Current;
AuthenticationResult authenticationResult;
// An attempt is first made to acquire the token silently.
// If that fails, then we try to acquire the token by prompting the user.
authenticationResult = await _authenticationContext.AcquireTokenSilentAsync(serviceResourceId, currentApp.ClientId);
if (authenticationResult.Status != AuthenticationStatus.Success)
{
// Try to authenticate by prompting the user
authenticationResult = await _authenticationContext.AcquireTokenAsync(serviceResourceId, currentApp.ClientId, currentApp.ReturnUri);
// Check the result of the authentication operation
if (authenticationResult.Status != AuthenticationStatus.Success)
{
// Something went wrong, probably the user cancelled the sign in process
return(null);
}
}
// Store relevant info about user and resource
_loggedInUser = authenticationResult.UserInfo.UniqueId;
// The new last authority is in the form https://login.windows.net/{TenantId}
_lastAuthority = App.Current.Resources["ida:AuthorizationUri"].ToString() + "/" + authenticationResult.TenantId;
UserAccount = authenticationResult.UserInfo.DisplayableId;
ServiceResourceId = serviceResourceId;
// If the acccess token has changed
if (!String.Equals(_accessToken, authenticationResult.AccessToken))
{
// Raise an event to let other components know that the token has changed,
// so they can react accordingly (for example, updating the data source)
AccessTokenChanged(null, EventArgs.Empty);
// and store the new acces token
_accessToken = authenticationResult.AccessToken;
}
return(_accessToken);
}
// The following is a list of all exceptions you should consider handling in your app.
// In the case of this sample, the exceptions are handled by returning null upstream.
catch (MissingConfigurationValueException mcve)
{
MessageDialogHelper.DisplayException(mcve);
// Connected services not added correctly, or permissions not set correctly.
_authenticationContext.TokenCache.Clear();
return(null);
}
catch (AuthenticationFailedException afe)
{
MessageDialogHelper.DisplayException(afe);
// Failed to authenticate the user
_authenticationContext.TokenCache.Clear();
return(null);
}
catch (ArgumentException ae)
{
MessageDialogHelper.DisplayException(ae as Exception);
// Argument exception
_authenticationContext.TokenCache.Clear();
return(null);
}
}