/// <summary>
/// Checks that a Graph client is available.
/// </summary>
/// <returns>The Graph client.</returns>
public static async Task <ActiveDirectoryClient> EnsureGraphClientCreatedAsync()
{
// Active Directory service endpoints
const string AadServiceResourceId = "https://graph.windows.net/";
Uri AadServiceEndpointUri = new Uri("https://graph.windows.net/");
try {
AuthenticationContext = new AuthenticationContext(AadAuthority);
TokenCacheItem cacheItem = null;
if (AuthenticationContext.TokenCache.ReadItems().Count() > 0)
{
// Bind the AuthenticationContext to the authority that sourced the token in the cache
// this is needed for the cache to work when asking for a token from that authority
// (the common endpoint never triggers cache hits)
cacheItem = AuthenticationContext.TokenCache.ReadItems().First();
AuthenticationContext = new AuthenticationContext(cacheItem.Authority);
}
else
{
// Nothing was found in the cache, so let's acquire a token.
var token = await AcquireTokenAsync(AuthenticationContext, AadServiceResourceId);
// Check the token
if (String.IsNullOrEmpty(token))
{
// User cancelled sign-in
return(null);
}
else
{
// If a token was acquired, the TokenCache will contain a TokenCacheItem containing
// all the details of the authorization.
cacheItem = AuthenticationContext.TokenCache.ReadItems().First();
}
}
// Store the Id of the logged-in user so that we can retrieve more user info later.
_loggedInUser = cacheItem.UniqueId;
// Create our ActiveDirectory client.
var client = new ActiveDirectoryClient(
new Uri(AadServiceEndpointUri, cacheItem.TenantId),
async() => await AcquireTokenAsync(AuthenticationContext, AadServiceResourceId));
return(client);
}
// 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 (DiscoveryFailedException dfe) {
MessageDialogHelper.DisplayException(dfe as Exception);
// Discovery failed.
AuthenticationContext.TokenCache.Clear();
return(null);
} 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);
}
}