/// <summary>
/// Gets a valid authentication token. Also refreshes the access token if it has expired.
/// </summary>
/// <remarks>
/// Used by the API request generators before making calls to the OneNote APIs.
/// </remarks>
/// <returns>valid authentication token</returns>
internal static async Task <AuthenticationResult> GetAuthenticationResult()
{
if (String.IsNullOrEmpty(AccessToken))
{
try
{
//look to see if we have an authentication context in cache already
//we would have gotten this when we authenticated previously
var allCachedItems = AuthContext.TokenCache.ReadItems();
var validCachedItems = allCachedItems
.Where(i => i.ExpiresOn > DateTimeOffset.UtcNow.UtcDateTime && IsO365Token(i.IdentityProvider))
.OrderByDescending(e => e.ExpiresOn);
var cachedItem = validCachedItems.First();
if (cachedItem != null)
{
//re-bind AuthenticationContext to the authority source of the cached token.
//this is needed for the cache to work when asking for a token from that authority.
#if WINDOWS_PHONE_APP
AuthContext = AuthenticationContext.CreateAsync(cachedItem.Authority, true).GetResults();
#else
AuthContext = new AuthenticationContext(cachedItem.Authority, true);
#endif
//try to get the AccessToken silently using the resourceId that was passed in
//and the client ID of the application.
_authenticationResult = await AuthContext.AcquireTokenSilentAsync(GetResourceHost(ResourceUri), ClientId);
RefreshAuthTokenIfNeeded().Wait();
}
}
catch (Exception)
{
//not in cache; we'll get it with the full oauth flow
}
}
if (string.IsNullOrEmpty(AccessToken))
{
try
{
AuthContext.TokenCache.Clear();
#if WINDOWS_PHONE_APP
_authenticationResult = await AuthContext.AcquireTokenSilentAsync(GetResourceHost(ResourceUri), ClientId);
if (_authenticationResult == null || string.IsNullOrEmpty(_authenticationResult.AccessToken))
{
AuthContext.AcquireTokenAndContinue(GetResourceHost(ResourceUri), ClientId, new Uri(RedirectUri), null);
}
#else
_authenticationResult =
await AuthContext.AcquireTokenAsync(GetResourceHost(ResourceUri), ClientId, new Uri(RedirectUri));
#endif
}
catch (Exception)
{
// Authentication failed
if (Debugger.IsAttached)
{
Debugger.Break();
}
}
}
return(_authenticationResult);
}