/// <summary>
/// Acquires an OAuth 2.0 access token from Azure AD for use with the Records365 Connector API.
/// </summary>
/// <param name="settings"></param>
/// <param name="useTokenCache"></param>
/// <returns></returns>
public async Task <AuthenticationResult> AcquireTokenAsync(AuthenticationHelperSettings settings, bool useTokenCache = true)
{
ValidationHelper.ArgumentNotNull(settings, nameof(settings));
ValidationHelper.ArgumentNotNullOrWhiteSpace(settings.AuthenticationResource, nameof(settings.AuthenticationResource));
ValidationHelper.ArgumentNotNullOrWhiteSpace(settings.ClientId, nameof(settings.ClientId));
var authority = GetAuthority(settings);
// sign in & get an authentication token...
var authenticationContext = useTokenCache
// by default an internal token cache is used
? new AuthenticationContext(authority)
// pass a null token cache so that the token must be retrieved from the authority
: new AuthenticationContext(authority, null);
#if NETSTANDARD2_0
//NOTE: The following call may throw a PlatformNotSupported exception that occurs the first time a token is acquired.
//However, the exception will not raise beyond this point, and the call will automatically retry and resolved a token on the second attempt.
//This is due to the first (throwing) attempt actually acquiring a token, storing it in the AuthenticationContext token cache, and then throwing an exception regardless.
//Later attempts simply use the cached token and thus avoid the issue. While undocumented, it is believed that this is the intended functionality.
var aadAuthenticationResult = await authenticationContext.AcquireTokenAsync(settings.AuthenticationResource, new ClientCredential(settings.ClientId, SecureStringToString(settings.ClientSecret))).ConfigureAwait(false);
#else
var aadAuthenticationResult = await authenticationContext.AcquireTokenAsync(settings.AuthenticationResource, new ClientCredential(settings.ClientId, new SecureClientSecret(settings.ClientSecret))).ConfigureAwait(false);
#endif
return(new AuthenticationResult
{
AccessTokenType = aadAuthenticationResult.AccessTokenType,
AccessToken = aadAuthenticationResult.AccessToken
});
}
private string GetAuthority(AuthenticationHelperSettings settings)
{
ValidationHelper.ArgumentNotNullOrWhiteSpace(settings.TenantDomainName, nameof(settings.TenantDomainName));
return(AuthEndpointPrefix + settings.TenantDomainName);
}