/// <summary>
/// Validates the request parameters.
/// </summary>
/// <param name="requestParams">The request parameters to validate.</param>
/// <exception cref="InvalidParameterException">Is thrown when the parameters are invalid.</exception>
public static void ThrowIfInvalidForAuthorizationRequest(this OAuth2Config requestParams)
{
if (requestParams == null)
{
throw new InvalidParameterException(nameof(OAuth2Config));
}
if (string.IsNullOrWhiteSpace(requestParams.AuthorizeServiceEndpoint))
{
throw new InvalidParameterException(string.Format("{0}.{1}", nameof(OAuth2Config), nameof(OAuth2Config.AuthorizeServiceEndpoint)));
}
if (string.IsNullOrWhiteSpace(requestParams.ClientId))
{
throw new InvalidParameterException(string.Format("{0}.{1}", nameof(OAuth2Config), nameof(OAuth2Config.ClientId)));
}
if (string.IsNullOrWhiteSpace(requestParams.RedirectUrl))
{
throw new InvalidParameterException(string.Format("{0}.{1}", nameof(OAuth2Config), nameof(OAuth2Config.RedirectUrl)));
}
}
/// <summary>
/// Builds the url which shows the authorization page of the OAuth2 web service, where the
/// user can confirm that the app is allowed to use the service.
/// </summary>
/// <remarks>
/// Client-side apps should show the web page in an external browser (or Android custom tab)
/// and not inside a WebView of the application (requirement for login with Google account).
/// </remarks>
/// <param name="config">The parameters of the OAuth2 service. The parameters
/// can be read from the OAuth2 web service after registration of the app.</param>
/// <param name="stateParam">A random string which will be passed to the OAuth2 web service,
/// and is returned in the response. An application should persist this state so it can
/// verify the response.</param>
/// <param name="codeVerifier">An optional random string [43-128 chars a-z,A-Z,0-9] which
/// will be passed to the OAuth2 web service. An application should persist this code
/// verifier, because it is required to fetch the token.</param>
/// <returns>A url which can be used to show the authorization page.</returns>
public static string BuildAuthorizationRequestUrl(OAuth2Config config, string stateParam, string codeVerifier)
{
config.ThrowIfInvalidForAuthorizationRequest();
Url result = new Url(config.AuthorizeServiceEndpoint)
.SetQueryParams(new
{
response_type = config.Flow.ToString().ToLowerInvariant(),
client_id = config.ClientId,
redirect_uri = config.RedirectUrl,
scope = config.Scope,
state = stateParam
});
if (!string.IsNullOrWhiteSpace(codeVerifier))
{
result.SetQueryParams(new
{
code_challenge = HashCodeVerifier(codeVerifier),
code_challenge_method = "S256"
});
}
return(result);
}