getClientCredentialsToken method

@override Future<OAuthToken> getClientCredentialsToken({ List<String>? scopes, })

Get token using client credentials

Implementation

@override
Future<OAuthToken> getClientCredentialsToken({List<String>? scopes}) async {
  final metadata = await _discoverMetadata();

  final body = <String, String>{
    'grant_type': 'client_credentials',
    'client_id': config.clientId,
    if (scopes != null && scopes.isNotEmpty) 'scope': scopes.join(' '),
  };

  final headers = <String, String>{
    'Content-Type': 'application/x-www-form-urlencoded',
    'Accept': 'application/json',
  };

  if (config.clientSecret != null) {
    final credentials = base64Encode(
      utf8.encode('${config.clientId}:${config.clientSecret}'),
    );
    headers['Authorization'] = 'Basic $credentials';
  }

  final response = await _httpClient.post(
    Uri.parse(metadata.tokenEndpoint),
    headers: headers,
    body: body.entries
        .map((e) => '${e.key}=${Uri.encodeComponent(e.value)}')
        .join('&'),
  );

  final json = jsonDecode(response.body) as Map<String, dynamic>;

  if (response.statusCode != 200) {
    throw OAuthError.fromJson(json);
  }

  return OAuthToken.fromJson(json);
}