Scripted REST Connector

init { HttpClientBuilder builder ->

        switch (ScriptedRESTConfiguration.AuthMethod.valueOf(c.defaultAuthMethod)) {
 // ......
            case ScriptedRESTConfiguration.AuthMethod.OAUTH:
                // define a request interceptor to set the Authorization header if absent or expired
                HttpRequestInterceptor requestInterceptor = { HttpRequest request, HttpContext context ->
                    if (null == context.getAttribute("oauth-request")) {
                        def exp = c.propertyBag.tokenExpiration as Long
                        if (c.propertyBag.accessToken == null || exp < System.currentTimeMillis() / 1000) {
                            new NewAccessToken(c).clientCredentials()
                        }
                        request.addHeader(new BasicHeader(HttpHeaders.AUTHORIZATION, "Bearer " + c.propertyBag.accessToken))
                    }
                }

                // define a response interceptor to catch a 401 response code and delete access token from cache
                HttpResponseInterceptor responseInterceptor = { HttpResponse response, HttpContext context ->
                    if (HttpStatus.SC_UNAUTHORIZED == response.statusLine.statusCode) {
                        if (c.propertyBag.accessToken != null) {
                            c.propertyBag.remove("accessToken")
                            Log.getLog(ScriptedRESTConnector.class).info("Code 401 - accessToken removed")
                        }
                    }
                }

                builder.addInterceptorLast(requestInterceptor)
                builder.addInterceptorLast(responseInterceptor)
                break

            default:
                throw new IllegalArgumentException()
        }
    }

class NewAccessToken {

    static final String  GRANT_TYPE = "grant_type"
    static final String  REFRESH_TOKEN = "refresh_token"
    static final String  CLIENT_CREDENTIALS = "client_credentials"
    static final String  CLIENT_ID = "client_id"
    static final String  CLIENT_SECRET = "client_secret"
    static final String  OAUTH_REQUEST = "oauth-request"

    Log logger = Log.getLog(NewAccessToken.class)
    ScriptedRESTConfiguration c = null
    final CloseableHttpClient client = null
    final HttpPost post = null

    NewAccessToken(ScriptedRESTConfiguration conf) {
        this.c = conf
        this.client = c.getHttpClient()
        this.post = new HttpPost(c.getOAuthTokenEndpoint())
        post.setHeader(HttpHeaders.CONTENT_TYPE, "application/x-www-form-urlencoded")
        post.setHeader(HttpHeaders.ACCEPT, "application/json")
    }

    @Synchronized
    void clientCredentials() {
        boolean expired = (c.propertyBag.tokenExpiration as Long) < System.currentTimeMillis() / 1000
        if (c.propertyBag.accessToken == null || expired ) {
            if (c.propertyBag.tokenExpiration != null && expired) {
                logger.info("Token expired!")
            }
            logger.info("Getting new access token...")

            final List<NameValuePair> pairs = new ArrayList<>()
            pairs.add(new BasicNameValuePair(GRANT_TYPE, CLIENT_CREDENTIALS))
            pairs.add(new BasicNameValuePair(CLIENT_ID, c.getOAuthClientId()))
            pairs.add(new BasicNameValuePair(CLIENT_SECRET, SecurityUtil.decrypt(c.getOAuthClientSecret())))
            post.setEntity(new UrlEncodedFormEntity(pairs))

            CloseableHttpResponse response = null
            try {
                HttpClientContext ctx = HttpClientContext.create()
                ctx.setAttribute(OAUTH_REQUEST, true)
                response = client.execute(post, ctx)
                int statusCode = response.getStatusLine().getStatusCode()
                if (HttpStatus.SC_OK == statusCode) {
                    def jsonSlurper = new JsonSlurper()
                    def oauthResponse = jsonSlurper.parseText(EntityUtils.toString(response.getEntity()))
                    c.propertyBag.accessToken = oauthResponse.access_token
                    c.propertyBag.tokenExpiration = System.currentTimeMillis() / 1000 + oauthResponse.expires_in as Long
                } else {
                    throw new InvalidCredentialException("Retrieve Access Token failed with code: " + statusCode)
                }
            } catch (ClientProtocolException ex) {
                logger.info("Trace: {0}", ex.getMessage())
                throw new ConnectorException(ex)
            } catch (IOException ex) {
                logger.info("Trace: {0}", ex.getMessage())
                throw new ConnectionFailedException(ex)
            } finally {
                try {
                    if (response != null) {
                        response.close()
                    }
                } catch (IOException e) {
                    logger.info("Can't close HttpResponse")
                }
            }
        }
    }
}