google oauth2 java client, googleoaauth2

GoogleClient.java

package org.jrichardsz.horus.third.google.client;

import java.util.Map;
import org.jrichardsz.horus.exceptions.BadGoogleResponseException;
import org.jrichardsz.horus.exceptions.GoogleOauthRestApiException;

public interface GoogleClient {

  public String getAuthorizeUrl(String redirectUri, String scope, String clientId);

  public Map<String, Object> getAccessToken(String authorizationCode, String clientId,
      String clientSecret, String redirect) throws GoogleOauthRestApiException;

  public String getDataUserFromPlusApi(String accessToken)
      throws BadGoogleResponseException, GoogleOauthRestApiException;

  public String getDataUserFromPeopleApi(String accessToken)
      throws BadGoogleResponseException, GoogleOauthRestApiException;

}

GoogleClientImpl.java

package org.jrichardsz.horus.third.google.client.impl;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.Map;
import org.jrichardsz.horus.common.HorusCommon;
import org.jrichardsz.horus.exceptions.BadGoogleResponseException;
import org.jrichardsz.horus.exceptions.GoogleOauthRestApiException;
import org.jrichardsz.horus.third.google.client.GoogleClient;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.HttpMethod;
import org.springframework.stereotype.Component;
import org.springframework.util.Assert;
import org.springframework.web.client.HttpClientErrorException;
import org.springframework.web.client.HttpServerErrorException;
import org.springframework.web.client.RestTemplate;
import org.springframework.web.util.UriComponentsBuilder;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.jayway.jsonpath.JsonPath;
import com.jayway.jsonpath.ReadContext;

@Component
public class GoogleClientImpl implements GoogleClient {

  private static final Logger logger = LoggerFactory.getLogger(GoogleClientImpl.class);

  public final String googleAuthUrlTemplate = "https://accounts.google.com/o/oauth2/v2/auth?"
      + "response_type=code&redirect_uri=%s&scope=%s&client_id=%s";

  private final String googleTokenGeneratorUrl = "https://accounts.google.com/o/oauth2/token?";
  private final String googlePeopleApiUrl = "https://people.googleapis.com/v1/people/me";
  private final String googlePlusApiUrl = "https://www.googleapis.com/plus/v1/people/me";
  private final String codeGrantType = "authorization_code";
  private final String prefixAuthHeader = "Bearer";

  public String getAuthorizeUrl(String redirectUri, String scope, String clientId) {
    // scope encode
    scope = encodeValue(scope);
    return String.format(googleAuthUrlTemplate, redirectUri, scope, clientId);
  }

  // Method to encode a string value using `UTF-8` encoding scheme
  private String encodeValue(String value) {
    try {
      return URLEncoder.encode(value, StandardCharsets.UTF_8.toString());
    } catch (UnsupportedEncodingException ex) {
      throw new RuntimeException(ex.getCause());
    }
  }

  @SuppressWarnings("unchecked")
  public Map<String, Object> getAccessToken(String authorizationCode, String clientId,
      String clientSecret, String redirect) throws GoogleOauthRestApiException {

    HttpURLConnection conn = null;
    try {
      StringBuilder urlParameters = new StringBuilder();
      urlParameters.append("code=").append(authorizationCode).append("&client_id=").append(clientId)
          .append("&client_secret=").append(clientSecret).append("&redirect_uri=").append(redirect)
          .append("&grant_type=").append(codeGrantType);

      URL url = new URL(googleTokenGeneratorUrl);
      conn = (HttpURLConnection) url.openConnection();
      conn.setDoOutput(true);
      conn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");

      OutputStreamWriter writer = new OutputStreamWriter(conn.getOutputStream());
      writer.write(urlParameters.toString());
      writer.flush();

      String tokenDataStr = "";
      BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));
      String line;
      while ((line = reader.readLine()) != null) {
        tokenDataStr = tokenDataStr + line;
      }
      writer.close();
      reader.close();

      ObjectMapper mapper = new ObjectMapper();
      Map<String, Object> tokenData = mapper.readValue(tokenDataStr, Map.class);

      return tokenData;
    } catch (IOException e) {
      String errorResponse = HorusCommon.inputStreamToString(conn.getErrorStream());
      logger.info("google response:" + errorResponse);
      throw new GoogleOauthRestApiException(String.format(
          "Google platform returns a error [%s] when oauth code was exchanged for the token.",
          e.getMessage()), e);
    } catch (HttpClientErrorException e) {
      String errorResponse = e.getResponseBodyAsString();
      logger.info("google response:" + errorResponse);
      throw new GoogleOauthRestApiException(String.format(
          "Google platform returns a error status code: %s when oauth code was exchanged for the token. Endpoint: %s",
          e.getRawStatusCode(), googleTokenGeneratorUrl), e);
    } catch (HttpServerErrorException e) {
      String errorResponse = e.getResponseBodyAsString();
      logger.info("google response:" + errorResponse);
      throw new GoogleOauthRestApiException(String.format(
          "Google platform returns a error status code: %s when oauth code was exchanged for the token. Endpoint: %s",
          e.getRawStatusCode(), googleTokenGeneratorUrl), e);
    } catch (Exception e) {
      String errorResponse = HorusCommon.inputStreamToString(conn.getErrorStream());
      logger.info("google response:" + errorResponse);
      throw new GoogleOauthRestApiException(String.format(
          "Unexpected error when oauth code was exchanged for the token in Google platform. Endpoint:%s",
          googleTokenGeneratorUrl), e);
    }
  }

  public String getDataUserFromPlusApi(String accessToken)
      throws BadGoogleResponseException, GoogleOauthRestApiException {

    HttpHeaders headers = new HttpHeaders();
    headers.set(HttpHeaders.AUTHORIZATION, prefixAuthHeader + " " + accessToken);

    RestTemplate restTemplate = new RestTemplate();

    String plusApiResponse = null;
    try {
      plusApiResponse = restTemplate
          .exchange(googlePlusApiUrl, HttpMethod.GET, new HttpEntity<>(headers), String.class)
          .getBody();
    } catch (HttpClientErrorException e) {
      String errorResponse = e.getResponseBodyAsString();
      logger.info("google response:" + errorResponse);
      throw new GoogleOauthRestApiException(String.format(
          "Google platform returns a error status code: %s when token was exchanged for the user information. Endpoint: %s",
          e.getRawStatusCode(), googlePlusApiUrl), e);
    } catch (HttpServerErrorException e) {
      throw new GoogleOauthRestApiException(String.format(
          "Google platform returns a error status code: %s when token was exchanged for the user information. Endpoint: %s",
          e.getRawStatusCode(), googlePlusApiUrl), e);
    } catch (Exception e) {
      throw new GoogleOauthRestApiException(String.format(
          "Unexpected error when oauth code was exchanged for the token in Google platform. Endpoint: %s",
          googlePlusApiUrl), e);
    }

    String email = null;

    try {
      ReadContext ctx = JsonPath.parse(plusApiResponse);
      email = ctx.read("$.emails[0].value");
      Assert.notNull(email,
          "email from google plus api response must not be null: " + googlePlusApiUrl);
    } catch (IllegalArgumentException e) {
      throw new BadGoogleResponseException(
          "Email cannot be extracted from google plus api response: " + plusApiResponse,
          "Email cannot be extracted from google plus api response", e);
    } catch (Exception e) {
      throw new BadGoogleResponseException(
          "Email cannot be extracted from google plus api response: " + plusApiResponse,
          "Email cannot be extracted from google plus api response", e);
    }


    return email;
  }

  @Override
  public String getDataUserFromPeopleApi(String accessToken)
      throws BadGoogleResponseException, GoogleOauthRestApiException {
    HttpHeaders headers = new HttpHeaders();
    headers.set(HttpHeaders.AUTHORIZATION, prefixAuthHeader + " " + accessToken);

    RestTemplate restTemplate = new RestTemplate();

    String peopleApiResponse = null;
    try {

      UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(googlePeopleApiUrl)
          .queryParam("personFields", "emailAddresses");

      peopleApiResponse = restTemplate
          .exchange(builder.toUriString(), HttpMethod.GET, new HttpEntity<>(headers), String.class)
          .getBody();
    } catch (HttpClientErrorException e) {
      String errorResponse = e.getResponseBodyAsString();
      logger.info("google response:" + errorResponse);
      throw new GoogleOauthRestApiException(String.format(
          "Google platform returns a error status code: %s when token was exchanged for the user information. Endpoint: %s",
          e.getRawStatusCode(), googlePeopleApiUrl), e);
    } catch (HttpServerErrorException e) {
      throw new GoogleOauthRestApiException(String.format(
          "Google platform returns a error status code: %s when token was exchanged for the user information. Endpoint: %s",
          e.getRawStatusCode(), googlePeopleApiUrl), e);
    } catch (Exception e) {
      throw new GoogleOauthRestApiException(String.format(
          "Unexpected error when oauth code was exchanged for the token in Google platform. Endpoint: %s",
          googlePeopleApiUrl), e);
    }

    String email = null;
    // expected response: 
    // https://gist.github.com/jrichardsz/585fba4ba7587dd41faea14fa32aa36b#file-personfields-emailaddresses
    try {
      ReadContext ctx = JsonPath.parse(peopleApiResponse);
      email = ctx.read("$.emailAddresses[0].value");
      Assert.notNull(email,
          "email from google people api response must not be null: " + googlePeopleApiUrl);
    } catch (IllegalArgumentException e) {
      throw new BadGoogleResponseException(
          "Email cannot be extracted from google people api response: " + peopleApiResponse,
          "Email cannot be extracted from google people api response", e);
    } catch (Exception e) {
      throw new BadGoogleResponseException(
          "Email cannot be extracted from google people api response: " + peopleApiResponse,
          "Email cannot be extracted from google people api response", e);
    }


    return email;
  }

}