public class GoogleAnalyticsAuth {
   
    private static final String APPLICATION_NAME = "GA Data Ingestion";
    private static final JsonFactory JSON_FACTORY = GsonFactory.getDefaultInstance();
    private static String KEY_FILE_LOCATION = "";
    private static final HttpTransport HTTP_TRANSPORT = new NetHttpTransport();
    private static String apiEmail = "";
    private static String jsonFilePath = "";
    private static String csvFilePath="";

    public static void main(String[] args) {
       
        KEY_FILE_LOCATION = args[0];
        apiEmail = args[1];
        jsonFilePath = args[2];
        csvFilePath = args[3];
           
        String dimsMetric = args[4];
        String dimsDimension = args[5];
        String startDate = args[6];
        String endDate = args[7];
       
        try {
            Analytics analytics = initializeAnalytic();
            String profile = getFirstProfileId(analytics);
            System.out.println("First Profile Id is: " + profile);
           
            GaData result = getResults(analytics, profile, dimsMetric, dimsDimension, startDate, endDate);

            generateJsonFile(result, jsonFilePath);
            generateCsvFile(result, csvFilePath);
           
            // System.out.println(json.getString("rows"));
            // System.out.println(generateHeaderString(result));
           
        } catch (Exception e) {
            e.printStackTrace();
        }

    }
   
    // Get Data
    private static GaData getResults(Analytics analytics, String profileId,
            String dimsMetric, String dimsDimension,
            String startDate, String endDate) throws IOException {
        // Query the Core Reporting API for the number of sessions
        // String dimsDate = ",ga:date, ga:hour";      
       
        Get get = analytics.data().ga().get("ga:" + profileId, startDate, endDate, dimsMetric);
        get.setDimensions(dimsDimension);
        get.setMaxResults(10000);
       
        return get.execute();
      }
   
    private static String generateHeaderString(GaData results) {
       
        String columns = "";
        List<ColumnHeaders> header = results.getColumnHeaders();
        Iterator<ColumnHeaders> iter = header.iterator();
        while (iter.hasNext()) {
            columns += iter.next().getName().replace("ga:",  "") + ",";
        }
        return columns.substring(0, columns.length() - 1);
    }
   
    private static void generateCsvFile(GaData results, String csvFilePath) {
       
        try {
            // (1) Prepare files
            FileWriter fWriter = new FileWriter(csvFilePath);
            BufferedWriter bWriter = new BufferedWriter(fWriter);
            PrintWriter out = new PrintWriter(bWriter);
           
            // (2) Write header
            out.println(generateHeaderString(results));
           
            // (3) Get data from GaData object
            List<List<String>> rows = results.getRows();
            Iterator<List<String>> iter = rows.iterator();
            while (iter.hasNext()) {
                Iterator<String> iter2 = iter.next().iterator();
                String row = "";
                while (iter2.hasNext()) {
                    row += iter2.next() + ",";
                }
                out.println(row.substring(0, row.length() - 1));
               
                // System.out.println(row.substring(0, row.length() - 1));
            } // end of first while loop
           
            // (4) Close the file
            out.close();
            System.out.println("CSV File has been created.");
           
        } catch (IOException e) {
            System.out.println("Problem with csv file IO operation: " + e.toString());
        }
    }

    private static void generateJsonFile(GaData results, String filePath) throws JSONException {
        try {
            // (1) Prepare files
            FileWriter fWriter = new FileWriter(filePath);
            BufferedWriter bWriter = new BufferedWriter(fWriter);
            PrintWriter out = new PrintWriter(bWriter);
            // (2) Create JSON Object and write into the file with indentation
            JSONObject json = new JSONObject(results);
            out.println(json.toString(4));
            // (3) Close the file
            out.close();
            System.out.println("JSON File has been created.");
        } catch (IOException e) {
            System.out.println("Problem with JSON file IO operation: " + e.toString());
        }
    }
   
    // AUTHENTICATION
   
    /**
     * Initializes an Analytics service object.
     *
     * @return An authorized Analytics service object.
     * @throws IOException
     * @throws GeneralSecurityException
     */
    private static Analytics initializeAnalytic() throws GeneralSecurityException, IOException {
       
        HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
        GoogleCredential credential = new GoogleCredential.Builder()
                .setTransport(HTTP_TRANSPORT)
                .setJsonFactory(JSON_FACTORY)
                .setServiceAccountId(apiEmail)
                .setServiceAccountScopes(Arrays.asList(AnalyticsScopes.ANALYTICS_READONLY))
                .setServiceAccountPrivateKeyFromP12File(new File(KEY_FILE_LOCATION)).build();
        /* Using JSON file for secret key
        GoogleCredential credential = GoogleCredential.fromStream(new FileInputStream(KEY_FILE_LOCATION))
                                                        .createScoped(AnalyticsScopes.all());
        */
       
        return new Analytics.Builder(httpTransport, JSON_FACTORY, credential)
                .setApplicationName(APPLICATION_NAME).build();
    }
   
    private static String getFirstProfileId(Analytics analytics) throws IOException {
        // Get the first view (profile) ID for the authorized user.
        String profileId = null;

        // Query for the list of all accounts associated with the service account.
        Accounts accounts = analytics.management().accounts().list().execute();

        if (accounts.getItems().isEmpty()) {
          System.err.println("No accounts found");
        } else {
          String firstAccountId = accounts.getItems().get(0).getId();

          // Query for the list of properties associated with the first account.
          Webproperties properties = analytics.management().webproperties()
              .list(firstAccountId).execute();

          if (properties.getItems().isEmpty()) {
            System.err.println("No Webproperties found");
          } else {
            String firstWebpropertyId = properties.getItems().get(0).getId();

            // Query for the list views (profiles) associated with the property.
            Profiles profiles = analytics.management().profiles()
                .list(firstAccountId, firstWebpropertyId).execute();

            if (profiles.getItems().isEmpty()) {
              System.err.println("No views (profiles) found");
            } else {
              // Return the first (view) profile associated with the property.
              profileId = profiles.getItems().get(0).getId();
            }
          }
        }
        return profileId;
      }
}