import com.google.api.client.auth.oauth2.Credential;
import com.google.api.client.extensions.java6.auth.oauth2.AuthorizationCodeInstalledApp;
import com.google.api.client.extensions.jetty.auth.oauth2.LocalServerReceiver;
import com.google.api.client.googleapis.auth.oauth2.GoogleAuthorizationCodeFlow;
import com.google.api.client.googleapis.auth.oauth2.GoogleClientSecrets;
import com.google.api.client.googleapis.auth.oauth2.GoogleCredential;
import com.google.api.client.googleapis.javanet.GoogleNetHttpTransport;
import com.google.api.client.http.HttpTransport;
import com.google.api.client.http.javanet.NetHttpTransport;
import com.google.api.client.json.JsonFactory;
import com.google.api.client.json.jackson2.JacksonFactory;
import com.google.api.client.util.store.FileDataStoreFactory;
import com.google.api.services.sheets.v4.Sheets;
import com.google.api.services.sheets.v4.SheetsScopes;
import com.google.api.services.sheets.v4.model.ValueRange;

import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.security.GeneralSecurityException;
import java.util.Collections;
import java.util.List;

public class SheetsQuickstart {
  private static final String APPLICATION_NAME = "Google Sheets API Java Quickstart";
  private static final JsonFactory JSON_FACTORY = JacksonFactory.getDefaultInstance();
  private static final String TOKENS_DIRECTORY_PATH = "tokens";

  /**
   * Global instance of the scopes required by this quickstart.
   * If modifying these scopes, delete your previously saved tokens/ folder.
   */
  private static final List<String> SCOPES = Collections.singletonList(SheetsScopes.SPREADSHEETS_READONLY);
  private static final String CREDENTIALS_FILE_PATH = "/credentials.json";

  /**
   * Creates an authorized Credential object.
   * @param HTTP_TRANSPORT The network HTTP Transport.
   * @return An authorized Credential object.
   * @throws IOException If the credentials.json file cannot be found.
   */
  private static Credential getCredentials(final NetHttpTransport HTTP_TRANSPORT) throws IOException {
    // Load client secrets.
    InputStream in = SheetsQuickstart.class.getResourceAsStream(CREDENTIALS_FILE_PATH);
    GoogleClientSecrets clientSecrets = GoogleClientSecrets.load(JSON_FACTORY, new InputStreamReader(in));

    // Build flow and trigger user authorization request.
    GoogleAuthorizationCodeFlow flow = new GoogleAuthorizationCodeFlow.Builder(
        HTTP_TRANSPORT, JSON_FACTORY, clientSecrets, SCOPES)
        .setDataStoreFactory(new FileDataStoreFactory(new java.io.File(TOKENS_DIRECTORY_PATH)))
        .setAccessType("offline")
        .build();
    LocalServerReceiver receiver = new LocalServerReceiver.Builder().setPort(8888).build();
    return new AuthorizationCodeInstalledApp(flow, receiver).authorize("user");
  }



  public static Sheets createSheetsService() throws IOException, GeneralSecurityException {
    HttpTransport httpTransport = GoogleNetHttpTransport.newTrustedTransport();
    JsonFactory jsonFactory = JacksonFactory.getDefaultInstance();

    // TODO: Change placeholder below to generate authentication credentials. See
    // https://developers.google.com/sheets/quickstart/java#step_3_set_up_the_sample
    //
    // Authorize using one of the following scopes:
    //   "https://www.googleapis.com/auth/drive"
    //   "https://www.googleapis.com/auth/drive.file"
    //   "https://www.googleapis.com/auth/spreadsheets"
    GoogleCredential credential = null;

    return new Sheets.Builder(httpTransport, jsonFactory, credential)
        .setApplicationName("Google-SheetsSample/0.1")
        .build();
  }
  /**
   * Prints the names and majors of students in a sample spreadsheet:
   * https://docs.google.com/spreadsheets/d/1BxiMVs0XRA5nFMdKvBdBZjgmUUqptlbs74OgvE2upms/edit
   */
  public static void main(String... args) throws IOException, GeneralSecurityException {
    // Build a new authorized API client service.
    final NetHttpTransport HTTP_TRANSPORT = GoogleNetHttpTransport.newTrustedTransport();
    final String spreadsheetId = "1Cz66gpzisC8O8J53LsJk_p0Rp8fQEK6I3Q1S2-6K4Ys";
    final String range = "A2:E";


    Sheets service = new Sheets.Builder(HTTP_TRANSPORT, JSON_FACTORY, getCredentials(HTTP_TRANSPORT))
        .setApplicationName(APPLICATION_NAME)
        .build();
    ValueRange response = service.spreadsheets().values()
        .get(spreadsheetId, range)
        .execute();


    List<List<Object>> values = response.getValues();
    if (values == null || values.isEmpty()) {
      System.out.println("No data found.");
    } else {
      System.out.println("Name, Major");
      for (List row : values) {
        // Print columns A and E, which correspond to indices 0 and 4.
        System.out.printf("%s, %s\n", row.get(0), row.get(1));
      }
    }
  }
}