content: package act.session;
  
  /*-
   * #%L
   * ACT Framework
   * %%
   * Copyright (C) 2014 - 2018 ActFramework
   * %%
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   * 
   *      http://www.apache.org/licenses/LICENSE-2.0
   * 
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   * #L%
   */
  
  import act.app.App;
  import act.conf.AppConfig;
  import org.joda.time.DateTime;
  import org.osgl.util.E;
  import org.osgl.util.S;
  
  import javax.inject.Inject;
  import javax.inject.Singleton;
  import java.util.Arrays;
  import java.util.concurrent.TimeUnit;
  
  @Singleton
  public class RotationSecretProvider {
  
      private String rawSecret;
      private String lastSecret;
      private String curSecret;
      private String nextSecret;
      private int periodInMinutes;
      private boolean rotateEnabled;
  
      @Inject
      public RotationSecretProvider(App app) {
          AppConfig<?> config = app.config();
          rawSecret = config.secret();
          rotateEnabled = config.rotateSecret();
          if (rotateEnabled) {
              int period = config.secretRotatePeriod();
              app.jobManager().every("secret-rotator", new Runnable() {
                  @Override
                  public void run() {
                      rotateSecret();
                  }
              }, period, TimeUnit.MINUTES);
              periodInMinutes = period;
              rotateSecret();
          }
      }
  
      public boolean isRotateEnabled() {
          return rotateEnabled;
      }
  
      public String rawSecret() {
          return rawSecret;
      }
  
      public String curSecret() {
          ensureRotateEnabled();
          return curSecret;
      }
  
      public String lastSecret() {
          ensureRotateEnabled();
          return lastSecret;
      }
  
      public String nextSecret() {
          ensureRotateEnabled();
          return nextSecret;
      }
  
      private static final int[] VALID_MINUTES = {
              1, 2, 3, 4, 5, 6, 10, 12, 15, 20, 30, 60
      };
  
      private static final int[] VALID_HOURS = {
              1, 2, 3, 4, 6, 8, 12, 24
      };
  
      public static int roundToPeriod(int minutes) {
          E.illegalArgumentIf(minutes <= 0);
          if (minutes > 60 * 24) {
              return 60 * 24;
          } else if (minutes > 60) {
              float f = minutes / 60f;
              int hours = Math.round(f);
              int pos = Arrays.binarySearch(VALID_HOURS, hours);
              return (pos >= 0 ? hours : VALID_HOURS[-(pos + 1)]) * 60;
          } if (minutes > 30) {
              int reminder = minutes % 30;
              return 0 == reminder ? minutes : minutes + (reminder < 15 ? -reminder : (30 - reminder));
          } else {
              int pos = Arrays.binarySearch(VALID_MINUTES, minutes);
              return pos >= 0 ? minutes : VALID_MINUTES[-(pos + 1)];
          }
      }
  
      private void rotateSecret() {
          ensureRotateEnabled();
          lastSecret = curSecret;
          curSecret = null != nextSecret ? nextSecret : calculateCurrentSecret();
          nextSecret = calculateNextSecret();
          if (null == lastSecret) {
              lastSecret = curSecret;
          }
      }
  
      private String calculateCurrentSecret() {
          return rawSecret + extension(0);
      }
  
      private String calculateNextSecret() {
          return rawSecret + extension(1);
      }
  
      private String extension(int forwardStep) {
          long trait;
          if (periodInMinutes > 60) {
              int periodInHours = periodInMinutes / 60;
              int hoursOfDay = DateTime.now().hourOfDay().get();
              int period = hoursOfDay / periodInHours;
              trait = currentHourStart().getMillis() / 1000 / 60;
              if (0 < period) {
                  trait += (period * 60);
              }
          } else {
              int minutesOfHour = DateTime.now().minuteOfHour().get();
              int period = minutesOfHour / periodInMinutes;
              trait = currentHourStart().getMillis() / 1000 / 60;
              if (0 < period) {
                  trait += period;
              }
          }
          if (forwardStep > 0) {
              trait += forwardStep * periodInMinutes;
          }
          return S.string(trait);
      }
  
      private void ensureRotateEnabled() {
          E.illegalStateIfNot(rotateEnabled, "secret rotate not enabled");
      }
  
  
      private static DateTime currentHourStart() {
          return DateTime.now().withMinuteOfHour(0).withSecondOfMinute(0).withMillisOfSecond(0);
      }
  
  }
  