/*
    * 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.
   */
  package org.gbif.ws.client;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import feign.RetryableException;
  import feign.Retryer;
  
  @SuppressWarnings("unused")
  public class ClientRetryer implements Retryer {
  
    private static final Logger LOG = LoggerFactory.getLogger(ClientRetryer.class);
  
    private final int maxAttempts;
    private final long period;
    private final double multiplier;
    int attempt;
    long sleptForMillis;
  
    public ClientRetryer() {
      this(1000, 3, 1.5);
    }
  
    public ClientRetryer(long period, int maxAttempts, double multiplier) {
      this.period = period;
      this.maxAttempts = maxAttempts;
      this.multiplier = multiplier;
      this.attempt = 1;
    }
  
    protected long currentTimeMillis() {
      return System.currentTimeMillis();
    }
  
    @Override
    public void continueOrPropagate(RetryableException e) {
      if (attempt++ >= maxAttempts) {
        LOG.error(
            "All {} retry attempts failed. Giving up. Last execution was: '{}: {}'",
            maxAttempts,
            e.getClass().getSimpleName(),
            e.getMessage());
        throw e;
      }
  
      long interval;
      if (e.retryAfter() != null) {
        interval = e.retryAfter().getTime() - currentTimeMillis();
        if (interval < 0) {
          return;
        }
      } else {
        interval = nextMaxInterval();
      }
      try {
        Thread.sleep(interval);
      } catch (InterruptedException ignored) {
        Thread.currentThread().interrupt();
        throw e;
      }
      sleptForMillis += interval;
    }
  
    /**
     * Calculates the time interval to a retry attempt. <br>
     * The interval increases exponentially with each attempt, at a rate of nextInterval *= multiplier
     * (where multiplier is the backoff factor), to the maximum interval.
     *
     * @return time in nanoseconds from now until the next attempt.
     */
    long nextMaxInterval() {
      return (long) (period * Math.pow(multiplier, attempt - 1));
    }
  
    @Override
    public Retryer clone() {
      return new ClientRetryer(period, maxAttempts, multiplier);
    }
  }