/*
 * Copyright 2017-present Open Networking Foundation
 *
 * 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 io.atomix.utils.concurrent;

import java.util.concurrent.ThreadLocalRandom;
import java.util.function.Function;
import java.util.function.Supplier;

/**
 * Retry utilities.
 */
public final class Retries {

  /**
   * Returns a function that retries execution on failure.
   * @param base base function
   * @param exceptionClass type of exception for which to retry
   * @param maxRetries max number of retries before giving up
   * @param maxDelayBetweenRetries max delay between successive retries. The actual delay is randomly picked from
   * the interval (0, maxDelayBetweenRetries]
   * @return function
   * @param <U> type of function input
   * @param <V> type of function output
   */
  public static <U, V> Function<U, V> retryable(Function<U, V> base,
                                                Class<? extends Throwable> exceptionClass,
                                                int maxRetries,
                                                int maxDelayBetweenRetries) {
    return new RetryingFunction<>(base, exceptionClass, maxRetries, maxDelayBetweenRetries);
  }

  /**
   * Returns a Supplier that retries execution on failure.
   * @param base base supplier
   * @param exceptionClass type of exception for which to retry
   * @param maxRetries max number of retries before giving up
   * @param maxDelayBetweenRetries max delay between successive retries. The actual delay is randomly picked from
   * the interval (0, maxDelayBetweenRetries]
   * @return supplier
   * @param <V> type of supplied result
   */
  public static <V> Supplier<V> retryable(Supplier<V> base,
                                          Class<? extends Throwable> exceptionClass,
                                          int maxRetries,
                                          int maxDelayBetweenRetries) {
    return () -> new RetryingFunction<>(v -> base.get(),
        exceptionClass,
        maxRetries,
        maxDelayBetweenRetries).apply(null);
  }

  /**
   * Suspends the current thread for a random number of millis between 0 and
   * the indicated limit.
   *
   * @param ms max number of millis
   */
  public static void randomDelay(int ms) {
    try {
      Thread.sleep(ThreadLocalRandom.current().nextInt(ms));
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted", e);
    }
  }

  /**
   * Suspends the current thread for a specified number of millis and nanos.
   *
   * @param ms    number of millis
   * @param nanos number of nanos
   */
  public static void delay(int ms, int nanos) {
    try {
      Thread.sleep(ms, nanos);
    } catch (InterruptedException e) {
      throw new RuntimeException("Interrupted", e);
    }
  }

  private Retries() {
  }

}