/*
    * ====================================================================
    * Licensed to the Apache Software Foundation (ASF) under one
    * or more contributor license agreements.  See the NOTICE file
    * distributed with this work for additional information
    * regarding copyright ownership.  The ASF licenses this file
    * to you 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  
  package org.apache.hc.client5.http.impl;
  
  import java.io.IOException;
  import java.io.InterruptedIOException;
  import java.net.ConnectException;
  import java.net.NoRouteToHostException;
  import java.net.UnknownHostException;
  import java.time.Instant;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.HashSet;
  import java.util.Set;
  
  import javax.net.ssl.SSLException;
  
  import org.apache.hc.client5.http.HttpRequestRetryStrategy;
  import org.apache.hc.client5.http.config.RequestConfig;
  import org.apache.hc.client5.http.protocol.HttpClientContext;
  import org.apache.hc.client5.http.utils.DateUtils;
  import org.apache.hc.core5.annotation.Contract;
  import org.apache.hc.core5.annotation.ThreadingBehavior;
  import org.apache.hc.core5.concurrent.CancellableDependency;
  import org.apache.hc.core5.http.ConnectionClosedException;
  import org.apache.hc.core5.http.Header;
  import org.apache.hc.core5.http.HttpHeaders;
  import org.apache.hc.core5.http.HttpRequest;
  import org.apache.hc.core5.http.HttpResponse;
  import org.apache.hc.core5.http.HttpStatus;
  import org.apache.hc.core5.http.Method;
  import org.apache.hc.core5.http.protocol.HttpContext;
  import org.apache.hc.core5.util.Args;
  import org.apache.hc.core5.util.TimeValue;
  import org.apache.hc.core5.util.Timeout;
  
  /**
   * Default implementation of the {@link HttpRequestRetryStrategy} interface.
   *
   * @since 5.0
   */
  @Contract(threading = ThreadingBehavior.STATELESS)
  public class DefaultHttpRequestRetryStrategy implements HttpRequestRetryStrategy {
  
      /**
       * Default instance of {@link DefaultHttpRequestRetryStrategy}.
       */
      public static final DefaultHttpRequestRetryStrategy INSTANCE = new DefaultHttpRequestRetryStrategy();
  
      /**
       * Maximum number of allowed retries
       */
      private final int maxRetries;
  
      /**
       * Retry interval between subsequent retries
       */
      private final TimeValue defaultRetryInterval;
  
      /**
       * Derived {@code IOExceptions} which shall not be retried
       */
      private final Set<Class<? extends IOException>> nonRetriableIOExceptionClasses;
  
      /**
       * HTTP status codes which shall be retried
       */
      private final Set<Integer> retriableCodes;
  
      protected DefaultHttpRequestRetryStrategy(
              final int maxRetries,
              final TimeValue defaultRetryInterval,
              final Collection<Class<? extends IOException>> clazzes,
              final Collection<Integer> codes) {
         Args.notNegative(maxRetries, "maxRetries");
         Args.notNull(defaultRetryInterval, "defaultRetryInterval");
         Args.check(TimeValue.isNonNegative(defaultRetryInterval), "Default retry interval is negative");
         this.maxRetries = maxRetries;
         this.defaultRetryInterval = defaultRetryInterval;
         this.nonRetriableIOExceptionClasses = new HashSet<>(clazzes);
         this.retriableCodes = new HashSet<>(codes);
     }
 
     /**
      * Create the HTTP request retry strategy using the following list of
      * non-retriable I/O exception classes:<br>
      * <ul>
      * <li>InterruptedIOException</li>
      * <li>UnknownHostException</li>
      * <li>ConnectException</li>
      * <li>ConnectionClosedException</li>
      * <li>NoRouteToHostException</li>
      * <li>SSLException</li>
      * </ul>
      *
      * and retriable HTTP status codes:<br>
      * <ul>
      * <li>SC_TOO_MANY_REQUESTS (429)</li>
      * <li>SC_SERVICE_UNAVAILABLE (503)</li>
      * </ul>
      *
      * @param maxRetries how many times to retry; 0 means no retries
      * @param defaultRetryInterval the default retry interval between
      * subsequent retries if the {@code Retry-After} header is not set
      * or invalid.
      */
     public DefaultHttpRequestRetryStrategy(
             final int maxRetries,
             final TimeValue defaultRetryInterval) {
         this(maxRetries, defaultRetryInterval,
                 Arrays.asList(
                         InterruptedIOException.class,
                         UnknownHostException.class,
                         ConnectException.class,
                         ConnectionClosedException.class,
                         NoRouteToHostException.class,
                         SSLException.class),
                 Arrays.asList(
                         HttpStatus.SC_TOO_MANY_REQUESTS,
                         HttpStatus.SC_SERVICE_UNAVAILABLE));
     }
 
     /**
      * Create the HTTP request retry strategy with a max retry count of 1,
      * default retry interval of 1 second, and using the following list of
      * non-retriable I/O exception classes:<br>
      * <ul>
      * <li>InterruptedIOException</li>
      * <li>UnknownHostException</li>
      * <li>ConnectException</li>
      * <li>ConnectionClosedException</li>
      * <li>SSLException</li>
      * </ul>
      *
      * and retriable HTTP status codes:<br>
      * <ul>
      * <li>SC_TOO_MANY_REQUESTS (429)</li>
      * <li>SC_SERVICE_UNAVAILABLE (503)</li>
      * </ul>
      */
     public DefaultHttpRequestRetryStrategy() {
         this(1, TimeValue.ofSeconds(1L));
     }
 
     @Override
     public boolean retryRequest(
             final HttpRequest request,
             final IOException exception,
             final int execCount,
             final HttpContext context) {
         Args.notNull(request, "request");
         Args.notNull(exception, "exception");
 
         if (execCount > this.maxRetries) {
             // Do not retry if over max retries
             return false;
         }
         if (this.nonRetriableIOExceptionClasses.contains(exception.getClass())) {
             return false;
         }
         for (final Class<? extends IOException> rejectException : this.nonRetriableIOExceptionClasses) {
             if (rejectException.isInstance(exception)) {
                 return false;
             }
         }
         if (request instanceof CancellableDependency && ((CancellableDependency) request).isCancelled()) {
             return false;
         }
 
         // Retry if the request is considered idempotent
         return handleAsIdempotent(request);
     }
 
     @Override
     public boolean retryRequest(
             final HttpResponse response,
             final int execCount,
             final HttpContext context) {
         Args.notNull(response, "response");
 
         if (context != null) {
             final HttpClientContext clientContext = HttpClientContext.cast(context);
             final RequestConfig requestConfig = clientContext.getRequestConfigOrDefault();
             final Timeout responseTimeout = requestConfig.getResponseTimeout();
             if (responseTimeout != null && defaultRetryInterval.compareTo(responseTimeout) > 0) {
                 return false;
             }
         }
         return execCount <= this.maxRetries && retriableCodes.contains(response.getCode());
     }
 
     @Override
     public TimeValue getRetryInterval(
             final HttpResponse response,
             final int execCount,
             final HttpContext context) {
         Args.notNull(response, "response");
 
         final Header header = response.getFirstHeader(HttpHeaders.RETRY_AFTER);
         TimeValue retryAfter = null;
         if (header != null) {
             final String value = header.getValue();
             try {
                 retryAfter = TimeValue.ofSeconds(Long.parseLong(value));
             } catch (final NumberFormatException ignore) {
                 final Instant retryAfterDate = DateUtils.parseStandardDate(value);
                 if (retryAfterDate != null) {
                     retryAfter =
                             TimeValue.ofMilliseconds(retryAfterDate.toEpochMilli() - System.currentTimeMillis());
                 }
             }
 
             if (TimeValue.isPositive(retryAfter)) {
                 return retryAfter;
             }
         }
         return this.defaultRetryInterval;
     }
 
     protected boolean handleAsIdempotent(final HttpRequest request) {
         return Method.isIdempotent(request.getMethod());
     }
 
 }