/*
    * Copyright 2019-2022 the original author or authors.
    *
    * 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.bremersee.exception.feign;
  
  import static feign.Util.RETRY_AFTER;
  import static java.time.format.DateTimeFormatter.RFC_1123_DATE_TIME;
  import static java.util.Objects.isNull;
  import static java.util.Objects.nonNull;
  import static java.util.concurrent.TimeUnit.SECONDS;
  
  import feign.Request.HttpMethod;
  import feign.Response;
  import feign.RetryableException;
  import feign.codec.ErrorDecoder;
  import java.io.IOException;
  import java.io.InputStream;
  import java.time.ZonedDateTime;
  import java.util.Collection;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  import java.util.Optional;
  import lombok.extern.slf4j.Slf4j;
  import org.bremersee.exception.RestApiExceptionParser;
  import org.bremersee.exception.RestApiExceptionParserImpl;
  import org.bremersee.exception.model.RestApiException;
  import org.springframework.http.HttpHeaders;
  import org.springframework.http.HttpStatusCode;
  import org.springframework.util.FileCopyUtils;
  
  /**
   * This error decoder produces either a {@link FeignClientException} or a
   * {@link feign.RetryableException}.
   *
   * @author Christian Bremer
   */
  @Slf4j
  public class FeignClientExceptionErrorDecoder implements ErrorDecoder {
  
    private final RestApiExceptionParser parser;
  
    /**
     * Instantiates a new feign client exception error decoder.
     */
    public FeignClientExceptionErrorDecoder() {
      this(null);
    }
  
    /**
     * Instantiates a new feign client exception error decoder.
     *
     * @param parser the parser
     */
    public FeignClientExceptionErrorDecoder(RestApiExceptionParser parser) {
      this.parser = nonNull(parser) ? parser : new RestApiExceptionParserImpl();
    }
  
    @Override
    public Exception decode(String methodKey, Response response) {
  
      if (log.isDebugEnabled()) {
        log.debug("Decoding feign exception at {}", methodKey);
      }
      Map<String, Collection<String>> headers = Objects
          .requireNonNullElseGet(response.headers(), Map::of);
      HttpHeaders httpHeaders = headers.entrySet()
          .stream()
          .collect(
              HttpHeaders::new,
              (a, b) -> a.addAll(b.getKey(), List.copyOf(b.getValue())),
              HttpHeaders::putAll);
      byte[] body = getResponseBody(response);
      RestApiException restApiException = parser.parseException(
          body,
          HttpStatusCode.valueOf(response.status()),
          httpHeaders);
      FeignClientException feignClientException = new FeignClientException(
          response.status(),
          String.format("Status %s reading %s", response.status(), methodKey),
          response.request(),
          headers,
          body,
          restApiException);
      return determineRetryAfter(httpHeaders.getFirst(RETRY_AFTER))
          .map(retryAfter -> (Exception) new RetryableException(
             response.status(),
             feignClientException.getMessage(),
             getHttpMethod(response),
             feignClientException,
             retryAfter,
             response.request()))
         .orElse(feignClientException);
   }
 
   /**
    * Get response body.
    *
    * @param response the response
    * @return the body as byte array
    */
   protected byte[] getResponseBody(Response response) {
     byte[] body;
     if (isNull(response.body())) {
       body = new byte[0];
     } else {
       try (InputStream in = response.body().asInputStream()) {
         body = FileCopyUtils.copyToByteArray(in);
       } catch (IOException e) {
         body = new byte[0];
       }
     }
     return body;
   }
 
   /**
    * Find http method.
    *
    * @param response the response
    * @return the http method
    */
   protected HttpMethod getHttpMethod(Response response) {
     if (isNull(response) || isNull(response.request())) {
       return null;
     }
     return response.request().httpMethod();
   }
 
   /**
    * Determine retry after.
    *
    * @param retryAfter the retry after
    * @return the optional
    */
   protected Optional<Long> determineRetryAfter(String retryAfter) {
     try {
       return Optional.ofNullable(retryAfter)
           .filter(retryAfterValue -> retryAfterValue.matches("^[0-9]+\\.?0*$"))
           .map(retryAfterValue -> retryAfterValue.replaceAll("\\.0*$", ""))
           .map(retryAfterValue -> SECONDS.toMillis(Long.parseLong(retryAfterValue)))
           .map(deltaMillis -> currentTimeMillis() + deltaMillis)
           .or(() -> Optional.ofNullable(retryAfter)
               .map(retryAfterValue -> ZonedDateTime
                   .parse(retryAfterValue, RFC_1123_DATE_TIME).toInstant().toEpochMilli()));
     } catch (Exception e) {
       log.warn("Parsing retry after date for feigns RetryableException failed.", e);
       return Optional.empty();
     }
   }
 
   /**
    * Returns the current time millis of the system.
    *
    * @return the current time millis of the system
    */
   protected long currentTimeMillis() {
     return System.currentTimeMillis();
   }
 
 }