/*
    * This file is part of ***  M y C o R e  ***
    * See http://www.mycore.de/ for details.
    *
    * MyCoRe is free software: you can redistribute it and/or modify
    * it under the terms of the GNU General Public License as published by
    * the Free Software Foundation, either version 3 of the License, or
    * (at your option) any later version.
    *
   * MyCoRe is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with MyCoRe.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  package org.mycore.restapi.v2;
  
  import java.util.List;
  import java.util.Optional;
  
  import org.apache.logging.log4j.LogManager;
  import org.apache.logging.log4j.Logger;
  
  import jakarta.ws.rs.WebApplicationException;
  import jakarta.ws.rs.core.Context;
  import jakarta.ws.rs.core.MediaType;
  import jakarta.ws.rs.core.Request;
  import jakarta.ws.rs.core.Response;
  import jakarta.ws.rs.core.Variant;
  import jakarta.ws.rs.ext.ExceptionMapper;
  
  public class MCRExceptionMapper implements ExceptionMapper<Exception> {
  
      private final static List<Variant> SUPPORTED_VARIANTS = Variant
          .mediaTypes(MediaType.APPLICATION_JSON_TYPE, MediaType.APPLICATION_XML_TYPE).build();
  
      private final static Logger LOGGER = LogManager.getLogger();
  
      @Context
      Request request;
  
      @Override
      public Response toResponse(Exception exception) {
          return Optional.ofNullable(request.selectVariant(SUPPORTED_VARIANTS))
              .map(v -> fromException(exception))
              .orElseGet(() -> (exception instanceof WebApplicationException)
                  ? ((WebApplicationException) exception).getResponse()
                  : null);
      }
  
      public static Response fromWebApplicationException(WebApplicationException wae) {
          if (wae.getResponse().hasEntity()) {
              //usually WAEs with entity do not arrive here
              LOGGER.warn("WebApplicationException already has an entity attached, forwarding response");
              return wae.getResponse();
          }
          final Response response = getResponse(wae, wae.getResponse().getStatus());
          response.getHeaders().putAll(wae.getResponse().getHeaders());
          return response;
      }
  
      public static Response fromException(Exception e) {
          if (e instanceof WebApplicationException) {
              return fromWebApplicationException((WebApplicationException) e);
          }
          return getResponse(e, Response.Status.INTERNAL_SERVER_ERROR.getStatusCode());
      }
  
      private static Response getResponse(Exception e, int statusCode) {
          MCRErrorResponse response = MCRErrorResponse.fromStatus(statusCode)
              .withCause(e)
              .withMessage(e.getMessage())
              .withDetail(Optional.of(e)
                  .map(ex -> (ex instanceof WebApplicationException) ? ex.getCause() : ex)
                  .map(Object::getClass)
                  .map(Class::getName)
                  .orElse(null));
          LogManager.getLogger().error(response::getLogMessage, e);
          return Response.status(response.getStatus())
              .entity(response)
              .build();
      }
  }