/*
    * This file is part of Waarp Project (named also Waarp or GG).
    *
    *  Copyright (c) 2019, Waarp SAS, and individual contributors by the @author
    *  tags. See the COPYRIGHT.txt in the distribution for a full listing of
    * individual contributors.
    *
    *  All Waarp Project 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.
   *
   * Waarp 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
   * Waarp . If not, see <http://www.gnu.org/licenses/>.
   */
  
  package org.waarp.openr66.protocol.http.restv2.utils;
  
  import com.fasterxml.jackson.core.JsonParseException;
  import com.fasterxml.jackson.core.JsonParser;
  import com.fasterxml.jackson.core.JsonProcessingException;
  import com.fasterxml.jackson.databind.DeserializationFeature;
  import com.fasterxml.jackson.databind.JsonMappingException;
  import com.fasterxml.jackson.databind.JsonNode;
  import com.fasterxml.jackson.databind.ObjectMapper;
  import com.fasterxml.jackson.databind.node.ObjectNode;
  import io.netty.handler.codec.http.FullHttpRequest;
  import io.netty.handler.codec.http.HttpRequest;
  import org.waarp.common.exception.InvalidArgumentException;
  import org.waarp.common.utility.ParametersChecker;
  import org.waarp.openr66.protocol.http.restv2.errors.RestErrorException;
  
  import javax.ws.rs.InternalServerErrorException;
  import javax.ws.rs.NotSupportedException;
  import java.io.IOException;
  
  import static javax.ws.rs.core.HttpHeaders.*;
  import static javax.ws.rs.core.MediaType.*;
  import static org.waarp.openr66.protocol.http.restv2.RestConstants.*;
  import static org.waarp.openr66.protocol.http.restv2.errors.RestErrors.*;
  
  /**
   * A series of utility methods for serializing and deserializing JSON.
   */
  public final class JsonUtils {
  
    /**
     * Makes the default constructor of this utility class inaccessible.
     */
    private JsonUtils() throws InstantiationException {
      throw new InstantiationException(
          getClass().getName() + " cannot be instantiated.");
    }
  
    // ######################### PUBLIC METHODS #################################
  
    /**
     * Converts an ObjectNode into a String.
     *
     * @param object the ObjectNode to convert
     *
     * @return the JSON object as a String
     *
     * @throws InternalServerErrorException if an unexpected error
     *     occurred
     */
    public static String nodeToString(final ObjectNode object) {
      try {
        final ObjectMapper mapper = new ObjectMapper();
        return mapper.writeValueAsString(object);
      } catch (final JsonProcessingException e) {
        throw new InternalServerErrorException(e);
      }
    }
  
    /**
     * Deserializes a request's content as an ObjectNode
     *
     * @param request the request to deserialize
     *
     * @return the deserialized JSON object
     *
     * @throws RestErrorException If the content is not a valid JSON
     *     object.
     * @throws NotSupportedException If the content type is not JSON.
     * @throws InternalServerErrorException if an unexpected error
     *     occurred
     */
    public static ObjectNode deserializeRequest(final HttpRequest request) {
      if (!(request instanceof FullHttpRequest)) {
        throw new RestErrorException(MISSING_BODY());
      }
  
      try {
        final String body =
           ((FullHttpRequest) request).content().toString(UTF8_CHARSET);
       try {
         ParametersChecker.checkSanityString(body);
       } catch (final InvalidArgumentException e) {
         throw new RestErrorException(MALFORMED_JSON(0, 0,
                                                     "The root JSON element contains invalid data"));
       }
       final ObjectMapper mapper = new ObjectMapper();
       mapper.enable(DeserializationFeature.FAIL_ON_READING_DUP_TREE_KEY);
       final JsonNode node = mapper.readTree(body);
 
       if (node.isObject()) {
         return (ObjectNode) node;
       } else {
         throw new RestErrorException(
             MALFORMED_JSON(0, 0, "The root JSON element is not an object"));
       }
     } catch (final JsonParseException e) {
       final String contentType = request.headers().get(CONTENT_TYPE);
       if (ParametersChecker.isEmpty(contentType)) {
         throw new NotSupportedException(APPLICATION_JSON);
       } else {
         throw new RestErrorException(MALFORMED_JSON(e.getLocation().getLineNr(),
                                                     e.getLocation()
                                                      .getColumnNr(),
                                                     e.getOriginalMessage()));
       }
     } catch (final JsonMappingException e) {
       final JsonParser parser = (JsonParser) e.getProcessor();
       try {
         final String field = parser.getCurrentName();
         if (field == null) {
           throw new RestErrorException(MISSING_BODY());
         } else {
           throw new RestErrorException(DUPLICATE_KEY(field));
         }
       } catch (final IOException ex) {
         throw new InternalServerErrorException(e);
       }
     } catch (final IOException e) {
       throw new InternalServerErrorException(e);
     }
   }
 }