/*
    * Copyright 2017 LINE Corporation
    *
    * LINE Corporation 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:
    *
    *   https://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 com.linecorp.centraldogma.common;
  
  import java.io.IOException;
  
  import javax.annotation.Nullable;
  
  import com.fasterxml.jackson.core.JsonParser;
  import com.fasterxml.jackson.databind.DeserializationContext;
  import com.fasterxml.jackson.databind.JsonMappingException;
  import com.fasterxml.jackson.databind.JsonNode;
  import com.fasterxml.jackson.databind.deser.std.StdDeserializer;
  
  /**
   * Deserializes JSON into a {@link Revision}.
   *
   * @see RevisionJsonSerializer
   */
  public class RevisionJsonDeserializer extends StdDeserializer<Revision> {
  
      private static final long serialVersionUID = -2337105643062794190L;
  
      /**
       * Creates a new instance.
       */
      public RevisionJsonDeserializer() {
          super(Revision.class);
      }
  
      @Override
      public Revision deserialize(JsonParser p, DeserializationContext ctx) throws IOException {
          final JsonNode node = p.readValueAsTree();
          if (node.isNumber()) {
              validateRevisionNumber(ctx, node, "major", false);
              return new Revision(node.intValue());
          }
  
          if (node.isTextual()) {
              try {
                  return new Revision(node.textValue());
              } catch (IllegalArgumentException e) {
                  ctx.reportInputMismatch(Revision.class, e.getMessage());
                  // Should never reach here.
                  throw new Error();
              }
          }
  
          if (!node.isObject()) {
              ctx.reportInputMismatch(Revision.class,
                                      "A revision must be a non-zero integer or " +
                                      "an object that contains \"major\" and \"minor\" properties.");
              // Should never reach here.
              throw new Error();
          }
  
          final JsonNode majorNode = node.get("major");
          final JsonNode minorNode = node.get("minor");
          final int major;
  
          validateRevisionNumber(ctx, majorNode, "major", false);
          major = majorNode.intValue();
          if (minorNode != null) {
              validateRevisionNumber(ctx, minorNode, "minor", true);
              if (minorNode.intValue() != 0) {
                  ctx.reportInputMismatch(Revision.class,
                                          "A revision must not have a non-zero \"minor\" property.");
              }
          }
  
          return new Revision(major);
      }
  
      private static void validateRevisionNumber(DeserializationContext ctx, @Nullable JsonNode node,
                                                 String type, boolean zeroAllowed) throws JsonMappingException {
          if (node == null) {
              ctx.reportInputMismatch(Revision.class, "missing %s revision number", type);
              // Should never reach here.
              throw new Error();
          }
  
          if (!node.canConvertToInt() || !zeroAllowed && node.intValue() == 0) {
              ctx.reportInputMismatch(Revision.class,
                                      "A %s revision number must be %s integer.",
                                      type, zeroAllowed ? "an" : "a non-zero");
              // Should never reach here.
             throw new Error();
         }
     }
 }