/*
    * 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.server.internal.storage.repository.git;
  
  import static java.util.Objects.requireNonNull;
  
  import java.io.IOException;
  import java.io.StringWriter;
  
  import com.fasterxml.jackson.core.JsonGenerator;
  import com.fasterxml.jackson.databind.JsonNode;
  
  import com.linecorp.centraldogma.common.Author;
  import com.linecorp.centraldogma.common.Commit;
  import com.linecorp.centraldogma.common.Markup;
  import com.linecorp.centraldogma.common.Revision;
  import com.linecorp.centraldogma.internal.Jackson;
  import com.linecorp.centraldogma.server.storage.StorageException;
  
  final class CommitUtil {
  
      private static final String FIELD_NAME_SUMMARY = "summary";
      private static final String FIELD_NAME_DETAIL = "detail";
      private static final String FIELD_NAME_MARKUP = "markup";
      private static final String FIELD_NAME_REVISION = "revision";
  
      static String toJsonString(String summary, String detail, Markup markup, Revision nextRevision) {
          try {
              final StringWriter stringWriter = new StringWriter();
              final JsonGenerator jsonGenerator = Jackson.createPrettyGenerator(stringWriter);
              jsonGenerator.writeStartObject();
              jsonGenerator.writeStringField(FIELD_NAME_SUMMARY, summary);
              jsonGenerator.writeStringField(FIELD_NAME_DETAIL, detail);
              jsonGenerator.writeStringField(FIELD_NAME_MARKUP, markup.nameLowercased());
              jsonGenerator.writeStringField(FIELD_NAME_REVISION, nextRevision.text());
              jsonGenerator.writeEndObject();
              jsonGenerator.close();
              return stringWriter.toString();
          } catch (IOException e) {
              throw new StorageException("failed to generate a JSON string", e);
          }
      }
  
      static Revision extractRevision(String jsonString) {
          try {
              final JsonNode jsonNode = Jackson.readTree(jsonString);
              return new Revision(Jackson.textValue(jsonNode.get(FIELD_NAME_REVISION), ""));
          } catch (Exception e) {
              throw new StorageException("failed to extract revision from " + jsonString, e);
          }
      }
  
      static Commit newCommit(Author author, long when, String jsonString) {
          requireNonNull(author, "author");
          when = when / 1000L * 1000L; // Drop the milliseconds
          try {
              final JsonNode jsonNode = Jackson.readTree(jsonString);
  
              final String summary = Jackson.textValue(jsonNode.get(FIELD_NAME_SUMMARY), "");
              final String detail = Jackson.textValue(jsonNode.get(FIELD_NAME_DETAIL), "");
  
              final Markup markup;
              switch (Jackson.textValue(jsonNode.get(FIELD_NAME_MARKUP), "")) {
              case "plaintext":
                  markup = Markup.PLAINTEXT;
                  break;
              case "markdown":
                  markup = Markup.MARKDOWN;
                  break;
              default:
                  markup = Markup.UNKNOWN;
              }
  
              final Revision revision = new Revision(Jackson.textValue(jsonNode.get(FIELD_NAME_REVISION), ""));
  
              return new Commit(revision, author, when, summary, detail, markup);
          } catch (Exception e) {
              throw new StorageException("failed to create a Commit", e);
          }
      }
  
      private CommitUtil() {}
  }