/*
    * 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.command;
  
  import static java.util.Objects.requireNonNull;
  
  import java.util.Objects;
  
  import javax.annotation.Nullable;
  
  import com.google.common.base.MoreObjects;
  
  import com.linecorp.centraldogma.common.Author;
  
  abstract class AbstractCommand<T> implements Command<T> {
  
      private final CommandType type;
      private final long timestamp;
      private final Author author;
  
      protected AbstractCommand(CommandType type, @Nullable Long timestamp, @Nullable Author author) {
          this.type = requireNonNull(type, "type");
          this.timestamp = timestamp != null ? timestamp : System.currentTimeMillis();
          this.author = author != null ? author : Author.SYSTEM;
      }
  
      @Override
      public final CommandType type() {
          return type;
      }
  
      @Override
      public final long timestamp() {
          return timestamp;
      }
  
      @Override
      public final Author author() {
          return author;
      }
  
      @Override
      public boolean equals(Object obj) {
          if (this == obj) {
              return true;
          }
          if (!(obj instanceof AbstractCommand)) {
              return false;
          }
  
          final AbstractCommand<?> that = (AbstractCommand<?>) obj;
          return type == that.type &&
                 timestamp == that.timestamp &&
                 author.equals(that.author);
      }
  
      @Override
      public int hashCode() {
          return Objects.hash(type, timestamp, author);
      }
  
      @Override
      public final String toString() {
          return toStringHelper().toString();
      }
  
      MoreObjects.ToStringHelper toStringHelper() {
          return MoreObjects.toStringHelper(this)
                            .add("type", type)
                            .add("timestamp", timestamp)
                            .add("author", author);
      }
  }