content: // Licensed to the Apache Software Foundation (ASF) under one
  // or more contributor license agreements.  See the NOTICE file
  // distributed with this work for additional information
  // regarding copyright ownership.  The ASF 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
  //
  //   http://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.cloud.storage.download;
  
  import java.util.Date;
  
  import org.apache.logging.log4j.Level;
  import org.apache.logging.log4j.Logger;
  import org.apache.logging.log4j.LogManager;
  
  import com.cloud.agent.api.storage.DownloadAnswer;
  
  public abstract class DownloadState {
      public static enum DownloadEvent {
          DOWNLOAD_ANSWER, ABANDON_DOWNLOAD, TIMEOUT_CHECK, DISCONNECT
      };
  
      protected Logger logger = LogManager.getLogger(getClass());
  
      private DownloadListener dl;
  
      public DownloadState(DownloadListener dl) {
          this.dl = dl;
      }
  
      protected DownloadListener getDownloadListener() {
          return dl;
      }
  
      public String handleEvent(DownloadEvent event, Object eventObj) {
          if (logger.isTraceEnabled()) {
              getDownloadListener().log("handleEvent, event type=" + event + ", curr state=" + getName(), Level.TRACE);
          }
          switch (event) {
              case DOWNLOAD_ANSWER:
                  DownloadAnswer answer = (DownloadAnswer)eventObj;
                  return handleAnswer(answer);
              case ABANDON_DOWNLOAD:
                  return handleAbort();
              case TIMEOUT_CHECK:
                  Date now = new Date();
                  long update = now.getTime() - dl.getLastUpdated().getTime();
                  return handleTimeout(update);
              case DISCONNECT:
                  return handleDisconnect();
          }
          return null;
      }
  
      public void onEntry(String prevState, DownloadEvent event, Object evtObj) {
          if (logger.isTraceEnabled()) {
              getDownloadListener().log("onEntry, event type=" + event + ", curr state=" + getName(), Level.TRACE);
          }
          if (event == DownloadEvent.DOWNLOAD_ANSWER) {
              getDownloadListener().callback((DownloadAnswer)evtObj);
          }
      }
  
      public void onExit() {
  
      }
  
      public abstract String handleTimeout(long updateMs);
  
      public abstract String handleAbort();
  
      public abstract String handleDisconnect();
  
      public abstract String handleAnswer(DownloadAnswer answer);
  
      public abstract String getName();
  
  }
  