/**
    * 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 org.apache.hadoop.hbase.hbtop.screen;
  
  import edu.umd.cs.findbugs.annotations.Nullable;
  import java.io.Closeable;
  import java.io.IOException;
  import java.util.List;
  import java.util.concurrent.TimeUnit;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.client.Admin;
  import org.apache.hadoop.hbase.client.Connection;
  import org.apache.hadoop.hbase.client.ConnectionFactory;
  import org.apache.hadoop.hbase.hbtop.RecordFilter;
  import org.apache.hadoop.hbase.hbtop.field.Field;
  import org.apache.hadoop.hbase.hbtop.mode.Mode;
  import org.apache.hadoop.hbase.hbtop.screen.top.TopScreenView;
  import org.apache.hadoop.hbase.hbtop.terminal.KeyPress;
  import org.apache.hadoop.hbase.hbtop.terminal.Terminal;
  import org.apache.hadoop.hbase.hbtop.terminal.impl.TerminalImpl;
  import org.apache.hadoop.hbase.hbtop.terminal.impl.batch.BatchTerminal;
  
  /**
   * This dispatches key presses and timers to the current {@link ScreenView}.
   */
  @InterfaceAudience.Private
  public class Screen implements Closeable {
  
    private static final Log LOG = LogFactory.getLog(Screen.class);
  
    private static final long SLEEP_TIMEOUT_MILLISECONDS = 100;
  
    private final Connection connection;
    private final Admin admin;
    private final Terminal terminal;
  
    private ScreenView currentScreenView;
    private Long timerTimestamp;
  
    public Screen(Configuration conf, long initialRefreshDelay, Mode initialMode,
      @Nullable List<Field> initialFields, @Nullable Field initialSortField,
      @Nullable Boolean initialAscendingSort, @Nullable List<RecordFilter> initialFilters,
      long numberOfIterations, boolean batchMode)
      throws IOException {
      connection = ConnectionFactory.createConnection(conf);
      admin = connection.getAdmin();
  
      // The first screen is the top screen
      if (batchMode) {
        terminal = new BatchTerminal();
      } else {
        terminal = new TerminalImpl("hbtop");
      }
      currentScreenView = new TopScreenView(this, terminal, initialRefreshDelay, admin,
        initialMode, initialFields, initialSortField, initialAscendingSort, initialFilters,
        numberOfIterations);
    }
  
    @Override
    public void close() throws IOException {
      try {
        admin.close();
      } finally {
        try {
          connection.close();
        } finally {
          terminal.close();
        }
      }
    }
  
    public void run() {
      currentScreenView.init();
      while (true) {
        try {
          KeyPress keyPress = terminal.pollKeyPress();
  
          ScreenView nextScreenView;
          if (keyPress != null) {
            // Dispatch the key press to the current screen
           nextScreenView = currentScreenView.handleKeyPress(keyPress);
         } else {
           if (timerTimestamp != null) {
             long now = System.currentTimeMillis();
             if (timerTimestamp <= now) {
               // Dispatch the timer to the current screen
               timerTimestamp = null;
               nextScreenView = currentScreenView.handleTimer();
             } else {
               TimeUnit.MILLISECONDS
                 .sleep(Math.min(timerTimestamp - now, SLEEP_TIMEOUT_MILLISECONDS));
               continue;
             }
           } else {
             TimeUnit.MILLISECONDS.sleep(SLEEP_TIMEOUT_MILLISECONDS);
             continue;
           }
         }
 
         // If the next screen is null, then exit
         if (nextScreenView == null) {
           return;
         }
 
         // If the next screen is not the previous, then go to the next screen
         if (nextScreenView != currentScreenView) {
           currentScreenView = nextScreenView;
           currentScreenView.init();
         }
       } catch (Exception e) {
         LOG.error("Caught an exception", e);
       }
     }
   }
 
   public void setTimer(long delay) {
     timerTimestamp = System.currentTimeMillis() + delay;
   }
 
   public void cancelTimer() {
     timerTimestamp = null;
   }
 }