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 org.apache.cassandra.tools.nodetool;
  
  import java.util.List;
  
  import org.apache.cassandra.io.util.File;
  import org.apache.cassandra.io.util.FileUtils;
  import org.apache.cassandra.tools.NodeProbe;
  import org.apache.cassandra.tools.NodeTool;
  import picocli.CommandLine;
  import picocli.CommandLine.Command;
  import picocli.CommandLine.Option;
  
  @Command(name = "history", description = "Print previously executed nodetool commands")
  public class History extends AbstractCommand
  {
      @Option(paramLabel = "commands",
      names = { "-n", "--num", "--number-of-commands" },
      description = "Number of commands to print, defaults to 1000.")
      public int commands = 1000;
  
      @Override
      protected void execute(NodeProbe probe)
      {
          if (commands < 1)
              throw new IllegalArgumentException("Number of commands to display has to be at least 1.");
  
          File historyFile = getHistoryFile();
          validateHistoryFile(historyFile);
  
          for (String line : commandsToPrint(historyFile))
              output.out.println(line);
      }
  
      @Override
      protected boolean shouldConnect() throws CommandLine.ExecutionException
      {
          return false;
      }
  
      File getHistoryFile()
      {
          return NodeTool.getHistoryFile();
      }
  
      List<String> commandsToPrint(File file)
      {
          List<String> historyCommands = FileUtils.readLines(file);
          int size = historyCommands.size();
          List<String> commandLines;
  
          if (commands > size)
              commandLines = historyCommands;
          else
              commandLines = historyCommands.subList(size - commands, size);
  
          return commandLines;
      }
  
      /**
       * Nodetool is appending command to history file before it is executed so us checking on its
       * existence and validating it is not technically necessary however nodetool is also swallowing
       * all errors when it was not succesful in appending to the history file so better to check here in that case.
       *
       * @param historyFile file to check that it is actually a file which exists and it is readable
       */
      void validateHistoryFile(File historyFile)
      {
          if (!historyFile.exists())
              throw new IllegalStateException(String.format("History file %s does not exist.%n", historyFile.absolutePath()));
  
          if (!historyFile.isFile())
              throw new IllegalStateException(String.format("History file %s is not a file.%n", historyFile.absolutePath()));
  
          if (!historyFile.isReadable())
              throw new IllegalStateException(String.format("History file %s is not readable.%n", historyFile.absolutePath()));
      }
  }
  