/*
    * 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.chukwa.inputtools.plugin;
  
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import org.json.simple.JSONObject;
  
  /**
   * Runs external command-line tools, captures output.
   * 
   * Subclasses are responsible for implementing getCmde(), which determines the
   * command to be invoked.
   * 
   */
  public abstract class ExecPlugin implements IPlugin {
    public final int statusOK = 100;
    public final int statusKO = -100;
  
    Process process = null;
  
    public ExecPlugin() {
  
    }
  
    public void stop() {
      if(process != null)
        process.destroy();
    }
  
    public int waitFor() throws InterruptedException {
      return process.waitFor();
    }
  
    public abstract String getCmde();
  
    public JSONObject postProcess(JSONObject execResult) {
      return execResult;
    }
  
    public JSONObject execute() {
      JSONObject result = new JSONObject();
      try {
        result.put("timestamp", System.currentTimeMillis());
  
        Runtime runtime = Runtime.getRuntime();
        process = runtime.exec(getCmde());
  
        OutputReader stdOut = new OutputReader(process, Output.stdOut);
        stdOut.start();
        OutputReader stdErr = new OutputReader(process, Output.stdErr);
        stdErr.start();
        int exitValue = process.waitFor();
        stdOut.join();
        stdErr.join();
        process.getInputStream().close(); //otherwise this implicitly stays open
        result.put("exitValue", exitValue);
        result.put("stdout", stdOut.output.toString());
        result.put("stderr", stdErr.output.toString());
        result.put("status", statusOK);
        process.getOutputStream().close();
        process.getErrorStream().close();
      } catch (Throwable e) {
        try {
          result.put("status", statusKO);
          result.put("errorLog", e.getMessage());
          if(e.getMessage().contains("Too many open files")) {
            //maybe die abruptly?  Error is ir-recoverable and runtime can reboot us.
  //        System.exit(1); 
          }
        } catch (Exception e1) {
          e1.printStackTrace();
        }
        e.printStackTrace();
      }
  
      return postProcess(result);
    }
  }
  
 
 enum Output {
   stdOut, stdErr
 };
 
 
 class OutputReader extends Thread {
   private Process process = null;
   private Output outputType = null;
   public StringBuilder output = new StringBuilder();
   public boolean isOk = true;
 
   public OutputReader(Process process, Output outputType) {
     this.process = process;
     this.outputType = outputType;
   }
 
   public void run() {
     try {
       String line = null;
       InputStream is = null;
       switch (this.outputType) {
       case stdOut:
         is = process.getInputStream();
         break;
       case stdErr:
         is = process.getErrorStream();
         break;
 
       }
 
       InputStreamReader isr = new InputStreamReader(is);
       BufferedReader br = new BufferedReader(isr);
       while ((line = br.readLine()) != null) {
         // System.out.println("========>>>>>>>["+line+"]");
         output.append(line).append("\n");
       }
       br.close();
     } catch (IOException e) {
       isOk = false;
       e.printStackTrace();
     } catch (Throwable e) {
       isOk = false;
       e.printStackTrace();
     }
   }
 }