/*
 *  Copyright 2015 TWO SIGMA OPEN SOURCE, LLC
 *
 *  Licensed 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.twosigma.beaker.cpp.utils;

import com.google.common.util.concurrent.ThreadFactoryBuilder;
import com.twosigma.beaker.jvm.object.SimpleEvaluationObject;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.Future;

public class CellGobblerManager {

  private static final CellGobblerManager instance = new CellGobblerManager();
  private final ExecutorService executor = Executors.newCachedThreadPool(new ThreadFactoryBuilder().setNameFormat("CellGobbler-%d").build());

  public static CellGobblerManager getInstance() {
    return instance;
  }

  private CellGobblerManager() {}

  public Future<?> startCellGobbler(InputStream inputStream, String type, SimpleEvaluationObject output) {
    return executor.submit(new CellGobbler(inputStream, type, output));
  }

  private static class CellGobbler implements Runnable {

    private static volatile boolean shutdownInprogress = false;

    private final InputStream is;
    private final String type;
    private final SimpleEvaluationObject output;

    private boolean isStillWaiting;

    private CellGobbler(
        InputStream is,
        String type,
        SimpleEvaluationObject output) {
      this.is = is;
      this.type = type;
      this.output = output;
    }

    public static void shuttingDown() {
      shutdownInprogress = true;
    }

    @Override
    public void run() {
      try (BufferedReader br = new BufferedReader(new InputStreamReader(is))) {
        String line;
        while ((line = br.readLine()) != null) {
          if (this.type.equals("stderr")) {
            output.appendError(line + "\n");
          } else {
            output.appendOutput(line + "\n");
          }
        }
      } catch (Exception ioe) {
        ioe.printStackTrace();
        if (!shutdownInprogress) {
          ioe.printStackTrace();
        }
      }
    }
  }
}