/*
 * 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.geode.internal.process;

import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

import org.apache.logging.log4j.Logger;

import org.apache.geode.distributed.AbstractLauncher.ServiceState;
import org.apache.geode.internal.logging.LogService;
import org.apache.geode.internal.process.ControlFileWatchdog.ControlRequestHandler;

/**
 * Exists inside a process launched by ServerLauncher or LocatorLauncher. Creates the PID file and
 * ControlFileWatchdogs to monitor working directory for creation of stop or status request files.
 * 
 * @since GemFire 8.0
 */
public final class ControllableProcess {
  private static final Logger logger = LogService.getLogger();

  private final File workingDir;
  private final File pidFile;
  private final LocalProcessLauncher launcher;
  private final ControlFileWatchdog stopRequestFileWatchdog;
  private final ControlFileWatchdog statusRequestFileWatchdog;

  public ControllableProcess(final ControlNotificationHandler handler, final File workingDir,
      final ProcessType processType, boolean force)
      throws FileAlreadyExistsException, IOException, PidUnavailableException {
    this.workingDir = workingDir;
    this.pidFile = new File(this.workingDir, processType.getPidFileName());

    deleteFiles(this.workingDir, processType);

    this.launcher = new LocalProcessLauncher(this.pidFile, force);

    final ControlRequestHandler stopHandler = new ControlRequestHandler() {
      @Override
      public void handleRequest() {
        handler.handleStop();
      }
    };
    final ControlRequestHandler statusHandler = new ControlRequestHandler() {
      @Override
      public void handleRequest() throws IOException {
        final ServiceState<?> state = handler.handleStatus();
        final File statusFile = new File(workingDir, processType.getStatusFileName());
        if (statusFile.exists()) {
          statusFile.delete();
        }
        final File statusFileTmp = new File(workingDir, processType.getStatusFileName() + ".tmp");
        if (statusFileTmp.exists()) {
          statusFileTmp.delete();
        }
        boolean created = statusFileTmp.createNewFile();
        assert created;
        final FileWriter writer = new FileWriter(statusFileTmp);
        writer.write(state.toJson());
        writer.flush();
        writer.close();
        boolean renamed = statusFileTmp.renameTo(statusFile);
        assert renamed;
      }
    };

    this.stopRequestFileWatchdog = new ControlFileWatchdog(workingDir,
        processType.getStopRequestFileName(), stopHandler, false);
    this.stopRequestFileWatchdog.start();
    this.statusRequestFileWatchdog = new ControlFileWatchdog(workingDir,
        processType.getStatusRequestFileName(), statusHandler, false);
    this.statusRequestFileWatchdog.start();
  }

  /**
   * Returns the process id (PID).
   * 
   * @return the process id (PID)
   */
  public int getPid() {
    return this.launcher.getPid();
  }

  /**
   * Returns the PID file.
   * 
   * @return the PID file
   */
  public File getPidFile() {
    return this.launcher.getPidFile();
  }

  public void stop() {
    try {
      this.statusRequestFileWatchdog.stop();
    } catch (InterruptedException e) {
      logger.warn("Interrupted while stopping status handler for controllable process.", e);
    } finally {
      try {
        this.stopRequestFileWatchdog.stop();
      } catch (InterruptedException e) {
        logger.warn("Interrupted while stopping stop handler for controllable process.", e);
      }
      this.launcher.close();
    }
  }

  protected File getWorkingDir() {
    return this.workingDir;
  }

  private static void deleteFiles(final File workingDir, final ProcessType processType) {
    deleteFile(workingDir, processType.getStatusRequestFileName());
    deleteFile(workingDir, processType.getStatusFileName());
    deleteFile(workingDir, processType.getStopRequestFileName());
  }

  private static void deleteFile(final File workingDir, final String fileName) {
    final File file = new File(workingDir, fileName);
    if (file.exists()) {
      file.delete();
    }
  }
}