// Copyright (C) 2012 The Android Open Source Project
//
// 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.google.gerrit.pgm.util;

import com.google.gerrit.extensions.events.LifecycleListener;
import com.google.gerrit.server.config.SitePaths;
import com.google.gerrit.server.git.GarbageCollection;
import com.google.gerrit.server.util.LogUtil;

import org.apache.log4j.Appender;
import org.apache.log4j.DailyRollingFileAppender;
import org.apache.log4j.Level;
import org.apache.log4j.LogManager;
import org.apache.log4j.Logger;
import org.apache.log4j.PatternLayout;
import org.apache.log4j.helpers.OnlyOnceErrorHandler;
import org.apache.log4j.spi.ErrorHandler;
import org.apache.log4j.spi.LoggingEvent;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;

public class GarbageCollectionLogFile {
  private static final org.slf4j.Logger log = LoggerFactory.getLogger(GarbageCollectionLogFile.class);

  public static LifecycleListener start(File sitePath)
      throws FileNotFoundException {
    File logdir = new SitePaths(sitePath).logs_dir;
    if (!logdir.exists() && !logdir.mkdirs()) {
      throw new Die("Cannot create log directory: " + logdir);
    }
    if (LogUtil.shouldConfigureLogSystem()) {
      initLogSystem(logdir);
    }

    return new LifecycleListener() {
      @Override
      public void start() {
      }

      @Override
      public void stop() {
        LogManager.getLogger(GarbageCollection.LOG_NAME).removeAllAppenders();
      }
    };
  }

  private static void initLogSystem(File logdir) {
    PatternLayout layout = new PatternLayout();
    layout.setConversionPattern("[%d] %-5p %x: %m%n");

    DailyRollingFileAppender dst = new DailyRollingFileAppender();
    dst.setName(GarbageCollection.LOG_NAME);
    dst.setLayout(layout);
    dst.setEncoding("UTF-8");
    dst.setFile(new File(resolve(logdir), GarbageCollection.LOG_NAME).getPath());
    dst.setImmediateFlush(true);
    dst.setAppend(true);
    dst.setThreshold(Level.INFO);
    dst.setErrorHandler(new LogErrorHandler());
    dst.activateOptions();
    dst.setErrorHandler(new OnlyOnceErrorHandler());

    Logger gcLogger = LogManager.getLogger(GarbageCollection.LOG_NAME);
    gcLogger.removeAllAppenders();
    gcLogger.addAppender(dst);
    gcLogger.setAdditivity(false);
  }

  private static File resolve(File logs_dir) {
    try {
      return logs_dir.getCanonicalFile();
    } catch (IOException e) {
      return logs_dir.getAbsoluteFile();
    }
  }

  private GarbageCollectionLogFile() {
  }

  private static final class LogErrorHandler implements ErrorHandler {
    @Override
    public void error(String message, Exception e, int errorCode,
        LoggingEvent event) {
      error(e != null ? e.getMessage() : message);
    }

    @Override
    public void error(String message, Exception e, int errorCode) {
      error(e != null ? e.getMessage() : message);
    }

    @Override
    public void error(String message) {
      log.error("Cannot open '" + GarbageCollection.LOG_NAME + "' log file: "
          + message);
    }

    @Override
    public void activateOptions() {
    }

    @Override
    public void setAppender(Appender appender) {
    }

    @Override
    public void setBackupAppender(Appender appender) {
    }

    @Override
    public void setLogger(Logger logger) {
    }
  }
}