/*
 * 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.iotdb.db.pipe.agent.runtime;

import org.apache.iotdb.commons.consensus.index.impl.SimpleProgressIndex;
import org.apache.iotdb.commons.exception.StartupException;
import org.apache.iotdb.commons.file.SystemFileFactory;
import org.apache.iotdb.db.conf.IoTDBConfig;
import org.apache.iotdb.db.conf.IoTDBDescriptor;
import org.apache.iotdb.db.storageengine.dataregion.tsfile.TsFileResource;

import org.apache.commons.io.FileUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.File;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.concurrent.atomic.AtomicLong;

import static org.apache.iotdb.consensus.ConsensusFactory.SIMPLE_CONSENSUS;

public class SimpleConsensusProgressIndexAssigner {

  private static final Logger LOGGER =
      LoggerFactory.getLogger(SimpleConsensusProgressIndexAssigner.class);

  private static final IoTDBConfig IOTDB_CONFIG = IoTDBDescriptor.getInstance().getConfig();

  private static final String PIPE_SYSTEM_DIR =
      IoTDBDescriptor.getInstance().getConfig().getSystemDir()
          + File.separator
          + "pipe"
          + File.separator;
  private static final String REBOOT_TIMES_FILE_NAME = "reboot_times.txt";

  private boolean isSimpleConsensusEnable = false;

  private int rebootTimes = 0;
  private final AtomicLong memtableFlushOrderId = new AtomicLong(0);

  public void start() throws StartupException {
    isSimpleConsensusEnable =
        IOTDB_CONFIG.getDataRegionConsensusProtocolClass().equals(SIMPLE_CONSENSUS);
    LOGGER.info("Start SimpleConsensusProgressIndexAssigner ...");

    try {
      makeDirIfNecessary();
      parseRebootTimes();
      recordRebootTimes();
    } catch (Exception e) {
      throw new StartupException(e);
    }
  }

  private void makeDirIfNecessary() throws IOException {
    File file = SystemFileFactory.INSTANCE.getFile(PIPE_SYSTEM_DIR);
    if (file.exists() && file.isDirectory()) {
      return;
    }
    FileUtils.forceMkdir(file);
  }

  private void parseRebootTimes() {
    File file = SystemFileFactory.INSTANCE.getFile(PIPE_SYSTEM_DIR + REBOOT_TIMES_FILE_NAME);
    if (!file.exists()) {
      rebootTimes = 0;
      return;
    }
    try {
      String content = FileUtils.readFileToString(file, StandardCharsets.UTF_8);
      rebootTimes = Integer.parseInt(content);
    } catch (IOException e) {
      LOGGER.error("Cannot parse reboot times from file {}", file.getAbsolutePath(), e);
      rebootTimes = 0;
    }
  }

  private void recordRebootTimes() throws IOException {
    File file = SystemFileFactory.INSTANCE.getFile(PIPE_SYSTEM_DIR + REBOOT_TIMES_FILE_NAME);
    FileUtils.writeStringToFile(file, String.valueOf(rebootTimes + 1), StandardCharsets.UTF_8);
  }

  public void assignIfNeeded(TsFileResource tsFileResource) {
    if (!isSimpleConsensusEnable) {
      return;
    }

    tsFileResource.updateProgressIndex(
        new SimpleProgressIndex(rebootTimes, memtableFlushOrderId.getAndIncrement()));
  }

  public SimpleProgressIndex getSimpleProgressIndexForTsFileRecovery() {
    return new SimpleProgressIndex(rebootTimes, memtableFlushOrderId.getAndIncrement());
  }
}
