/*
 * 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.storageengine.rescon.disk.strategy;

import org.apache.iotdb.commons.utils.JVMCommonUtils;
import org.apache.iotdb.db.exception.DiskSpaceInsufficientException;

import java.io.IOException;

public class MinFolderOccupiedSpaceFirstStrategy extends DirectoryStrategy {

  @Override
  public int nextFolderIndex() throws DiskSpaceInsufficientException {
    return getMinOccupiedSpaceFolder();
  }

  private int getMinOccupiedSpaceFolder() throws DiskSpaceInsufficientException {
    int minIndex = -1;
    long minSpace = Long.MAX_VALUE;

    for (int i = 0; i < folders.size(); i++) {
      String folder = folders.get(i);
      if (!JVMCommonUtils.hasSpace(folder)) {
        continue;
      }

      long space = 0;
      try {
        space = JVMCommonUtils.getOccupiedSpace(folder);
      } catch (IOException e) {
        logger.error("Cannot calculate occupied space for path {}.", folder, e);
      }
      if (space < minSpace) {
        minSpace = space;
        minIndex = i;
      }
    }

    if (minIndex == -1) {
      throw new DiskSpaceInsufficientException(folders);
    }

    return minIndex;
  }
}
