/**
 * 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.hadoop.hdfs.server.datanode;

import java.util.regex.Pattern;

import java.io.File;
import java.io.IOException;
import java.net.URI;
import java.util.regex.Matcher;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.fs.LocalFileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.StorageType;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hdfs.server.datanode.checker.Checkable;
import org.apache.hadoop.hdfs.server.datanode.checker.VolumeCheckResult;
import org.apache.hadoop.util.DiskChecker;
import org.apache.hadoop.util.StringUtils;

/**
 * Encapsulates the URI and storage medium that together describe a
 * storage directory.
 * The default storage medium is assumed to be DISK, if none is specified.
 *
 */
@InterfaceAudience.Private
public class StorageLocation
    implements Checkable<StorageLocation.CheckContext, VolumeCheckResult> {
  final StorageType storageType;
  final File file;

  /** Regular expression that describes a storage uri with a storage type.
   *  e.g. [Disk]/storages/storage1/
   */
  private static final Pattern regex = Pattern.compile("^\\[(\\w*)\\](.+)$");

  private StorageLocation(StorageType storageType, URI uri) {
    this.storageType = storageType;

    if (uri.getScheme() == null ||
        "file".equalsIgnoreCase(uri.getScheme())) {
      // drop any (illegal) authority in the URI for backwards compatibility
      this.file = new File(uri.getPath());
    } else {
      throw new IllegalArgumentException("Unsupported URI schema in " + uri);
    }
  }

  public StorageType getStorageType() {
    return this.storageType;
  }

  URI getUri() {
    return file.toURI();
  }

  public File getFile() {
    return this.file;
  }

  /**
   * Attempt to parse a storage uri with storage class and URI. The storage
   * class component of the uri is case-insensitive.
   *
   * @param rawLocation Location string of the format [type]uri, where [type] is
   *                    optional.
   * @return A StorageLocation object if successfully parsed, null otherwise.
   *         Does not throw any exceptions.
   */
  public static StorageLocation parse(String rawLocation)
      throws IOException, SecurityException {
    Matcher matcher = regex.matcher(rawLocation);
    StorageType storageType = StorageType.DEFAULT;
    String location = rawLocation;

    if (matcher.matches()) {
      String classString = matcher.group(1);
      location = matcher.group(2);
      if (!classString.isEmpty()) {
        storageType =
            StorageType.valueOf(StringUtils.toUpperCase(classString));
      }
    }

    return new StorageLocation(storageType, new Path(location).toUri());
  }

  @Override
  public String toString() {
    return "[" + storageType + "]" + file.toURI();
  }

  @Override
  public boolean equals(Object obj) {
    if (obj == this) {
      return true;
    } else if (obj == null || !(obj instanceof StorageLocation)) {
      return false;
    }
    return toString().equals(obj.toString());
  }

  @Override
  public int hashCode() {
    return toString().hashCode();
  }

  @Override  // Checkable
  public VolumeCheckResult check(CheckContext context) throws IOException {
    DiskChecker.checkDir(
        context.localFileSystem,
        new Path(file.toURI()),
        context.expectedPermission);
    return VolumeCheckResult.HEALTHY;
  }

  /**
   * Class to hold the parameters for running a {@link #check}.
   */
  public static final class CheckContext {
    private final LocalFileSystem localFileSystem;
    private final FsPermission expectedPermission;

    public CheckContext(LocalFileSystem localFileSystem,
                        FsPermission expectedPermission) {
      this.localFileSystem = localFileSystem;
      this.expectedPermission = expectedPermission;
    }
  }
}