/**
 * 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.security.alias;

import org.apache.hadoop.classification.InterfaceAudience;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FSDataOutputStream;
import org.apache.hadoop.fs.FileStatus;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.permission.FsPermission;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URI;

/**
 * CredentialProvider based on Java's KeyStore file format. The file may be
 * stored in any Hadoop FileSystem using the following name mangling:
 * jceks://hdfs@nn1.example.com/my/creds.jceks ->
 * hdfs://nn1.example.com/my/creds.jceks jceks://file/home/larry/creds.jceks ->
 * file:///home/larry/creds.jceks
 */
@InterfaceAudience.Private
public class JavaKeyStoreProvider extends AbstractJavaKeyStoreProvider {
  public static final String SCHEME_NAME = "jceks";

  private FileSystem fs;
  private FsPermission permissions;

  private JavaKeyStoreProvider(URI uri, Configuration conf)
      throws IOException {
    super(uri, conf);
  }

  @Override
  protected String getSchemeName() {
    return SCHEME_NAME;
  }

  @Override
  protected OutputStream getOutputStreamForKeystore() throws IOException {
    FSDataOutputStream out = FileSystem.create(fs, getPath(), permissions);
    return out;
  }

  @Override
  protected boolean keystoreExists() throws IOException {
    return fs.exists(getPath());
  }

  @Override
  protected InputStream getInputStreamForFile() throws IOException {
    return fs.open(getPath());
  }

  @Override
  protected void createPermissions(String perms) {
    permissions = new FsPermission(perms);
  }

  @Override
  protected void stashOriginalFilePermissions() throws IOException {
    // save off permissions in case we need to
    // rewrite the keystore in flush()
    FileStatus s = fs.getFileStatus(getPath());
    permissions = s.getPermission();
  }

  protected void initFileSystem(URI uri, Configuration conf)
      throws IOException {
    super.initFileSystem(uri, conf);
    fs = getPath().getFileSystem(conf);
  }

  /**
   * The factory to create JksProviders, which is used by the ServiceLoader.
   */
  public static class Factory extends CredentialProviderFactory {
    @Override
    public CredentialProvider createProvider(URI providerName,
        Configuration conf) throws IOException {
      if (SCHEME_NAME.equals(providerName.getScheme())) {
        return new JavaKeyStoreProvider(providerName, conf);
      }
      return null;
    }
  }
}