/**
 *
 * 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.hbase.master;

import java.io.IOException;

import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.FileSystem;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.fs.permission.FsAction;
import org.apache.hadoop.fs.permission.FsPermission;
import org.apache.hadoop.hbase.ClusterId;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.backup.HFileArchiver;
import org.apache.hadoop.hbase.client.ColumnFamilyDescriptor;
import org.apache.hadoop.hbase.client.ColumnFamilyDescriptorBuilder;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.client.RegionInfoBuilder;
import org.apache.hadoop.hbase.client.TableDescriptor;
import org.apache.hadoop.hbase.client.TableDescriptorBuilder;
import org.apache.hadoop.hbase.exceptions.DeserializationException;
import org.apache.hadoop.hbase.fs.HFileSystem;
import org.apache.hadoop.hbase.log.HBaseMarkers;
import org.apache.hadoop.hbase.mob.MobConstants;
import org.apache.hadoop.hbase.procedure2.store.wal.WALProcedureStore;
import org.apache.hadoop.hbase.regionserver.HRegion;
import org.apache.hadoop.hbase.util.Bytes;
import org.apache.hadoop.hbase.util.FSTableDescriptors;
import org.apache.hadoop.hbase.util.FSUtils;
import org.apache.hadoop.ipc.RemoteException;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This class abstracts a bunch of operations the HMaster needs to interact with
 * the underlying file system like creating the initial layout, checking file
 * system status, etc.
 */
@InterfaceAudience.Private
public class MasterFileSystem {
  private static final Logger LOG = LoggerFactory.getLogger(MasterFileSystem.class);

  /** Parameter name for HBase instance root directory permission*/
  public static final String HBASE_DIR_PERMS = "hbase.rootdir.perms";

  /** Parameter name for HBase WAL directory permission*/
  public static final String HBASE_WAL_DIR_PERMS = "hbase.wal.dir.perms";

  // HBase configuration
  private final Configuration conf;
  // Persisted unique cluster ID
  private ClusterId clusterId;
  // Keep around for convenience.
  private final FileSystem fs;
  // Keep around for convenience.
  private final FileSystem walFs;
  // root log directory on the FS
  private final Path rootdir;
  // hbase temp directory used for table construction and deletion
  private final Path tempdir;
  // root hbase directory on the FS
  private final Path walRootDir;


  /*
   * In a secure env, the protected sub-directories and files under the HBase rootDir
   * would be restricted. The sub-directory will have '700' except the bulk load staging dir,
   * which will have '711'.  The default '700' can be overwritten by setting the property
   * 'hbase.rootdir.perms'. The protected files (version file, clusterId file) will have '600'.
   * The rootDir itself will be created with HDFS default permissions if it does not exist.
   * We will check the rootDir permissions to make sure it has 'x' for all to ensure access
   * to the staging dir. If it does not, we will add it.
   */
  // Permissions for the directories under rootDir that need protection
  private final FsPermission secureRootSubDirPerms;
  // Permissions for the files under rootDir that need protection
  private final FsPermission secureRootFilePerms = new FsPermission("600");
  // Permissions for bulk load staging directory under rootDir
  private final FsPermission HiddenDirPerms = FsPermission.valueOf("-rwx--x--x");

  private boolean isSecurityEnabled;

  public MasterFileSystem(Configuration conf) throws IOException {
    this.conf = conf;
    // Set filesystem to be that of this.rootdir else we get complaints about
    // mismatched filesystems if hbase.rootdir is hdfs and fs.defaultFS is
    // default localfs.  Presumption is that rootdir is fully-qualified before
    // we get to here with appropriate fs scheme.
    this.rootdir = FSUtils.getRootDir(conf);
    this.tempdir = new Path(this.rootdir, HConstants.HBASE_TEMP_DIRECTORY);
    // Cover both bases, the old way of setting default fs and the new.
    // We're supposed to run on 0.20 and 0.21 anyways.
    this.fs = this.rootdir.getFileSystem(conf);
    this.walRootDir = FSUtils.getWALRootDir(conf);
    this.walFs = FSUtils.getWALFileSystem(conf);
    FSUtils.setFsDefault(conf, new Path(this.walFs.getUri()));
    walFs.setConf(conf);
    FSUtils.setFsDefault(conf, new Path(this.fs.getUri()));
    // make sure the fs has the same conf
    fs.setConf(conf);
    this.secureRootSubDirPerms = new FsPermission(conf.get("hbase.rootdir.perms", "700"));
    this.isSecurityEnabled = "kerberos".equalsIgnoreCase(conf.get("hbase.security.authentication"));
    // setup the filesystem variable
    createInitialFileSystemLayout();
    HFileSystem.addLocationsOrderInterceptor(conf);
  }

  /**
   * Create initial layout in filesystem.
   * <ol>
   * <li>Check if the meta region exists and is readable, if not create it.
   * Create hbase.version and the hbase:meta directory if not one.
   * </li>
   * </ol>
   * Idempotent.
   */
  private void createInitialFileSystemLayout() throws IOException {

    final String[] protectedSubDirs = new String[] {
        HConstants.BASE_NAMESPACE_DIR,
        HConstants.HFILE_ARCHIVE_DIRECTORY,
        HConstants.HBCK_SIDELINEDIR_NAME,
        MobConstants.MOB_DIR_NAME
    };

    final String[] protectedSubLogDirs = new String[] {
      HConstants.HREGION_LOGDIR_NAME,
      HConstants.HREGION_OLDLOGDIR_NAME,
      HConstants.CORRUPT_DIR_NAME,
      WALProcedureStore.MASTER_PROCEDURE_LOGDIR
    };
    // check if the root directory exists
    checkRootDir(this.rootdir, conf, this.fs);

    // Check the directories under rootdir.
    checkTempDir(this.tempdir, conf, this.fs);
    for (String subDir : protectedSubDirs) {
      checkSubDir(new Path(this.rootdir, subDir), HBASE_DIR_PERMS);
    }

    final String perms;
    if (!this.walRootDir.equals(this.rootdir)) {
      perms = HBASE_WAL_DIR_PERMS;
    } else {
      perms = HBASE_DIR_PERMS;
    }
    for (String subDir : protectedSubLogDirs) {
      checkSubDir(new Path(this.walRootDir, subDir), perms);
    }

    checkStagingDir();

    // Handle the last few special files and set the final rootDir permissions
    // rootDir needs 'x' for all to support bulk load staging dir
    if (isSecurityEnabled) {
      fs.setPermission(new Path(rootdir, HConstants.VERSION_FILE_NAME), secureRootFilePerms);
      fs.setPermission(new Path(rootdir, HConstants.CLUSTER_ID_FILE_NAME), secureRootFilePerms);
    }
    FsPermission currentRootPerms = fs.getFileStatus(this.rootdir).getPermission();
    if (!currentRootPerms.getUserAction().implies(FsAction.EXECUTE)
        || !currentRootPerms.getGroupAction().implies(FsAction.EXECUTE)
        || !currentRootPerms.getOtherAction().implies(FsAction.EXECUTE)) {
      LOG.warn("rootdir permissions do not contain 'excute' for user, group or other. "
        + "Automatically adding 'excute' permission for all");
      fs.setPermission(
        this.rootdir,
        new FsPermission(currentRootPerms.getUserAction().or(FsAction.EXECUTE), currentRootPerms
            .getGroupAction().or(FsAction.EXECUTE), currentRootPerms.getOtherAction().or(
          FsAction.EXECUTE)));
    }
  }

  public FileSystem getFileSystem() {
    return this.fs;
  }

  protected FileSystem getWALFileSystem() { return this.walFs; }

  public Configuration getConfiguration() {
    return this.conf;
  }

  /**
   * @return HBase root directory.
   */
  public Path getRootDir() {
    return this.rootdir;
  }

  /**
   * @return HBase WAL root directory, usually the same as {@link #getRootDir()} but can be
   *   different if hfiles on one fs and WALs on another. The 'WALs' dir gets made underneath
   *   the root dir returned here; i.e. this is '/hbase', not '/hbase/WALs'.
   */
  public Path getWALRootDir() {
    return this.walRootDir;
  }

  /**
   * @return the directory for a give {@code region}.
   */
  public Path getRegionDir(RegionInfo region) {
    return FSUtils.getRegionDir(FSUtils.getTableDir(getRootDir(), region.getTable()), region);
  }

  /**
   * @return HBase temp dir.
   */
  public Path getTempDir() {
    return this.tempdir;
  }

  /**
   * @return The unique identifier generated for this cluster
   */
  public ClusterId getClusterId() {
    return clusterId;
  }

  /**
   * Get the rootdir.  Make sure its wholesome and exists before returning.
   * @param rd
   * @param c
   * @param fs
   * @return hbase.rootdir (after checks for existence and bootstrapping if
   * needed populating the directory with necessary bootup files).
   * @throws IOException
   */
  private Path checkRootDir(final Path rd, final Configuration c, final FileSystem fs)
      throws IOException {
    // If FS is in safe mode wait till out of it.
    FSUtils.waitOnSafeMode(c, c.getInt(HConstants.THREAD_WAKE_FREQUENCY, 10 * 1000));

    // Filesystem is good. Go ahead and check for hbase.rootdir.
    try {
      if (!fs.exists(rd)) {
        fs.mkdirs(rd);
        // DFS leaves safe mode with 0 DNs when there are 0 blocks.
        // We used to handle this by checking the current DN count and waiting until
        // it is nonzero. With security, the check for datanode count doesn't work --
        // it is a privileged op. So instead we adopt the strategy of the jobtracker
        // and simply retry file creation during bootstrap indefinitely. As soon as
        // there is one datanode it will succeed. Permission problems should have
        // already been caught by mkdirs above.
        FSUtils.setVersion(fs, rd, c.getInt(HConstants.THREAD_WAKE_FREQUENCY,
          10 * 1000), c.getInt(HConstants.VERSION_FILE_WRITE_ATTEMPTS,
            HConstants.DEFAULT_VERSION_FILE_WRITE_ATTEMPTS));
      } else {
        if (!fs.isDirectory(rd)) {
          throw new IllegalArgumentException(rd.toString() + " is not a directory");
        }
        // as above
        FSUtils.checkVersion(fs, rd, true, c.getInt(HConstants.THREAD_WAKE_FREQUENCY,
          10 * 1000), c.getInt(HConstants.VERSION_FILE_WRITE_ATTEMPTS,
            HConstants.DEFAULT_VERSION_FILE_WRITE_ATTEMPTS));
      }
    } catch (DeserializationException de) {
      LOG.error(HBaseMarkers.FATAL, "Please fix invalid configuration for "
        + HConstants.HBASE_DIR, de);
      IOException ioe = new IOException();
      ioe.initCause(de);
      throw ioe;
    } catch (IllegalArgumentException iae) {
      LOG.error(HBaseMarkers.FATAL, "Please fix invalid configuration for "
        + HConstants.HBASE_DIR + " " + rd.toString(), iae);
      throw iae;
    }
    // Make sure cluster ID exists
    if (!FSUtils.checkClusterIdExists(fs, rd, c.getInt(
        HConstants.THREAD_WAKE_FREQUENCY, 10 * 1000))) {
      FSUtils.setClusterId(fs, rd, new ClusterId(), c.getInt(HConstants.THREAD_WAKE_FREQUENCY, 10 * 1000));
    }
    clusterId = FSUtils.getClusterId(fs, rd);

    // Make sure the meta region directory exists!
    if (!FSUtils.metaRegionExists(fs, rd)) {
      bootstrap(rd, c);
    }

    // Create tableinfo-s for hbase:meta if not already there.
    // assume, created table descriptor is for enabling table
    // meta table is a system table, so descriptors are predefined,
    // we should get them from registry.
    FSTableDescriptors fsd = new FSTableDescriptors(c, fs, rd);
    fsd.createTableDescriptor(fsd.get(TableName.META_TABLE_NAME));

    return rd;
  }

  /**
   * Make sure the hbase temp directory exists and is empty.
   * NOTE that this method is only executed once just after the master becomes the active one.
   */
  private void checkTempDir(final Path tmpdir, final Configuration c, final FileSystem fs)
      throws IOException {
    // If the temp directory exists, clear the content (left over, from the previous run)
    if (fs.exists(tmpdir)) {
      // Archive table in temp, maybe left over from failed deletion,
      // if not the cleaner will take care of them.
      for (Path tabledir: FSUtils.getTableDirs(fs, tmpdir)) {
        for (Path regiondir: FSUtils.getRegionDirs(fs, tabledir)) {
          HFileArchiver.archiveRegion(fs, this.rootdir, tabledir, regiondir);
        }
      }
      if (!fs.delete(tmpdir, true)) {
        throw new IOException("Unable to clean the temp directory: " + tmpdir);
      }
    }

    // Create the temp directory
    if (isSecurityEnabled) {
      if (!fs.mkdirs(tmpdir, secureRootSubDirPerms)) {
        throw new IOException("HBase temp directory '" + tmpdir + "' creation failure.");
      }
    } else {
      if (!fs.mkdirs(tmpdir)) {
        throw new IOException("HBase temp directory '" + tmpdir + "' creation failure.");
      }
    }
  }

  /**
   * Make sure the directories under rootDir have good permissions. Create if necessary.
   * @param p
   * @throws IOException
   */
  private void checkSubDir(final Path p, final String dirPermsConfName) throws IOException {
    FileSystem fs = p.getFileSystem(conf);
    FsPermission dirPerms = new FsPermission(conf.get(dirPermsConfName, "700"));
    if (!fs.exists(p)) {
      if (isSecurityEnabled) {
        if (!fs.mkdirs(p, secureRootSubDirPerms)) {
          throw new IOException("HBase directory '" + p + "' creation failure.");
        }
      } else {
        if (!fs.mkdirs(p)) {
          throw new IOException("HBase directory '" + p + "' creation failure.");
        }
      }
    }
    else {
      if (isSecurityEnabled && !dirPerms.equals(fs.getFileStatus(p).getPermission())) {
        // check whether the permission match
        LOG.warn("Found HBase directory permissions NOT matching expected permissions for "
            + p.toString() + " permissions=" + fs.getFileStatus(p).getPermission()
            + ", expecting " + dirPerms + ". Automatically setting the permissions. "
            + "You can change the permissions by setting \"" + dirPermsConfName + "\" in hbase-site.xml "
            + "and restarting the master");
        fs.setPermission(p, dirPerms);
      }
    }
  }

  /**
   * Check permissions for bulk load staging directory. This directory has special hidden
   * permissions. Create it if necessary.
   * @throws IOException
   */
  private void checkStagingDir() throws IOException {
    Path p = new Path(this.rootdir, HConstants.BULKLOAD_STAGING_DIR_NAME);
    try {
      if (!this.fs.exists(p)) {
        if (!this.fs.mkdirs(p, HiddenDirPerms)) {
          throw new IOException("Failed to create staging directory " + p.toString());
        }
      } else {
        this.fs.setPermission(p, HiddenDirPerms);
      }
    } catch (IOException e) {
      LOG.error("Failed to create or set permission on staging directory " + p.toString());
      throw new IOException("Failed to create or set permission on staging directory "
          + p.toString(), e);
    }
  }

  private static void bootstrap(final Path rd, final Configuration c)
  throws IOException {
    LOG.info("BOOTSTRAP: creating hbase:meta region");
    try {
      // Bootstrapping, make sure blockcache is off.  Else, one will be
      // created here in bootstrap and it'll need to be cleaned up.  Better to
      // not make it in first place.  Turn off block caching for bootstrap.
      // Enable after.
      TableDescriptor metaDescriptor = new FSTableDescriptors(c).get(TableName.META_TABLE_NAME);
      HRegion meta = HRegion.createHRegion(RegionInfoBuilder.FIRST_META_REGIONINFO, rd,
          c, setInfoFamilyCachingForMeta(metaDescriptor, false), null);
      meta.close();
    } catch (IOException e) {
        e = e instanceof RemoteException ?
                ((RemoteException)e).unwrapRemoteException() : e;
      LOG.error("bootstrap", e);
      throw e;
    }
  }

  /**
   * Enable in memory caching for hbase:meta
   */
  public static TableDescriptor setInfoFamilyCachingForMeta(TableDescriptor metaDescriptor, final boolean b) {
    TableDescriptorBuilder builder = TableDescriptorBuilder.newBuilder(metaDescriptor);
    for (ColumnFamilyDescriptor hcd: metaDescriptor.getColumnFamilies()) {
      if (Bytes.equals(hcd.getName(), HConstants.CATALOG_FAMILY)) {
        builder.modifyColumnFamily(ColumnFamilyDescriptorBuilder.newBuilder(hcd)
                .setBlockCacheEnabled(b)
                .setInMemory(b)
                .build());
      }
    }
    return builder.build();
  }

  public void deleteFamilyFromFS(RegionInfo region, byte[] familyName)
      throws IOException {
    deleteFamilyFromFS(rootdir, region, familyName);
  }

  public void deleteFamilyFromFS(Path rootDir, RegionInfo region, byte[] familyName)
      throws IOException {
    // archive family store files
    Path tableDir = FSUtils.getTableDir(rootDir, region.getTable());
    HFileArchiver.archiveFamily(fs, conf, region, tableDir, familyName);

    // delete the family folder
    Path familyDir = new Path(tableDir,
      new Path(region.getEncodedName(), Bytes.toString(familyName)));
    if (fs.delete(familyDir, true) == false) {
      if (fs.exists(familyDir)) {
        throw new IOException("Could not delete family "
            + Bytes.toString(familyName) + " from FileSystem for region "
            + region.getRegionNameAsString() + "(" + region.getEncodedName()
            + ")");
      }
    }
  }

  public void stop() {
  }

  public void logFileSystemState(Logger log) throws IOException {
    FSUtils.logFileSystemState(fs, rootdir, log);
  }
}