/**
    * 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.snapshot;
  
  import java.io.IOException;
  import java.net.URI;
  import java.security.PrivilegedExceptionAction;
  import java.util.Collections;
  import java.util.concurrent.TimeUnit;
  
  import com.google.common.collect.ListMultimap;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FSDataInputStream;
  import org.apache.hadoop.fs.FSDataOutputStream;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.FileUtil;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.fs.permission.FsPermission;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.client.Admin;
  import org.apache.hadoop.hbase.client.Connection;
  import org.apache.hadoop.hbase.client.ConnectionFactory;
  import org.apache.hadoop.hbase.protobuf.ProtobufUtil;
  import org.apache.hadoop.hbase.protobuf.generated.HBaseProtos.SnapshotDescription;
  import org.apache.hadoop.hbase.security.User;
  import org.apache.hadoop.hbase.security.access.AccessControlLists;
  import org.apache.hadoop.hbase.security.access.TablePermission;
  import org.apache.hadoop.hbase.util.EnvironmentEdgeManager;
  import org.apache.hadoop.hbase.util.FSUtils;
  
  /**
   * Utility class to help manage {@link SnapshotDescription SnapshotDesriptions}.
   * <p>
   * Snapshots are laid out on disk like this:
   *
   * <pre>
   * /hbase/.snapshots
   *          /.tmp                &lt;---- working directory
   *          /[snapshot name]     &lt;----- completed snapshot
   * </pre>
   *
   * A completed snapshot named 'completed' then looks like (multiple regions, servers, files, etc.
   * signified by '...' on the same directory depth).
   *
   * <pre>
   * /hbase/.snapshots/completed
   *                   .snapshotinfo          &lt;--- Description of the snapshot
   *                   .tableinfo             &lt;--- Copy of the tableinfo
   *                    /.logs
   *                        /[server_name]
   *                            /... [log files]
   *                         ...
   *                   /[region name]           &lt;---- All the region's information
   *                   .regioninfo              &lt;---- Copy of the HRegionInfo
   *                      /[column family name]
   *                          /[hfile name]     &lt;--- name of the hfile in the real region
   *                          ...
   *                      ...
   *                    ...
   * </pre>
   *
   * Utility methods in this class are useful for getting the correct locations for different parts of
   * the snapshot, as well as moving completed snapshots into place (see
   * {@link #completeSnapshot}, and writing the
   * {@link SnapshotDescription} to the working snapshot directory.
   */
  @InterfaceAudience.Private
  public final class SnapshotDescriptionUtils {
  
    /**
     * Filter that only accepts completed snapshot directories
     */
    public static class CompletedSnaphotDirectoriesFilter extends FSUtils.BlackListDirFilter {
  
      /**
       * @param fs
       */
      public CompletedSnaphotDirectoriesFilter(FileSystem fs) {
        super(fs, Collections.singletonList(SNAPSHOT_TMP_DIR_NAME));
      }
   }
 
   private static final Log LOG = LogFactory.getLog(SnapshotDescriptionUtils.class);
   /**
    * Version of the fs layout for a snapshot. Future snapshots may have different file layouts,
    * which we may need to read in differently.
    */
   public static final int SNAPSHOT_LAYOUT_VERSION = SnapshotManifestV2.DESCRIPTOR_VERSION;
 
   // snapshot directory constants
   /**
    * The file contains the snapshot basic information and it is under the directory of a snapshot.
    */
   public static final String SNAPSHOTINFO_FILE = ".snapshotinfo";
 
   /** Temporary directory under the snapshot directory to store in-progress snapshots */
   public static final String SNAPSHOT_TMP_DIR_NAME = ".tmp";
 
   /**
    * The configuration property that determines the filepath of the snapshot
    * base working directory
    */
   public static final String SNAPSHOT_WORKING_DIR = "hbase.snapshot.working.dir";
 
   // snapshot operation values
   /** Default value if no start time is specified */
   public static final long NO_SNAPSHOT_START_TIME_SPECIFIED = 0;
 
   // Default value if no ttl is specified for Snapshot
   private static final long NO_SNAPSHOT_TTL_SPECIFIED = 0;
 
   public static final String MASTER_SNAPSHOT_TIMEOUT_MILLIS = "hbase.snapshot.master.timeout.millis";
 
   /** By default, wait 300 seconds for a snapshot to complete */
   public static final long DEFAULT_MAX_WAIT_TIME = 60000 * 5 ;
 
 
   /**
    * By default, check to see if the snapshot is complete (ms)
    * @deprecated Use {@link #DEFAULT_MAX_WAIT_TIME} instead.
    * */
   @Deprecated
   public static final int SNAPSHOT_TIMEOUT_MILLIS_DEFAULT = 60000 * 5;
 
   /**
    * Conf key for # of ms elapsed before injecting a snapshot timeout error when waiting for
    * completion.
    * @deprecated Use {@link #MASTER_SNAPSHOT_TIMEOUT_MILLIS} instead.
    */
   @Deprecated
   public static final String SNAPSHOT_TIMEOUT_MILLIS_KEY = "hbase.snapshot.master.timeoutMillis";
 
   private SnapshotDescriptionUtils() {
     // private constructor for utility class
   }
 
   /**
    * @param conf {@link Configuration} from which to check for the timeout
    * @param type type of snapshot being taken
    * @param defaultMaxWaitTime Default amount of time to wait, if none is in the configuration
    * @return the max amount of time the master should wait for a snapshot to complete
    */
   public static long getMaxMasterTimeout(Configuration conf, SnapshotDescription.Type type,
       long defaultMaxWaitTime) {
     String confKey;
     switch (type) {
     case DISABLED:
     default:
       confKey = MASTER_SNAPSHOT_TIMEOUT_MILLIS;
     }
     return Math.max(conf.getLong(confKey, defaultMaxWaitTime),
         conf.getLong(SNAPSHOT_TIMEOUT_MILLIS_KEY, defaultMaxWaitTime));
   }
 
   /**
    * Get the snapshot root directory. All the snapshots are kept under this directory, i.e.
    * ${hbase.rootdir}/.snapshot
    * @param rootDir hbase root directory
    * @return the base directory in which all snapshots are kept
    */
   public static Path getSnapshotRootDir(final Path rootDir) {
     return new Path(rootDir, HConstants.SNAPSHOT_DIR_NAME);
   }
 
   /**
    * Get the directory for a specified snapshot. This directory is a sub-directory of snapshot root
    * directory and all the data files for a snapshot are kept under this directory.
    * @param snapshot snapshot being taken
    * @param rootDir hbase root directory
    * @return the final directory for the completed snapshot
    */
   public static Path getCompletedSnapshotDir(final SnapshotDescription snapshot, final Path rootDir) {
     return getCompletedSnapshotDir(snapshot.getName(), rootDir);
   }
 
   /**
    * Get the directory for a completed snapshot. This directory is a sub-directory of snapshot root
    * directory and all the data files for a snapshot are kept under this directory.
    * @param snapshotName name of the snapshot being taken
    * @param rootDir hbase root directory
    * @return the final directory for the completed snapshot
    */
   public static Path getCompletedSnapshotDir(final String snapshotName, final Path rootDir) {
     return getSpecifiedSnapshotDir(getSnapshotsDir(rootDir), snapshotName);
   }
 
   /**
    * Get the general working directory for snapshots - where they are built, where they are
    * temporarily copied on export, etc.
    * @param rootDir root directory of the HBase installation
    * @param conf Configuration of the HBase instance
    * @return Path to the snapshot tmp directory, relative to the passed root directory
    */
   public static Path getWorkingSnapshotDir(final Path rootDir, final Configuration conf) {
     return new Path(conf.get(SNAPSHOT_WORKING_DIR,
         getDefaultWorkingSnapshotDir(rootDir).toString()));
   }
 
   /**
    * Get the directory to build a snapshot, before it is finalized
    * @param snapshot snapshot that will be built
    * @param rootDir root directory of the hbase installation
    * @param conf Configuration of the HBase instance
    * @return {@link Path} where one can build a snapshot
    */
   public static Path getWorkingSnapshotDir(SnapshotDescription snapshot, final Path rootDir,
       Configuration conf) {
     return getWorkingSnapshotDir(snapshot.getName(), rootDir, conf);
   }
 
   /**
    * Get the directory to build a snapshot, before it is finalized
    * @param snapshotName name of the snapshot
    * @param rootDir root directory of the hbase installation
    * @param conf Configuration of the HBase instance
    * @return {@link Path} where one can build a snapshot
    */
   public static Path getWorkingSnapshotDir(String snapshotName, final Path rootDir,
       Configuration conf) {
     return getSpecifiedSnapshotDir(getWorkingSnapshotDir(rootDir, conf), snapshotName);
   }
 
   /**
    * Get the directory within the given filepath to store the snapshot instance
    * @param snapshotsDir directory to store snapshot directory within
    * @param snapshotName name of the snapshot to take
    * @return the final directory for the snapshot in the given filepath
    */
   private static final Path getSpecifiedSnapshotDir(final Path snapshotsDir, String snapshotName) {
     return new Path(snapshotsDir, snapshotName);
   }
 
   /**
    * @param rootDir hbase root directory
    * @return the directory for all completed snapshots;
    */
   public static final Path getSnapshotsDir(Path rootDir) {
     return new Path(rootDir, HConstants.SNAPSHOT_DIR_NAME);
   }
 
   /**
    * Determines if the given workingDir is a subdirectory of the given "root directory"
    * @param workingDir a directory to check
    * @param rootDir root directory of the HBase installation
    * @return true if the given workingDir is a subdirectory of the given root directory,
    *   false otherwise
    */
   public static boolean isSubDirectoryOf(final Path workingDir, final Path rootDir) {
     return workingDir.toString().startsWith(rootDir.toString() + Path.SEPARATOR);
   }
 
   /**
    * Determines if the given workingDir is a subdirectory of the default working snapshot directory
    * @param workingDir a directory to check
    * @param conf configuration for the HBase cluster
    * @return true if the given workingDir is a subdirectory of the default working directory for
    *   snapshots, false otherwise
    */
   public static boolean isWithinDefaultWorkingDir(final Path workingDir, Configuration conf)
       throws IOException {
     Path defaultWorkingDir = getDefaultWorkingSnapshotDir(FSUtils.getRootDir(conf));
     return workingDir.equals(defaultWorkingDir) || isSubDirectoryOf(workingDir, defaultWorkingDir);
   }
 
   /**
    * Get the default working directory for snapshots - where they are built, where they are
    * temporarily copied on export, etc.
    * @param rootDir root directory of the HBase installation
    * @return Path to the default snapshot tmp directory, relative to the passed root directory
    */
   private static Path getDefaultWorkingSnapshotDir(final Path rootDir) {
     return new Path(getSnapshotsDir(rootDir), SNAPSHOT_TMP_DIR_NAME);
   }
 
   /**
    * Convert the passed snapshot description into a 'full' snapshot description based on default
    * parameters, if none have been supplied. This resolves any 'optional' parameters that aren't
    * supplied to their default values.
    * @param snapshot general snapshot descriptor
    * @param conf Configuration to read configured snapshot defaults if snapshot is not complete
    * @return a valid snapshot description
    * @throws IllegalArgumentException if the {@link SnapshotDescription} is not a complete
    *           {@link SnapshotDescription}.
    */
   public static SnapshotDescription validate(SnapshotDescription snapshot, Configuration conf)
       throws IllegalArgumentException, IOException {
     if (!snapshot.hasTable()) {
       throw new IllegalArgumentException(
         "Descriptor doesn't apply to a table, so we can't build it.");
     }
 
     // set the creation time, if one hasn't been set
     long time = snapshot.getCreationTime();
     if (time == SnapshotDescriptionUtils.NO_SNAPSHOT_START_TIME_SPECIFIED) {
       time = EnvironmentEdgeManager.currentTime();
       LOG.debug("Creation time not specified, setting to:" + time + " (current time:"
           + EnvironmentEdgeManager.currentTime() + ").");
       SnapshotDescription.Builder builder = snapshot.toBuilder();
       builder.setCreationTime(time);
       snapshot = builder.build();
     }
     long ttl = snapshot.getTtl();
     // set default ttl(sec) if it is not set already or the value is out of the range
     if (ttl == SnapshotDescriptionUtils.NO_SNAPSHOT_TTL_SPECIFIED ||
         ttl > TimeUnit.MILLISECONDS.toSeconds(Long.MAX_VALUE)) {
       final long defaultSnapshotTtl = conf.getLong(HConstants.DEFAULT_SNAPSHOT_TTL_CONFIG_KEY,
           HConstants.DEFAULT_SNAPSHOT_TTL);
       if (LOG.isDebugEnabled()) {
         LOG.debug("Snapshot current TTL value: " + ttl + " resetting it to default value: " +
           defaultSnapshotTtl);
       }
       ttl = defaultSnapshotTtl;
     }
     SnapshotDescription.Builder builder = snapshot.toBuilder();
     builder.setTtl(ttl);
     snapshot = builder.build();
 
     // set the acl to snapshot if security feature is enabled.
     if(isSecurityAvailable(conf)){
       snapshot = writeAclToSnapshotDescription(snapshot, conf);
     }
 
     return snapshot;
   }
 
   /**
    * Write the snapshot description into the working directory of a snapshot
    * @param snapshot description of the snapshot being taken
    * @param workingDir working directory of the snapshot
    * @param fs {@link FileSystem} on which the snapshot should be taken
    * @throws IOException if we can't reach the filesystem and the file cannot be cleaned up on
    *           failure
    */
   public static void writeSnapshotInfo(SnapshotDescription snapshot, Path workingDir, FileSystem fs)
       throws IOException {
     FsPermission perms = FSUtils.getFilePermissions(fs, fs.getConf(),
       HConstants.DATA_FILE_UMASK_KEY);
     Path snapshotInfo = new Path(workingDir, SnapshotDescriptionUtils.SNAPSHOTINFO_FILE);
     try {
       FSDataOutputStream out = FSUtils.create(fs, snapshotInfo, perms, true);
       try {
         snapshot.writeTo(out);
       } finally {
         out.close();
       }
     } catch (IOException e) {
       // if we get an exception, try to remove the snapshot info
       if (!fs.delete(snapshotInfo, false)) {
         String msg = "Couldn't delete snapshot info file: " + snapshotInfo;
         LOG.error(msg);
         throw new IOException(msg);
       }
     }
   }
 
   /**
    * Read in the {@link SnapshotDescription} stored for the snapshot in the passed directory
    * @param fs filesystem where the snapshot was taken
    * @param snapshotDir directory where the snapshot was stored
    * @return the stored snapshot description
    * @throws CorruptedSnapshotException if the
    * snapshot cannot be read
    */
   public static SnapshotDescription readSnapshotInfo(FileSystem fs, Path snapshotDir)
       throws CorruptedSnapshotException {
     Path snapshotInfo = new Path(snapshotDir, SNAPSHOTINFO_FILE);
     try {
       FSDataInputStream in = null;
       try {
         in = fs.open(snapshotInfo);
         SnapshotDescription desc = SnapshotDescription.parseFrom(in);
         return desc;
       } finally {
         if (in != null) in.close();
       }
     } catch (IOException e) {
       throw new CorruptedSnapshotException("Couldn't read snapshot info from:" + snapshotInfo, e);
     }
   }
 
   /**
    * Move the finished snapshot to its final, publicly visible directory - this marks the snapshot
    * as 'complete'.
    * @param snapshotDir The file path of the completed snapshots
    * @param workingDir The file path of the in progress snapshots
    * @param fs {@link FileSystem} The file system of the completed snapshots
    * @param workingDirFs The file system of the in progress snapshots
    * @throws org.apache.hadoop.hbase.snapshot.SnapshotCreationException if the
    * snapshot could not be moved
    * @throws IOException the filesystem could not be reached
    */
   public static void completeSnapshot(Path snapshotDir, Path workingDir, FileSystem fs,
       FileSystem workingDirFs, Configuration conf) throws SnapshotCreationException, IOException {
     LOG.debug("Snapshot is done, just moving the snapshot from " + workingDir + " to "
         + snapshotDir);
     if (!workingDirFs.exists(workingDir)) {
       throw new IOException("Failed to moving nonexistent snapshot working directory "
           + workingDir + " to " + snapshotDir);
     }
     // If the working and completed snapshot directory are on the same file system, attempt
     // to rename the working snapshot directory to the completed location. If that fails,
     // or the file systems differ, attempt to copy the directory over, throwing an exception
     // if this fails
     URI workingURI = workingDirFs.getUri();
     URI rootURI = fs.getUri();
 
     if ((shouldSkipRenameSnapshotDirectories(workingURI, rootURI)
         || !fs.rename(workingDir, snapshotDir))
          && !FileUtil.copy(workingDirFs, workingDir, fs, snapshotDir, true, true, conf)) {
       throw new SnapshotCreationException("Failed to copy working directory(" + workingDir
           + ") to completed directory(" + snapshotDir + ").");
     }
   }
 
   static boolean shouldSkipRenameSnapshotDirectories(URI workingURI, URI rootURI) {
     // check scheme, e.g. file, hdfs
     if (workingURI.getScheme() == null &&
         (rootURI.getScheme() != null && !rootURI.getScheme().equalsIgnoreCase("file"))) {
       return true;
     }
     if (workingURI.getScheme() != null && !workingURI.getScheme().equals(rootURI.getScheme())) {
       return true;
     }
 
     // check Authority, e.g. localhost:port
     if (workingURI.getAuthority() == null && rootURI.getAuthority() != null) {
       return true;
     }
     if (workingURI.getAuthority() != null &&
         !workingURI.getAuthority().equals(rootURI.getAuthority())) {
       return true;
     }
 
     // check UGI/userInfo
     if (workingURI.getUserInfo() == null && rootURI.getUserInfo() != null) {
       return true;
     }
     if (workingURI.getUserInfo() != null &&
         !workingURI.getUserInfo().equals(rootURI.getUserInfo())) {
       return true;
     }
 
     return false;
   }
 
 
   /**
    * Check if the user is this table snapshot's owner
    * @param snapshot the table snapshot description
    * @param user the user
    * @return true if the user is the owner of the snapshot,
    *         false otherwise or the snapshot owner field is not present.
    */
   public static boolean isSnapshotOwner(final SnapshotDescription snapshot, final User user) {
     if (user == null) return false;
     if (!snapshot.hasOwner()) return false;
     return snapshot.getOwner().equals(user.getShortName());
   }
 
   public static boolean isSecurityAvailable(Configuration conf) throws IOException {
     Connection conn = ConnectionFactory.createConnection(conf);
     try {
       Admin admin = conn.getAdmin();
       try {
         return admin.tableExists(AccessControlLists.ACL_TABLE_NAME);
       } finally {
         admin.close();
       }
     } finally {
       conn.close();
     }
   }
 
   private static SnapshotDescription writeAclToSnapshotDescription(
       final SnapshotDescription snapshot, final Configuration conf) throws IOException {
     ListMultimap<String, TablePermission> perms =
         User.runAsLoginUser(new PrivilegedExceptionAction<ListMultimap<String, TablePermission>>() {
           @Override
           public ListMultimap<String, TablePermission> run() throws Exception {
             return AccessControlLists.getTablePermissions(conf,
               TableName.valueOf(snapshot.getTable()));
           }
         });
     return snapshot.toBuilder().setUsersAndPermissions(ProtobufUtil.toUserTablePermissions(perms))
         .build();
   }
 }