/**
    * 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.io;
  
  import java.io.IOException;
  import java.util.regex.Matcher;
  import java.util.regex.Pattern;
  
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.TableName;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.HRegionInfo;
  import org.apache.hadoop.hbase.regionserver.HRegion;
  import org.apache.hadoop.hbase.regionserver.StoreFileInfo;
  import org.apache.hadoop.hbase.util.FSUtils;
  import org.apache.hadoop.hbase.util.HFileArchiveUtil;
  import org.apache.hadoop.hbase.util.Pair;
  
  /**
   * HFileLink describes a link to an hfile.
   *
   * An hfile can be served from a region or from the hfile archive directory (/hbase/.archive)
   * HFileLink allows to access the referenced hfile regardless of the location where it is.
   *
   * <p>Searches for hfiles in the following order and locations:
   * <ul>
   *  <li>/hbase/table/region/cf/hfile</li>
   *  <li>/hbase/.archive/table/region/cf/hfile</li>
   * </ul>
   *
   * The link checks first in the original path if it is not present
   * it fallbacks to the archived path.
   */
  @InterfaceAudience.Private
  public class HFileLink extends FileLink {
    private static final Log LOG = LogFactory.getLog(HFileLink.class);
  
    /**
     * A non-capture group, for HFileLink, so that this can be embedded.
     * The HFileLink describe a link to an hfile in a different table/region
     * and the name is in the form: table=region-hfile.
     * <p>
     * Table name is ([a-zA-Z_0-9][a-zA-Z_0-9.-]*), so '=' is an invalid character for the table name.
     * Region name is ([a-f0-9]+), so '-' is an invalid character for the region name.
     * HFile is ([0-9a-f]+(?:_SeqId_[0-9]+_)?) covering the plain hfiles (uuid)
     * and the bulk loaded (_SeqId_[0-9]+_) hfiles.
     */
    public static final String LINK_NAME_REGEX =
      String.format("(?:(?:%s=)?)%s=%s-%s",
        TableName.VALID_NAMESPACE_REGEX, TableName.VALID_TABLE_QUALIFIER_REGEX,
        HRegionInfo.ENCODED_REGION_NAME_REGEX, StoreFileInfo.HFILE_NAME_REGEX);
  
    /** Define the HFile Link name parser in the form of: table=region-hfile */
    //made package private for testing
    static final Pattern LINK_NAME_PATTERN =
      Pattern.compile(String.format("^(?:(%s)(?:\\=))?(%s)=(%s)-(%s)$",
        TableName.VALID_NAMESPACE_REGEX, TableName.VALID_TABLE_QUALIFIER_REGEX,
        HRegionInfo.ENCODED_REGION_NAME_REGEX, StoreFileInfo.HFILE_NAME_REGEX));
  
    /**
     * The pattern should be used for hfile and reference links
     * that can be found in /hbase/table/region/family/
     */
    private static final Pattern REF_OR_HFILE_LINK_PATTERN =
      Pattern.compile(String.format("^(?:(%s)(?:=))?(%s)=(%s)-(.+)$",
        TableName.VALID_NAMESPACE_REGEX, TableName.VALID_TABLE_QUALIFIER_REGEX,
        HRegionInfo.ENCODED_REGION_NAME_REGEX));
  
    private final Path archivePath;
    private final Path originPath;
    private final Path tempPath;
  
    /**
     * Dead simple hfile link constructor
     */
    public HFileLink(final Path originPath, final Path tempPath,
                     final Path archivePath) {
      this.tempPath  = tempPath;
     this.originPath = originPath;
     this.archivePath = archivePath;
 
     setLocations(originPath, tempPath, archivePath);
   }
 
   /**
    * @param conf {@link Configuration} from which to extract specific archive locations
    * @param hFileLinkPattern The path ending with a HFileLink pattern. (table=region-hfile)
    * @throws IOException on unexpected error.
    */
   public static final HFileLink buildFromHFileLinkPattern(Configuration conf, Path hFileLinkPattern)
           throws IOException {
     return buildFromHFileLinkPattern(FSUtils.getRootDir(conf),
             HFileArchiveUtil.getArchivePath(conf), hFileLinkPattern);
   }
 
   /**
    * @param rootDir Path to the root directory where hbase files are stored
    * @param archiveDir Path to the hbase archive directory
    * @param hFileLinkPattern The path of the HFile Link.
    */
   public final static HFileLink buildFromHFileLinkPattern(final Path rootDir,
                                                           final Path archiveDir,
                                                           final Path hFileLinkPattern) {
     Path hfilePath = getHFileLinkPatternRelativePath(hFileLinkPattern);
     Path tempPath = new Path(new Path(rootDir, HConstants.HBASE_TEMP_DIRECTORY), hfilePath);
     Path originPath = new Path(rootDir, hfilePath);
     Path archivePath = new Path(archiveDir, hfilePath);
     return new HFileLink(originPath, tempPath, archivePath);
   }
 
   /**
    * Create an HFileLink relative path for the table/region/family/hfile location
    * @param table Table name
    * @param region Region Name
    * @param family Family Name
    * @param hfile HFile Name
    * @return the relative Path to open the specified table/region/family/hfile link
    */
   public static Path createPath(final TableName table, final String region,
                                 final String family, final String hfile) {
     if (HFileLink.isHFileLink(hfile)) {
       return new Path(family, hfile);
     }
     return new Path(family, HFileLink.createHFileLinkName(table, region, hfile));
   }
 
   /**
    * Create an HFileLink instance from table/region/family/hfile location
    * @param conf {@link Configuration} from which to extract specific archive locations
    * @param table Table name
    * @param region Region Name
    * @param family Family Name
    * @param hfile HFile Name
    * @return Link to the file with the specified table/region/family/hfile location
    * @throws IOException on unexpected error.
    */
   public static HFileLink build(final Configuration conf, final TableName table,
                                  final String region, final String family, final String hfile)
           throws IOException {
     return HFileLink.buildFromHFileLinkPattern(conf, createPath(table, region, family, hfile));
   }
 
   /**
    * @return the origin path of the hfile.
    */
   public Path getOriginPath() {
     return this.originPath;
   }
 
   /**
    * @return the path of the archived hfile.
    */
   public Path getArchivePath() {
     return this.archivePath;
   }
 
   /**
    * @param path Path to check.
    * @return True if the path is a HFileLink.
    */
   public static boolean isHFileLink(final Path path) {
     return isHFileLink(path.getName());
   }
 
 
   /**
    * @param fileName File name to check.
    * @return True if the path is a HFileLink.
    */
   public static boolean isHFileLink(String fileName) {
     Matcher m = LINK_NAME_PATTERN.matcher(fileName);
     if (!m.matches()) return false;
     return m.groupCount() > 2 && m.group(4) != null && m.group(3) != null && m.group(2) != null;
   }
 
   /**
    * Convert a HFileLink path to a table relative path.
    * e.g. the link: /hbase/test/0123/cf/testtb=4567-abcd
    *      becomes: /hbase/testtb/4567/cf/abcd
    *
    * @param path HFileLink path
    * @return Relative table path
    * @throws IOException on unexpected error.
    */
   private static Path getHFileLinkPatternRelativePath(final Path path) {
     // table=region-hfile
     Matcher m = REF_OR_HFILE_LINK_PATTERN.matcher(path.getName());
     if (!m.matches()) {
       throw new IllegalArgumentException(path.getName() + " is not a valid HFileLink pattern!");
     }
 
     // Convert the HFileLink name into a real table/region/cf/hfile path.
     TableName tableName = TableName.valueOf(m.group(1), m.group(2));
     String regionName = m.group(3);
     String hfileName = m.group(4);
     String familyName = path.getParent().getName();
     Path tableDir = FSUtils.getTableDir(new Path("./"), tableName);
     return new Path(tableDir, new Path(regionName, new Path(familyName,
         hfileName)));
   }
 
   /**
    * Get the HFile name of the referenced link
    *
    * @param fileName HFileLink file name
    * @return the name of the referenced HFile
    */
   public static String getReferencedHFileName(final String fileName) {
     Matcher m = REF_OR_HFILE_LINK_PATTERN.matcher(fileName);
     if (!m.matches()) {
       throw new IllegalArgumentException(fileName + " is not a valid HFileLink name!");
     }
     return(m.group(4));
   }
 
   /**
    * Get the Region name of the referenced link
    *
    * @param fileName HFileLink file name
    * @return the name of the referenced Region
    */
   public static String getReferencedRegionName(final String fileName) {
     Matcher m = REF_OR_HFILE_LINK_PATTERN.matcher(fileName);
     if (!m.matches()) {
       throw new IllegalArgumentException(fileName + " is not a valid HFileLink name!");
     }
     return(m.group(3));
   }
 
   /**
    * Get the Table name of the referenced link
    *
    * @param fileName HFileLink file name
    * @return the name of the referenced Table
    */
   public static TableName getReferencedTableName(final String fileName) {
     Matcher m = REF_OR_HFILE_LINK_PATTERN.matcher(fileName);
     if (!m.matches()) {
       throw new IllegalArgumentException(fileName + " is not a valid HFileLink name!");
     }
     return(TableName.valueOf(m.group(1), m.group(2)));
   }
 
   /**
    * Create a new HFileLink name
    *
    * @param hfileRegionInfo - Linked HFile Region Info
    * @param hfileName - Linked HFile name
    * @return file name of the HFile Link
    */
   public static String createHFileLinkName(final HRegionInfo hfileRegionInfo,
       final String hfileName) {
     return createHFileLinkName(hfileRegionInfo.getTable(),
             hfileRegionInfo.getEncodedName(), hfileName);
   }
 
   /**
    * Create a new HFileLink name
    *
    * @param tableName - Linked HFile table name
    * @param regionName - Linked HFile region name
    * @param hfileName - Linked HFile name
    * @return file name of the HFile Link
    */
   public static String createHFileLinkName(final TableName tableName,
       final String regionName, final String hfileName) {
     String s = String.format("%s=%s-%s",
         tableName.getNameAsString().replace(TableName.NAMESPACE_DELIM, '='),
         regionName, hfileName);
     return s;
   }
 
   /**
    * Create a new HFileLink
    *
    * <p>It also adds a back-reference to the hfile back-reference directory
    * to simplify the reference-count and the cleaning process.
    *
    * @param conf {@link Configuration} to read for the archive directory name
    * @param fs {@link FileSystem} on which to write the HFileLink
    * @param dstFamilyPath - Destination path (table/region/cf/)
    * @param hfileRegionInfo - Linked HFile Region Info
    * @param hfileName - Linked HFile name
    * @return true if the file is created, otherwise the file exists.
    * @throws IOException on file or parent directory creation failure
    */
   public static boolean create(final Configuration conf, final FileSystem fs,
       final Path dstFamilyPath, final HRegionInfo hfileRegionInfo,
       final String hfileName) throws IOException {
     return create(conf, fs, dstFamilyPath, hfileRegionInfo, hfileName, true);
   }
 
   /**
    * Create a new HFileLink
    *
    * <p>It also adds a back-reference to the hfile back-reference directory
    * to simplify the reference-count and the cleaning process.
    *
    * @param conf {@link Configuration} to read for the archive directory name
    * @param fs {@link FileSystem} on which to write the HFileLink
    * @param dstFamilyPath - Destination path (table/region/cf/)
    * @param hfileRegionInfo - Linked HFile Region Info
    * @param hfileName - Linked HFile name
    * @param createBackRef - Whether back reference should be created. Defaults to true.
    * @return true if the file is created, otherwise the file exists.
    * @throws IOException on file or parent directory creation failure
    */
   public static boolean create(final Configuration conf, final FileSystem fs,
       final Path dstFamilyPath, final HRegionInfo hfileRegionInfo,
       final String hfileName, final boolean createBackRef) throws IOException {
     TableName linkedTable = hfileRegionInfo.getTable();
     String linkedRegion = hfileRegionInfo.getEncodedName();
     return create(conf, fs, dstFamilyPath, linkedTable, linkedRegion, hfileName, createBackRef);
   }
 
   /**
    * Create a new HFileLink
    *
    * <p>It also adds a back-reference to the hfile back-reference directory
    * to simplify the reference-count and the cleaning process.
    *
    * @param conf {@link Configuration} to read for the archive directory name
    * @param fs {@link FileSystem} on which to write the HFileLink
    * @param dstFamilyPath - Destination path (table/region/cf/)
    * @param linkedTable - Linked Table Name
    * @param linkedRegion - Linked Region Name
    * @param hfileName - Linked HFile name
    * @return true if the file is created, otherwise the file exists.
    * @throws IOException on file or parent directory creation failure
    */
   public static boolean create(final Configuration conf, final FileSystem fs,
       final Path dstFamilyPath, final TableName linkedTable, final String linkedRegion,
       final String hfileName) throws IOException {
     return create(conf, fs, dstFamilyPath, linkedTable, linkedRegion, hfileName, true);
   }
 
   /**
    * Create a new HFileLink
    *
    * <p>It also adds a back-reference to the hfile back-reference directory
    * to simplify the reference-count and the cleaning process.
    *
    * @param conf {@link Configuration} to read for the archive directory name
    * @param fs {@link FileSystem} on which to write the HFileLink
    * @param dstFamilyPath - Destination path (table/region/cf/)
    * @param linkedTable - Linked Table Name
    * @param linkedRegion - Linked Region Name
    * @param hfileName - Linked HFile name
    * @param createBackRef - Whether back reference should be created. Defaults to true.
    * @return true if the file is created, otherwise the file exists.
    * @throws IOException on file or parent directory creation failure
    */
   public static boolean create(final Configuration conf, final FileSystem fs,
       final Path dstFamilyPath, final TableName linkedTable, final String linkedRegion,
       final String hfileName, final boolean createBackRef) throws IOException {
     String familyName = dstFamilyPath.getName();
     String regionName = dstFamilyPath.getParent().getName();
     String tableName = FSUtils.getTableName(dstFamilyPath.getParent().getParent())
         .getNameAsString();
 
     String name = createHFileLinkName(linkedTable, linkedRegion, hfileName);
     String refName = createBackReferenceName(tableName, regionName);
 
     // Make sure the destination directory exists
     fs.mkdirs(dstFamilyPath);
 
     // Make sure the FileLink reference directory exists
     Path archiveStoreDir = HFileArchiveUtil.getStoreArchivePath(conf,
           linkedTable, linkedRegion, familyName);
     Path backRefPath = null;
     if (createBackRef) {
       Path backRefssDir = getBackReferencesDir(archiveStoreDir, hfileName);
       fs.mkdirs(backRefssDir);
 
       // Create the reference for the link
       backRefPath = new Path(backRefssDir, refName);
       fs.createNewFile(backRefPath);
     }
     try {
       // Create the link
       return fs.createNewFile(new Path(dstFamilyPath, name));
     } catch (IOException e) {
       LOG.error("couldn't create the link=" + name + " for " + dstFamilyPath, e);
       // Revert the reference if the link creation failed
       if (createBackRef) {
         fs.delete(backRefPath, false);
       }
       throw e;
     }
   }
 
   /**
    * Create a new HFileLink starting from a hfileLink name
    *
    * <p>It also adds a back-reference to the hfile back-reference directory
    * to simplify the reference-count and the cleaning process.
    *
    * @param conf {@link Configuration} to read for the archive directory name
    * @param fs {@link FileSystem} on which to write the HFileLink
    * @param dstFamilyPath - Destination path (table/region/cf/)
    * @param hfileLinkName - HFileLink name (it contains hfile-region-table)
    * @return true if the file is created, otherwise the file exists.
    * @throws IOException on file or parent directory creation failure
    */
   public static boolean createFromHFileLink(final Configuration conf, final FileSystem fs,
       final Path dstFamilyPath, final String hfileLinkName)
           throws IOException {
     return createFromHFileLink(conf, fs, dstFamilyPath, hfileLinkName, true);
   }
 
   /**
    * Create a new HFileLink starting from a hfileLink name
    *
    * <p>It also adds a back-reference to the hfile back-reference directory
    * to simplify the reference-count and the cleaning process.
    *
    * @param conf {@link Configuration} to read for the archive directory name
    * @param fs {@link FileSystem} on which to write the HFileLink
    * @param dstFamilyPath - Destination path (table/region/cf/)
    * @param hfileLinkName - HFileLink name (it contains hfile-region-table)
    * @param createBackRef - Whether back reference should be created. Defaults to true.
    * @return true if the file is created, otherwise the file exists.
    * @throws IOException on file or parent directory creation failure
    */
   public static boolean createFromHFileLink(final Configuration conf, final FileSystem fs,
       final Path dstFamilyPath, final String hfileLinkName, final boolean createBackRef)
           throws IOException {
     Matcher m = LINK_NAME_PATTERN.matcher(hfileLinkName);
     if (!m.matches()) {
       throw new IllegalArgumentException(hfileLinkName + " is not a valid HFileLink name!");
     }
     return create(conf, fs, dstFamilyPath, TableName.valueOf(m.group(1), m.group(2)),
         m.group(3), m.group(4), createBackRef);
   }
 
   /**
    * Create the back reference name
    */
   //package-private for testing
   static String createBackReferenceName(final String tableNameStr,
                                         final String regionName) {
 
     return regionName + "." + tableNameStr.replace(TableName.NAMESPACE_DELIM, '=');
   }
 
   /**
    * Get the full path of the HFile referenced by the back reference
    *
    * @param rootDir root hbase directory
    * @param linkRefPath Link Back Reference path
    * @return full path of the referenced hfile
    * @throws IOException on unexpected error.
    */
   public static Path getHFileFromBackReference(final Path rootDir, final Path linkRefPath) {
     Pair<TableName, String> p = parseBackReferenceName(linkRefPath.getName());
     TableName linkTableName = p.getFirst();
     String linkRegionName = p.getSecond();
 
     String hfileName = getBackReferenceFileName(linkRefPath.getParent());
     Path familyPath = linkRefPath.getParent().getParent();
     Path regionPath = familyPath.getParent();
     Path tablePath = regionPath.getParent();
 
     String linkName = createHFileLinkName(FSUtils.getTableName(tablePath),
             regionPath.getName(), hfileName);
     Path linkTableDir = FSUtils.getTableDir(rootDir, linkTableName);
     Path regionDir = HRegion.getRegionDir(linkTableDir, linkRegionName);
     return new Path(new Path(regionDir, familyPath.getName()), linkName);
   }
 
   static Pair<TableName, String> parseBackReferenceName(String name) {
     int separatorIndex = name.indexOf('.');
     String linkRegionName = name.substring(0, separatorIndex);
     String tableSubstr = name.substring(separatorIndex + 1)
         .replace('=', TableName.NAMESPACE_DELIM);
     TableName linkTableName = TableName.valueOf(tableSubstr);
     return new Pair<TableName, String>(linkTableName, linkRegionName);
   }
 
   /**
    * Get the full path of the HFile referenced by the back reference
    *
    * @param conf {@link Configuration} to read for the archive directory name
    * @param linkRefPath Link Back Reference path
    * @return full path of the referenced hfile
    * @throws IOException on unexpected error.
    */
   public static Path getHFileFromBackReference(final Configuration conf, final Path linkRefPath)
       throws IOException {
     return getHFileFromBackReference(FSUtils.getRootDir(conf), linkRefPath);
   }
 
 }