/*
 * 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.hadoop.conf.Configuration;
import org.apache.hadoop.fs.Path;
import org.apache.hadoop.hbase.HConstants;
import org.apache.hadoop.hbase.TableName;
import org.apache.hadoop.hbase.client.RegionInfo;
import org.apache.hadoop.hbase.client.RegionInfoBuilder;
import org.apache.hadoop.hbase.mob.MobConstants;
import org.apache.hadoop.hbase.regionserver.HRegion;
import org.apache.hadoop.hbase.regionserver.StoreFileInfo;
import org.apache.hadoop.hbase.util.CommonFSUtils;
import org.apache.hadoop.hbase.util.HFileArchiveUtil;
import org.apache.hadoop.hbase.util.Pair;
import org.apache.yetus.audience.InterfaceAudience;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * 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
@edu.umd.cs.findbugs.annotations.SuppressWarnings(value = "EQ_DOESNT_OVERRIDE_EQUALS",
    justification = "To be fixed but warning suppressed for now")
public class HFileLink extends FileLink {
  private static final Logger LOG = LoggerFactory.getLogger(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 ([\p{IsAlphabetic}\p{Digit}][\p{IsAlphabetic}\p{Digit}.-]*), 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.
   * <p>
   * Here is an example name: /hbase/test/0123/cf/testtb=4567-abcd where 'testtb' is table name and
   * '4567' is region name and 'abcd' is filename.
   */
  public static final String LINK_NAME_REGEX = String.format("(?:(?:%s=)?)%s=%s-%s",
    TableName.VALID_NAMESPACE_REGEX, TableName.VALID_TABLE_QUALIFIER_REGEX,
    RegionInfoBuilder.ENCODED_REGION_NAME_REGEX, StoreFileInfo.HFILE_NAME_REGEX);

  /** Define the HFile Link name parser in the form of: table=region-hfile */
  public static final Pattern LINK_NAME_PATTERN =
    Pattern.compile(String.format("^(?:(%s)(?:\\=))?(%s)=(%s)-(%s)$",
      TableName.VALID_NAMESPACE_REGEX, TableName.VALID_TABLE_QUALIFIER_REGEX,
      RegionInfoBuilder.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, RegionInfoBuilder.ENCODED_REGION_NAME_REGEX));

  private final Path archivePath;
  private final Path originPath;
  private final Path mobPath;
  private final Path tempPath;

  /**
   * Dead simple hfile link constructor
   */
  public HFileLink(final Path originPath, final Path tempPath, final Path mobPath,
    final Path archivePath) {
    this.tempPath = tempPath;
    this.originPath = originPath;
    this.mobPath = mobPath;
    this.archivePath = archivePath;
    setLocations(originPath, archivePath, tempPath, mobPath);
  }

  /**
   * @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(CommonFSUtils.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 mobPath = new Path(new Path(rootDir, MobConstants.MOB_DIR_NAME), hfilePath);
    Path archivePath = new Path(archiveDir, hfilePath);
    return new HFileLink(originPath, tempPath, mobPath, 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));
  }

  /** Returns the origin path of the hfile. */
  public Path getOriginPath() {
    return this.originPath;
  }

  /** Returns the path of the archived hfile. */
  public Path getArchivePath() {
    return this.archivePath;
  }

  /** Returns the path of the mob hfiles. */
  public Path getMobPath() {
    return this.mobPath;
  }

  /**
   * @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) {
    // The LINK_NAME_PATTERN regex is not computationally trivial, so see if we can fast-fail
    // on a simple heuristic first. The regex contains a literal "=", so if that character
    // isn't in the fileName, then the regex cannot match.
    if (!fileName.contains("=")) {
      return false;
    }

    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 = CommonFSUtils.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 RegionInfo 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 the back reference name
   */
  // package-private for testing
  public 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
   */
  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(CommonFSUtils.getTableName(tablePath), regionPath.getName(), hfileName);
    Path linkTableDir = CommonFSUtils.getTableDir(rootDir, linkTableName);
    Path regionDir = HRegion.getRegionDir(linkTableDir, linkRegionName);
    return new Path(new Path(regionDir, familyPath.getName()), linkName);
  }

  public 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<>(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(CommonFSUtils.getRootDir(conf), linkRefPath);
  }

}