/**
    *
    * 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.wal;
  
  import java.io.IOException;
  import java.util.ArrayList;
  import java.util.Collections;
  import java.util.List;
  import java.util.concurrent.atomic.AtomicBoolean;
  import java.util.regex.Pattern;
  
  import com.google.common.annotations.VisibleForTesting;
  import org.apache.commons.logging.Log;
  import org.apache.commons.logging.LogFactory;
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.classification.InterfaceStability;
  import org.apache.hadoop.conf.Configuration;
  import org.apache.hadoop.fs.FSDataInputStream;
  import org.apache.hadoop.fs.FileSystem;
  import org.apache.hadoop.fs.Path;
  import org.apache.hadoop.hbase.HConstants;
  import org.apache.hadoop.hbase.ServerName;
  import org.apache.hadoop.hbase.util.FSUtils;
  
  // imports for things that haven't moved from regionserver.wal yet.
  import org.apache.hadoop.hbase.regionserver.wal.FSHLog;
  import org.apache.hadoop.hbase.regionserver.wal.ProtobufLogWriter;
  import org.apache.hadoop.hbase.regionserver.wal.WALActionsListener;
  
  /**
   * A WAL Provider that returns a single thread safe WAL that writes to Hadoop FS.
   * By default, this implementation picks a directory in Hadoop FS based on a combination of
   * <ul>
   *   <li>the HBase root WAL directory
   *   <li>HConstants.HREGION_LOGDIR_NAME
   *   <li>the given factory's factoryId (usually identifying the regionserver by host:port)
   * </ul>
   * It also uses the providerId to diffentiate among files.
   *
   */
  @InterfaceAudience.Private
  @InterfaceStability.Evolving
  public class DefaultWALProvider implements WALProvider {
    private static final Log LOG = LogFactory.getLog(DefaultWALProvider.class);
  
    // Only public so classes back in regionserver.wal can access
    public interface Reader extends WAL.Reader {
      /**
       * @param fs File system.
       * @param path Path.
       * @param c Configuration.
       * @param s Input stream that may have been pre-opened by the caller; may be null.
       */
      void init(FileSystem fs, Path path, Configuration c, FSDataInputStream s) throws IOException;
    }
  
    // Only public so classes back in regionserver.wal can access
    public interface Writer extends WALProvider.Writer {
      void init(FileSystem fs, Path path, Configuration c, boolean overwritable) throws IOException;
    }
  
    protected volatile FSHLog log = null;
    private WALFactory factory = null;
    private Configuration conf = null;
    private List<WALActionsListener> listeners = null;
    private String providerId = null;
    private AtomicBoolean initialized = new AtomicBoolean(false);
    // for default wal provider, logPrefix won't change
    private String logPrefix = null;
  
    /**
     * we synchronized on walCreateLock to prevent wal recreation in different threads
     */
    private final Object walCreateLock = new Object();
  
    /**
     * @param factory factory that made us, identity used for FS layout. may not be null
     * @param conf may not be null
     * @param listeners may be null
     * @param providerId differentiate between providers from one facotry, used for FS layout. may be
     *                   null
     */
    @Override
   public void init(final WALFactory factory, final Configuration conf,
       final List<WALActionsListener> listeners, String providerId) throws IOException {
     if (!initialized.compareAndSet(false, true)) {
       throw new IllegalStateException("WALProvider.init should only be called once.");
     }
     this.factory = factory;
     this.conf = conf;
     this.listeners = listeners;
     this.providerId = providerId;
     // get log prefix
     StringBuilder sb = new StringBuilder().append(factory.factoryId);
     if (providerId != null) {
       if (providerId.startsWith(WAL_FILE_NAME_DELIMITER)) {
         sb.append(providerId);
       } else {
         sb.append(WAL_FILE_NAME_DELIMITER).append(providerId);
       }
     }
     logPrefix = sb.toString();
   }
 
   @Override
   public List<WAL> getWALs() throws IOException {
     if (log == null) {
       return Collections.emptyList();
     }
     List<WAL> wals = new ArrayList<WAL>();
     wals.add(log);
     return wals;
   }
 
   @Override
   public WAL getWAL(final byte[] identifier, byte[] namespace) throws IOException {
     if (log == null) {
       // only lock when need to create wal, and need to lock since
       // creating hlog on fs is time consuming
       synchronized (walCreateLock) {
         if (log == null) {
           log = new FSHLog(FSUtils.getWALFileSystem(conf), FSUtils.getWALRootDir(conf),
               getWALDirectoryName(factory.factoryId), HConstants.HREGION_OLDLOGDIR_NAME, conf,
               listeners, true, logPrefix,
               META_WAL_PROVIDER_ID.equals(providerId) ? META_WAL_PROVIDER_ID : null);
         }
       }
     }
     return log;
   }
 
   @Override
   public void close() throws IOException {
     if (log != null) log.close();
   }
 
   @Override
   public void shutdown() throws IOException {
     if (log != null) log.shutdown();
   }
 
   // should be package private; more visible for use in FSHLog
   public static final String WAL_FILE_NAME_DELIMITER = ".";
   /** The hbase:meta region's WAL filename extension */
   @VisibleForTesting
   public static final String META_WAL_PROVIDER_ID = ".meta";
   static final String DEFAULT_PROVIDER_ID = "default";
 
   // Implementation details that currently leak in tests or elsewhere follow
   /** File Extension used while splitting an WAL into regions (HBASE-2312) */
   public static final String SPLITTING_EXT = "-splitting";
 
   /**
    * iff the given WALFactory is using the DefaultWALProvider for meta and/or non-meta,
    * count the number of files (rolled and active). if either of them aren't, count 0
    * for that provider.
    */
   @Override
   public long getNumLogFiles() {
     return log == null ? 0 : this.log.getNumLogFiles();
   }
 
   /**
    * iff the given WALFactory is using the DefaultWALProvider for meta and/or non-meta,
    * count the size of files (rolled and active). if either of them aren't, count 0
    * for that provider.
    */
   @Override
   public long getLogFileSize() {
     return log == null ? 0 : this.log.getLogFileSize();
   }
 
   /**
    * returns the number of rolled WAL files.
    */
   @VisibleForTesting
   public static int getNumRolledLogFiles(WAL wal) {
     return ((FSHLog)wal).getNumRolledLogFiles();
   }
 
   /**
    * return the current filename from the current wal.
    */
   @VisibleForTesting
   public static Path getCurrentFileName(final WAL wal) {
     return ((FSHLog)wal).getCurrentFileName();
   }
 
   /**
    * request a log roll, but don't actually do it.
    */
   @VisibleForTesting
   static void requestLogRoll(final WAL wal) {
     ((FSHLog)wal).requestLogRoll();
   }
 
   /**
    * It returns the file create timestamp from the file name.
    * For name format see {@link #validateWALFilename(String)}
    * public until remaining tests move to o.a.h.h.wal
    * @param wal must not be null
    * @return the file number that is part of the WAL file name
    */
   @VisibleForTesting
   public static long extractFileNumFromWAL(final WAL wal) {
     final Path walName = ((FSHLog)wal).getCurrentFileName();
     if (walName == null) {
       throw new IllegalArgumentException("The WAL path couldn't be null");
     }
     final String[] walPathStrs = walName.toString().split("\\" + WAL_FILE_NAME_DELIMITER);
     return Long.parseLong(walPathStrs[walPathStrs.length - (isMetaFile(walName) ? 2:1)]);
   }
 
   /**
    * Pattern used to validate a WAL file name
    * see {@link #validateWALFilename(String)} for description.
    */
   private static final Pattern pattern = Pattern.compile(".*\\.\\d*("+META_WAL_PROVIDER_ID+")*");
 
   /**
    * A WAL file name is of the format:
    * &lt;wal-name&gt;{@link #WAL_FILE_NAME_DELIMITER}&lt;file-creation-timestamp&gt;[.meta].
    *
    * provider-name is usually made up of a server-name and a provider-id
    *
    * @param filename name of the file to validate
    * @return <tt>true</tt> if the filename matches an WAL, <tt>false</tt>
    *         otherwise
    */
   public static boolean validateWALFilename(String filename) {
     return pattern.matcher(filename).matches();
   }
 
   /**
    * Construct the directory name for all WALs on a given server.
    *
    * @param serverName
    *          Server name formatted as described in {@link ServerName}
    * @return the relative WAL directory name, e.g.
    *         <code>.logs/1.example.org,60030,12345</code> if
    *         <code>serverName</code> passed is
    *         <code>1.example.org,60030,12345</code>
    */
   public static String getWALDirectoryName(final String serverName) {
     StringBuilder dirName = new StringBuilder(HConstants.HREGION_LOGDIR_NAME);
     dirName.append("/");
     dirName.append(serverName);
     return dirName.toString();
   }
 
   /**
    * Pulls a ServerName out of a Path generated according to our layout rules.
    *
    * In the below layouts, this method ignores the format of the logfile component.
    *
    * Current format:
    *
    * [base directory for hbase]/hbase/.logs/ServerName/logfile
    *      or
    * [base directory for hbase]/hbase/.logs/ServerName-splitting/logfile
    *
    * Expected to work for individual log files and server-specific directories.
    *
    * @return null if it's not a log file. Returns the ServerName of the region
    *         server that created this log file otherwise.
    */
   public static ServerName getServerNameFromWALDirectoryName(Configuration conf, String path)
       throws IOException {
     if (path == null
         || path.length() <= HConstants.HREGION_LOGDIR_NAME.length()) {
       return null;
     }
 
     if (conf == null) {
       throw new IllegalArgumentException("parameter conf must be set");
     }
 
     final String walDir = FSUtils.getWALRootDir(conf).toString();
 
     final StringBuilder startPathSB = new StringBuilder(walDir);
     if (!walDir.endsWith("/"))
       startPathSB.append('/');
     startPathSB.append(HConstants.HREGION_LOGDIR_NAME);
     if (!HConstants.HREGION_LOGDIR_NAME.endsWith("/"))
       startPathSB.append('/');
     final String startPath = startPathSB.toString();
 
     String fullPath;
     try {
       fullPath = FileSystem.get(conf).makeQualified(new Path(path)).toString();
     } catch (IllegalArgumentException e) {
       LOG.info("Call to makeQualified failed on " + path + " " + e.getMessage());
       return null;
     }
 
     if (!fullPath.startsWith(startPath)) {
       return null;
     }
 
     final String serverNameAndFile = fullPath.substring(startPath.length());
 
     if (serverNameAndFile.indexOf('/') < "a,0,0".length()) {
       // Either it's a file (not a directory) or it's not a ServerName format
       return null;
     }
 
     Path p = new Path(path);
     return getServerNameFromWALDirectoryName(p);
   }
 
   /**
    * This function returns region server name from a log file name which is in one of the following
    * formats:
    * <ul>
    *   <li>hdfs://&lt;name node&gt;/hbase/.logs/&lt;server name&gt;-splitting/...</li>
    *   <li>hdfs://&lt;name node&gt;/hbase/.logs/&lt;server name&gt;/...</li>
    * </ul>
    * @param logFile
    * @return null if the passed in logFile isn't a valid WAL file path
    */
   public static ServerName getServerNameFromWALDirectoryName(Path logFile) {
     String logDirName = logFile.getParent().getName();
     // We were passed the directory and not a file in it.
     if (logDirName.equals(HConstants.HREGION_LOGDIR_NAME)) {
       logDirName = logFile.getName();
     }
     ServerName serverName = null;
     if (logDirName.endsWith(SPLITTING_EXT)) {
       logDirName = logDirName.substring(0, logDirName.length() - SPLITTING_EXT.length());
     }
     try {
       serverName = ServerName.parseServerName(logDirName);
     } catch (IllegalArgumentException ex) {
       serverName = null;
       LOG.warn("Cannot parse a server name from path=" + logFile + "; " + ex.getMessage());
     }
     if (serverName != null && serverName.getStartcode() < 0) {
       LOG.warn("Invalid log file path=" + logFile);
       serverName = null;
     }
     return serverName;
   }
 
   public static boolean isMetaFile(Path p) {
     return isMetaFile(p.getName());
   }
 
   public static boolean isMetaFile(String p) {
     if (p != null && p.endsWith(META_WAL_PROVIDER_ID)) {
       return true;
     }
     return false;
   }
 
   /**
    * public because of FSHLog. Should be package-private
    */
   public static Writer createWriter(final Configuration conf, final FileSystem fs, final Path path,
       final boolean overwritable)
       throws IOException {
     // Configuration already does caching for the Class lookup.
     Class<? extends Writer> logWriterClass = conf.getClass("hbase.regionserver.hlog.writer.impl",
         ProtobufLogWriter.class, Writer.class);
     Writer writer = null;
     try {
       writer = logWriterClass.getDeclaredConstructor().newInstance();
       FileSystem rootFs = FileSystem.get(path.toUri(), conf);
       writer.init(rootFs, path, conf, overwritable);
       return writer;
     } catch (Exception e) {
       LOG.debug("Error instantiating log writer.", e);
       if (writer != null) {
         try{
           writer.close();
         } catch(IOException ee){
           LOG.error("cannot close log writer", ee);
         }
       }
       throw new IOException("cannot get log writer", e);
     }
   }
 
   /**
    * Get prefix of the log from its name, assuming WAL name in format of
    * log_prefix.filenumber.log_suffix @see {@link FSHLog#getCurrentFileName()}
    * @param name Name of the WAL to parse
    * @return prefix of the log
    */
   public static String getWALPrefixFromWALName(String name) {
     int endIndex = name.replaceAll(META_WAL_PROVIDER_ID, "").lastIndexOf(".");
     return name.substring(0, endIndex);
   }
 
 }