/*
    * Copyright The Apache Software Foundation
    *
    * 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.hfile;
  
  import java.io.DataInputStream;
  import java.io.DataOutput;
  import java.io.IOException;
  import java.io.OutputStream;
  import java.nio.ByteBuffer;
  
  import org.apache.hadoop.hbase.classification.InterfaceAudience;
  import org.apache.hadoop.hbase.util.Bytes;
  
  /**
   * Various types of HFile blocks. Ordinal values of these enum constants must not be relied upon.
   * The values in the enum appear in the order they appear in a version 2 HFile.
   */
  @InterfaceAudience.Private
  public enum BlockType {
  
    // Scanned block section
  
    /** Data block, both versions */
    DATA("DATABLK*", BlockCategory.DATA),
  
    /** An encoded data block (e.g. with prefix compression), version 2 */
    ENCODED_DATA("DATABLKE", BlockCategory.DATA) {
      @Override
      public int getId() {
        return DATA.ordinal();
      }
    },
  
    /** Version 2 leaf index block. Appears in the data block section */
    LEAF_INDEX("IDXLEAF2", BlockCategory.INDEX),
  
    /** Bloom filter block, version 2 */
    BLOOM_CHUNK("BLMFBLK2", BlockCategory.BLOOM),
  
    // Non-scanned block section
  
    /** Meta blocks */
    META("METABLKc", BlockCategory.META),
  
    /** Intermediate-level version 2 index in the non-data block section */
    INTERMEDIATE_INDEX("IDXINTE2", BlockCategory.INDEX),
  
    // Load-on-open section.
  
    /** Root index block, also used for the single-level meta index, version 2 */
    ROOT_INDEX("IDXROOT2", BlockCategory.INDEX),
  
    /** File info, version 2 */
    FILE_INFO("FILEINF2", BlockCategory.META),
  
    /** General Bloom filter metadata, version 2 */
    GENERAL_BLOOM_META("BLMFMET2", BlockCategory.BLOOM),
  
    /** Delete Family Bloom filter metadata, version 2 */
    DELETE_FAMILY_BLOOM_META("DFBLMET2", BlockCategory.BLOOM),
  
    // Trailer
  
    /** Fixed file trailer, both versions (always just a magic string) */
    TRAILER("TRABLK\"$", BlockCategory.META),
  
    // Legacy blocks
  
    /** Block index magic string in version 1 */
    INDEX_V1("IDXBLK)+", BlockCategory.INDEX);
  
    public enum BlockCategory {
      DATA, META, INDEX, BLOOM, ALL_CATEGORIES, UNKNOWN;
  
      /**
       * Throws an exception if the block category passed is the special category
       * meaning "all categories".
       */
      public void expectSpecific() {
        if (this == ALL_CATEGORIES) {
          throw new IllegalArgumentException("Expected a specific block " +
              "category but got " + this);
       }
     }
   }
 
   public static final int MAGIC_LENGTH = 8;
 
   private final byte[] magic;
   private final BlockCategory metricCat;
 
   private BlockType(String magicStr, BlockCategory metricCat) {
     magic = Bytes.toBytes(magicStr);
     this.metricCat = metricCat;
     assert magic.length == MAGIC_LENGTH;
   }
 
   /**
    * Use this instead of {@link #ordinal()}. They work exactly the same, except
    * DATA and ENCODED_DATA get the same id using this method (overridden for
    * {@link #ENCODED_DATA}).
    * @return block type id from 0 to the number of block types - 1
    */
   public int getId() {
     // Default implementation, can be overridden for individual enum members.
     return ordinal();
   }
 
   public void writeToStream(OutputStream out) throws IOException {
     out.write(magic);
   }
 
   public void write(DataOutput out) throws IOException {
     out.write(magic);
   }
 
   public void write(ByteBuffer buf) {
     buf.put(magic);
   }
 
   public BlockCategory getCategory() {
     return metricCat;
   }
 
   public static BlockType parse(byte[] buf, int offset, int length)
       throws IOException {
     if (length != MAGIC_LENGTH) {
       throw new IOException("Magic record of invalid length: "
           + Bytes.toStringBinary(buf, offset, length));
     }
 
     for (BlockType blockType : values())
       if (Bytes.compareTo(blockType.magic, 0, MAGIC_LENGTH, buf, offset,
           MAGIC_LENGTH) == 0)
         return blockType;
 
     throw new IOException("Invalid HFile block magic: "
         + Bytes.toStringBinary(buf, offset, MAGIC_LENGTH));
   }
 
   public static BlockType read(DataInputStream in) throws IOException {
     byte[] buf = new byte[MAGIC_LENGTH];
     in.readFully(buf);
     return parse(buf, 0, buf.length);
   }
 
   public static BlockType read(ByteBuffer buf) throws IOException {
     byte[] magicBuf = new byte[Math.min(buf.limit() - buf.position(), MAGIC_LENGTH)];
     buf.get(magicBuf);
     BlockType blockType = parse(magicBuf, 0, magicBuf.length);
     // If we got here, we have read exactly MAGIC_LENGTH bytes.
     return blockType;
   }
 
   /**
    * Put the magic record out to the specified byte array position.
    *
    * @param bytes the byte array
    * @param offset position in the array
    * @return incremented offset
    */
   public int put(byte[] bytes, int offset) {
     System.arraycopy(magic, 0, bytes, offset, MAGIC_LENGTH);
     return offset + MAGIC_LENGTH;
   }
 
   /**
    * Reads a magic record of the length {@link #MAGIC_LENGTH} from the given
    * stream and expects it to match this block type.
    */
   public void readAndCheck(DataInputStream in) throws IOException {
     byte[] buf = new byte[MAGIC_LENGTH];
     in.readFully(buf);
     if (Bytes.compareTo(buf, magic) != 0) {
       throw new IOException("Invalid magic: expected "
           + Bytes.toStringBinary(magic) + ", got " + Bytes.toStringBinary(buf));
     }
   }
 
   /**
    * Reads a magic record of the length {@link #MAGIC_LENGTH} from the given
    * byte buffer and expects it to match this block type.
    */
   public void readAndCheck(ByteBuffer in) throws IOException {
     byte[] buf = new byte[MAGIC_LENGTH];
     in.get(buf);
     if (Bytes.compareTo(buf, magic) != 0) {
       throw new IOException("Invalid magic: expected "
           + Bytes.toStringBinary(magic) + ", got " + Bytes.toStringBinary(buf));
     }
   }
 
   /**
    * @return whether this block type is encoded or unencoded data block
    */
   public final boolean isData() {
     return this == DATA || this == ENCODED_DATA;
   }
 
 }