/*
    * 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.util.Random;
  
  import org.apache.hadoop.hbase.KeyValue;
  
  /**
   * These helper methods generate random byte[]'s data for KeyValues
   */
  public class RandomKeyValueUtil {
    public static final String COLUMN_FAMILY_NAME = "_-myColumnFamily-_";
    private static final int MIN_ROW_OR_QUALIFIER_LENGTH = 64;
    private static final int MAX_ROW_OR_QUALIFIER_LENGTH = 128;
  
    private RandomKeyValueUtil() { }
  
    public static final char randomReadableChar(Random rand) {
      int i = rand.nextInt(26 * 2 + 10 + 1);
      if (i < 26) {
        return (char) ('A' + i);
      }
      i -= 26;
      if (i < 26) {
        return (char) ('a' + i);
      }
      i -= 26;
      if (i < 10) {
        return (char) ('0' + i);
      }
      i -= 10;
      assert i == 0;
      return '_';
    }
  
    public static KeyValue randomKeyValue(Random rand) {
      return new KeyValue(randomRowOrQualifier(rand),
        COLUMN_FAMILY_NAME.getBytes(), randomRowOrQualifier(rand),
        randomValue(rand));
    }
  
    public static byte[] randomRowOrQualifier(Random rand) {
      StringBuilder field = new StringBuilder();
      int fieldLen = MIN_ROW_OR_QUALIFIER_LENGTH
          + rand.nextInt(MAX_ROW_OR_QUALIFIER_LENGTH
          - MIN_ROW_OR_QUALIFIER_LENGTH + 1);
      for (int i = 0; i < fieldLen; ++i) {
        field.append(randomReadableChar(rand));
      }
      return field.toString().getBytes();
    }
  
    public static byte[] randomValue(Random rand) {
      StringBuilder v = new StringBuilder();
      for (int j = 0; j < 1 + rand.nextInt(2000); ++j) {
        v.append((char) (32 + rand.nextInt(95)));
      }
      byte[] valueBytes = v.toString().getBytes();
      return valueBytes;
    }
  
    /**
     * Generates a random key that is guaranteed to increase as the given index i
     * increases. The result consists of a prefix, which is a deterministic
     * increasing function of i, and a random suffix.
     *
     * @param rand random number generator to use
     * @param i the index to use
     * @return the random key
     */
    public static byte[] randomOrderedKey(Random rand, int i) {
      StringBuilder k = new StringBuilder();
  
      // The fixed-length lexicographically increasing part of the key.
      for (int bitIndex = 31; bitIndex >= 0; --bitIndex) {
        if ((i & (1 << bitIndex)) == 0) {
          k.append("a");
        } else {
          k.append("b");
        }
      }
  
      // A random-length random suffix of the key.
     for (int j = 0; j < rand.nextInt(50); ++j) {
       k.append(randomReadableChar(rand));
     }
 
     byte[] keyBytes = k.toString().getBytes();
     return keyBytes;
   }
 
   public static byte[] randomOrderedFixedLengthKey(Random rand, int i, int suffixLength) {
     StringBuilder k = new StringBuilder();
 
     // The fixed-length lexicographically increasing part of the key.
     for (int bitIndex = 31; bitIndex >= 0; --bitIndex) {
       if ((i & (1 << bitIndex)) == 0) {
         k.append("a");
       } else {
         k.append("b");
       }
     }
 
     // A random suffix of the key.
     for (int j = 0; j < suffixLength; ++j) {
       k.append(randomReadableChar(rand));
     }
 
     byte[] keyBytes = k.toString().getBytes();
     return keyBytes;
   }
 
   public static byte[] randomFixedLengthValue(Random rand, int valueLength) {
     StringBuilder v = new StringBuilder();
     for (int j = 0; j < valueLength; ++j) {
       v.append((char) (32 + rand.nextInt(95)));
     }
 
     byte[] valueBytes = v.toString().getBytes();
     return valueBytes;
   }
 }