content: /*
   * 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 com.datastax.oss.driver.internal.core.metadata.token;
  
  import com.datastax.oss.driver.api.core.metadata.token.Token;
  import com.datastax.oss.driver.api.core.metadata.token.TokenRange;
  import com.datastax.oss.driver.shaded.guava.common.collect.Lists;
  import com.datastax.oss.protocol.internal.util.Bytes;
  import java.math.BigInteger;
  import java.nio.ByteBuffer;
  import java.util.List;
  import net.jcip.annotations.Immutable;
  
  @Immutable
  public class ByteOrderedTokenRange extends TokenRangeBase {
  
    private static final BigInteger TWO = BigInteger.valueOf(2);
  
    public ByteOrderedTokenRange(ByteOrderedToken start, ByteOrderedToken end) {
      super(start, end, ByteOrderedTokenFactory.MIN_TOKEN);
    }
  
    @Override
    protected TokenRange newTokenRange(Token start, Token end) {
      return new ByteOrderedTokenRange(((ByteOrderedToken) start), ((ByteOrderedToken) end));
    }
  
    @Override
    protected List<Token> split(Token rawStartToken, Token rawEndToken, int numberOfSplits) {
      int tokenOrder = rawStartToken.compareTo(rawEndToken);
  
      // ]min,min] means the whole ring. However, since there is no "max token" with this partitioner,
      // we can't come up with a magic end value that would cover the whole ring
      if (tokenOrder == 0 && rawStartToken.equals(ByteOrderedTokenFactory.MIN_TOKEN)) {
        throw new IllegalArgumentException("Cannot split whole ring with ordered partitioner");
      }
  
      ByteOrderedToken startToken = (ByteOrderedToken) rawStartToken;
      ByteOrderedToken endToken = (ByteOrderedToken) rawEndToken;
  
      int significantBytes;
      BigInteger start, end, range, ringEnd, ringLength;
      BigInteger bigNumberOfSplits = BigInteger.valueOf(numberOfSplits);
      if (tokenOrder < 0) {
        // Since tokens are compared lexicographically, convert to integers using the largest length
        // (ex: given 0x0A and 0x0BCD, switch to 0x0A00 and 0x0BCD)
        significantBytes = Math.max(startToken.getValue().capacity(), endToken.getValue().capacity());
  
        // If the number of splits does not fit in the difference between the two integers, use more
        // bytes (ex: cannot fit 4 splits between 0x01 and 0x03, so switch to 0x0100 and 0x0300)
        // At most 4 additional bytes will be needed, since numberOfSplits is an integer.
        int addedBytes = 0;
        while (true) {
          start = toBigInteger(startToken.getValue(), significantBytes);
          end = toBigInteger(endToken.getValue(), significantBytes);
          range = end.subtract(start);
          if (addedBytes == 4 || start.equals(end) || range.compareTo(bigNumberOfSplits) >= 0) {
            break;
          }
          significantBytes += 1;
          addedBytes += 1;
        }
        ringEnd = ringLength = null; // won't be used
      } else {
        // Same logic except that we wrap around the ring
        significantBytes = Math.max(startToken.getValue().capacity(), endToken.getValue().capacity());
        int addedBytes = 0;
        while (true) {
          start = toBigInteger(startToken.getValue(), significantBytes);
          end = toBigInteger(endToken.getValue(), significantBytes);
          ringLength = TWO.pow(significantBytes * 8);
          ringEnd = ringLength.subtract(BigInteger.ONE);
          range = end.subtract(start).add(ringLength);
          if (addedBytes == 4 || range.compareTo(bigNumberOfSplits) >= 0) {
            break;
          }
          significantBytes += 1;
          addedBytes += 1;
        }
      }
  
      List<BigInteger> values = super.split(start, range, ringEnd, ringLength, numberOfSplits);
      List<Token> tokens = Lists.newArrayListWithExpectedSize(values.size());
      for (BigInteger value : values) {
        tokens.add(new ByteOrderedToken(toBytes(value, significantBytes)));
      }
      return tokens;
    }
  
    // Convert a token's byte array to a number in order to perform computations.
    // This depends on the number of "significant bytes" that we use to normalize all tokens to the
    // same size.
    // For example if the token is 0x01 but significantBytes is 2, the result is 8 (0x0100).
    private BigInteger toBigInteger(ByteBuffer bb, int significantBytes) {
      byte[] bytes = Bytes.getArray(bb);
      byte[] target;
      if (significantBytes != bytes.length) {
        target = new byte[significantBytes];
        System.arraycopy(bytes, 0, target, 0, bytes.length);
      } else {
        target = bytes;
      }
      return new BigInteger(1, target);
    }
  
    // Convert a numeric representation back to a byte array.
    // Again, the number of significant bytes matters: if the input value is 1 but significantBytes is
    // 2, the
    // expected result is 0x0001 (a simple conversion would produce 0x01).
    protected ByteBuffer toBytes(BigInteger value, int significantBytes) {
      byte[] rawBytes = value.toByteArray();
      byte[] result;
      if (rawBytes.length == significantBytes) {
        result = rawBytes;
      } else {
        result = new byte[significantBytes];
        int start, length;
        if (rawBytes[0] == 0) {
          // that's a sign byte, ignore (it can cause rawBytes.length == significantBytes + 1)
          start = 1;
          length = rawBytes.length - 1;
        } else {
          start = 0;
          length = rawBytes.length;
        }
        System.arraycopy(rawBytes, start, result, significantBytes - length, length);
      }
      return ByteBuffer.wrap(result);
    }
  }
  