gemfire-core/src/main/java/com/gemstone/gemfire/internal/redis/executor/string/SetBitExecutor.java

package com.gemstone.gemfire.internal.redis.executor.string;

import java.util.List;

import com.gemstone.gemfire.cache.Region;
import com.gemstone.gemfire.internal.redis.ByteArrayWrapper;
import com.gemstone.gemfire.internal.redis.Command;
import com.gemstone.gemfire.internal.redis.Coder;
import com.gemstone.gemfire.internal.redis.ExecutionHandlerContext;
import com.gemstone.gemfire.internal.redis.RedisConstants.ArityDef;

public class SetBitExecutor extends StringExecutor {

  private final String ERROR_NOT_INT = "The number provided must be numeric";

  private final String ERROR_VALUE = "The value is out of range, must be 0 or 1";

  private final String ERROR_ILLEGAL_OFFSET = "The offset is out of range, must be greater than or equal to 0  and at most 4294967295 (512MB)";

  @Override
  public void executeCommand(Command command, ExecutionHandlerContext context) {
    List<byte[]> commandElems = command.getProcessedCommand();

    Region<ByteArrayWrapper, ByteArrayWrapper> r = context.getRegionCache().getStringsRegion();

    if (commandElems.size() < 4) {
      command.setResponse(Coder.getErrorResponse(context.getByteBufAllocator(), ArityDef.SETBIT));
      return;
    }

    ByteArrayWrapper key = command.getKey();
    checkAndSetDataType(key, context);
    ByteArrayWrapper wrapper = r.get(key);

    long offset;
    int value;
    int returnBit = 0;
    try {
      byte[] offAr = commandElems.get(2);
      byte[] valAr = commandElems.get(3);
      offset = Coder.bytesToLong(offAr);
      value = Coder.bytesToInt(valAr);
    } catch (NumberFormatException e) {
      command.setResponse(Coder.getErrorResponse(context.getByteBufAllocator(), ERROR_NOT_INT));
      return;
    }

    if (value != 0 && value != 1) {
      command.setResponse(Coder.getErrorResponse(context.getByteBufAllocator(), ERROR_VALUE));
      return;
    }

    if (offset < 0 || offset > 4294967295L) {
      command.setResponse(Coder.getErrorResponse(context.getByteBufAllocator(), ERROR_ILLEGAL_OFFSET));
      return;
    }

    int byteIndex = (int) (offset / 8);
    offset %= 8;

    if (wrapper == null) {
      byte[] bytes = new byte[byteIndex + 1];
      if (value == 1)
        bytes[byteIndex] = (byte) (0x80 >> offset);
      r.put(key, new ByteArrayWrapper(bytes));
      command.setResponse(Coder.getIntegerResponse(context.getByteBufAllocator(), 0));
    } else {

      byte[] bytes = wrapper.toBytes();
      if (byteIndex < bytes.length)
        returnBit = (bytes[byteIndex] & (0x80 >> offset)) >> (7 - offset);
        else 
          returnBit = 0;

      if (byteIndex < bytes.length) {
        bytes[byteIndex] = value == 1 ? (byte) (bytes[byteIndex] | (0x80 >> offset)) : (byte) (bytes[byteIndex] & ~(0x80 >> offset));
        r.put(key, new ByteArrayWrapper(bytes));
      } else {
        byte[] newBytes = new byte[byteIndex + 1];
        System.arraycopy(bytes, 0, newBytes, 0, bytes.length);
        newBytes[byteIndex] = value == 1 ? (byte) (newBytes[byteIndex] | (0x80 >> offset)) : (byte) (newBytes[byteIndex] & ~(0x80 >> offset));
        r.put(key, new ByteArrayWrapper(newBytes));
      }

      command.setResponse(Coder.getIntegerResponse(context.getByteBufAllocator(), returnBit));
    }

  }

}