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Java client for Arcus memcached
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/*
 * arcus-java-client : Arcus Java client
 * Copyright 2010-2014 NAVER Corp.
 *
 * Licensed 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 net.spy.memcached.collection;

import net.spy.memcached.util.BTreeUtil;

/**
 * Ascii protocol implementation for "bop gbp" (B+Tree get by position)
 *
 * {@code
 * bop gbp   \r\n
 * VALUE  \r\n
 *  []  \r\n
 * END\r\n (CLIENT_ERROR, NOT_FOUND, UNREADABLE, TYPE_MISMATCH, NOT_FOUND_ELEMENT)
 * }
 */
public class BTreeGetByPosition extends CollectionGet {

  public static final int HEADER_EFLAG_POSITION = 1; // 0-based

  private static final String command = "bop gbp";

  private final BTreeOrder order;
  private final String range;
  private final int posFrom;
  private final int posTo;

  private BKeyObject bkey;
  private byte[] eflag;
  private int bytes;

  public BTreeGetByPosition(BTreeOrder order, int pos) {
    this.headerCount = 2;
    this.order = order;
    this.range = String.valueOf(pos);
    this.posFrom = pos;
    this.posTo = pos;
  }

  public BTreeGetByPosition(BTreeOrder order, int posFrom, int posTo) {
    this.headerCount = 2;
    this.order = order;
    this.range = String.valueOf(posFrom) + ".." + String.valueOf(posTo);
    this.posFrom = posFrom;
    this.posTo = posTo;
  }

  public BTreeOrder getOrder() {
    return order;
  }

  public String getRange() {
    return range;
  }

  public String stringify() {
    if (str != null) {
      return str;
    }
    StringBuilder b = new StringBuilder();
    b.append(order.getAscii());
    b.append(" ");
    b.append(range);

    str = b.toString();
    return str;
  }

  public String getCommand() {
    return command;
  }

  @Override
  public boolean headerReady(int spaceCount) {
    return spaceCount == 2;
  }

  @Override
  public byte[] getAddtionalArgs() {
    return null;
  }

  private static final int BKEY = 0;
  private static final int EFLAG_OR_BYTES = 1;
  private static final int BYTES = 2;

  /*
   * VALUE  \r\n
   *  []  \r\n
   * END\r\n
   */
  public void decodeItemHeader(String itemHeader) {
    String[] splited = itemHeader.split(" ");
    boolean hasEFlag = false;

    // 
    if (splited[BKEY].startsWith("0x")) {
      this.bkey = new BKeyObject(splited[0].substring(2));
    } else {
      this.bkey = new BKeyObject(Long.parseLong(splited[0]));
    }

    //  or 
    if (splited[EFLAG_OR_BYTES].startsWith("0x")) {
      // 
      hasEFlag = true;
      this.eflag = BTreeUtil
              .hexStringToByteArrays(splited[EFLAG_OR_BYTES].substring(2));
    } else {
      this.bytes = Integer.parseInt(splited[EFLAG_OR_BYTES]);
    }

    // 
    if (hasEFlag) {
      this.bytes = Integer.parseInt(splited[BYTES]);
    }

    this.dataLength = bytes;
  }

  public BKeyObject getBkey() {
    return bkey;
  }

  public byte[] getEflag() {
    return eflag;
  }

  public int getBytes() {
    return bytes;
  }

  public int getPosFrom() {
    return posFrom;
  }

  public int getPosTo() {
    return posTo;
  }

  public boolean isReversed() {
    return posFrom > posTo;
  }

}