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 org.apache.camel.component.smpp;
  
  import java.util.concurrent.locks.Lock;
  import java.util.concurrent.locks.ReentrantLock;
  
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  public class SmppSplitter {
  
      /**
       * The length of the UDH in bytes.
       * <p/>
       * The real length of the header must be 6 bytes, but the first byte that contains the length of the header must not
       * be counted.
       */
      protected static final int UDHIE_HEADER_LENGTH = 0x05;
  
      /**
       * The real length of the UDH header.
       * <p/>
       * The real length of the UDH header is {@link #UDHIE_HEADER_LENGTH} {@code + 1}.
       *
       * @see #UDHIE_HEADER_LENGTH
       */
      protected static final int UDHIE_HEADER_REAL_LENGTH = UDHIE_HEADER_LENGTH + 1;
  
      /**
       * The length of the reference number of the SAR fragmet of the UDH header.
       * <p/>
       * The length can be 1 or 2 bytes and is considered to be 1 byte.
       */
      protected static final int UDHIE_SAR_REF_NUM_LENGTH = 1;
  
      /**
       * The value that identifier length of the SAR fragment.
       * <p/>
       * {@code 0x00} value must be used if the length of the reference number is 1 byte.<br/>
       * {@code 0x08} value must be used if the length of the reference number is 2 bytes.
       */
      protected static final byte UDHIE_IDENTIFIER_SAR = 0x00;
  
      /**
       * The length of the SAR fragment.
       * <p/>
       * {@code 0x03} value must be used if the length of the reference number is 1 byte.<br/>
       * {@code 0x04} value must be used if the length of the reference number is 2 bytes.
       */
      protected static final byte UDHIE_SAR_LENGTH = 0x03;
  
      /**
       * The maximum length of the message in bytes.
       */
      protected static final int MAX_MSG_BYTE_LENGTH = 140;
  
      /**
       * The maximum amount of segments in the multipart message.
       */
      protected static final int MAX_SEG_COUNT = 255;
  
      private static final Logger LOG = LoggerFactory.getLogger(SmppSplitter.class);
      private static final Lock LOCK = new ReentrantLock();
  
      /**
       * Current reference number.
       */
      private static int refNum;
  
      private final int messageLength;
      private final int segmentLength;
      private final int currentLength;
  
      protected SmppSplitter(int messageLength, int segmentLength, int currentLength) {
          this.messageLength = messageLength;
          this.segmentLength = segmentLength;
          this.currentLength = currentLength;
      }
  
      /**
       * Returns reference number which length is {@link #UDHIE_SAR_REF_NUM_LENGTH}.
       *
       * @return the reference number of the multipart message
       */
      protected static byte getReferenceNumber() {
          LOCK.lock();
          try {
              refNum++;
              if (refNum == 256) {
                  refNum = 1;
              }
              return (byte) refNum;
          } finally {
              LOCK.unlock();
          }
      }
  
      protected static byte getCurrentReferenceNumber() {
          LOCK.lock();
          try {
              return (byte) refNum;
          } finally {
              LOCK.unlock();
          }
      }
  
      /**
       * only needed for the unit tests
       */
      protected static void resetCurrentReferenceNumber() {
          LOCK.lock();
          try {
              SmppSplitter.refNum = 0;
          } finally {
              LOCK.unlock();
          }
      }
  
      public byte[][] split(byte[] message) {
          if (!isSplitRequired()) {
              return new byte[][] { message };
          }
  
          int segmentLength = getSegmentLength();
  
          // determine how many messages
          int segmentNum = message.length / segmentLength;
          int messageLength = message.length;
          if (segmentNum > MAX_SEG_COUNT) {
              // this is too long, can't fit, so chop
              segmentNum = MAX_SEG_COUNT;
              messageLength = segmentNum * segmentLength;
          }
          if ((messageLength % segmentLength) > 0) {
              segmentNum++;
          }
  
          byte[][] segments = new byte[segmentNum][];
  
          int lengthOfData;
          byte refNum = getReferenceNumber();
          for (int i = 0; i < segmentNum; i++) {
              LOG.trace("segment number = {}", i);
              if (segmentNum - i == 1) {
                  lengthOfData = messageLength - i * segmentLength;
              } else {
                  lengthOfData = segmentLength;
              }
              LOG.trace("Length of data = {}", lengthOfData);
  
              segments[i] = new byte[UDHIE_HEADER_REAL_LENGTH + lengthOfData];
              LOG.trace("segments[{}].length = {}", i, segments[i].length);
  
              segments[i][0] = UDHIE_HEADER_LENGTH; // doesn't include itself, is header length
              // SAR identifier
              segments[i][1] = UDHIE_IDENTIFIER_SAR;
              // SAR length
              segments[i][2] = UDHIE_SAR_LENGTH;
              // DATAGRAM REFERENCE NUMBER
              segments[i][3] = refNum;
              // total number of segments
              segments[i][4] = (byte) segmentNum;
              // segment #
              segments[i][5] = (byte) (i + 1);
              // now copy the data
              System.arraycopy(message, i * segmentLength, segments[i], UDHIE_HEADER_REAL_LENGTH, lengthOfData);
          }
  
          return segments;
      }
  
      protected boolean isSplitRequired() {
          return getCurrentLength() > getMessageLength();
      }
  
      /**
       * Gets maximum message length.
       *
       * @return maximum message length
       */
      public int getMessageLength() {
          return messageLength;
      }
  
      /**
       * Gets maximum segment length.
       *
       * @return maximum segment length
       */
      public int getSegmentLength() {
          return segmentLength;
      }
  
      /**
       * Gets length of the message to split.
       *
       * @return length of the message to split
       */
      public int getCurrentLength() {
          return currentLength;
      }
  }
  