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.bifromq.mqtt.utils;
  
  import static io.netty.buffer.ByteBufUtil.utf8Bytes;
  
  import io.netty.handler.codec.mqtt.MqttConnectMessage;
  import io.netty.handler.codec.mqtt.MqttFixedHeader;
  import io.netty.handler.codec.mqtt.MqttMessage;
  
  /**
   * The interface for calculating the size of the mqtt message.
   */
  public interface IMQTTMessageSizer {
      int MIN_CONTROL_PACKET_SIZE = 16;
      IMQTTMessageSizer.MqttMessageSize TWO_BYTES_REMAINING_LENGTH =
          new IMQTTMessageSizer.MqttMessageSize() {
              @Override
              public int encodedBytes() {
                  return 4;
              }
  
              @Override
              public int encodedBytes(boolean includeUserProps, boolean includeReasonString) {
                  return 4;
              }
          };
      IMQTTMessageSizer.MqttMessageSize ZERO_BYTES_REMAINING_LENGTH =
          new IMQTTMessageSizer.MqttMessageSize() {
              @Override
              public int encodedBytes() {
                  return 2;
              }
  
              @Override
              public int encodedBytes(boolean includeUserProps, boolean includeReasonString) {
                  return 2;
              }
          };
  
      static IMQTTMessageSizer mqtt3() {
          return MQTT3MessageSizer.INSTANCE;
      }
  
      static IMQTTMessageSizer mqtt5() {
          return MQTT5MessageSizer.INSTANCE;
      }
  
      static int sizeBinary(byte[] binary) {
          // 2 bytes for encoding size prefix in Binary Data, [MQTT5-1.5.6]
          return 2 + binary.length;
      }
  
      static int sizeUTF8EncodedString(String s) {
          int rsBytes = utf8Bytes(s);
          // 2 bytes for encoding size prefix in UTF-8 Encoded String, [MQTT5-1.5.7]
          return 2 + rsBytes;
      }
  
      static int varIntBytes(int i) {
          int bytes = 0;
          do {
              int digit = i % 128;
              i /= 128;
              if (i > 0) {
                  digit |= 0x80;
              }
              bytes++;
          } while (i > 0);
          return bytes;
      }
  
      MqttMessageSize sizeOf(MqttMessage message);
  
      int lastWillSize(MqttConnectMessage message);
  
      /**
       * Calculate the size of the message by the fixed header from decoded mqtt message.
       *
       * @param header the fixed header of the message
       * @return the size of the message
       */
      default int sizeByHeader(MqttFixedHeader header) {
          int remainingLength = header.remainingLength();
          int fixedHeaderSize = 1;
          int remainingLengthSize = 1; // at least one byte
          if (remainingLength > 127) {
              remainingLengthSize = 2;
              if (remainingLength > 16383) {
                  remainingLengthSize = 3;
                  if (remainingLength > 2097151) {
                      remainingLengthSize = 4;
                  }
              }
          }
          return fixedHeaderSize + remainingLengthSize + remainingLength;
      }
  
      interface MqttMessageSize {
          int encodedBytes();
  
          int encodedBytes(boolean includeUserProps, boolean includeReasonString);
      }
  }
  