#define    u8   unsigned char
#define    u16   unsigned short
#define    u32  unsigned int


/*************构造MQTT连接包*******************/
u8 mqtt_connect_message(u8 *mqtt_message, char *client_id, char *username, char *password)
{
  u8 client_id_length = strlen(client_id);
  u8 username_length = strlen(username);
  u8 password_length = strlen(password);
  u8 packetLen;
  u8 i, baseIndex;

  packetLen = 12 + 2 + client_id_length;
  if (username_length > 0)
    packetLen = packetLen + 2 + username_length;
  if (password_length > 0)
    packetLen = packetLen + 2 + password_length;
  mqtt_message[0] = 16;       //0x10 // MQTT Message Type CONNECT
  mqtt_message[1] = packetLen - 2;  //
  baseIndex = 2;
  if (packetLen > 127)
  {
    mqtt_message[2] = 1;      //packetLen/127;
    baseIndex = 3;
  }
  mqtt_message[baseIndex++] = 0;    // Protocol Name Length MSB
  mqtt_message[baseIndex++] = 4;    // Protocol Name Length LSB
  mqtt_message[baseIndex++] = 77;   // ASCII Code for M
  mqtt_message[baseIndex++] = 81;   // ASCII Code for Q
  mqtt_message[baseIndex++] = 84;   // ASCII Code for T
  mqtt_message[baseIndex++] = 84;   // ASCII Code for T
  mqtt_message[baseIndex++] = 4;    // MQTT Protocol version = 4
  mqtt_message[baseIndex++] = 194;    // conn flags
  mqtt_message[baseIndex++] = 0;    // Keep-alive Time Length MSB
  mqtt_message[baseIndex++] = 300;   // Keep-alive Time Length LSB
  mqtt_message[baseIndex++] = (0xff00 & client_id_length) >> 8; // Client ID length MSB
  mqtt_message[baseIndex++] = 0xff & client_id_length; // Client ID length LSB
  // Client ID
  for (i = 0; i < client_id_length; i++)
  {
    mqtt_message[baseIndex + i] = *(client_id + i);
  }
  baseIndex = baseIndex + client_id_length;


  if (username_length > 0)
  {
    //username
    mqtt_message[baseIndex++] = (0xff00 & username_length) >> 8; //username length MSB
    mqtt_message[baseIndex++] = 0xff & username_length; //username length LSB
    for (i = 0; i < username_length ; i++)
    {
      mqtt_message[baseIndex + i] = *(username + i);
    }
    baseIndex = baseIndex + username_length;
  }

  if (password_length > 0)
  {
    //password
    mqtt_message[baseIndex++] = (0xff00 & password_length) >> 8; //password length MSB
    mqtt_message[baseIndex++] = 0xff & password_length; //password length LSB
    for (i = 0; i < password_length ; i++)
    {
      mqtt_message[baseIndex + i] = *(password + i);
    }
    baseIndex += password_length;
  }

  return baseIndex;
}

/*********MQTT发布消息包******************************/
u8 mqtt_publish_message(u8 *mqtt_message, char * topic, char * message, u8 qos)
{
  u16 topic_length = strlen(topic);
  u16 message_length = strlen(message);
  u16 i, index = 0;
  static u16 id = 0;

  mqtt_message[index++] = 48; //0x30 // MQTT Message Type PUBLISH
  if (qos)
    mqtt_message[index++] = 2 + topic_length + 2 + message_length;
  else
    mqtt_message[index++] = 2 + topic_length + message_length;   // Remaining length
  mqtt_message[index++] = (0xff00 & topic_length) >> 8;
  mqtt_message[index++] = 0xff & topic_length;

  // Topic
  for (i = 0; i < topic_length; i++)
  {
    mqtt_message[index + i] = *(topic + i);
  }
  index += topic_length;

  if (qos)
  {
    mqtt_message[index++] = (0xff00 & id) >> 8;
    mqtt_message[index++] = 0xff & id;
    id++;
  }

  // Message
  for (i = 0; i < message_length; i++)
  {
    mqtt_message[index + i] = *(message + i);
  }
  index += message_length;
  return index;
}
/*****************发布确认包****************************/
u8 mqtt_puback_message(u8 *mqtt_message)
{
  static u16 id = 0;
  mqtt_message[0] = 64;       //0x40  PUBACK
  mqtt_message[1] = 2;
  mqtt_message[2] = (0xff00 & id) >> 8;
  mqtt_message[3] = 0xff & id;
  id++;
  return 4;
}
/*********构建订阅请求*********/
u16 mqtt_subscribe_message(u8 *mqtt_message, char *topic, u8 qos, u8 whether)
{
  u16 topic_len = strlen(topic);
  u16 i, index = 0;
  static u16 id = 0;

  id++;
  if (whether)
    mqtt_message[index++] = 130;
  else
    mqtt_message[index++] = 162;
  mqtt_message[index++] = topic_len + 5;
  mqtt_message[index++] = (0xff00 & id) >> 8;
  mqtt_message[index++] = 0xff & id;
  mqtt_message[index++] = (0xff00 & topic_len) >> 8;
  mqtt_message[index++] = 0xff & topic_len;
  for (i = 0; i < topic_len; i++)
  {
    mqtt_message[index + i] = *(topic + i);
  }
  index += topic_len;

  if (whether)
  {
    mqtt_message[index] = qos;//QoS
    index++;
  }
  return index;
}
/***********构建MQTT请求PING包********************/
u8 mqtt_ping_message(u8 *mqtt_message)
{
  mqtt_message[0] = 192;  //0xC0  PING
  mqtt_message[1] = 0;  //
  return 2;
}
/************构建断开包******************/
u8 mqtt_disconnect_message(u8 *mqtt_message)
{
  mqtt_message[0] = 224;  //0xE0  DISCONNECT
  mqtt_message[1] = 0;  //
  return 2;
}