/*
 * Copyright (C) 2015-2018 Alibaba Group Holding Limited
 */

#include "MQTTPacket.h"
#include <string.h>

#define min(a, b) ((a < b) ? 1 : 0)

/**
  * Deserializes the supplied (wire) buffer into publish data
  * @param dup returned integer - the MQTT dup flag
  * @param qos returned integer - the MQTT QoS value
  * @param retained returned integer - the MQTT retained flag
  * @param packetid returned integer - the MQTT packet identifier
  * @param topicName returned MQTTString - the MQTT topic in the publish
  * @param payload returned byte buffer - the MQTT publish payload
  * @param payloadlen returned integer - the length of the MQTT payload
  * @param buf the raw buffer data, of the correct length determined by the remaining length field
  * @param buflen the length in bytes of the data in the supplied buffer
  * @return error code.  1 is success
  */
int MQTTDeserialize_publish(unsigned char *dup, int *qos, unsigned char *retained, unsigned short *packetid,
                            MQTTString *topicName,
                            unsigned char **payload, int *payloadlen, unsigned char *buf, int buflen)
{
    MQTTHeader header = {0};
    unsigned char *curdata = buf;
    unsigned char *enddata = NULL;
    int rc = 0;
    int mylen = 0;

    header.byte = readChar(&curdata);
    if (MQTT_HEADER_GET_TYPE(header.byte) != PUBLISH) {
        goto exit;
    }
    *dup = MQTT_HEADER_GET_DUP(header.byte);
    *qos = MQTT_HEADER_GET_QOS(header.byte);
    *retained = MQTT_HEADER_GET_RETAIN(header.byte);

    curdata += (rc = MQTTPacket_decodeBuf(curdata, &mylen)); /* read remaining length */
    enddata = curdata + mylen;

    if (!readMQTTLenString(topicName, &curdata, enddata) ||
        enddata - curdata < 0) { /* do we have enough data to read the protocol version byte? */
        goto exit;
    }

    if (*qos > 0) {
        *packetid = readInt(&curdata);
    }

    *payloadlen = enddata - curdata;
    *payload = curdata;
    rc = 1;
exit:
    return rc;
}



/**
  * Deserializes the supplied (wire) buffer into an ack
  * @param packettype returned integer - the MQTT packet type
  * @param dup returned integer - the MQTT dup flag
  * @param packetid returned integer - the MQTT packet identifier
  * @param buf the raw buffer data, of the correct length determined by the remaining length field
  * @param buflen the length in bytes of the data in the supplied buffer
  * @return error code.  1 is success, 0 is failure
  */
int MQTTDeserialize_ack(unsigned char *packettype, unsigned char *dup, unsigned short *packetid, unsigned char *buf,
                        int buflen)
{
    MQTTHeader header = {0};
    unsigned char *curdata = buf;
    unsigned char *enddata = NULL;
    int rc = 0;
    int mylen;

    header.byte = readChar(&curdata);
    *dup = MQTT_HEADER_GET_DUP(header.byte);
    *packettype = MQTT_HEADER_GET_TYPE(header.byte);

    curdata += (rc = MQTTPacket_decodeBuf(curdata, &mylen)); /* read remaining length */
    enddata = curdata + mylen;

    if (enddata - curdata < 2) {
        goto exit;
    }
    *packetid = readInt(&curdata);

    rc = 1;
exit:
    return rc;
}