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

#include "MQTTPacket.h"

#include <string.h>

/**
  * Determines the length of the MQTT unsubscribe packet that would be produced using the supplied parameters
  * @param count the number of topic filter strings in topicFilters
  * @param topicFilters the array of topic filter strings to be used in the publish
  * @return the length of buffer needed to contain the serialized version of the packet
  */
int MQTTSerialize_unsubscribeLength(int count, MQTTString topicFilters[])
{
    int i;
    int len = 2; /* packetid */

    for (i = 0; i < count; ++i) {
        len += 2 + MQTTstrlen(topicFilters[i]);    /* length + topic*/
    }
    return len;
}


/**
  * Serializes the supplied unsubscribe data into the supplied buffer, ready for sending
  * @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
  * @param dup integer - the MQTT dup flag
  * @param packetid integer - the MQTT packet identifier
  * @param count - number of members in the topicFilters array
  * @param topicFilters - array of topic filter names
  * @return the length of the serialized data.  <= 0 indicates error
  */
int MQTTSerialize_unsubscribe(unsigned char *buf, int buflen, unsigned char dup, unsigned short packetid,
                              int count, MQTTString topicFilters[])
{
    unsigned char *ptr = buf;
    MQTTHeader header = {0};
    int rem_len = 0;
    int rc = -1;
    int i = 0;

    if (MQTTPacket_len(rem_len = MQTTSerialize_unsubscribeLength(count, topicFilters)) > buflen) {
        rc = MQTTPACKET_BUFFER_TOO_SHORT;
        goto exit;
    }

    header.byte = 0;
    MQTT_HEADER_SET_TYPE(header.byte, UNSUBSCRIBE);
    MQTT_HEADER_SET_DUP(header.byte, dup);
    MQTT_HEADER_SET_QOS(header.byte, 1);
    writeChar(&ptr, header.byte); /* write header */

    ptr += MQTTPacket_encode(ptr, rem_len); /* write remaining length */;

    writeInt(&ptr, packetid);

    for (i = 0; i < count; ++i) {
        writeMQTTString(&ptr, topicFilters[i]);
    }

    rc = ptr - buf;
exit:
    return rc;
}


/**
  * Deserializes the supplied (wire) buffer into unsuback data
  * @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_unsuback(unsigned short *packetid, unsigned char *buf, int buflen)
{
    unsigned char type = 0;
    unsigned char dup = 0;
    int rc = 0;

    rc = MQTTDeserialize_ack(&type, &dup, packetid, buf, buflen);
    if (type == UNSUBACK) {
        rc = 1;
    }
    return rc;
}