/*
 * egts.c
 *
 *  Created on: Jun 4, 2021
 *      Author: zemon
 */


#include "egts.h"
#include "egts_crc.h"
#include "string.h"

#define EGTS_TIMESTAMP_EPOCH_OFFSET 1262304000 // epoch timestamp of  Fri, 01 Jan 2010 00:00:00 GMT

uint32_t toEgtsTimestamp(uint32_t ts) {
    return ts - EGTS_TIMESTAMP_EPOCH_OFFSET;
}


uint16_t vEgtsPackSrv(
        uint8_t *out,
        uint8_t flags,
        eEgtsServiceId sourceServiceId,
        eEgtsServiceId recipientServiceId,
        uint32_t epochTimestamp,
        eEgtsSubRecordId subRecordType,
        tEgtsServiceSubRecordGenerator subRecGen,
        void *subRecArgs
) {

    uint16_t subRecordLength = subRecGen(out + 14, subRecArgs);

    *(uint16_t *) (out + 0) = subRecordLength + 3;    //data length

    *(uint16_t *) (out + 2) = 0x0001;            //counter

////////////////////////////////////////////////////////////////////////////////////////////////////////
//	|                          flags                            |
//	  Sender  Rcver  Group  Prior  hasTime  hasEvntID  hasObjId
//	   DEV     SRV   None   value   exist      not       not
//	    1       0     0      10       1         0         0     => 10010100 =>  0x94
    out[4] = flags;
//////////////////////////////////////////////////////////////////////////////////////////////////////////

    //time
    *(uint32_t *) (out + 5) = toEgtsTimestamp(epochTimestamp);

    //SourceServType
    *(uint8_t *) (out + 9) = (uint8_t) sourceServiceId;

    //RecipientServType
    *(uint8_t *) (out + 10) = (uint8_t) recipientServiceId;

    //SRT
    *(uint8_t *) (out + 11) = subRecordType; //(uint8_t) SRT;

    //SRL
    *(uint16_t *) (out + 12) = subRecordLength;

    return subRecordLength + 14;
}

uint16_t vEgtsPackTransport(
        uint16_t cid,
        uint16_t packetId,
        uint8_t *out,
        uint8_t srvFlags,
        eEgtsPacketTypeId packetTypeId,
        eEgtsServiceId sourceServiceId,
        eEgtsServiceId recipientServiceId,
        uint32_t timestamp,
        eEgtsSubRecordId subRecordType,
        tEgtsServiceSubRecordGenerator subRecGen,
        void *subRecArgs
) {

    uint8_t ptOffset = 0;

    if (packetTypeId == EGTS_PT_RESPONSE) {
        ptOffset = 3;
    }

    uint16_t srvLen = ptOffset + vEgtsPackSrv(
            out + TRANSPORT_HEADER_LENGTH+ptOffset,
            srvFlags,
            sourceServiceId,
            recipientServiceId,
            timestamp,
            subRecordType,
            subRecGen,
            subRecArgs
    );

    out[0] = 0x01;//version
    out[1] = 0x00;//secure key
    out[2] = 0x01;//flags
    out[3] = 0x0B;//header length
    out[4] = 0x00;//header encoding

    *((uint16_t *) (out + 5)) = srvLen;

    *((uint16_t *) (out + 7)) = packetId;//package Id

    out[9] = packetTypeId;//Packet type

    out[10] = CRC8EGTS(out, 10);//Header CRC

    if (packetTypeId == EGTS_PT_RESPONSE) {
        *((uint16_t *) (out + 11)) = cid;// response packet id
        out[13] = 0b0000;//Packet type
    }

    *((uint16_t *) (out + TRANSPORT_HEADER_LENGTH + srvLen)) = CRC16EGTS(out + TRANSPORT_HEADER_LENGTH, srvLen);

    return TRANSPORT_HEADER_LENGTH + srvLen + 2;
}