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

#include <stdio.h>
#include <string.h>

#include "CoAPSerialize.h"
#include "iotx_coap_internal.h"

int CoAPSerialize_Header(CoAPMessage *msg, unsigned char *buf,
                         unsigned short buflen)
{
    if (4 > buflen) {
        return 0;
    }
    buf[0] =
        (((msg->header.version & 0x3) << 6) | ((msg->header.type & 0x3) << 4)) |
        (msg->header.tokenlen & 0x0F);

    buf[1] = msg->header.code;
    buf[2] = (msg->header.msgid & 0xFF00) >> 8;
    buf[3] = (msg->header.msgid & 0x00FF);

    return 4;
}

int CoAPSerialize_Token(CoAPMessage *msg, unsigned char *buf,
                        unsigned short buflen)
{
    int i = 0;

    if (buflen < msg->header.tokenlen) {
        return 0;
    }
    for (i = 0; i < msg->header.tokenlen; i++) {
        buf[i] = msg->token[i];
    }
    return msg->header.tokenlen;
}

static unsigned short CoAPSerialize_Option(CoAPMsgOption *option,
                                           unsigned char *buf)
{
    unsigned char *ptr = buf;

    if (269 <= option->num) {
        *ptr = ((14 & 0x0F) << 4);
    } else if (13 <= option->num) {
        *ptr = ((13 & 0x0F) << 4);
    } else {
        *ptr = option->num << 4;
    }

    if (269 <= option->len) {
        *ptr |= (14 & 0x0F);
    } else if (13 <= option->len) {
        *ptr |= (13 & 0x0F);
    } else {
        *ptr |= (option->len & 0x0F);
    }
    ptr++;

    if (269 <= option->num) {
        *ptr = (unsigned char)(((option->num - 269) & 0xFF00) >> 8);
        *(ptr + 1) = (unsigned char)(((option->num - 269) & 0x00FF));
        ptr += 2;
    } else if (13 <= option->num) {
        *ptr = (unsigned char)(option->num - 13);
        ptr++;
    }

    if (269 <= option->len) {
        *ptr = (unsigned char)(((option->len - 269) & 0xFF00) >> 8);
        *(ptr + 1) = (unsigned char)(((option->len - 269) & 0x00FF));
        ptr += 2;
    } else if (13 <= option->len) {
        *ptr = (unsigned char)(option->len - 13);
        ptr++;
    }

    memcpy(ptr, option->val, option->len);
    ptr += option->len;

    return (int)(ptr - buf);
}

unsigned short CoAPSerialize_Options(CoAPMessage *msg, unsigned char *buf,
                                     unsigned short buflen)
{
    int i = 0;
    unsigned short count = 0;

    for (i = 0; i < msg->optcount; i++) {
        unsigned short len = 0;
        len = CoAPSerialize_Option(&msg->options[i], &buf[count]);
        if (0 < len) {
            count += len;
        } else {
            return 0;
        }
    }

    return count;
}

static unsigned short CoAPSerialize_OptionLen(CoAPMsgOption *option)
{
    unsigned short len = 1;

    if (269 <= option->num) {
        len += 2;
    } else if (13 <= option->num) {
        len += 1;
    } else {
    }

    if (269 <= option->len) {
        len += 2;
    } else if (13 <= option->len) {
        len += 1;
    } else {
    }

    len += option->len;
    return len;
}

unsigned short CoAPSerialize_OptionsLen(CoAPMessage *msg)
{
    int i = 0;
    unsigned short count = 0;

    for (i = 0; i < msg->optcount; i++) {
        unsigned short len = 0;
        len = CoAPSerialize_OptionLen(&msg->options[i]);
        if (0 < len) {
            count += len;
        } else {
            return 0;
        }
    }

    return count;
}

int CoAPSerialize_Payload(CoAPMessage *msg, unsigned char *buf, int buflen)
{
    if (msg->payloadlen + 1 > buflen) {
        return 0;
    }
    if (msg->payloadlen > 0 && NULL != msg->payload) {
        *buf = 0xFF;
        buf++;
        memcpy(buf, msg->payload, msg->payloadlen);
        return msg->payloadlen + 1;
    } else {
        return 0;
    }
}

unsigned short CoAPSerialize_MessageLength(CoAPMessage *msg)
{
    unsigned short msglen = 4;

    msglen += msg->header.tokenlen;
    msglen += CoAPSerialize_OptionsLen(msg);

    if (0 < msg->payloadlen) {
        msglen += msg->payloadlen;
        msglen += 1; /*CoAP payload marker*/
    }

    return msglen;
}

int CoAPSerialize_Message(CoAPMessage *msg, unsigned char *buf,
                          unsigned short buflen)
{
    unsigned char *ptr = buf;
    unsigned short count = 0;
    unsigned short remlen = buflen;

    if (NULL == buf || NULL == msg) {
        return COAP_ERROR_INVALID_PARAM;
    }

    count = CoAPSerialize_Header(msg, ptr, remlen);
    ptr += count;
    remlen -= count;

    count = CoAPSerialize_Token(msg, ptr, remlen);
    ptr += count;
    remlen -= count;

    count = CoAPSerialize_Options(msg, ptr, remlen);
    ptr += count;
    remlen -= count;

    count = CoAPSerialize_Payload(msg, ptr, remlen);
    ptr += count;
    remlen -= count;

    return buflen - remlen;
}