#include <string.h>

#include <arpa/inet.h>

#include "dhcp4.h"

namespace dhcp4 {

  int make_message(void * buf,
                   uint32_t bootp_message_type,
                   uint32_t transaction_id,
                   uint8_t const * chaddr,
                   uint32_t dhcp_message_type)
  {
    memset(buf, 0, (sizeof (message)));
    message * msg = reinterpret_cast<message *>(buf);

    msg->op = bootp_message_type;
    msg->htype = htype::ethernet;
    msg->hlen = 6;
    msg->xid = htonl(transaction_id);
    memcpy(msg->chaddr, chaddr, 6);

    int index = 0;

    uint8_t * cookie = &msg->options[index];
    index += 4;
    cookie[0] = 0x63;
    cookie[1] = 0x82;
    cookie[2] = 0x53;
    cookie[3] = 0x63;

    uint8_t * message_type = &msg->options[index];
    index += 2 + 1;
    message_type[0] = option::message_type;
    message_type[1] = 1; // length
    message_type[2] = dhcp_message_type;

    {
      uint8_t * prl = &msg->options[index];
      int length = 4;
      index += 2 + length;
      prl[0] = option::parameter_request_list;
      prl[1] = length;
      prl[2] = 1; // subnet mask
      prl[3] = 3; // router
      prl[4] = 6; // domain name server
      prl[5] = 28; // broadcast address
    }

    if (0) {
      uint8_t * message_size = &msg->options[index];
      int length = 2;
      index += 2 + length;
      message_size[0] = option::maximum_message_size;
      message_size[1] = length;
      message_size[2] = 0x05;
      message_size[3] = 0xc0;
    }

    uint8_t * end = &msg->options[index];
    index += 1;
    end[0] = 255;

    return (sizeof (message)) + index;
  }
}