#pragma once

#include <stdint.h>
#include <assert.h>

namespace dhcp4 {

  struct __attribute__((packed)) message {
    uint8_t op; // message type
    uint8_t htype; // hardware type
    uint8_t hlen; // hardware address length
    uint8_t hops;
    uint32_t xid; // transaction id
    uint16_t secs; // seconds elapsed
    uint16_t flags;
    uint32_t ciaddr; // client IP address
    uint32_t yiaddr; // your (client) IP address
    uint32_t siaddr; // next server IP address
    uint32_t giaddr; // relay agent IP address
    uint8_t chaddr[16]; // client hardware address
    uint8_t sname[64];
    uint8_t file[128];
    uint8_t options[];
  };

  struct options {
    int message_type; // 53
    uint32_t subnet_mask; // 1
    uint32_t router; // 3
    uint32_t domain_name_server; // 6
  };

  struct op {
    enum {
      bootrequest = 1,
      bootreply = 2,
    };
  };

  struct htype {
    enum {
      ethernet = 1,
    };
  };

  static_assert((sizeof (message)) == 236);

  struct option {
    enum {
      subnet_mask = 1,
      router = 3,
      domain_name_server = 6,
      broadcast_address = 28,
      ip_address_lease_time = 51,
      option_overload = 52,
      message_type = 53,
      server_identifier = 54,
      parameter_request_list = 55,
      maximum_message_size = 57,
      client_identifier = 61,
    };
  };

  struct message_type {
    enum {
      dhcpdiscover = 1,
      dhcpoffer = 2,
      dhcprequest = 3,
      dhcpdecline = 4,
      dhcpack = 5,
      dhcpnak = 6,
      dhcprelease = 7,
      dhcpinform = 8,
    };
  };

  int make_message(void * buf,
                   uint32_t bootp_message_type,
                   uint32_t transaction_id,
                   uint8_t const * chaddr,
                   uint32_t dhcp_message_type);

  void parse_options(message const * m, int options_length, options * o);
}