package dhcp

import (
	"fmt"
	"io"
)

type OptionTag uint8

func (opt OptionTag) String() string {
	s, ok := optionStrings[opt]
	if !ok {
		return fmt.Sprintf("<unknown DHCP option [%d]>", opt)
	}

	return s
}

type Option func(req *Packet, r io.Reader) error

const (
	OptionTagPadding              OptionTag = 0
	OptionTagSubnetMask           OptionTag = 1
	OptionTagTimeOffset           OptionTag = 2
	OptionTagRouter               OptionTag = 3
	OptionTagDomainNameServer     OptionTag = 6
	OptionTagHostName             OptionTag = 12
	OptionTagDomainName           OptionTag = 15
	OptionTagInterfaceMTU         OptionTag = 26
	OptionTagBroadcastAddress     OptionTag = 28
	OptionTagNTPServers           OptionTag = 42
	OptionTagNBNS                 OptionTag = 44
	OptionTagNBScope              OptionTag = 47
	OptionTagMessageType          OptionTag = 53
	OptionTagParameterRequestList OptionTag = 55
	OptionTagDHCPMaxMessageSize   OptionTag = 57
	OptionTagClientID             OptionTag = 61
	OptionTagDomainSearch         OptionTag = 119
	OptionTagClasslessStaticRoute OptionTag = 121
	OptionTagEnd                  OptionTag = 255
)

var optionStrings = map[OptionTag]string{
	OptionTagPadding:              "pad",
	OptionTagSubnetMask:           "subnet mask",
	OptionTagTimeOffset:           "time offset from UTC",
	OptionTagRouter:               "routers",
	OptionTagDomainNameServer:     "domain name servers",
	OptionTagHostName:             "host name",
	OptionTagDomainName:           "domain name",
	OptionTagInterfaceMTU:         "interface MTU",
	OptionTagBroadcastAddress:     "broadcast address",
	OptionTagNTPServers:           "NTP servers",
	OptionTagNBNS:                 "NetBIOS name servers",
	OptionTagNBScope:              "NetBIOS scope",
	OptionTagMessageType:          "message type",
	OptionTagParameterRequestList: "parameter request list",
	OptionTagDHCPMaxMessageSize:   "DHCP max message size",
	OptionTagClientID:             "client ID",
	OptionTagDomainSearch:         "search domain",
	OptionTagClasslessStaticRoute: "classless static route",
	OptionTagEnd:                  "end",
}

type DHCPMessageType uint8

const (
	DHCPMessageTypeDiscover DHCPMessageType = 1
	DHCPMessageTypeOffer    DHCPMessageType = 2
	DHCPMessageTypeRequest  DHCPMessageType = 3
	DHCPMessageTypeDecline  DHCPMessageType = 4
	DHCPMessageTypeAck      DHCPMessageType = 5
	DHCPMessageTypeNAK      DHCPMessageType = 6
	DHCPMessageTypeRelease  DHCPMessageType = 7
	DHCPMessageTypeInform   DHCPMessageType = 8
)