package dhcpd

import (
	"net"
	"time"
)

// DHCPServer - DHCP server interface
type DHCPServer interface {
	// ResetLeases - reset leases
	ResetLeases(leases []*Lease)
	// GetLeases - get leases
	GetLeases(flags int) []Lease
	// AddStaticLease - add a static lease
	AddStaticLease(lease Lease) error
	// RemoveStaticLease - remove a static lease
	RemoveStaticLease(l Lease) error
	// FindMACbyIP - find a MAC address by IP address in the currently active DHCP leases
	FindMACbyIP(ip net.IP) net.HardwareAddr

	// WriteDiskConfig4 - copy disk configuration
	WriteDiskConfig4(c *V4ServerConf)
	// WriteDiskConfig6 - copy disk configuration
	WriteDiskConfig6(c *V6ServerConf)

	// Start - start server
	Start() error
	// Stop - stop server
	Stop()

	getLeasesRef() []*Lease
}

// V4ServerConf - server configuration
type V4ServerConf struct {
	Enabled       bool   `yaml:"-" json:"-"`
	InterfaceName string `yaml:"-" json:"-"`

	GatewayIP  net.IP `yaml:"gateway_ip" json:"gateway_ip"`
	SubnetMask net.IP `yaml:"subnet_mask" json:"subnet_mask"`

	// The first & the last IP address for dynamic leases
	// Bytes [0..2] of the last allowed IP address must match the first IP
	RangeStart net.IP `yaml:"range_start" json:"range_start"`
	RangeEnd   net.IP `yaml:"range_end" json:"range_end"`

	LeaseDuration uint32 `yaml:"lease_duration" json:"lease_duration"` // in seconds

	// IP conflict detector: time (ms) to wait for ICMP reply
	// 0: disable
	ICMPTimeout uint32 `yaml:"icmp_timeout_msec" json:"-"`

	// Custom Options.
	//
	// Option with arbitrary hexadecimal data:
	//     DEC_CODE hex HEX_DATA
	// where DEC_CODE is a decimal DHCPv4 option code in range [1..255]
	//
	// Option with IP data (only 1 IP is supported):
	//     DEC_CODE ip IP_ADDR
	Options []string `yaml:"options" json:"-"`

	ipRange *ipRange

	leaseTime  time.Duration // the time during which a dynamic lease is considered valid
	dnsIPAddrs []net.IP      // IPv4 addresses to return to DHCP clients as DNS server addresses

	// subnet contains the DHCP server's subnet.  The IP is the IP of the
	// gateway.
	subnet *net.IPNet

	options []dhcpOption

	// notify is a way to signal to other components that leases have
	// change.  notify must be called outside of locked sections, since the
	// clients might want to get the new data.
	//
	// TODO(a.garipov): This is utter madness and must be refactored.  It
	// just begs for deadlock bugs and other nastiness.
	notify func(uint32)
}

// V6ServerConf - server configuration
type V6ServerConf struct {
	Enabled       bool   `yaml:"-" json:"-"`
	InterfaceName string `yaml:"-" json:"-"`

	// The first IP address for dynamic leases
	// The last allowed IP address ends with 0xff byte
	RangeStart net.IP `yaml:"range_start" json:"range_start"`

	LeaseDuration uint32 `yaml:"lease_duration" json:"lease_duration"` // in seconds

	RASLAACOnly  bool `yaml:"ra_slaac_only" json:"-"`  // send ICMPv6.RA packets without MO flags
	RAAllowSLAAC bool `yaml:"ra_allow_slaac" json:"-"` // send ICMPv6.RA packets with MO flags

	ipStart    net.IP        // starting IP address for dynamic leases
	leaseTime  time.Duration // the time during which a dynamic lease is considered valid
	dnsIPAddrs []net.IP      // IPv6 addresses to return to DHCP clients as DNS server addresses

	// Server calls this function when leases data changes
	notify func(uint32)
}

type dhcpOption struct {
	code uint8
	data []byte
}