// This is lease support for nclient4

package nclient4

import (
	"fmt"
	"net"
	"time"

	"github.com/insomniacslk/dhcp/dhcpv4"
)

// Lease contains a DHCPv4 lease after DORA.
// note: Lease doesn't include binding interface name
type Lease struct {
	Offer        *dhcpv4.DHCPv4
	ACK          *dhcpv4.DHCPv4
	CreationTime time.Time
}

// Release send DHCPv4 release messsage to server, based on specified lease.
// release is sent as unicast per RFC2131, section 4.4.4.
// Note: some DHCP server requries of using assigned IP address as source IP,
// use nclient4.WithUnicast to create client for such case.
func (c *Client) Release(lease *Lease, modifiers ...dhcpv4.Modifier) error {
	if lease == nil {
		return fmt.Errorf("lease is nil")
	}
	req, err := dhcpv4.NewReleaseFromACK(lease.ACK, modifiers...)
	if err != nil {
		return fmt.Errorf("fail to create release request,%w", err)
	}
	_, err = c.conn.WriteTo(req.ToBytes(), &net.UDPAddr{IP: lease.ACK.Options.Get(dhcpv4.OptionServerIdentifier), Port: ServerPort})
	if err == nil {
		c.logger.PrintMessage("sent message:", req)
	}
	return err
}