package server

import (
	"fmt"
	"net"

	"git.wntrmute.dev/kyle/kdhcp/log"
	"github.com/insomniacslk/dhcp/dhcpv4"
)

type Server struct {
	cfg  *Config
	conn net.PacketConn
}

func (srv *Server) Listen() (err error) {
	if srv.conn != nil {
		srv.conn.Close()
	}

	log.Debugf("attempting to set up packet listener on %s 0.0.0.0:%d", DefaultNetwork, srv.cfg.Port)
	srv.conn, err = net.ListenPacket(DefaultNetwork, fmt.Sprintf(":%d", srv.cfg.Port))
	if err != nil {
		return err
	}

	return nil
}

func (srv *Server) Close() error {
	if srv.conn != nil {
		return srv.conn.Close()
	}
	return nil
}

func (srv *Server) ReadFrom() (*Packet, error) {
	b := make([]byte, srv.cfg.MaxPacketSize)
	n, addr, err := srv.conn.ReadFrom(b)
	if err != nil {
		return nil, err
	}

	packet := &Packet{
		Data: b[:n],
		Addr: addr,
	}
	packet.Raw, err = dhcpv4.FromBytes(b[:n])
	if err != nil {
		return packet, err
	}

	return packet, nil
}

func NewServer(cfg *Config) (*Server, error) {
	srv := &Server{
		cfg: cfg,
	}

	err := srv.Listen()
	if err != nil {
		return nil, err
	}

	return srv, nil
}