package server

import (
	"github.com/miekg/dns"
	"log/slog"
)

func handleQuery(w dns.ResponseWriter, req *dns.Msg) {
	if len(req.Question) == 0 {
		m := new(dns.Msg)
		m.SetRcode(req, dns.RcodeFormatError)
		_ = w.WriteMsg(m)
		return
	}

	resp := buildResponse(req)

	if err := w.WriteMsg(resp); err != nil {
		slog.Error("write response failed",
			"err", err,
			"qname", req.Question[0].Name,
			"qtype", dns.TypeToString[req.Question[0].Qtype],
		)
		return
	}
	slog.Info("query served",
		"qname", req.Question[0].Name,
		"qtype", dns.TypeToString[req.Question[0].Qtype],
		"rcode", dns.RcodeToString[resp.Rcode],
		"client", w.RemoteAddr().String(),
	)
}

func buildResponse(req *dns.Msg) *dns.Msg {
	if len(req.Question) == 0 {
		m := new(dns.Msg)
		m.SetRcode(req, dns.RcodeFormatError)
		return m
	}
	q := req.Question[0]
	resp := new(dns.Msg)
	resp.SetReply(req)
	resp.Authoritative = false

	if opt := req.IsEdns0(); opt != nil {
		resp.SetEdns0(4096, false)
	}

	if q.Name == "example.com." && q.Qtype == dns.TypeA {
		resp.Answer = []dns.RR{
			&dns.A{
				Hdr: dns.RR_Header{
					Name:   q.Name,
					Rrtype: dns.TypeA,
					Class:  dns.ClassINET,
					Ttl:    60,
				},
				A: []byte{127, 0, 0, 1},
			},
		}
	} else {
		resp.Rcode = dns.RcodeNameError
	}
	return resp
}