package godns_test

import (
	"context"
	"net"
	"strings"
	"sync/atomic"
	"testing"
	"time"

	godns "gitea.neitzel.de/konrad/go-dns"
	"github.com/miekg/dns"
)

func TestUpdateFallsBackToTCPWhenUDPTruncated(t *testing.T) {
	t.Parallel()

	var udpHits, tcpHits atomic.Int32
	mux := dns.NewServeMux()
	mux.HandleFunc("example.test.", func(w dns.ResponseWriter, r *dns.Msg) {
		if r.IsTsig() == nil {
			t.Error("UPDATE request missing TSIG")
		}
		msg := new(dns.Msg)
		msg.SetReply(r)
		if _, ok := w.RemoteAddr().(*net.UDPAddr); ok {
			udpHits.Add(1)
			msg.Truncated = true
			_ = w.WriteMsg(msg)
			return
		}
		tcpHits.Add(1)
		_ = w.WriteMsg(msg)
	})

	udp, tcp := startDNSServers(t, mux)
	client, err := godns.NewClient(udp, "example.test", fixtureTSIG())
	if err != nil {
		t.Fatal(err)
	}
	_ = tcp

	rec, err := godns.A("new.example.test", 300, net.ParseIP("192.0.2.99"))
	if err != nil {
		t.Fatal(err)
	}
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	result, err := client.Update(ctx, godns.Add(rec))
	if err != nil {
		t.Fatal(err)
	}
	if result.Rcode != "NOERROR" {
		t.Fatalf("rcode: %s", result.Rcode)
	}
	if udpHits.Load() < 1 {
		t.Fatal("expected a UDP attempt")
	}
	if tcpHits.Load() < 1 {
		t.Fatal("expected TCP fallback")
	}
}

func startDNSServers(t *testing.T, handler dns.Handler) (udpAddr, tcpAddr string) {
	t.Helper()

	secrets := map[string]string{"go-dns-test.": fixtureSecret}

	acceptUpdate := func(dh dns.Header) dns.MsgAcceptAction {
		return dns.MsgAccept
	}
	udpSrv := &dns.Server{Addr: "127.0.0.1:0", Net: "udp", Handler: handler, TsigSecret: secrets, MsgAcceptFunc: acceptUpdate}
	udpReady := make(chan struct{})
	udpSrv.NotifyStartedFunc = func() { close(udpReady) }
	go func() { _ = udpSrv.ListenAndServe() }()
	<-udpReady
	t.Cleanup(func() { _ = udpSrv.Shutdown() })

	udpAddr = udpSrv.PacketConn.LocalAddr().String()
	_, port, err := net.SplitHostPort(udpAddr)
	if err != nil {
		t.Fatal(err)
	}

	tcpSrv := &dns.Server{Addr: "127.0.0.1:" + port, Net: "tcp", Handler: handler, TsigSecret: secrets, MsgAcceptFunc: acceptUpdate}
	tcpReady := make(chan struct{})
	tcpSrv.NotifyStartedFunc = func() { close(tcpReady) }
	go func() { _ = tcpSrv.ListenAndServe() }()
	<-tcpReady
	t.Cleanup(func() { _ = tcpSrv.Shutdown() })

	return udpAddr, tcpSrv.Listener.Addr().String()
}

func TestAddChangeDescribesInsert(t *testing.T) {
	t.Parallel()

	rec, err := godns.A("www.example.test", 300, net.ParseIP("192.0.2.10"))
	if err != nil {
		t.Fatal(err)
	}
	change := godns.Add(rec)
	if change.Action != godns.ActionAdd {
		t.Fatalf("action: %v", change.Action)
	}
	if change.Record.Type != "A" {
		t.Fatalf("record: %+v", change.Record)
	}
}

func TestDeleteChangeDescribesRemove(t *testing.T) {
	t.Parallel()

	rec, err := godns.TXT("bad.example.test", 300, "stale")
	if err != nil {
		t.Fatal(err)
	}
	change := godns.Delete(rec)
	if change.Action != godns.ActionDelete {
		t.Fatalf("action: %v", change.Action)
	}
	if !strings.Contains(change.Record.RData, "stale") {
		t.Fatalf("rdata: %q", change.Record.RData)
	}
}