package rfc2136

import (
	"testing"

	"github.com/miekg/dns"
)

func mustRR(t *testing.T, s string) dns.RR {
	t.Helper()
	rr, err := dns.NewRR(s)
	if err != nil {
		t.Fatalf("failed to parse RR %q: %v", s, err)
	}
	return rr
}

func TestStore_AddLookup(t *testing.T) {
	s := newStore()

	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "token-1"`))

	got := s.Lookup("foo.example.com.", dns.TypeTXT)
	if len(got) != 1 {
		t.Fatalf("Lookup TXT: got %d records, want 1", len(got))
	}
	if got[0].String() != `foo.example.com.	60	IN	TXT	"token-1"` {
		t.Errorf("unexpected RR: %s", got[0].String())
	}
}

func TestStore_AddMultipleRRsetEntries(t *testing.T) {
	s := newStore()
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "token-1"`))
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "token-2"`))

	got := s.Lookup("foo.example.com.", dns.TypeTXT)
	if len(got) != 2 {
		t.Errorf("RRset size = %d, want 2 (both TXT values)", len(got))
	}
}

func TestStore_AddDedupes(t *testing.T) {
	s := newStore()
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "same"`))
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "same"`))

	got := s.Lookup("foo.example.com.", dns.TypeTXT)
	if len(got) != 1 {
		t.Errorf("RRset size = %d, want 1 (duplicate ignored)", len(got))
	}
}

func TestStore_LookupCaseInsensitive(t *testing.T) {
	s := newStore()
	s.Add(mustRR(t, `FOO.example.com. 60 IN TXT "token"`))

	if got := s.Lookup("foo.EXAMPLE.com.", dns.TypeTXT); len(got) != 1 {
		t.Errorf("case-insensitive lookup failed: got %d", len(got))
	}
}

func TestStore_LookupMissingNameReturnsNil(t *testing.T) {
	s := newStore()
	if got := s.Lookup("nope.example.com.", dns.TypeTXT); got != nil {
		t.Errorf("expected nil for missing name, got %v", got)
	}
}

func TestStore_LookupNameExistsWrongTypeReturnsNil(t *testing.T) {
	s := newStore()
	s.Add(mustRR(t, `foo.example.com. 60 IN A 192.0.2.1`))

	if got := s.Lookup("foo.example.com.", dns.TypeTXT); got != nil {
		t.Errorf("expected nil for wrong type (A exists but not TXT), got %v", got)
	}
	if !s.NameExists("foo.example.com.") {
		t.Errorf("NameExists should return true (A record exists)")
	}
}

func TestStore_RemoveRRset(t *testing.T) {
	s := newStore()
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "a"`))
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "b"`))
	s.Add(mustRR(t, `foo.example.com. 60 IN A 192.0.2.1`))

	s.RemoveRRset("foo.example.com.", dns.TypeTXT)

	if got := s.Lookup("foo.example.com.", dns.TypeTXT); got != nil {
		t.Errorf("TXT RRset should be gone, got %v", got)
	}
	if got := s.Lookup("foo.example.com.", dns.TypeA); len(got) != 1 {
		t.Errorf("A record should survive RRset deletion, got %v", got)
	}
	if !s.NameExists("foo.example.com.") {
		t.Errorf("name should still exist (A remains)")
	}
}

func TestStore_RemoveRRsetReapsEmptyName(t *testing.T) {
	s := newStore()
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "a"`))
	s.RemoveRRset("foo.example.com.", dns.TypeTXT)

	if s.NameExists("foo.example.com.") {
		t.Errorf("name should have been reaped after last RRset removed")
	}
}

func TestStore_RemoveRR(t *testing.T) {
	s := newStore()
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "keep"`))
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "drop"`))

	s.RemoveRR(mustRR(t, `foo.example.com. 60 IN TXT "drop"`))

	got := s.Lookup("foo.example.com.", dns.TypeTXT)
	if len(got) != 1 {
		t.Fatalf("RRset size after RemoveRR = %d, want 1", len(got))
	}
	if got[0].(*dns.TXT).Txt[0] != "keep" {
		t.Errorf("wrong RR remained: %v", got[0])
	}
}

func TestStore_RemoveName(t *testing.T) {
	s := newStore()
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "a"`))
	s.Add(mustRR(t, `foo.example.com. 60 IN A 192.0.2.1`))

	s.RemoveName("foo.example.com.")

	if s.NameExists("foo.example.com.") {
		t.Errorf("name should be gone after RemoveName")
	}
}

func TestStore_GenerationBumpsOnMutation(t *testing.T) {
	s := newStore()
	start := s.generation()

	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "a"`))
	if s.generation() != start+1 {
		t.Errorf("generation after Add: %d, want %d", s.generation(), start+1)
	}

	// Re-adding the same RR is a no-op → generation must NOT bump.
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "a"`))
	if s.generation() != start+1 {
		t.Errorf("generation after duplicate Add: %d, want %d (no bump)", s.generation(), start+1)
	}

	s.RemoveRRset("foo.example.com.", dns.TypeTXT)
	if s.generation() != start+2 {
		t.Errorf("generation after RemoveRRset: %d, want %d", s.generation(), start+2)
	}

	// Removing again is a no-op → no bump.
	s.RemoveRRset("foo.example.com.", dns.TypeTXT)
	if s.generation() != start+2 {
		t.Errorf("generation after no-op RemoveRRset: %d, want %d", s.generation(), start+2)
	}
}

func TestStore_LookupReturnsCopy(t *testing.T) {
	// The returned slice must be a copy so external mutations don't
	// affect store state.
	s := newStore()
	s.Add(mustRR(t, `foo.example.com. 60 IN TXT "original"`))

	got := s.Lookup("foo.example.com.", dns.TypeTXT)
	got[0] = mustRR(t, `foo.example.com. 60 IN TXT "tampered"`)

	// Re-lookup should still see the original.
	again := s.Lookup("foo.example.com.", dns.TypeTXT)
	if again[0].(*dns.TXT).Txt[0] != "original" {
		t.Errorf("Lookup returned shared slice — store corrupted by external mutation: %v", again[0])
	}
}