package bind

import (
	"encoding/hex"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
)

// probeOut frames body the way zoneStateProbe does, so the parser is exercised
// on realistic input.
func probeOut(body ...string) string {
	body = append(body, probeOrphanOpen, probeOrphanShut)
	return strings.Join(append(append([]string{probeBegin}, body...), probeEnd, ""), "\n")
}

func journalHeader(magic string, begin, end uint32) []byte {
	b := make([]byte, 32)
	copy(b, magic)
	put := func(off int, v uint32) {
		b[off] = byte(v >> 24)
		b[off+1] = byte(v >> 16)
		b[off+2] = byte(v >> 8)
		b[off+3] = byte(v)
	}
	put(16, begin)
	put(24, end)
	return b
}

func TestParseZoneSerial(t *testing.T) {
	bindDump := `$ORIGIN .
$TTL 3600	; 1 hour
k8s.syd1.au.unkin.net	IN SOA	ns1.k8s.syd1.au.unkin.net. hostmaster.k8s.syd1.au.unkin.net. (
				16         ; serial
				300        ; refresh (5 minutes)
				60         ; retry (1 minute)
				1209600    ; expire (2 weeks)
				60         ; minimum (1 minute)
				)
`
	cases := []struct {
		name    string
		content string
		want    int64
		ok      bool
	}{
		{"bind dump", bindDump, 16, true},
		{"seed", renderSeedZone("example.com", "10.0.0.1", nil, 42), 42, true},
		{"single line", "@ IN SOA ns1.example.com. hostmaster.example.com. 7 300 60 1209600 60\n", 7, true},
		{"glued paren", "@ IN SOA ns. host. (9 300 60 1209600 60)\n", 9, true},
		{"no soa", "$TTL 3600\nwww IN A 192.0.2.1\n", 0, false},
		{"truncated", "@ IN SOA ns.\n", 0, false},
		{"non numeric serial", "@ IN SOA ns. host. ( abc 300 )\n", 0, false},
	}
	for _, c := range cases {
		got, ok := ParseZoneSerial(c.content)
		if got != c.want || ok != c.ok {
			t.Errorf("%s: ParseZoneSerial = (%d,%v) want (%d,%v)", c.name, got, ok, c.want, c.ok)
		}
	}
}

func TestParseJournalHeader(t *testing.T) {
	begin, end, ok := parseJournalHeader(journalHeader(";BIND LOG V9.2\n", 10, 16))
	if !ok || begin != 10 || end != 16 {
		t.Errorf("V9.2 header = (%d,%d,%v) want (10,16,true)", begin, end, ok)
	}
	if _, _, ok := parseJournalHeader(journalHeader("not a journal\n", 10, 16)); ok {
		t.Error("bad magic should not parse")
	}
	if _, _, ok := parseJournalHeader([]byte(";BIND LOG V9.2\n")); ok {
		t.Error("truncated header should not parse")
	}
}

func TestParseZoneDiskState(t *testing.T) {
	out := probeOut(
		"zonefile=1",
		probeHeadOpen,
		"@ IN SOA ns. host. ( 5 300 60 1209600 60 )",
		probeHeadShut,
		"journal=1",
		"jnl="+hex.EncodeToString(journalHeader(";BIND LOG V9.2\n", 3, 8)),
	)
	st, ok := parseZoneDiskState(out)
	if !ok {
		t.Fatalf("well-formed probe rejected: %q", out)
	}
	if !st.ZoneFile || !st.ZoneSerialOK || st.ZoneSerial != 5 {
		t.Errorf("zone file state wrong: %+v", st)
	}
	if !st.Journal || !st.JournalOK || st.JournalBegin != 3 || st.JournalEnd != 8 {
		t.Errorf("journal state wrong: %+v", st)
	}

	empty, ok := parseZoneDiskState(probeOut("zonefile=0", "journal=0"))
	if !ok || empty.ZoneFile || empty.Journal {
		t.Errorf("empty state wrong: %+v (ok=%v)", empty, ok)
	}
}

// A probe that returns nothing useful must not be read as "fresh install": the
// shell exits 0 after its last printf and stderr is dropped on success, so a
// missing tool or a truncated stream is otherwise invisible.
func TestParseZoneDiskStateRejectsDegradedProbe(t *testing.T) {
	live := probeHeadOpen + "\n@ IN SOA ns. host. ( 5 300 60 1209600 60 )\n" + probeHeadShut
	cases := map[string]string{
		"empty output":         "",
		"whitespace only":      "\n\n",
		"no framing":           "zonefile=0\njournal=0\n",
		"no terminator":        probeBegin + "\nzonefile=0\njournal=0\n",
		"cut before zone file": probeBegin + "\n",
		"cut mid head":         probeBegin + "\nzonefile=1\n" + probeHeadOpen + "\n@ IN SOA ns. host. ( 5",
		"cut after head":       probeBegin + "\nzonefile=1\n" + live + "\n",
		"no zone declaration":  probeOut("journal=0"),
		"no journal branch":    probeOut("zonefile=1", live),
		"journal without hex":  probeOut("zonefile=0", "journal=1"),
		"duplicate zone decl":  probeOut("zonefile=0", "zonefile=1", "journal=0"),
		"header without file":  probeOut("zonefile=0", "journal=0", "jnl=00"),
		"no orphan block": strings.Join(
			[]string{probeBegin, "zonefile=0", "journal=0", probeEnd, ""}, "\n"),
		"orphan block unterminated": strings.Join(
			[]string{probeBegin, "zonefile=0", "journal=0", probeOrphanOpen, probeEnd, ""}, "\n"),
		"duplicate orphan block": strings.Join(
			[]string{probeBegin, "zonefile=0", "journal=0", probeOrphanOpen, probeOrphanShut,
				probeOrphanOpen, probeOrphanShut, probeEnd, ""}, "\n"),
	}
	for name, out := range cases {
		// The zero state is a legitimate fresh install, so rejection has to
		// happen here: ZoneDiskState turns it into an error and nothing plans.
		if st, ok := parseZoneDiskState(out); ok {
			t.Errorf("%s: degraded probe accepted as %+v", name, st)
		}
	}
}

// applyPlan models what the pod filesystem looks like after the plan runs, so
// a second PlanSeed can be checked for idempotence.
func applyPlan(st ZoneDiskState, p SeedPlan) ZoneDiskState {
	if p.QuarantineJournal {
		st.Journal, st.JournalBegin, st.JournalEnd, st.JournalOK = false, 0, 0, false
	}
	if p.QuarantineZoneFile {
		st.ZoneFile, st.ZoneSerial, st.ZoneSerialOK = false, 0, false
	}
	if p.WriteSeed {
		st.ZoneFile, st.ZoneSerial, st.ZoneSerialOK = true, p.Serial, true
	}
	return st
}

func TestPlanSeedFreshInstall(t *testing.T) {
	p := PlanSeed(ZoneDiskState{})
	if !p.WriteSeed || p.Serial != 1 {
		t.Fatalf("fresh install should seed at serial 1, got %+v", p)
	}
	if p.QuarantineZoneFile || p.QuarantineJournal {
		t.Errorf("fresh install should quarantine nothing, got %+v", p)
	}
}

func TestPlanSeedOrphanJournal(t *testing.T) {
	st := ZoneDiskState{Journal: true, JournalBegin: 10, JournalEnd: 16, JournalOK: true}
	p := PlanSeed(st)
	if !p.WriteSeed {
		t.Fatalf("orphan journal should still seed, got %+v", p)
	}
	if !p.QuarantineJournal || p.QuarantineZoneFile {
		t.Errorf("only the journal should be quarantined, got %+v", p)
	}
	if p.Serial <= 16 {
		t.Errorf("seed serial %d must exceed the journal end serial 16", p.Serial)
	}
	if p.QuarantineSuffix != ".orphaned-16" {
		t.Errorf("quarantine suffix should be deterministic, got %q", p.QuarantineSuffix)
	}
}

func TestPlanSeedFileRegressedBehindJournal(t *testing.T) {
	// The production failure: a skeleton at serial 1 left next to a journal at
	// serial 16, which BIND refuses to replay ("out of range").
	st := ZoneDiskState{
		ZoneFile: true, ZoneSerial: 1, ZoneSerialOK: true,
		Journal: true, JournalBegin: 10, JournalEnd: 16, JournalOK: true,
	}
	p := PlanSeed(st)
	if !p.WriteSeed || p.Serial <= 16 {
		t.Fatalf("reseed must land above the journal end serial, got %+v", p)
	}
	if !p.QuarantineJournal || !p.QuarantineZoneFile {
		t.Errorf("the unloadable pair should both be moved aside, got %+v", p)
	}

	after := applyPlan(st, p)
	if after.Journal {
		t.Error("journal should be gone after quarantine")
	}
	if next := PlanSeed(after); next != (SeedPlan{}) {
		t.Errorf("second reconcile should be a no-op, got %+v", next)
	}
	if after.ZoneSerial != p.Serial {
		t.Errorf("second reconcile changed the serial: %d want %d", after.ZoneSerial, p.Serial)
	}
}

func TestPlanSeedLeavesHealthyZoneAlone(t *testing.T) {
	cases := []struct {
		name string
		st   ZoneDiskState
	}{
		{"file and covering journal", ZoneDiskState{
			ZoneFile: true, ZoneSerial: 16, ZoneSerialOK: true,
			Journal: true, JournalBegin: 10, JournalEnd: 20, JournalOK: true,
		}},
		{"file at journal end", ZoneDiskState{
			ZoneFile: true, ZoneSerial: 20, ZoneSerialOK: true,
			Journal: true, JournalBegin: 10, JournalEnd: 20, JournalOK: true,
		}},
		{"file without journal", ZoneDiskState{ZoneFile: true, ZoneSerial: 16, ZoneSerialOK: true}},
		{"unreadable journal header", ZoneDiskState{
			ZoneFile: true, ZoneSerial: 16, ZoneSerialOK: true, Journal: true,
		}},
		{"unparsable zone file", ZoneDiskState{ZoneFile: true}},
	}
	for _, c := range cases {
		if p := PlanSeed(c.st); p != (SeedPlan{}) {
			t.Errorf("%s: live data must not be touched, got %+v", c.name, p)
		}
	}
}

func TestPlanSeedStaleJournalBehindFile(t *testing.T) {
	st := ZoneDiskState{
		ZoneFile: true, ZoneSerial: 30, ZoneSerialOK: true,
		Journal: true, JournalBegin: 10, JournalEnd: 16, JournalOK: true,
	}
	p := PlanSeed(st)
	if p.WriteSeed || p.QuarantineZoneFile {
		t.Fatalf("a file ahead of its journal is live data, got %+v", p)
	}
	if !p.QuarantineJournal {
		t.Errorf("the unreplayable journal should be moved aside, got %+v", p)
	}
	if next := PlanSeed(applyPlan(st, p)); next != (SeedPlan{}) {
		t.Errorf("second reconcile should be a no-op, got %+v", next)
	}
}

func TestPlanSeedFreshInstallIdempotent(t *testing.T) {
	st := ZoneDiskState{}
	p := PlanSeed(st)
	after := applyPlan(st, p)
	if next := PlanSeed(after); next != (SeedPlan{}) {
		t.Fatalf("second reconcile of a fresh zone should be a no-op, got %+v", next)
	}
	if after.ZoneSerial != 1 {
		t.Errorf("serial reset on second reconcile: %d", after.ZoneSerial)
	}
}

func TestPlanSeedSerialWrap(t *testing.T) {
	st := ZoneDiskState{Journal: true, JournalBegin: 1 << 31, JournalEnd: 1<<32 - 1, JournalOK: true}
	if h, known := highestSerial(st); !known || h != 1<<32-1 {
		t.Fatalf("highestSerial = (%d,%v) want (%d,true): the wrap branch is not being reached", h, known, int64(1)<<32-1)
	}
	p := PlanSeed(st)
	if p.Serial != 1 {
		t.Fatalf("serial after wrap = %d want 1", p.Serial)
	}
	if !serialLT(st.JournalEnd, p.Serial) {
		t.Errorf("wrapped serial %d must still sort after journal end %d", p.Serial, st.JournalEnd)
	}
}

// Serials above 2^31 must not be flattened to 1: RFC 1982 comparison against a
// zero placeholder reads them as older, and secondaries reject the regression.
func TestPlanSeedHighSerialJournal(t *testing.T) {
	st := ZoneDiskState{Journal: true, JournalBegin: 1<<31 - 10, JournalEnd: 1 << 31, JournalOK: true}
	p := PlanSeed(st)
	if !p.WriteSeed {
		t.Fatalf("orphan journal should still seed, got %+v", p)
	}
	if p.Serial != 1<<31+1 {
		t.Errorf("seed serial = %d want %d", p.Serial, int64(1)<<31+1)
	}
	if !serialLT(st.JournalEnd, p.Serial) {
		t.Errorf("seed serial %d must sort after journal end %d", p.Serial, st.JournalEnd)
	}
	if p.QuarantineSuffix != ".orphaned-2147483648" {
		t.Errorf("quarantine suffix = %q", p.QuarantineSuffix)
	}
}

// An orphan journal whose header will not parse (no od, EACCES, short read)
// hides how far the zone had advanced, so quarantining it and reseeding at 1
// would regress live data.
func TestPlanSeedBlocksOnUnreadableOrphanJournal(t *testing.T) {
	p := PlanSeed(ZoneDiskState{Journal: true})
	if p.Blocked == "" {
		t.Fatalf("an unreadable orphan journal must block, got %+v", p)
	}
	if p.WriteSeed || p.QuarantineJournal || p.QuarantineZoneFile {
		t.Errorf("a blocked plan must touch nothing, got %+v", p)
	}
}

func TestSeedZoneRoundTripsThroughParser(t *testing.T) {
	content := renderSeedZone("200.18.198.in-addr.arpa", "198.18.200.8", nil, 17)
	got, ok := ParseZoneSerial(content)
	if !ok || got != 17 {
		t.Fatalf("seed zone serial = (%d,%v) want (17,true)", got, ok)
	}
}

func TestQuarantinePathsAreSuffixed(t *testing.T) {
	path := ZoneFilePath("example.com")
	if JournalPath(path) != path+".jnl" {
		t.Fatalf("journal path = %q", JournalPath(path))
	}
	cmd := moveAside(JournalPath(path), ".orphaned-16")
	if !strings.Contains(cmd, "'"+path+".jnl.orphaned-16'") {
		t.Errorf("quarantine command should rename, not delete: %s", cmd)
	}
	if strings.Contains(cmd, "rm ") {
		t.Errorf("quarantine must never delete: %s", cmd)
	}
}

// A repeat incident computes the same suffix, so the rename must not overwrite
// the copy preserved by the previous one.
func TestMoveAsidePreservesEarlierQuarantine(t *testing.T) {
	sh, err := exec.LookPath("sh")
	if err != nil {
		t.Skipf("no POSIX shell: %v", err)
	}
	dir := t.TempDir()
	path := filepath.Join(dir, "db.example.com")

	for _, content := range []string{"first", "second"} {
		if err := os.WriteFile(path, []byte(content), 0o600); err != nil {
			t.Fatal(err)
		}
		out, err := exec.Command(sh, "-c", moveAside(path, ".orphaned-16")).CombinedOutput()
		if err != nil {
			t.Fatalf("moveAside(%s): %v (%s)", content, err, out)
		}
	}

	if _, err := os.Stat(path); err == nil {
		t.Error("the quarantined file should have been renamed away")
	}
	entries, err := os.ReadDir(dir)
	if err != nil {
		t.Fatal(err)
	}
	found := map[string]bool{}
	for _, e := range entries {
		b, err := os.ReadFile(filepath.Join(dir, e.Name()))
		if err != nil {
			t.Fatal(err)
		}
		found[string(b)] = true
	}
	for _, want := range []string{"first", "second"} {
		if !found[want] {
			t.Errorf("quarantine destroyed %q: %v", want, found)
		}
	}
}

func TestParseJournalHeaderRejectsPaddingGarbage(t *testing.T) {
	h := journalHeader(";BIND LOG V9\n", 10, 16)
	h[15] = 'x'
	if _, _, ok := parseJournalHeader(h); ok {
		t.Error("format field must match all 16 bytes")
	}
}

func TestShellQuoteEscapesQuotes(t *testing.T) {
	sh, err := exec.LookPath("sh")
	if err != nil {
		t.Skipf("no POSIX shell: %v", err)
	}
	evil := `a'; touch pwned; echo '`
	out, err := exec.Command(sh, "-c", "printf %s "+shellQuote(evil)).Output()
	if err != nil {
		t.Fatal(err)
	}
	if string(out) != evil {
		t.Errorf("shellQuote round trip = %q want %q", out, evil)
	}
}

// The probe is shell, so run it and check the parser agrees with what is
// actually on disk; a syntax slip or a missing field would otherwise only
// surface as a seed over live data.
func TestZoneStateProbeRoundTrip(t *testing.T) {
	sh, err := exec.LookPath("sh")
	if err != nil {
		t.Skipf("no POSIX shell: %v", err)
	}
	for _, tool := range []string{"head", "od", "tr"} {
		if _, err := exec.LookPath(tool); err != nil {
			t.Skipf("probe needs %s: %v", tool, err)
		}
	}

	cases := []struct {
		name    string
		zone    string
		jnl     []byte
		orphans []string
		want    ZoneDiskState
	}{
		{name: "fresh install"},
		{
			name: "zone file only",
			zone: renderSeedZone("example.com", "10.0.0.1", nil, 42),
			want: ZoneDiskState{ZoneFile: true, ZoneSerial: 42, ZoneSerialOK: true},
		},
		{
			name: "zone file and journal",
			zone: renderSeedZone("example.com", "10.0.0.1", nil, 12),
			jnl:  journalHeader(";BIND LOG V9.2\n", 10, 16),
			want: ZoneDiskState{
				ZoneFile: true, ZoneSerial: 12, ZoneSerialOK: true,
				Journal: true, JournalBegin: 10, JournalEnd: 16, JournalOK: true,
			},
		},
		{
			name: "orphan journal",
			jnl:  journalHeader(";BIND LOG V9.2\n", 10, 16),
			want: ZoneDiskState{Journal: true, JournalBegin: 10, JournalEnd: 16, JournalOK: true},
		},
		{
			name: "journal with unreadable header",
			jnl:  []byte("garbage"),
			want: ZoneDiskState{Journal: true},
		},
		{
			name:    "quarantine evidence only",
			orphans: []string{".orphaned-16", ".jnl.orphaned-16"},
			want:    ZoneDiskState{OrphanSerial: 16, OrphanSerialOK: true},
		},
		{
			name:    "repeat quarantine keeps the highest serial",
			orphans: []string{".orphaned-16", ".orphaned-30", ".orphaned-30.1"},
			want:    ZoneDiskState{OrphanSerial: 30, OrphanSerialOK: true},
		},
		{
			name:    "live zone beside old quarantine evidence",
			zone:    renderSeedZone("example.com", "10.0.0.1", nil, 42),
			orphans: []string{".orphaned-16"},
			want: ZoneDiskState{
				ZoneFile: true, ZoneSerial: 42, ZoneSerialOK: true,
				OrphanSerial: 16, OrphanSerialOK: true,
			},
		},
	}
	for _, c := range cases {
		path := filepath.Join(t.TempDir(), "db.example.com")
		if c.zone != "" {
			if err := os.WriteFile(path, []byte(c.zone), 0o600); err != nil {
				t.Fatal(err)
			}
		}
		if c.jnl != nil {
			if err := os.WriteFile(JournalPath(path), c.jnl, 0o600); err != nil {
				t.Fatal(err)
			}
		}
		for _, suffix := range c.orphans {
			if err := os.WriteFile(path+suffix, []byte("preserved"), 0o600); err != nil {
				t.Fatal(err)
			}
		}
		out, err := exec.Command(sh, "-c", zoneStateProbe(path)).Output()
		if err != nil {
			t.Fatalf("%s: probe failed: %v", c.name, err)
		}
		got, ok := parseZoneDiskState(string(out))
		if !ok {
			t.Errorf("%s: probe output rejected: %q", c.name, out)
			continue
		}
		if got != c.want {
			t.Errorf("%s: state = %+v want %+v (out %q)", c.name, got, c.want, out)
		}
	}
}

// applyPlanInterrupted models the plan being cut off between the quarantine
// renames and the new zone file landing: the PVC holds no zone data at all, and
// the .orphaned-<serial> siblings are the only record of how far it had got.
func applyPlanInterrupted(st ZoneDiskState, p SeedPlan) ZoneDiskState {
	h, known := highestSerial(st)
	if p.QuarantineJournal {
		st.Journal, st.JournalBegin, st.JournalEnd, st.JournalOK = false, 0, 0, false
	}
	if p.QuarantineZoneFile {
		st.ZoneFile, st.ZoneSerial, st.ZoneSerialOK = false, 0, false
	}
	if known && (p.QuarantineJournal || p.QuarantineZoneFile) {
		st.OrphanSerial, st.OrphanSerialOK = h, true
	}
	return st
}

// A reconcile that quarantined and then failed to write leaves a directory that
// looks fresh. Seeding it at 1 loads cleanly but every secondary holding the
// old serial refuses the transfer, so the zone goes permanently stale.
func TestPlanSeedInterruptedTransitionDoesNotRegressSerial(t *testing.T) {
	st := ZoneDiskState{
		ZoneFile: true, ZoneSerial: 1, ZoneSerialOK: true,
		Journal: true, JournalBegin: 10, JournalEnd: 16, JournalOK: true,
	}
	first := PlanSeed(st)
	if !first.WriteSeed {
		t.Fatalf("a file behind its journal should be reseeded, got %+v", first)
	}

	after := applyPlanInterrupted(st, first)
	if after.ZoneFile || after.Journal {
		t.Fatalf("the interrupted state should hold no zone data, got %+v", after)
	}

	retry := PlanSeed(after)
	if !retry.WriteSeed {
		t.Fatalf("a zone with nothing on disk must still be seeded, got %+v", retry)
	}
	if !serialLT(16, retry.Serial) {
		t.Errorf("reseed at %d regressed below the quarantined serial 16", retry.Serial)
	}
	if retry.Serial != first.Serial {
		t.Errorf("retry seeded at %d, the interrupted attempt planned %d", retry.Serial, first.Serial)
	}
	if retry.QuarantineZoneFile || retry.QuarantineJournal {
		t.Errorf("there is nothing left to quarantine, got %+v", retry)
	}
	if next := PlanSeed(applyPlan(after, retry)); next != (SeedPlan{}) {
		t.Errorf("third reconcile should be a no-op, got %+v", next)
	}
}

// Quarantine evidence is a floor, never a trigger: it must not disturb a zone
// that is healthy now, and it must not unblock an unjudgeable journal.
func TestPlanSeedOrphanEvidenceDoesNotDisturbLiveData(t *testing.T) {
	healthy := ZoneDiskState{
		ZoneFile: true, ZoneSerial: 20, ZoneSerialOK: true,
		Journal: true, JournalBegin: 10, JournalEnd: 20, JournalOK: true,
		OrphanSerial: 99, OrphanSerialOK: true,
	}
	if p := PlanSeed(healthy); p != (SeedPlan{}) {
		t.Errorf("a healthy zone must not be touched, got %+v", p)
	}
	blocked := ZoneDiskState{Journal: true, OrphanSerial: 99, OrphanSerialOK: true}
	if p := PlanSeed(blocked); p.Blocked == "" {
		t.Errorf("an unreadable orphan journal must still block, got %+v", p)
	}
}

func TestParseOrphanSerial(t *testing.T) {
	base := ZoneFilePath("example.com")
	cases := []struct {
		name string
		want int64
		ok   bool
	}{
		{base + ".orphaned-16", 16, true},
		{JournalPath(base) + ".orphaned-16", 16, true},
		{base + ".orphaned-16.3", 16, true},
		{base + ".orphaned-4294967295", 4294967295, true},
		{base + ".orphaned-", 0, false},
		{base + ".orphaned-abc", 0, false},
		{base + ".orphaned-4294967296", 0, false},
		{base, 0, false},
		{base + ".jnl", 0, false},
	}
	for _, c := range cases {
		got, ok := parseOrphanSerial(c.name)
		if got != c.want || ok != c.ok {
			t.Errorf("parseOrphanSerial(%q) = (%d,%v) want (%d,%v)", c.name, got, ok, c.want, c.ok)
		}
	}
	if _, ok := orphanSerial(nil); ok {
		t.Error("no siblings means no recorded serial, not serial 0")
	}
	// Serial 0 is legitimate and must not read as "nothing found".
	if h, ok := orphanSerial([]string{base + ".orphaned-0"}); !ok || h != 0 {
		t.Errorf("orphanSerial = (%d,%v) want (0,true)", h, ok)
	}
}