package bind

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

func requireShell(t *testing.T, tools ...string) string {
	t.Helper()
	sh, err := exec.LookPath("sh")
	if err != nil {
		t.Skipf("no POSIX shell: %v", err)
	}
	for _, tool := range tools {
		if _, err := exec.LookPath(tool); err != nil {
			t.Skipf("seed script needs %s: %v", tool, err)
		}
	}
	return sh
}

// inFlightZone lays out the state the operator actually hit in production: a
// zone file a previous reconcile clobbered back to serial 1, with the journal
// that carries the live records up to 16.
func inFlightZone(t *testing.T) (dir, path string) {
	t.Helper()
	dir = t.TempDir()
	path = filepath.Join(dir, "db.example.com")
	if err := os.WriteFile(path, []byte(renderSeedZone("example.com", "10.0.0.1", nil, 1)), 0o600); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(JournalPath(path), journalHeader(";BIND LOG V9.2\n", 10, 16), 0o600); err != nil {
		t.Fatal(err)
	}
	return dir, path
}

func runSeedScript(t *testing.T, sh, path string, plan SeedPlan, content, stdin string) error {
	t.Helper()
	return runSeedScriptWithPath(t, sh, path, plan, content, stdin, "")
}

func runSeedScriptWithPath(t *testing.T, sh, path string, plan SeedPlan, content, stdin, pathEnv string) error {
	t.Helper()
	cmd := exec.Command(sh, "-c", seedScript(path, plan, len(content)))
	cmd.Stdin = strings.NewReader(stdin)
	if pathEnv != "" {
		cmd.Env = append(os.Environ(), "PATH="+pathEnv)
	}
	return cmd.Run()
}

// shimPath puts a stand-in for tool at the front of a PATH, so the generated
// script meets a failing command where a real image would meet a working one.
func shimPath(t *testing.T, tool, body string) string {
	t.Helper()
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, tool), []byte("#!/bin/sh\n"+body+"\n"), 0o755); err != nil {
		t.Fatal(err)
	}
	return dir + string(os.PathListSeparator) + os.Getenv("PATH")
}

func realTool(t *testing.T, tool string) string {
	t.Helper()
	p, err := exec.LookPath(tool)
	if err != nil {
		t.Skipf("need %s: %v", tool, err)
	}
	return p
}

// assertZoneUntouched checks the in-flight layout survived a failed run whole:
// live serial 1 still at path, journal still there, nothing quarantined and no
// staging file left behind.
func assertZoneUntouched(t *testing.T, dir, path string) {
	t.Helper()
	found := siblings(t, dir)
	serial, ok := ParseZoneSerial(found[filepath.Base(path)])
	if !ok || serial != 1 {
		t.Errorf("zone file was replaced by a failed run: serial = (%d,%v)", serial, ok)
	}
	if _, ok := found[filepath.Base(JournalPath(path))]; !ok {
		t.Error("the journal was lost by a failed run")
	}
	for name := range found {
		if strings.Contains(name, quarantineMarker) {
			t.Errorf("a failed run must not leave a quarantined file: %s", name)
		}
	}
}

func probeState(t *testing.T, sh, path string) ZoneDiskState {
	t.Helper()
	out, err := exec.Command(sh, "-c", zoneStateProbe(path)).Output()
	if err != nil {
		t.Fatalf("probe failed: %v", err)
	}
	st, ok := parseZoneDiskState(string(out))
	if !ok {
		t.Fatalf("probe output rejected: %q", out)
	}
	return st
}

func siblings(t *testing.T, dir string) map[string]string {
	t.Helper()
	entries, err := os.ReadDir(dir)
	if err != nil {
		t.Fatal(err)
	}
	found := map[string]string{}
	for _, e := range entries {
		b, err := os.ReadFile(filepath.Join(dir, e.Name()))
		if err != nil {
			t.Fatal(err)
		}
		found[e.Name()] = string(b)
	}
	return found
}

// A stdin stream cut mid-transfer gives cat a short file and exits 0. The seed
// must refuse to install it, and must not have quarantined anything on the way:
// a run that stopped here has to leave the zone exactly as it found it.
func TestSeedScriptInterruptedWriteLeavesDiskUntouched(t *testing.T) {
	sh := requireShell(t, "wc", "tr", "mv", "rm", "mkdir", "dirname")
	dir, path := inFlightZone(t)

	plan := PlanSeed(probeState(t, sh, path))
	if !plan.WriteSeed || !plan.QuarantineZoneFile || !plan.QuarantineJournal {
		t.Fatalf("expected a reseed over both files, got %+v", plan)
	}
	content := renderSeedZone("example.com", "10.0.0.1", nil, plan.Serial)

	if err := runSeedScript(t, sh, path, plan, content, content[:len(content)/2]); err == nil {
		t.Fatal("a truncated seed write must fail rather than install a torn zone file")
	}

	serial, ok := ParseZoneSerial(siblings(t, dir)[filepath.Base(path)])
	if !ok || serial != 1 {
		t.Errorf("the zone file was damaged by the interrupted seed: serial = (%d,%v)", serial, ok)
	}
	for name := range siblings(t, dir) {
		if strings.Contains(name, quarantineMarker) {
			t.Errorf("nothing should have been quarantined before the write landed: %s", name)
		}
		if strings.HasSuffix(name, seedTempSuffix) {
			t.Errorf("the staging file should have been cleaned up: %s", name)
		}
	}

	// The retry must still see the journal and reseed above it, not at 1.
	retry := PlanSeed(probeState(t, sh, path))
	if retry != plan {
		t.Errorf("retry planned %+v, want the original %+v", retry, plan)
	}
}

func TestSeedScriptInstallsOverQuarantinedFiles(t *testing.T) {
	sh := requireShell(t, "wc", "tr", "mv", "rm", "mkdir", "dirname")
	dir, path := inFlightZone(t)

	plan := PlanSeed(probeState(t, sh, path))
	content := renderSeedZone("example.com", "10.0.0.1", nil, plan.Serial)
	if err := runSeedScript(t, sh, path, plan, content, content); err != nil {
		t.Fatalf("seed script: %v", err)
	}

	st := probeState(t, sh, path)
	if !st.ZoneFile || st.ZoneSerial != plan.Serial {
		t.Errorf("installed state = %+v want serial %d", st, plan.Serial)
	}
	if st.Journal {
		t.Error("the unreplayable journal should have been moved aside")
	}
	found := siblings(t, dir)
	for _, want := range []string{"db.example.com.orphaned-16", "db.example.com.jnl.orphaned-16"} {
		if _, ok := found[want]; !ok {
			t.Errorf("missing preserved file %s: %v", want, keys(found))
		}
	}
	if _, ok := found[filepath.Base(path)+seedTempSuffix]; ok {
		t.Error("the staging file should have been renamed into place")
	}
	if next := PlanSeed(st); next != (SeedPlan{}) {
		t.Errorf("second reconcile should be a no-op, got %+v", next)
	}
}

// The seed has to work on a PVC that has never held this zone, directories
// included.
func TestSeedScriptFreshInstall(t *testing.T) {
	sh := requireShell(t, "wc", "tr", "mv", "rm", "mkdir", "dirname")
	path := filepath.Join(t.TempDir(), "zones", "db.example.com")

	plan := PlanSeed(ZoneDiskState{})
	content := renderSeedZone("example.com", "10.0.0.1", nil, plan.Serial)
	if err := runSeedScript(t, sh, path, plan, content, content); err != nil {
		t.Fatalf("seed script: %v", err)
	}
	if st := probeState(t, sh, path); !st.ZoneFile || st.ZoneSerial != 1 {
		t.Errorf("fresh install state = %+v want serial 1", st)
	}
}

func keys(m map[string]string) []string {
	out := make([]string, 0, len(m))
	for k := range m {
		out = append(out, k)
	}
	return out
}

// A rename that fails leaves live data where it is, so the install must not
// happen: the skeleton beside a higher-serial journal is the production failure
// this seed exists to avoid.
func TestSeedScriptFailedQuarantineAbortsInstall(t *testing.T) {
	sh := requireShell(t, "wc", "tr", "mv", "rm", "mkdir", "dirname")
	dir, path := inFlightZone(t)
	pathEnv := shimPath(t, "mv", `case "$*" in *`+quarantineMarker+`*) exit 1;; esac
exec `+realTool(t, "mv")+` "$@"`)

	plan := PlanSeed(probeState(t, sh, path))
	content := renderSeedZone("example.com", "10.0.0.1", nil, plan.Serial)
	if err := runSeedScriptWithPath(t, sh, path, plan, content, content, pathEnv); err == nil {
		t.Fatal("a failed quarantine must fail the seed")
	}
	assertZoneUntouched(t, dir, path)
}

// The size guard has to fail closed: an image without wc cannot measure the
// staged file, and an unverified file must never be installed.
func TestSeedScriptUnmeasurableStagingAbortsInstall(t *testing.T) {
	sh := requireShell(t, "wc", "tr", "mv", "rm", "mkdir", "dirname")
	dir, path := inFlightZone(t)
	pathEnv := shimPath(t, "wc", "exit 127")

	plan := PlanSeed(probeState(t, sh, path))
	content := renderSeedZone("example.com", "10.0.0.1", nil, plan.Serial)
	if err := runSeedScriptWithPath(t, sh, path, plan, content, content, pathEnv); err == nil {
		t.Fatal("an unmeasurable staging file must fail the seed")
	}
	assertZoneUntouched(t, dir, path)
	if _, ok := siblings(t, dir)[filepath.Base(path)+seedTempSuffix]; ok {
		t.Error("the staging file should have been cleaned up")
	}
}

func TestSeedScriptFailedMkdirAbortsInstall(t *testing.T) {
	sh := requireShell(t, "wc", "tr", "mv", "rm", "mkdir", "dirname")
	dir, path := inFlightZone(t)
	pathEnv := shimPath(t, "mkdir", "exit 1")

	plan := PlanSeed(probeState(t, sh, path))
	content := renderSeedZone("example.com", "10.0.0.1", nil, plan.Serial)
	if err := runSeedScriptWithPath(t, sh, path, plan, content, content, pathEnv); err == nil {
		t.Fatal("a failed mkdir must fail the seed")
	}
	assertZoneUntouched(t, dir, path)
}

// The probe decides whether there is anything to preserve, so a tool it cannot
// run must be an error rather than a state that reads as "nothing readable".
func TestZoneStateProbeFailedToolIsAnError(t *testing.T) {
	sh := requireShell(t, "head", "od", "tr")
	_, path := inFlightZone(t)
	pathEnv := shimPath(t, "tr", "exit 127")

	cmd := exec.Command(sh, "-c", zoneStateProbe(path))
	cmd.Env = append(os.Environ(), "PATH="+pathEnv)
	out, err := cmd.Output()
	if err == nil {
		t.Fatalf("probe reported success without reading the journal header: %q", out)
	}
}