package apply

// Issue 1024, novox/hq ADR 0422: a directory that says unknown "move-out" keeps only what it knows, and moves every
// other path into a kept folder under the account's home, listed before it is moved.

import (
	"context"
	"encoding/json"
	"errors"
	"os"
	osuser "os/user"
	"path/filepath"
	"strings"
	"syscall"
	"testing"
	"time"

	"github.com/novox/mesh-host/internal/store"
	"golang.org/x/sys/unix"
)

// me is the account running the test, which owns the home the test names.
func me() string {
	u, err := osuser.Current()
	if err != nil {
		panic(err)
	}
	return u.Username
}

// aMoveOutHome is a home the test names, of the account running the test, so no chown needs privilege.
func aMoveOutHome(t *testing.T) string {
	t.Helper()
	home := filepath.Join(t.TempDir(), "home", "agent")
	if err := os.MkdirAll(home, 0o755); err != nil {
		t.Fatal(err)
	}
	wasHomes, wasAccounts := homes, accountsOfHomes
	homes = func() []string { return []string{home} }
	accountsOfHomes = func() map[string]homeAccount {
		return map[string]homeAccount{home: {Name: me(), UID: os.Getuid()}}
	}
	t.Cleanup(func() { homes, accountsOfHomes = wasHomes, wasAccounts })
	return home
}

func put(t *testing.T, path, content string, age time.Duration) {
	t.Helper()
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
		t.Fatal(err)
	}
	old := time.Now().Add(-age)
	if err := os.Chtimes(path, old, old); err != nil {
		t.Fatal(err)
	}
}

func keptLists(t *testing.T, home string) []string {
	t.Helper()
	out, _ := filepath.Glob(filepath.Join(keptRoot(home), "*", "*.json"))
	return out
}

func readList(t *testing.T, path string) []movedEntry {
	t.Helper()
	raw, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	var list []movedEntry
	if err := json.Unmarshal(raw, &list); err != nil {
		t.Fatal(err)
	}
	return list
}

func TestAMoveOutDirectoryMovesOnlyWhatIsNotKnown(t *testing.T) {
	home := aMoveOutHome(t)
	dir := filepath.Join(home, ".ssh")
	outside := filepath.Join(t.TempDir(), "target")
	put(t, outside, "elsewhere", time.Hour)
	put(t, filepath.Join(dir, "config"), "declared", time.Hour)
	put(t, filepath.Join(dir, "known_hosts"), "knows", time.Hour)
	put(t, filepath.Join(dir, "x", "inside"), "in x", time.Hour)
	put(t, filepath.Join(dir, "stray"), "stray content", time.Hour)
	put(t, filepath.Join(dir, "oldfolder", "deep", "f"), "deep", time.Hour)
	put(t, filepath.Join(dir, "young"), "just made", 5*time.Second)
	if err := os.Symlink(outside, filepath.Join(dir, "alink")); err != nil {
		t.Fatal(err)
	}
	old := time.Now().Add(-time.Hour)
	_ = os.Chtimes(filepath.Join(dir, "oldfolder"), old, old)
	_ = os.Chtimes(filepath.Join(dir, "x"), old, old)
	// A named pipe stands for the socket: a socket's path is too long under a test directory to bind.
	if err := syscall.Mkfifo(filepath.Join(dir, "agent.sock"), 0o644); err != nil {
		t.Fatal(err)
	}
	_ = os.Chtimes(filepath.Join(dir, "agent.sock"), old, old)
	// The directory itself and its declared file are old enough too.
	// The symbolic link is older than a minute as well.
	ts := []unix.Timespec{unix.NsecToTimespec(old.UnixNano()), unix.NsecToTimespec(old.UnixNano())}
	if err := unix.UtimesNanoAt(unix.AT_FDCWD, filepath.Join(dir, "alink"), ts, unix.AT_SYMLINK_NOFOLLOW); err != nil {
		t.Fatal(err)
	}

	var logged []string
	report, _, err := Apply(context.Background(), archHost(t), declare(t,
		`{"id":"mod.dir","type":"directory","path":"`+dir+`","owner":"`+me()+`","unknown":"move-out","knows":["known_hosts","x/"]},`+
			`{"id":"mod.config","type":"file","path":"`+dir+`/config","content":"declared"}`),
		store.State{}, store.OriginDeclared, noServices, func(s string) { logged = append(logged, s) }, nil)
	if err != nil {
		t.Fatal(err)
	}
	_ = report
	for _, kept := range []string{"config", "known_hosts", "x/inside", "young", "agent.sock"} {
		if !exists(filepath.Join(dir, kept)) {
			t.Errorf("%s should stay", kept)
		}
	}
	for _, gone := range []string{"stray", "oldfolder", "alink"} {
		if exists(filepath.Join(dir, gone)) {
			t.Errorf("%s should have moved", gone)
		}
	}
	lists := keptLists(t, home)
	if len(lists) != 1 {
		t.Fatalf("one list expected, got %v", lists)
	}
	if !strings.Contains(lists[0], filepath.Join("mesh-moved", "mod")) {
		t.Errorf("the module's name is not in the kept path: %s", lists[0])
	}
	list := readList(t, lists[0])
	if len(list) != 3 {
		t.Fatalf("the list names three paths: %+v", list)
	}
	kept := strings.TrimSuffix(lists[0], ".json")
	for _, e := range list {
		if !strings.HasPrefix(e.To, kept+string(os.PathSeparator)) || !exists(e.To) {
			t.Errorf("not at %s: %+v", kept, e)
		}
	}
	if b, _ := os.ReadFile(filepath.Join(kept, "stray")); string(b) != "stray content" {
		t.Errorf("content changed: %q", b)
	}
	if b, _ := os.ReadFile(filepath.Join(kept, "oldfolder", "deep", "f")); string(b) != "deep" {
		t.Errorf("the folder was not moved whole: %q", b)
	}
	if info, err := os.Lstat(filepath.Join(kept, "alink")); err != nil || info.Mode()&os.ModeSymlink == 0 {
		t.Errorf("the link is not still a link: %v", err)
	}
	if !strings.Contains(strings.Join(logged, "\n"), "(ADR 0422)") {
		t.Errorf("the moves were not logged: %v", logged)
	}
	if len(report.Left) != 1 || filepath.Base(report.Left[0].Path) != "agent.sock" {
		t.Errorf("the report does not list the pipe it left: %+v", report.Left)
	}
	if len(report.MovedOut) != 3 {
		t.Errorf("the report does not count the moves: %+v", report.MovedOut)
	}
}

func TestAMoveOutListIsWrittenBeforeTheMove(t *testing.T) {
	home := aMoveOutHome(t)
	dir := filepath.Join(home, "d")
	put(t, filepath.Join(dir, "a"), "a", time.Hour)
	put(t, filepath.Join(dir, "b"), "b", time.Hour)
	was := renamePath
	renamePath = func(h, from, to string) error {
		if filepath.Base(from) == "b" {
			return errors.New("injected")
		}
		return was(h, from, to)
	}
	t.Cleanup(func() { renamePath = was })
	_, _, err := applyOnce(t, `{"id":"mod.dir","type":"directory","path":"`+dir+`","owner":"`+me()+`","unknown":"move-out"}`, nil, store.State{})
	if err == nil {
		t.Fatal("a failed move must fail the resource")
	}
	if !exists(filepath.Join(dir, "b")) || exists(filepath.Join(dir, "a")) {
		t.Error("b stays, a moved")
	}
	lists := keptLists(t, home)
	if len(lists) != 1 {
		t.Fatalf("lists: %v", lists)
	}
	names := map[string]bool{}
	for _, e := range readList(t, lists[0]) {
		names[filepath.Base(e.From)] = true
	}
	if !names["a"] || !names["b"] {
		t.Errorf("the entry for the failed move was not listed first: %v", names)
	}
}

func TestAMoveOutThatMovedNothingMakesNothing(t *testing.T) {
	home := aMoveOutHome(t)
	dir := filepath.Join(home, "d")
	put(t, filepath.Join(dir, "known"), "k", time.Hour)
	put(t, filepath.Join(dir, "young"), "y", time.Second)
	if _, _, err := applyOnce(t, `{"id":"mod.dir","type":"directory","path":"`+dir+`","owner":"`+me()+`","unknown":"move-out","knows":["known"]}`, nil, store.State{}); err != nil {
		t.Fatal(err)
	}
	if exists(keptRoot(home)) {
		t.Error("a kept folder was made with nothing to move")
	}
	// And when every move fails, what was made goes.
	put(t, filepath.Join(dir, "stray"), "s", time.Hour)
	was := renamePath
	renamePath = func(string, string, string) error { return errors.New("injected") }
	t.Cleanup(func() { renamePath = was })
	if _, _, err := applyOnce(t, `{"id":"mod.dir","type":"directory","path":"`+dir+`","owner":"`+me()+`","unknown":"move-out","knows":["known"]}`, nil, store.State{}); err == nil {
		t.Fatal("expected a failure")
	}
	if len(keptLists(t, home)) != 0 {
		t.Error("a list stayed though nothing moved")
	}
	if matches, _ := filepath.Glob(filepath.Join(keptRoot(home), "*", "*")); len(matches) != 0 {
		t.Errorf("a kept folder stayed though nothing moved: %v", matches)
	}
}

func TestAMoveOutOfANestedStrayThatFailsLeavesNoKeptFolder(t *testing.T) {
	home := aMoveOutHome(t)
	dir := filepath.Join(home, "d")
	put(t, filepath.Join(dir, "x", "f"), "declared", time.Hour)
	put(t, filepath.Join(dir, "x", "stray"), "s", time.Hour)
	was := renamePath
	renamePath = func(string, string, string) error { return errors.New("injected") }
	t.Cleanup(func() { renamePath = was })
	_, _, err := applyOnce(t, `{"id":"mod.dir","type":"directory","path":"`+dir+`","owner":"`+me()+`","unknown":"move-out"},`+
		`{"id":"mod.f","type":"file","path":"`+dir+`/x/f","content":"declared","owner":"`+me()+`"}`, nil, store.State{})
	if err == nil {
		t.Fatal("expected a failure")
	}
	if exists(keptRoot(home)) {
		matches, _ := filepath.Glob(filepath.Join(keptRoot(home), "*", "*"))
		t.Errorf("something was left behind though nothing moved: %v", matches)
	}
}

// A link swapped into a parent folder, on either side, between the look and the move, is not followed.
func TestAMoveOutDoesNotFollowALinkSwappedIntoAParent(t *testing.T) {
	for _, side := range []string{"from", "to"} {
		t.Run(side, func(t *testing.T) {
			home := aMoveOutHome(t)
			dir := filepath.Join(home, "d")
			outside := filepath.Join(t.TempDir(), "etc")
			put(t, filepath.Join(outside, "stray"), "root's", time.Hour)
			put(t, filepath.Join(dir, "x", "f"), "declared", time.Hour)
			put(t, filepath.Join(dir, "x", "stray"), "s", time.Hour)
			was := renamePath
			renamePath = func(h, from, to string) error {
				victim := filepath.Dir(from)
				if side == "to" {
					victim = filepath.Dir(to)
					_ = os.Remove(filepath.Join(victim, "nothing"))
				}
				if err := os.RemoveAll(victim); err != nil {
					t.Fatal(err)
				}
				if side == "from" {
					put(t, filepath.Join(outside, "other"), "o", time.Hour)
				}
				if err := os.Symlink(outside, victim); err != nil {
					t.Fatal(err)
				}
				return was(h, from, to)
			}
			t.Cleanup(func() { renamePath = was })
			_, _, err := applyOnce(t, `{"id":"mod.dir","type":"directory","path":"`+dir+`","owner":"`+me()+`","unknown":"move-out"},`+
				`{"id":"mod.f","type":"file","path":"`+dir+`/x/f","content":"declared","owner":"`+me()+`"}`, nil, store.State{})
			if err == nil {
				t.Fatal("a move through a swapped link must fail")
			}
			if b, e := os.ReadFile(filepath.Join(outside, "stray")); e != nil || string(b) != "root's" {
				t.Errorf("the file outside the home was touched: %q %v", b, e)
			}
			entries, _ := os.ReadDir(outside)
			if side == "to" && len(entries) != 1 || side == "from" && len(entries) != 2 {
				t.Errorf("something was moved into or out of the folder outside the home: %v", entries)
			}
		})
	}
}

func TestOtherUnknownValuesAndNoValueMoveNothing(t *testing.T) {
	home := aMoveOutHome(t)
	for _, v := range []string{`,"unknown":"program"`, `,"unknown":"module"`, ``} {
		dir := filepath.Join(home, "d")
		put(t, filepath.Join(dir, "stray"), "s", time.Hour)
		if _, _, err := applyOnce(t, `{"id":"mod.dir","type":"directory","path":"`+dir+`","owner":"`+me()+`"`+v+`}`, nil, store.State{}); err != nil {
			t.Fatal(err)
		}
		if !exists(filepath.Join(dir, "stray")) || exists(keptRoot(home)) {
			t.Errorf("%q moved something", v)
		}
	}
}

func TestAMoveOutArchiveKeepsWhatItUnpackedAndMovesAStray(t *testing.T) {
	home := aMoveOutHome(t)
	dir := filepath.Join(home, "theme")
	put(t, filepath.Join(dir, "stray"), "s", time.Hour)
	res, _ := archiveDecl(t, "mod.theme", dir, map[string]string{"one.txt": "1", "sub/two.txt": "2"}, "")
	res = strings.Replace(res, `"path":`, `"owner":"`+me()+`","unknown":"move-out","path":`, 1)
	if _, _, err := Apply(context.Background(), archHost(t), declare(t, res), store.State{},
		store.OriginDeclared, noServices, nil, nil); err != nil {
		t.Fatal(err)
	}
	for _, f := range []string{"one.txt", "sub/two.txt"} {
		if !exists(filepath.Join(dir, f)) {
			t.Errorf("%s was moved", f)
		}
	}
	if exists(filepath.Join(dir, "stray")) || len(keptLists(t, home)) != 1 {
		t.Error("the stray file did not move")
	}
}

func TestMoveOutNeedsAHome(t *testing.T) {
	aMoveOutHome(t)
	dir := filepath.Join(t.TempDir(), "elsewhere")
	put(t, filepath.Join(dir, "stray"), "s", time.Hour)
	_, _, err := applyOnce(t, `{"id":"mod.dir","type":"directory","path":"`+dir+`","owner":"`+me()+`","unknown":"move-out"}`, nil, store.State{})
	if err == nil || !strings.Contains(err.Error(), "home") {
		t.Fatalf("expected a refusal naming the home: %v", err)
	}
	if !exists(filepath.Join(dir, "stray")) {
		t.Error("something moved")
	}
}

func TestMoveOutRefusesAnotherFileSystem(t *testing.T) {
	home := aMoveOutHome(t)
	dir := filepath.Join(home, "d")
	put(t, filepath.Join(dir, "stray"), "s", time.Hour)
	was := deviceOf
	deviceOf = func(p string) (uint64, error) {
		if p == dir {
			return 1, nil
		}
		return 2, nil
	}
	t.Cleanup(func() { deviceOf = was })
	_, _, err := applyOnce(t, `{"id":"mod.dir","type":"directory","path":"`+dir+`","owner":"`+me()+`","unknown":"move-out"}`, nil, store.State{})
	if err == nil || !strings.Contains(err.Error(), "file system") {
		t.Fatalf("expected a refusal naming the file systems: %v", err)
	}
	if !exists(filepath.Join(dir, "stray")) || exists(keptRoot(home)) {
		t.Error("something moved or was made")
	}
}