package main

import (
	"context"
	"encoding/json"
	"errors"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"testing"
	"time"
)

// The secret every test that has one uses; it must never appear in anything the module says.
const testPassword = "s3cr3t-Pa55"

// fakeSystem is a machine under a temporary root with a recorded service manager.
type fakeSystem struct {
	// mu guards calls, units and reachable, for a test that runs RunApply beside itself.
	mu    sync.Mutex
	t     *testing.T
	root  string
	calls []string
	// units are the service manager's answers: ActiveState and UnitFileState by unit.
	units map[string]map[string]string
	// reachable are the host:port pairs that answer.
	reachable map[string]bool
}

func newSystem(t *testing.T) *fakeSystem {
	f := &fakeSystem{t: t, root: t.TempDir(), units: map[string]map[string]string{}, reachable: map[string]bool{}}
	for _, d := range []string{UnitDir, RunDir, BusDir, "/etc/mesh-mounts", "/proc/self", "/var/lib/mesh/mounts"} {
		if err := os.MkdirAll(filepath.Join(f.root, d), 0o755); err != nil {
			t.Fatal(err)
		}
	}
	f.write("/proc/self/mountinfo", "")
	// The mesh keeps no data on this machine, as the controller said through the bundle.
	f.write(DataFile, `{"machine":"workstation","paths":[]}`)
	return f
}

func (f *fakeSystem) write(p, content string) {
	f.t.Helper()
	full := filepath.Join(f.root, p)
	if err := os.MkdirAll(filepath.Dir(full), 0o755); err != nil {
		f.t.Fatal(err)
	}
	if err := os.WriteFile(full, []byte(content), 0o644); err != nil {
		f.t.Fatal(err)
	}
}

func (f *fakeSystem) read(p string) string {
	b, _ := os.ReadFile(filepath.Join(f.root, p))
	return string(b)
}

func (f *fakeSystem) run(_ context.Context, name string, args ...string) (string, error) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.calls = append(f.calls, name+" "+strings.Join(args, " "))
	if name != "systemctl" || len(args) == 0 {
		return "", nil
	}
	switch args[0] {
	case "show":
		if len(args) >= 5 && args[3] == "--value" {
			return f.units[args[4]]["ActiveState"] + "\n", nil
		}
		var blocks []string
		for _, u := range args {
			if !strings.HasSuffix(u, ".mount") && !strings.HasSuffix(u, ".automount") {
				continue
			}
			s := f.units[u]
			blocks = append(blocks, "Id="+u+"\nActiveState="+orDefault(s["ActiveState"], "inactive")+"\nSubState=dead\nResult="+
				orDefault(s["Result"], "success")+"\nUnitFileState="+orDefault(s["UnitFileState"], "disabled"))
		}
		return strings.Join(blocks, "\n\n") + "\n", nil
	case "enable":
		u := args[len(args)-1]
		f.units[u] = map[string]string{"ActiveState": "active", "UnitFileState": "enabled"}
	case "start":
		u := args[len(args)-1]
		if f.units[u] == nil {
			f.units[u] = map[string]string{}
		}
		f.units[u]["ActiveState"], f.units[u]["Result"] = "active", "success"
	case "reset-failed":
		u := args[len(args)-1]
		if f.units[u]["ActiveState"] == "failed" {
			f.units[u]["ActiveState"], f.units[u]["Result"] = "inactive", "success"
		}
	}
	return "", nil
}

func (f *fakeSystem) machine() *Machine {
	return &Machine{Root: f.root, Run: f.run, Escalate: f.run, LookPath: func(string) bool { return true }}
}

func (f *fakeSystem) applier(now time.Time) *Applier {
	return &Applier{M: f.machine(), Act: true, Judge: true,
		Dial: func(addr string, _ time.Duration) error {
			f.mu.Lock()
			defer f.mu.Unlock()
			if f.reachable[addr] {
				return nil
			}
			return errors.New("dial tcp " + addr + ": connect: no route to host")
		},
		Now:    func() time.Time { return now },
		Lookup: func(string) (int, int, error) { return 1000, 1000, nil },
	}
}

func (f *fakeSystem) called(prefix string) bool {
	f.mu.Lock()
	defer f.mu.Unlock()
	for _, c := range f.calls {
		if strings.HasPrefix(c, prefix) {
			return true
		}
	}
	return false
}

// everything is every file under the root, for a search that a secret appears nowhere it should not.
func (f *fakeSystem) everything(except ...string) string {
	var b strings.Builder
	filepath.Walk(f.root, func(p string, info os.FileInfo, err error) error {
		if err != nil || info.IsDir() {
			return nil
		}
		for _, e := range except {
			if strings.HasSuffix(p, e) {
				return nil
			}
		}
		raw, _ := os.ReadFile(p)
		b.Write(raw)
		return nil
	})
	return b.String()
}

const config = "shares=library=/srv/library downloads=/srv/downloads:ro\n" +
	"sources=games=smb://192.0.2.76/Share@/mnt/games usb=disk:1234-ABCD@/mnt/usb\n" +
	"server=homeserver\nat=192.0.2.10\nnode=workstation\naccount=operator\n" +
	"secret=/var/lib/mesh/mounts/smb-credentials.secret\nstate=/var/lib/mesh/mounts\n"

func exportsAnswer(t *testing.T, shares ...ServerShare) string {
	raw, err := json.Marshal(ExportsAnswer{Server: "homeserver", At: "192.0.2.10", Shares: shares})
	if err != nil {
		t.Fatal(err)
	}
	return string(raw)
}

var (
	library   = ServerShare{Name: "library", Path: "/tank/media", Access: "rw", UID: 1001, GID: 2000, Live: true, To: []ShareClient{{Node: "workstation", Address: "10.0.0.3", Access: "rw"}}}
	downloads = ServerShare{Name: "downloads", Path: "/tank/downloads", Access: "rw", UID: 1001, GID: 2000, Live: true, To: []ShareClient{{Node: "workstation", Address: "10.0.0.3", Access: "rw"}}}
)

func TestTheSettingsAreReadAndWhatCannotBeIsSaidPlainly(t *testing.T) {
	shares, problems := ParseShares("library=/srv/library  downloads=/srv/downloads:ro,bad Upper=/x other=relative library=/srv/again root=/")
	if len(shares) != 2 || shares[0] != (Wanted{"library", "/srv/library", false}) || shares[1] != (Wanted{"downloads", "/srv/downloads", true}) {
		t.Fatalf("shares %+v", shares)
	}
	want := []string{`"bad" is not name=mountpoint`, `"Upper" is not lower-case`, `"relative" is not an absolute path`, "named twice", `"/" is the system's own directory`}
	for i, w := range want {
		if i >= len(problems) || !strings.Contains(problems[i], w) {
			t.Errorf("problem %d: want %q in %q", i, w, problems)
		}
	}
	if s, p := ParseShares("none"); len(s) != 0 || len(p) != 0 {
		t.Errorf("none is nothing: %v %v", s, p)
	}
	sources, problems := ParseSources("games=smb://192.0.2.76/Share@/mnt/games:ro usb=disk:1234-ABCD@/mnt/usb ftp=ftp://x/y@/mnt/x nomount=smb://h/s")
	if len(sources) != 2 || sources[0].Kind != "smb" || sources[0].Host != "192.0.2.76" || sources[0].Share != "Share" || !sources[0].ReadOnly ||
		sources[1].Kind != "disk" || sources[1].UUID != "1234-ABCD" {
		t.Fatalf("sources %+v", sources)
	}
	if len(problems) != 2 || !strings.Contains(problems[0], "neither smb://") || !strings.Contains(problems[1], "names no mount point") {
		t.Errorf("problems %q", problems)
	}
	if err := CheckMountpoint("/etc/x"); err == nil {
		t.Error("a mount point under /etc is the system's")
	}
}

func TestAMountPointIsNamedAsSystemdEscapeNamesIt(t *testing.T) {
	for in, want := range map[string]string{
		"/srv/library":                "srv-library",
		"/storage/media":              "storage-media",
		"/mnt/my-disk":                `mnt-my\x2ddisk`,
		"/mnt/.hidden":                `mnt-.hidden`,
		"/.x":                         `\x2ex`,
		"/srv/a b":                    `srv-a\x20b`,
		"/dev/disk/by-uuid/1234-ABCD": `dev-disk-by\x2duuid-1234\x2dABCD`,
	} {
		if got := EscapePath(in); got != want {
			t.Errorf("EscapePath(%q) = %q, want %q", in, got, want)
		}
	}
}

func TestANodesShareIsMountedHardWhenWritableAndSoftWhenNot(t *testing.T) {
	rw := NFSPair(Wanted{Name: "library", Mountpoint: "/srv/library"}, "192.0.2.10", library)
	for _, want := range []string{"What=192.0.2.10:/tank/media", "Where=/srv/library", "Type=nfs4",
		"Options=vers=4.2,hard,timeo=150,retrans=3,_netdev", "TimeoutSec=30", "After=network-online.target"} {
		if !strings.Contains(rw.Mount, want) {
			t.Errorf("the read-write mount lacks %q:\n%s", want, rw.Mount)
		}
	}
	if !strings.HasPrefix(rw.Mount, Marker) || !strings.HasPrefix(rw.Automount, Marker) {
		t.Error("both units open with the module's marker")
	}
	if strings.Contains(rw.Mount, "[Install]") {
		t.Error("the mount is never enabled: only the automount is")
	}
	for _, want := range []string{"[Automount]\nWhere=/srv/library\nTimeoutIdleSec=600", "WantedBy=remote-fs.target"} {
		if !strings.Contains(rw.Automount, want) {
			t.Errorf("the automount lacks %q:\n%s", want, rw.Automount)
		}
	}
	if rw.MountUnit != "srv-library.mount" || rw.AutoUnit != "srv-library.automount" || rw.Probe != "192.0.2.10:2049" {
		t.Errorf("names %+v", rw)
	}
	ro := NFSPair(Wanted{Name: "downloads", Mountpoint: "/srv/downloads", ReadOnly: true}, "192.0.2.10", downloads)
	if !strings.Contains(ro.Mount, "Options=ro,vers=4.2,soft,") {
		t.Errorf("a read-only share is mounted ro and soft:\n%s", ro.Mount)
	}
	served := library
	served.Access = "ro"
	if p := NFSPair(Wanted{Name: "library", Mountpoint: "/srv/library"}, "192.0.2.10", served); !strings.Contains(p.Mount, "Options=ro,") {
		t.Error("a share the server exports read-only is mounted read-only")
	}
}

func TestAnOccasionalSourceWaitsTenSecondsAndNeverFailsABoot(t *testing.T) {
	smb := SMBPair(Source{Name: "games", Kind: "smb", Host: "192.0.2.76", Share: "Share", Mountpoint: "/mnt/games"}, "/var/lib/mesh/mounts/smb-games.credentials", 1000, 1000)
	for _, want := range []string{"What=//192.0.2.76/Share", "Type=cifs", "credentials=/var/lib/mesh/mounts/smb-games.credentials", "nofail", "uid=1000,gid=1000", "TimeoutSec=10"} {
		if !strings.Contains(smb.Mount, want) {
			t.Errorf("the SMB mount lacks %q:\n%s", want, smb.Mount)
		}
	}
	if !smb.Occasional || smb.Probe != "192.0.2.76:445" || strings.Contains(smb.Mount, "password") {
		t.Errorf("smb %+v", smb)
	}
	disk := DiskPair(Source{Name: "usb", Kind: "disk", UUID: "1234-ABCD", Mountpoint: "/mnt/usb"})
	dev := `dev-disk-by\x2duuid-1234\x2dABCD.device`
	if !strings.Contains(disk.Mount, "BindsTo="+dev) || !strings.Contains(disk.Mount, "What=/dev/disk/by-uuid/1234-ABCD") {
		t.Errorf("the disk's mount goes with the disk:\n%s", disk.Mount)
	}
	if strings.Contains(disk.Automount, "BindsTo") || !strings.Contains(disk.Automount, "WantedBy=local-fs.target") {
		t.Errorf("the disk's automount stays armed when the disk is away:\n%s", disk.Automount)
	}
}

func TestALookWritesArmsAndRemovesOnlyTheModulesOwnUnits(t *testing.T) {
	f := newSystem(t)
	f.write(ConfigFile, config)
	f.write(ExportsFile, exportsAnswer(t, library, downloads))
	f.write("/var/lib/mesh/mounts/smb-credentials.secret", "[games]\nusername=root\npassword="+testPassword+"\n")
	// The operator's own unit for the downloads' mount point: never written over.
	f.write(filepath.Join(UnitDir, "srv-downloads.mount"), "[Mount]\nWhat=elsewhere\n")
	// A pair of the module's whose mount point nothing names any more.
	f.write(filepath.Join(UnitDir, "srv-old.mount"), Marker+"\n[Mount]\n")
	f.write(filepath.Join(UnitDir, "srv-old.automount"), Marker+"\n[Automount]\n")
	f.reachable["192.0.2.10:2049"] = true
	now := time.Date(2026, 10, 8, 19, 21, 0, 0, time.UTC)

	st := f.applier(now).Look(context.Background())

	if got := f.read(filepath.Join(UnitDir, "srv-library.mount")); !strings.Contains(got, "What=192.0.2.10:/tank/media") {
		t.Errorf("the library's mount: %q", got)
	}
	if got := f.read(filepath.Join(UnitDir, "srv-downloads.mount")); got != "[Mount]\nWhat=elsewhere\n" {
		t.Errorf("a unit file that is not the module's is left byte for byte: %q", got)
	}
	if _, err := os.Stat(filepath.Join(f.root, UnitDir, "srv-old.mount")); !os.IsNotExist(err) {
		t.Error("the module's pair nothing names any more is removed")
	}
	for _, c := range []string{"systemctl disable --now srv-old.automount", "systemctl stop srv-old.mount", "systemctl daemon-reload",
		"systemctl enable --now srv-library.automount", "systemctl enable --now mnt-games.automount", "systemctl enable --now mnt-usb.automount"} {
		if !f.called(c) {
			t.Errorf("not called: %s (calls %q)", c, f.calls)
		}
	}
	if f.called("systemctl enable --now srv-downloads.automount") {
		t.Error("the refused share is not armed")
	}
	if info, err := os.Stat(filepath.Join(f.root, "/srv/library")); err != nil || !info.IsDir() {
		t.Error("a missing mount point is made")
	}
	creds := filepath.Join(f.root, "/var/lib/mesh/mounts/smb-games.credentials")
	if info, err := os.Stat(creds); err != nil || info.Mode().Perm() != 0o600 {
		t.Fatalf("the source's login is a file only root reads: %v", err)
	}
	if b, _ := os.ReadFile(creds); string(b) != "username=root\npassword="+testPassword+"\n" {
		t.Errorf("credentials file %q", b)
	}

	states := map[string]ShareStatus{}
	for _, s := range st.Shares {
		states[s.Name] = s
	}
	if states["library"].State != StateArmed || states["games"].State != StateAbsent || states["usb"].State != StateAbsent {
		t.Errorf("states %+v", states)
	}
	if d := states["downloads"]; d.State != StateFailed || !strings.Contains(d.Why, "not the module's") {
		t.Errorf("downloads %+v", d)
	}
	if !strings.Contains(states["games"].Why, "not present") || states["games"].Since != now.Format(time.RFC3339) {
		t.Errorf("games %+v", states["games"])
	}
	// The password is in the secret and in the credentials file, and nowhere else.
	if strings.Contains(f.everything("smb-credentials.secret", "smb-games.credentials"), testPassword) {
		t.Error("the password leaked into a file the module wrote")
	}
	raw, _ := json.Marshal(f.machine().Health(now))
	if strings.Contains(string(raw), testPassword) {
		t.Error("the password leaked into the health")
	}

	// A second look a minute later changes nothing and keeps since.
	f.calls = nil
	later := now.Add(time.Minute)
	st = f.applier(later).Look(context.Background())
	if f.called("systemctl daemon-reload") || f.called("systemctl enable") {
		t.Errorf("a look with nothing to change changes nothing: %q", f.calls)
	}
	for _, s := range st.Shares {
		if s.Since != now.Format(time.RFC3339) {
			t.Errorf("%s since %s, want the first look's", s.Name, s.Since)
		}
	}
}

func TestASilentServerRemovesNoMount(t *testing.T) {
	f := newSystem(t)
	f.write(ConfigFile, "shares=library=/srv/library\nserver=homeserver\nat=192.0.2.10\n")
	f.write(filepath.Join(UnitDir, "srv-library.mount"), Marker+"\nkept\n")
	f.write(filepath.Join(UnitDir, "srv-library.automount"), Marker+"\nkept\n")
	st := f.applier(time.Now()).Look(context.Background())
	if f.read(filepath.Join(UnitDir, "srv-library.mount")) != Marker+"\nkept\n" {
		t.Error("with no answer from the server the pair stays as it is")
	}
	if len(st.Shares) != 1 || st.Shares[0].State != StateUnreachable || !strings.Contains(st.Shares[0].Why, "has not been read from the bus yet") {
		t.Errorf("shares %+v", st.Shares)
	}
	// And a missing config file writes and removes nothing.
	g := newSystem(t)
	g.write(filepath.Join(UnitDir, "srv-x.mount"), Marker+"\n")
	st = g.applier(time.Now()).Look(context.Background())
	if _, err := os.Stat(filepath.Join(g.root, UnitDir, "srv-x.mount")); err != nil || len(st.Problems) == 0 {
		t.Errorf("without its config the process removes nothing and says why: %v %v", err, st.Problems)
	}
}

func TestAMissingLoginIsSaidWithItsRemedyAndTheSourceIsNotMounted(t *testing.T) {
	f := newSystem(t)
	f.write(ConfigFile, "sources=games=smb://192.0.2.76/Share@/mnt/games\nsecret=/var/lib/mesh/mounts/smb-credentials.secret\nstate=/var/lib/mesh/mounts\n")
	f.write("/var/lib/mesh/mounts/smb-credentials.secret", "[other]\nusername=x\npassword="+testPassword+"\n")
	now := time.Now()
	st := f.applier(now).Look(context.Background())
	if len(st.Shares) != 1 || st.Shares[0].State != StateFailed ||
		!strings.Contains(st.Shares[0].Why, "secret accept <node> mounts smb-credentials --from <file>") {
		t.Fatalf("shares %+v", st.Shares)
	}
	if _, err := os.Stat(filepath.Join(f.root, UnitDir, "mnt-games.mount")); !os.IsNotExist(err) {
		t.Error("a source without its login gets no units")
	}
	h := f.machine().Health(now)
	if h.Healthy || !strings.Contains(h.Why, "login is not given") || strings.Contains(h.Why, testPassword) {
		t.Errorf("health %+v", h)
	}
	creds, problems := ParseSMBCredentials("[a]\nusername=u\npassword=" + testPassword + "\nbogus=1\n[b]\npassword=p\n")
	if creds["a"].Password != testPassword || len(problems) != 2 || strings.Contains(strings.Join(problems, " "), testPassword) {
		t.Errorf("creds %v problems %q", len(creds), problems)
	}
}

func TestTheHealthGivesAShareFiveMinutesAndAnAbsentSourceNone(t *testing.T) {
	now := time.Date(2026, 10, 8, 19, 30, 0, 0, time.Local)
	at := func(d time.Duration) string { return now.Add(-d).Format(time.RFC3339) }
	st := Status{Looked: at(10 * time.Second), Server: "homeserver", Shares: []ShareStatus{
		{Name: "library", Kind: "nfs", Mountpoint: "/srv/library", State: StateUnreachable, Since: at(4 * time.Minute), Why: "192.0.2.10:2049 does not answer"},
		{Name: "games", Kind: "smb", Occasional: true, Mountpoint: "/mnt/games", State: StateAbsent, Since: at(3 * time.Hour)},
	}}
	if h := Judge(st, nil, now); !h.Healthy || !strings.Contains(strings.Join(h.Said, " "), "games at /mnt/games: not present since 16:30") {
		t.Errorf("under five minutes, and an absent source, are healthy: %+v", h)
	}
	st.Shares[0].Since = at(9 * time.Minute)
	h := Judge(st, nil, now)
	if h.Healthy || !strings.Contains(h.Why, "The share library of homeserver is not reachable from this machine since 19:21") {
		t.Errorf("five minutes away raises: %+v", h)
	}
	st.Shares = []ShareStatus{{Name: "library", Kind: "nfs", Mountpoint: "/srv/library", State: StateFailed, Since: at(time.Minute),
		Why: "its automount srv-library.automount is not armed (inactive)"}}
	if h := Judge(st, nil, now); h.Healthy {
		t.Error("an automount not armed is raised at once")
	}
	st.Looked = at(3 * time.Minute)
	st.Shares = nil
	if h := Judge(st, nil, now); h.Healthy || !strings.Contains(h.Why, "last looked") {
		t.Errorf("a stale look is raised: %+v", h)
	}
	if h := Judge(Status{}, errors.New("not present"), now); h.Healthy {
		t.Error("no status is unhealthy")
	}
	if h := Judge(Status{Looked: at(time.Second)}, nil, now); !h.Healthy || h.Why != "This machine is asked to mount nothing." {
		t.Errorf("nothing asked: %+v", h)
	}
}

// The workstation's two lines as they were found (research 038), in documentation addresses.
const operatorsFstab = "UUID=ad8b / ext4 rw,relatime 0 1\n" +
	"192.0.2.10:/tank/media  /srv/library  nfs  defaults,_netdev  0 0\n" +
	"//192.0.2.76/Share  /mnt/games  cifs  username=root,password=" + testPassword + ",iocharset=utf8,sec=ntlmssp  0 0\n"

func TestAnFstabLineIsTakenOverOnlyOnceItsReplacementIsArmed(t *testing.T) {
	f := newSystem(t)
	f.write("/etc/fstab", operatorsFstab)
	m := f.machine()
	now := time.Date(2026, 10, 8, 20, 0, 0, 0, time.UTC)
	ctx := context.Background()

	a, err := m.Adopt(ctx, "/mnt/games", false, "", now)
	if err != nil || a.Done || !strings.HasPrefix(a.Said, "Would be refused now: the module has no unit pair") {
		t.Fatalf("no pair yet: %+v %v", a, err)
	}
	if strings.Contains(a.Was, testPassword) || !strings.Contains(a.Was, "password=(redacted)") {
		t.Errorf("the dry run says the line without its password: %q", a.Was)
	}
	if _, err := m.AdoptAsRoot(ctx, "/mnt/games", now); err == nil {
		t.Fatal("the root half refuses too")
	}
	if f.read("/etc/fstab") != operatorsFstab {
		t.Fatal("a refusal changes nothing")
	}

	f.write(filepath.Join(UnitDir, "mnt-games.mount"), Marker+"\n")
	f.write(filepath.Join(UnitDir, "mnt-games.automount"), Marker+"\n")
	f.units["mnt-games.automount"] = map[string]string{"ActiveState": "inactive"}
	if _, err := m.AdoptAsRoot(ctx, "/mnt/games", now); err == nil || !strings.Contains(err.Error(), "not armed") {
		t.Fatalf("an automount not armed refuses: %v", err)
	}
	f.units["mnt-games.automount"] = map[string]string{"ActiveState": "active"}
	if a, err := m.Adopt(ctx, "/mnt/games", false, "", now); err != nil || !strings.HasPrefix(a.Said, "A dry run") || a.Line != 3 {
		t.Fatalf("dry run: %+v %v", a, err)
	}
	if _, err := m.Adopt(ctx, "/mnt/games", true, "", now); err == nil {
		t.Error("confirm without why is refused")
	}

	a, err = m.AdoptAsRoot(ctx, "/mnt/games", now)
	if err != nil || !a.Done || a.Line != 3 || a.Copy != "/etc/fstab.mesh-adopted-20261008-200000" {
		t.Fatalf("adopt: %+v %v", a, err)
	}
	got := f.read("/etc/fstab")
	lines := strings.Split(got, "\n")
	if lines[0] != "UUID=ad8b / ext4 rw,relatime 0 1" || lines[1] != "192.0.2.10:/tank/media  /srv/library  nfs  defaults,_netdev  0 0" {
		t.Errorf("every other line is kept byte for byte:\n%s", got)
	}
	if !strings.HasPrefix(lines[2], AdoptedPrefix+"2026-10-08: //192.0.2.76/Share") || strings.Contains(got, testPassword) {
		t.Errorf("the line is commented out with its password redacted:\n%s", got)
	}
	info, err := os.Stat(filepath.Join(f.root, a.Copy))
	if err != nil || info.Mode().Perm() != 0o600 || f.read(a.Copy) != operatorsFstab {
		t.Errorf("the file as it was is kept, root only: %v", err)
	}
	if !f.called("systemctl daemon-reload") {
		t.Error("the service manager reloads")
	}
	raw, _ := json.Marshal(a)
	if strings.Contains(string(raw), testPassword) {
		t.Error("the answer holds the password")
	}
	if _, err := m.AdoptAsRoot(ctx, "/mnt/games", now); err == nil || !strings.Contains(err.Error(), "no line for /mnt/games") {
		t.Errorf("a line taken over is not taken twice: %v", err)
	}
	if _, _, err := PlanAdoption("a /x nfs d 0 0\nb /x nfs d 0 0\n", "/x", now); err == nil || !strings.Contains(err.Error(), "more than one line") {
		t.Errorf("two lines for one mount point are left to a person: %v", err)
	}
}

func TestAFailedAskKeepsTheLastAnswer(t *testing.T) {
	cfg := ParseConfig("shares=library=/srv/library\nserver=homeserver\nat=192.0.2.10\n")
	now := time.Now()
	var asked string
	ok := func(key string) (json.RawMessage, error) {
		asked = key
		return json.RawMessage(`{"shares":[{"name":"library","path":"/tank/media","access":"rw","uid":1001,"gid":2000,"live":true}]}`), nil
	}
	first := AskExports(cfg, ExportsAnswer{}, ok, now)
	if asked != "homeserver" || len(first.Shares) != 1 || first.Error != "" {
		t.Fatalf("first %+v asked %q", first, asked)
	}
	fail := func(string) (json.RawMessage, error) { return nil, errors.New("no responders") }
	second := AskExports(cfg, first, fail, now.Add(time.Minute))
	empty := AskExports(cfg, first, func(string) (json.RawMessage, error) { return nil, nil }, now)
	if !strings.Contains(empty.Error, "keeps nothing") || len(empty.Shares) != 1 {
		t.Errorf("a machine with nothing kept yet: %+v", empty)
	}
	if second.Error != "no responders" || len(second.Shares) != 1 || second.Answered != first.Answered {
		t.Errorf("second %+v", second)
	}
	if got := ParseConfig("at=homeserver.mesh.example\n").ServerNode(); got != "homeserver" {
		t.Errorf("without from, the first label of at: %q", got)
	}
}

func TestTheBundlePutsWhatTheProcessFoundOnTheBus(t *testing.T) {
	f := newSystem(t)
	f.write(ConfigFile, "shares=library=/srv/library\nserver=homeserver\nat=192.0.2.10\n")
	f.write(StatusFile, `{"looked":"2026-10-08T19:21:00Z","shares":[{"name":"library","state":"armed"}]}`)
	var put []string
	last := ""
	ask := func(string) (json.RawMessage, error) { return json.RawMessage(`{"shares":[]}`), nil }
	said := f.machine().Share("workstation", ask, func(key string, _ any) error { put = append(put, key); return nil }, &last, time.Now())
	if len(said) != 0 || len(put) != 1 || put[0] != "workstation" || !strings.Contains(f.read(ExportsFile), `"server": "homeserver"`) {
		t.Errorf("said %q put %q exports %q", said, put, f.read(ExportsFile))
	}
	f.machine().Share("workstation", ask, func(key string, _ any) error { put = append(put, key); return nil }, &last, time.Now())
	if len(put) != 1 {
		t.Error("an unchanged status is not put again")
	}
}

// In production the acting process and the judging one are two: apply writes and arms and says nothing
// of how the shares are; watch writes and arms nothing and says how they are.
func TestApplyActsAndWatchJudgesAndNeitherDoesTheOthersWork(t *testing.T) {
	f := newSystem(t)
	f.write(ConfigFile, config)
	f.write(ExportsFile, exportsAnswer(t, library, downloads))
	f.write("/var/lib/mesh/mounts/smb-credentials.secret", "[other]\nusername=x\npassword="+testPassword+"\n")
	f.write(filepath.Join(UnitDir, "srv-downloads.mount"), "[Mount]\nWhat=elsewhere\n")
	f.reachable["192.0.2.10:2049"] = true
	now := time.Now()

	apply := f.applier(now)
	apply.Judge = false
	apply.Look(context.Background())
	if _, err := os.Stat(filepath.Join(f.root, StatusFile)); !os.IsNotExist(err) {
		t.Error("apply leaves no status: that is watch's")
	}
	if !f.called("systemctl enable --now srv-library.automount") || f.read(filepath.Join(UnitDir, "srv-library.mount")) == "" {
		t.Fatal("apply writes and arms")
	}
	applied, err := readJSON[Applied](f.machine(), AppliedFile)
	if err != nil || len(applied.NotSet) != 2 {
		t.Fatalf("apply says what it could not set up: %+v %v", applied, err)
	}

	f.calls = nil
	watch := f.applier(now)
	watch.Act = false
	f.write(filepath.Join(UnitDir, "srv-gone.mount"), Marker+"\n")
	st := watch.Look(context.Background())
	for _, c := range f.calls {
		if !strings.HasPrefix(c, "systemctl show") {
			t.Errorf("watch only reads the service manager: %s", c)
		}
	}
	if _, err := os.Stat(filepath.Join(f.root, UnitDir, "srv-gone.mount")); err != nil {
		t.Error("watch removes nothing")
	}
	states := map[string]string{}
	for _, s := range st.Shares {
		states[s.Name] = s.State
	}
	if states["library"] != StateArmed || states["downloads"] != StateFailed || states["games"] != StateFailed || states["usb"] != StateAbsent {
		t.Errorf("watch says how each is: %v", states)
	}
	if strings.Contains(f.everything("smb-credentials.secret"), testPassword) {
		t.Error("the password leaked")
	}
}

// setUnit sets one unit's state as the service manager answers it, under the lock.
func (f *fakeSystem) setUnit(unit string, state map[string]string) {
	f.mu.Lock()
	defer f.mu.Unlock()
	f.units[unit] = state
}