package main

// What wants a unit, and a failed record cleared (novox/hq issue 332): over a fake runner and a fake
// directory listing, so no link is made to test them (the mesh makes no symbolic links, its tests
// included); the real listing is tested on what a temporary directory holds without one.

import (
	"errors"
	"io/fs"
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"testing"
)

// tree is a fake file system of directories, each a list of entries; a directory not in it does not exist.
type tree map[string][]Entry

func (t tree) readDir(dir string) ([]Entry, error) {
	if e, ok := t[dir]; ok {
		if e == nil {
			return nil, fs.ErrPermission
		}
		return e, nil
	}
	return nil, fs.ErrNotExist
}

const home = "/home/operator"

func withTree(m *Manager, t tree) *Manager {
	m.Home, m.ReadDir = home, t.readDir
	m.Lstat = func(path string) (Entry, error) {
		for _, e := range t[filepath.Dir(path)] {
			if e.Name == filepath.Base(path) {
				return e, nil
			}
		}
		return Entry{}, fs.ErrNotExist
	}
	return m
}

// The leftover of a removed package: its file is gone, an enable link in the account's own configuration
// still names it, and the manager still has default.target wanting it.
func greenclip() tree {
	user := home + "/.config/systemd/user"
	return tree{
		user: {{Name: "default.target.wants", Dir: true}, {Name: "timers.target.wants", Dir: true}, {Name: "clip.service"}},
		user + "/default.target.wants": {
			{Name: "greenclip.service", Link: "/usr/lib/systemd/user/greenclip.service", Dangles: true},
			{Name: "pipewire.service", Link: "/usr/lib/systemd/user/pipewire.service"},
		},
		user + "/timers.target.wants":                {{Name: "backup.timer", Link: "/usr/lib/systemd/user/backup.timer"}},
		"/usr/lib/systemd/user":                      {{Name: "pipewire.service"}, {Name: "sockets.target.wants", Dir: true}},
		"/usr/lib/systemd/user/sockets.target.wants": {{Name: "pipewire.socket", Link: "../pipewire.socket"}},
	}
}

func showAndReverse(show, reverse string) func(c call) Ran {
	return func(c call) Ran {
		for _, a := range c.args {
			if a == "show" {
				return Ran{Stdout: show}
			}
			if a == "list-dependencies" {
				return Ran{Stdout: reverse}
			}
		}
		return Ran{}
	}
}

func TestWantedByFindsADanglingEnableLinkInTheAccountsOwnConfiguration(t *testing.T) {
	var calls []call
	run := fake(showAndReverse(
		"LoadState=not-found\nActiveState=failed\nSubState=failed\nUnitFileState=\nFragmentPath=\nWantedBy=default.target\nRequiredBy=\nTriggeredBy=\n",
		"greenclip.service\n  default.target\n"), &calls)
	answer, err := withTree(operator(run), greenclip()).WantedBy(User, "greenclip.service")
	if err != nil {
		t.Fatal(err)
	}
	links := answer["links"].([]EnableLink)
	want := []EnableLink{{Path: home + "/.config/systemd/user/default.target.wants/greenclip.service", Of: "default.target",
		Dependency: "Wants", Target: "/usr/lib/systemd/user/greenclip.service", Dangles: true, Link: true,
		Whose: "the operator account's own configuration", removable: true}}
	if !reflect.DeepEqual(links, want) {
		t.Fatalf("links %+v", links)
	}
	manager := answer["manager"].(map[string]any)
	if !reflect.DeepEqual(manager["WantedBy"], []string{"default.target"}) || manager["LoadState"] != "not-found" {
		t.Fatalf("manager %+v", manager)
	}
	if _, empty := manager["RequiredBy"]; empty {
		t.Fatal("an empty property is answered as a dependency")
	}
	if !reflect.DeepEqual(manager["reverse"], []string{"default.target"}) {
		t.Fatalf("reverse %v", manager["reverse"])
	}
	said := strings.Join(answer["findings"].([]string), "\n")
	if !strings.Contains(said, "default.target.wants/greenclip.service makes default.target want greenclip.service") ||
		!strings.Contains(said, "which does not exist") || !strings.Contains(said, "reset-failed") {
		t.Fatalf("findings %q", said)
	}
	if _, has := answer["unread"]; has {
		t.Fatalf("a directory that does not exist was said as unread: %v", answer["unread"])
	}
	// Read-only: the manager is only asked.
	for _, c := range calls {
		if c.args[1] != "show" && c.args[1] != "list-dependencies" {
			t.Fatalf("WantedBy ran %v", c.args)
		}
		if c.args[0] != "--user" {
			t.Fatalf("a user-scope question went to the system manager: %v", c.args)
		}
	}
	// The unit comes after "--", so a name that slipped past would still not be an option.
	last := calls[len(calls)-1].args
	if last[len(last)-2] != "--" {
		t.Fatalf("%v", last)
	}
}

func TestWantedByMatchesALinkByWhatItPointsAt(t *testing.T) {
	user := home + "/.config/systemd/user"
	fsys := tree{
		user: {{Name: "graphical-session.target.requires", Dir: true}},
		user + "/graphical-session.target.requires": {{Name: "clipboard.service", Link: "/usr/lib/systemd/user/greenclip.service"}},
	}
	answer, err := withTree(operator(fake(showAndReverse("LoadState=loaded\n", "greenclip.service\n"), nil)), fsys).WantedBy(User, "greenclip.service")
	if err != nil {
		t.Fatal(err)
	}
	links := answer["links"].([]EnableLink)
	if len(links) != 1 || links[0].Dependency != "Requires" || links[0].Of != "graphical-session.target" || links[0].Dangles {
		t.Fatalf("%+v", links)
	}
}

func TestWantedBySaysWhenNothingNamesTheUnit(t *testing.T) {
	answer, err := withTree(operator(fake(showAndReverse("LoadState=not-found\nActiveState=failed\nWantedBy=\n", "gone.service\n"), nil)), greenclip()).WantedBy(User, "gone.service")
	if err != nil {
		t.Fatal(err)
	}
	if len(answer["links"].([]EnableLink)) != 0 {
		t.Fatalf("%v", answer["links"])
	}
	said := strings.Join(answer["findings"].([]string), "\n")
	if !strings.Contains(said, "nothing names gone.service in the directories searched:") {
		t.Fatalf("%q", said)
	}
}

func TestWantedBySaysAnUnreadableDirectoryAndAManagerThatDoesNotAnswer(t *testing.T) {
	fsys := greenclip()
	fsys["/etc/systemd/user"] = nil // unreadable
	run := fake(func(call) Ran { return Ran{Status: 1, Stderr: "Failed to connect to bus: No such file or directory"} }, nil)
	answer, err := withTree(operator(run), fsys).WantedBy(User, "greenclip.service")
	if err != nil {
		t.Fatalf("an unreachable manager failed the whole answer: %v", err)
	}
	manager := answer["manager"].(map[string]any)
	if e, _ := manager["error"].(string); !strings.Contains(e, "does not answer") {
		t.Fatalf("%+v", manager)
	}
	if len(answer["links"].([]EnableLink)) != 1 {
		t.Fatal("the links on disk were not read without the manager")
	}
	unread, _ := answer["unread"].([]string)
	if len(unread) != 1 || !strings.HasPrefix(unread[0], "/etc/systemd/user: ") {
		t.Fatalf("%v", unread)
	}
	said := strings.Join(answer["findings"].([]string), "\n")
	if !strings.Contains(said, "only the links on disk are known") || !strings.Contains(said, "could not be read") {
		t.Fatalf("%q", said)
	}
	if strings.Contains(said, "nothing names") {
		t.Fatal("an incomplete answer said nothing names the unit")
	}
}

func TestWantedByInTheSystemScopeReadsTheMachinesDirectoriesUnescalated(t *testing.T) {
	var calls []call
	fsys := tree{
		"/etc/systemd/system":                         {{Name: "multi-user.target.wants", Dir: true}},
		"/etc/systemd/system/multi-user.target.wants": {{Name: "sshd.service", Link: "/usr/lib/systemd/system/sshd.service"}},
	}
	m := withTree(operator(fake(showAndReverse("LoadState=loaded\nWantedBy=multi-user.target\n", "sshd.service\nmulti-user.target\ngraphical.target\n"), &calls)), fsys)
	answer, err := m.WantedBy(System, "sshd.service")
	if err != nil {
		t.Fatal(err)
	}
	for _, c := range calls {
		if c.cmd != "systemctl" {
			t.Fatalf("a read was escalated: %s %v", c.cmd, c.args)
		}
	}
	links := answer["links"].([]EnableLink)
	if len(links) != 1 || links[0].Whose != "the machine's configuration" {
		t.Fatalf("%+v", links)
	}
	if !reflect.DeepEqual(answer["manager"].(map[string]any)["reverse"], []string{"multi-user.target", "graphical.target"}) {
		t.Fatalf("%v", answer["manager"])
	}
	for _, d := range answer["searched"].([]ConfigDir) {
		if strings.HasPrefix(d.Path, home) {
			t.Fatal("the system scope searched the account's home")
		}
	}
}

func TestWantedByRefusesAUnitThatReadsAsAnOption(t *testing.T) {
	m := withTree(operator(fake(func(call) Ran { t.Fatal("ran"); return Ran{} }, nil)), tree{})
	if _, err := m.WantedBy(User, "--all"); err == nil {
		t.Fatal("an option was taken as a unit")
	}
}

func TestResetFailedClearsOneUnitEscalatedOnlyInTheSystemScope(t *testing.T) {
	if p, a := escalated("systemctl", []string{"reset-failed", "x.mount"}, System, 1000); p != "sudo" || !reflect.DeepEqual(a, []string{"-n", "systemctl", "reset-failed", "x.mount"}) {
		t.Fatalf("%s %v", p, a)
	}
	var calls []call
	m := operator(fake(func(c call) Ran {
		if c.args[1] == "show" {
			return Ran{Stdout: "LoadState=not-found\nActiveState=inactive\nSubState=dead\nUnitFileState=\nFragmentPath=\n"}
		}
		return Ran{}
	}, &calls))
	var reset stdioTool
	for _, tool := range tools(m) {
		if tool.Name == seat+".reset-failed" {
			reset = stdioTool{tool.Run}
		}
	}
	if reset.run == nil {
		t.Fatal("reset-failed is not served")
	}
	out, err := reset.run(map[string]any{"unit": "greenclip.service", "scope": "user"})
	if err != nil {
		t.Fatal(err)
	}
	if !reflect.DeepEqual(calls[0].args, []string{"--user", "reset-failed", "--", "greenclip.service"}) || calls[0].cmd != "systemctl" {
		t.Fatalf("%s %v", calls[0].cmd, calls[0].args)
	}
	answer := out.(map[string]any)
	if answer["active"] != "inactive" || answer["verb"] != "reset-failed" {
		t.Fatalf("%v", answer)
	}
	if _, err := reset.run(map[string]any{"scope": "user"}); err == nil {
		t.Fatal("reset-failed without a unit would reset every failed unit")
	}
	if _, err := reset.run(map[string]any{"unit": "-a", "scope": "user"}); err == nil {
		t.Fatal("an option was taken as a unit")
	}
}

type stdioTool struct {
	run func(map[string]any) (any, error)
}

// **A glob is not a unit** (the review of mesh-catalog #137): systemctl expands it to every loaded unit it
// matches, so `reset-failed` or `stop` of "*" would act on all of them. Refused before anything runs, for
// every verb taking a unit.
func TestAGlobIsRefusedAsAUnitByEveryVerb(t *testing.T) {
	for _, bad := range []string{"*", "*.service", "foo?.service", "a[bc].mount"} {
		if unitArg(bad) == nil {
			t.Errorf("%q accepted", bad)
		}
	}
	var calls []call
	m := withTree(operator(fake(func(call) Ran { return Ran{} }, &calls)), tree{})
	m.State = t.TempDir()
	for _, tool := range tools(m) {
		verb := strings.TrimPrefix(tool.Name, seat+".")
		if verb == "units" || verb == "failed" {
			continue // a pattern, and no unit
		}
		_, err := tool.Run(map[string]any{"unit": "*", "scope": "user", "why": "test"})
		if err == nil {
			t.Errorf("%s accepted {\"unit\":\"*\"}", verb)
		}
	}
	if len(calls) != 0 {
		t.Fatalf("a glob reached the manager: %v", calls)
	}
}

// The unit is given after "--" to show as well as to an act, so nothing after it is read as an option.
func TestTheUnitComesAfterTheEndOfOptions(t *testing.T) {
	var calls []call
	m := operator(fake(func(call) Ran { return Ran{Stdout: "LoadState=loaded\n"} }, &calls))
	if _, err := m.Status(System, "sshd.service"); err != nil {
		t.Fatal(err)
	}
	a := calls[0].args
	if a[0] != "show" || a[len(a)-2] != "--" || a[len(a)-1] != "sshd.service" {
		t.Fatalf("%v", a)
	}
}

// A target that could not be looked at, for any reason but its not existing, is neither dangling nor not:
// it is said as the error it was, and the answer does not say nothing names the unit.
func TestALinkWhoseTargetCannotBeLookedAtIsNotSaidToDangle(t *testing.T) {
	user := home + "/.config/systemd/user"
	fsys := tree{
		user:                           {{Name: "default.target.wants", Dir: true}},
		user + "/default.target.wants": {{Name: "x.service", Link: "/mnt/away/x.service", Error: "stat /mnt/away/x.service: permission denied"}},
	}
	answer, err := withTree(operator(fake(showAndReverse("LoadState=loaded\n", "x.service\n"), nil)), fsys).WantedBy(User, "x.service")
	if err != nil {
		t.Fatal(err)
	}
	links := answer["links"].([]EnableLink)
	if len(links) != 1 || links[0].Dangles || links[0].Error == "" {
		t.Fatalf("%+v", links)
	}
	said := strings.Join(answer["findings"].([]string), "\n")
	if !strings.Contains(said, "could not be looked at: stat /mnt/away/x.service: permission denied") || strings.Contains(said, "does not exist") {
		t.Fatalf("%q", said)
	}
}

// A *.wants directory that is itself a link is followed only into the directories searched: one leading
// elsewhere is said and not read, so neither the search nor a removal after it can be pointed anywhere.
func TestALinkedDependencyDirectoryIsFollowedOnlyIntoTheSearchedDirectories(t *testing.T) {
	user := home + "/.config/systemd/user"
	fsys := tree{
		user: {
			{Name: "default.target.wants", Link: "/srv/elsewhere"},
			{Name: "graphical-session.target.wants", Link: "/etc/systemd/user/shared.wants"},
		},
		"/srv/elsewhere":                 {{Name: "x.service", Link: "/gone/x.service", Dangles: true}},
		"/etc/systemd/user/shared.wants": {{Name: "x.service", Link: "/gone/x.service", Dangles: true}},
	}
	read := []string{}
	m := withTree(operator(fake(showAndReverse("LoadState=not-found\n", "x.service\n"), nil)), fsys)
	inner := m.ReadDir
	m.ReadDir = func(dir string) ([]Entry, error) { read = append(read, dir); return inner(dir) }
	answer, err := m.WantedBy(User, "x.service")
	if err != nil {
		t.Fatal(err)
	}
	for _, d := range read {
		if d == "/srv/elsewhere" {
			t.Fatal("a linked .wants outside the searched directories was followed")
		}
	}
	links := answer["links"].([]EnableLink)
	if len(links) != 1 || links[0].Path != user+"/graphical-session.target.wants/x.service" || links[0].removable {
		t.Fatalf("%+v", links)
	}
	unread, _ := answer["unread"].([]string)
	if len(unread) != 1 || !strings.Contains(unread[0], "outside the directories searched, not followed") {
		t.Fatalf("%v", unread)
	}
}

// "Nothing names it" is only ever said of the directories searched, and the account's own are not among
// them when its home is not known — which is said.
func TestNothingNamesItIsSaidOfTheDirectoriesSearchedAndTheHomeWhenUnknown(t *testing.T) {
	m := withTree(operator(fake(showAndReverse("LoadState=not-found\n", "x.service\n"), nil)), tree{})
	m.Home = ""
	answer, err := m.WantedBy(User, "x.service")
	if err != nil {
		t.Fatal(err)
	}
	for _, d := range answer["searched"].([]ConfigDir) {
		if strings.Contains(d.Path, ".config") || strings.Contains(d.Path, ".local") || d.Path == "" {
			t.Fatalf("searched %q without a home", d.Path)
		}
	}
	said := strings.Join(answer["findings"].([]string), "\n")
	if !strings.Contains(said, "nothing names x.service in the directories searched, which are not all of them") ||
		!strings.Contains(said, "the account's home is not known") {
		t.Fatalf("%q", said)
	}
	m.Home = home
	answer, _ = m.WantedBy(User, "x.service")
	said = strings.Join(answer["findings"].([]string), "\n")
	if !strings.Contains(said, "nothing names x.service in the directories searched:") {
		t.Fatalf("%q", said)
	}
}

// Every directory systemd reads units from, in both scopes (systemd.unit(5)).
func TestTheSearchedDirectoriesAreTheManagersLoadPath(t *testing.T) {
	m := withTree(operator(nil), tree{})
	paths := func(s Scope) string {
		var out []string
		for _, d := range m.configDirs(s) {
			out = append(out, d.Path)
		}
		return strings.Join(out, "\n")
	}
	for _, want := range []string{"/etc/systemd/system.control", "/run/systemd/transient", "/run/systemd/generator.early",
		"/etc/systemd/system", "/run/systemd/system", "/run/systemd/generator", "/usr/local/lib/systemd/system",
		"/usr/lib/systemd/system", "/run/systemd/generator.late"} {
		if !strings.Contains(paths(System)+"\n", want+"\n") {
			t.Errorf("system scope does not search %s", want)
		}
	}
	for _, want := range []string{home + "/.config/systemd/user.control", "/run/user/1000/systemd/user", home + "/.config/systemd/user",
		"/etc/systemd/user", "/etc/xdg/systemd/user", home + "/.local/share/systemd/user", "/usr/local/lib/systemd/user", "/usr/lib/systemd/user"} {
		if !strings.Contains(paths(User)+"\n", want+"\n") {
			t.Errorf("user scope does not search %s", want)
		}
	}
}

// The real listing, by lstat, on what a temporary directory holds: a directory, a file, and a directory
// that does not exist or cannot be read.
func TestReadDirListsByLstat(t *testing.T) {
	dir := t.TempDir()
	if err := os.Mkdir(filepath.Join(dir, "default.target.wants"), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dir, "x.service"), []byte("[Unit]\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	entries, err := readDir(dir)
	if err != nil {
		t.Fatal(err)
	}
	want := []Entry{{Name: "default.target.wants", Dir: true}, {Name: "x.service"}}
	if !reflect.DeepEqual(entries, want) {
		t.Fatalf("%+v", entries)
	}
	if e, err := lstatEntry(filepath.Join(dir, "x.service")); err != nil || e.Link != "" || e.Dangles || e.Dir {
		t.Fatalf("%+v %v", e, err)
	}
	if _, err := readDir(filepath.Join(dir, "absent")); !errors.Is(err, fs.ErrNotExist) {
		t.Fatalf("a missing directory: %v", err)
	}
	if os.Getuid() != 0 {
		locked := filepath.Join(dir, "locked")
		if err := os.Mkdir(locked, 0o000); err != nil {
			t.Fatal(err)
		}
		defer os.Chmod(locked, 0o755)
		if _, err := readDir(locked); err == nil || errors.Is(err, fs.ErrNotExist) {
			t.Fatalf("an unreadable directory read as %v", err)
		}
	}
	// And through the search: a real tree with no link in it names nothing, and says so.
	m := operator(fake(showAndReverse("LoadState=not-found\n", "x.service\n"), nil))
	m.Home, m.ReadDir = dir, readDir
	answer, err := m.WantedBy(User, "x.service")
	if err != nil {
		t.Fatal(err)
	}
	if len(answer["links"].([]EnableLink)) != 0 {
		t.Fatalf("%v", answer["links"])
	}
}