package units

import (
	"context"
	"errors"
	"strings"
	"testing"
	"time"

	"github.com/novox/mesh-host/internal/declaration"
)

// The reading of failed units (novox/hq issue 315, "how it is checked"): a failed unit a module states,
// writes or installs is that module's, in either manager; one no module places is the machine's; a unit
// liveness judges is left to it; the two-look rule holds both ways; a manager that cannot be read is
// unread, never healthy; and only reads are asked.

type fakeReader struct {
	failed  map[string][]Listed // by "system" or "user:<account>"
	shown   map[string]Shown    // by unit
	owners  map[string]string   // by path
	unread  map[string]error
	ownerQs int
}

func mgr(scope, user string) string {
	if scope == ScopeUser {
		return "user:" + user
	}
	return "system"
}

func (f *fakeReader) Failed(_ context.Context, scope, user string) ([]Listed, error) {
	if err := f.unread[mgr(scope, user)]; err != nil {
		return nil, err
	}
	return f.failed[mgr(scope, user)], nil
}

func (f *fakeReader) Show(_ context.Context, _, _ string, units []string) (map[string]Shown, error) {
	out := map[string]Shown{}
	for _, u := range units {
		out[u] = f.shown[u]
	}
	return out, nil
}

func (f *fakeReader) PackageOwning(_ context.Context, path string) (string, bool, error) {
	f.ownerQs++
	p, ok := f.owners[path]
	return p, ok, nil
}

// shanks is the desktop as found on 2026-10-08: two mounts of the machine's own mount table, the
// Razer daemon's packaged user unit, and a unit a removed package left behind.
func shanks() *fakeReader {
	return &fakeReader{
		failed: map[string][]Listed{
			"system": {{Unit: "mnt-recalbox.mount", Load: "loaded"}, {Unit: "storage-media.mount", Load: "loaded"}},
			"user:operator": {{Unit: "greenclip.service", Load: "not-found"},
				{Unit: "openrazer-daemon.service", Load: "loaded"}},
		},
		shown: map[string]Shown{
			"mnt-recalbox.mount":       {FragmentPath: "/run/systemd/generator/mnt-recalbox.mount", Result: "exit-code"},
			"storage-media.mount":      {FragmentPath: "/run/systemd/generator/storage-media.mount", Result: "timeout"},
			"greenclip.service":        {},
			"openrazer-daemon.service": {FragmentPath: "/usr/lib/systemd/user/openrazer-daemon.service", Result: "exit-code"},
		},
		owners: map[string]string{"/usr/lib/systemd/user/openrazer-daemon.service": "openrazer-daemon"},
	}
}

func declared() *declaration.Declaration {
	return &declaration.Declaration{Resources: []declaration.Resource{
		&declaration.Package{ID: "openrazer.daemon", Type: declaration.TypePackage, Package: "openrazer-daemon"},
		&declaration.Package{ID: "clipmenu.greenclip", Type: declaration.TypePackage, Package: "rofi-greenclip", Absent: true},
		&declaration.User{ID: "zsh.account", Type: declaration.TypeUser, Name: "operator"},
		&declaration.Service{ID: "sshd.run", Type: declaration.TypeService, Unit: "sshd.service", State: "running"},
		&declaration.Service{ID: "power.after-boot", Type: declaration.TypeService, Unit: "mesh-power-after-boot.service"},
		&declaration.File{ID: "watcher.unit", Type: declaration.TypeFile, Path: "/home/operator/.config/systemd/user/watcher.service"},
	}}
}

var t0 = time.Date(2026, 10, 8, 12, 0, 0, 0, time.UTC)

func lookTwice(t *testing.T, j *Judge) Statement {
	t.Helper()
	now := t0
	j.Now = func() time.Time { return now }
	first, _ := j.Look(context.Background())
	if len(first.Failed) != 0 {
		t.Fatalf("a unit was said failed on its first look: %+v", first.Failed)
	}
	now = now.Add(15 * time.Second)
	st, _ := j.Look(context.Background())
	return st
}

func TestTheModulesAndTheMachinesFailures(t *testing.T) {
	r := shanks()
	j := New(r)
	j.Set(OwnedBy(declared(), nil))
	st := lookTwice(t, j)
	if st.State != Degraded {
		t.Fatalf("state %q, want degraded", st.State)
	}
	owned := st.Owned()
	if len(owned) != 1 || owned[0].Unit != "openrazer-daemon.service" || owned[0].Module != "openrazer" ||
		owned[0].Resource != "openrazer.daemon" || owned[0].Via != ViaPackage || owned[0].Scope != ScopeUser {
		t.Fatalf("the Razer daemon's packaged user unit is openrazer's: %+v", owned)
	}
	if owned[0].Since != t0 || owned[0].Streak != 2 || owned[0].Result != "exit-code" {
		t.Fatalf("since the first look that found it, two in a row, how it failed: %+v", owned[0])
	}
	var machine []string
	for _, f := range st.Unowned() {
		machine = append(machine, f.Scope+"/"+f.Unit)
	}
	want := "system/mnt-recalbox.mount system/storage-media.mount user/greenclip.service"
	if strings.Join(machine, " ") != want {
		t.Fatalf("the machine's own: %v, want %s", machine, want)
	}
}

func TestADeclaredUnitAndAWrittenFileAreTheirModules(t *testing.T) {
	r := &fakeReader{
		failed: map[string][]Listed{
			"system":        {{Unit: "mesh-power-after-boot.service", Load: "loaded"}, {Unit: "sshd.service", Load: "loaded"}},
			"user:operator": {{Unit: "watcher.service", Load: "loaded"}},
		},
		shown: map[string]Shown{
			"watcher.service": {FragmentPath: "/home/operator/.config/systemd/user/watcher.service"},
		},
	}
	j := New(r)
	j.Set(OwnedBy(declared(), nil))
	st := lookTwice(t, j)
	got := map[string]string{}
	for _, f := range st.Failed {
		got[f.Unit] = f.Module + " " + f.Via
	}
	if got["mesh-power-after-boot.service"] != "power unit" {
		t.Errorf("a stateless service the declaration names is its module's: %q", got["mesh-power-after-boot.service"])
	}
	if got["watcher.service"] != "watcher file" {
		t.Errorf("a user unit the mesh wrote is its module's: %q", got["watcher.service"])
	}
	if _, said := got["sshd.service"]; said {
		t.Errorf("a service stated running is liveness's to judge, and said once: %v", got)
	}
	if r.ownerQs != 0 {
		t.Errorf("the package database was asked %d time(s) for units the declaration already names", r.ownerQs)
	}
}

func TestTwoLooksEachWay(t *testing.T) {
	r := shanks()
	j := New(r)
	j.Set(OwnedBy(declared(), nil))
	now := t0
	j.Now = func() time.Time { return now }
	st, changed := j.Look(context.Background())
	if len(st.Failed) != 0 || !changed {
		t.Fatalf("first look: nothing said failed, the state said: %+v %v", st.Failed, changed)
	}
	now = now.Add(15 * time.Second)
	if st, changed = j.Look(context.Background()); len(st.Failed) != 4 || !changed {
		t.Fatalf("second look: four said failed: %+v %v", st.Failed, changed)
	}
	now = now.Add(15 * time.Second)
	if _, changed = j.Look(context.Background()); changed {
		t.Fatal("a third look the same is no change")
	}
	// The operator mounts the media library again: no longer failed on the first look that says so.
	r.failed["system"] = r.failed["system"][:1]
	now = now.Add(15 * time.Second)
	st, changed = j.Look(context.Background())
	if len(st.Failed) != 3 || !changed {
		t.Fatalf("a unit no longer failed is no longer said: %+v", st.Failed)
	}
	// Every manager clean: running.
	r.failed = map[string][]Listed{}
	now = now.Add(15 * time.Second)
	if st, _ = j.Look(context.Background()); st.State != Running || len(st.Failed) != 0 {
		t.Fatalf("no failed unit is running: %+v", st)
	}
}

func TestAManagerThatCannotBeReadIsUnread(t *testing.T) {
	r := shanks()
	j := New(r)
	j.Set(OwnedBy(declared(), nil))
	lookTwice(t, j)
	r.unread = map[string]error{"user:operator": errors.New("Failed to connect to bus: No medium found")}
	st, _ := j.Look(context.Background())
	if len(st.Unread) != 1 || !strings.Contains(st.Unread[0], "operator") {
		t.Fatalf("the account manager is said unread: %v", st.Unread)
	}
	// Its failures are not counted while unread, and not forgotten either: back on the next read, said
	// at once, from when they were first found.
	r.unread = nil
	st, _ = j.Look(context.Background())
	for _, f := range st.Failed {
		if f.Unit == "openrazer-daemon.service" && f.Since == t0 {
			return
		}
	}
	t.Fatalf("a manager read again says what it held, from when it was first found: %+v", st.Failed)
}

func TestNoManagerReadIsUnknown(t *testing.T) {
	r := &fakeReader{unread: map[string]error{"system": errors.New("systemctl: not found"),
		"user:operator": errors.New("systemctl: not found")}}
	j := New(r)
	j.Set(OwnedBy(declared(), nil))
	if st, _ := j.Look(context.Background()); st.State != Unknown {
		t.Fatalf("no manager read is unknown, never running: %q", st.State)
	}
}

func TestAnAdoptedMachinesHoldingIsTheMachines(t *testing.T) {
	d := &declaration.Declaration{Resources: []declaration.Resource{
		&declaration.Service{ID: "found.cups", Type: declaration.TypeService, Unit: "cups.service"},
	}}
	o := OwnedBy(d, map[string]bool{"found.cups": true})
	if _, ok := o.Units["system/cups.service"]; ok {
		t.Fatal("a unit an adopted machine holds as found is the machine's, not a module's")
	}
}

func TestTheReaderOnlyReads(t *testing.T) {
	var asked []string
	run := func(_ context.Context, name string, args ...string) (string, error) {
		asked = append(asked, name+" "+strings.Join(args, " "))
		switch {
		case name == "systemctl" && contains(args, "list-units"):
			return "● greenclip.service not-found failed failed greenclip.service\n" +
				"openrazer-daemon.service loaded failed failed Daemon to manage razer devices in userspace\n", nil
		case name == "systemctl" && contains(args, "show"):
			return "Id=greenclip.service\nFragmentPath=\nResult=start-limit-hit\n\n" +
				"Id=openrazer-daemon.service\nFragmentPath=/usr/lib/systemd/user/openrazer-daemon.service\nResult=exit-code\n", nil
		case name == "pacman" && contains(args, "-Qqo"):
			return "openrazer-daemon\n", nil
		}
		return "", nil
	}
	e := Exec{Run: run, System: "arch"}
	listed, err := e.Failed(context.Background(), ScopeUser, "operator")
	if err != nil || len(listed) != 2 || listed[0].Unit != "greenclip.service" || listed[0].Load != "not-found" {
		t.Fatalf("the list, its mark skipped: %+v %v", listed, err)
	}
	shown, err := e.Show(context.Background(), ScopeUser, "operator", []string{"greenclip.service", "openrazer-daemon.service"})
	if err != nil || shown["openrazer-daemon.service"].FragmentPath == "" || shown["greenclip.service"].Result != "start-limit-hit" {
		t.Fatalf("the show: %+v %v", shown, err)
	}
	if pkg, ok, err := e.PackageOwning(context.Background(), "/usr/lib/systemd/user/openrazer-daemon.service"); !ok ||
		pkg != "openrazer-daemon" || err != nil {
		t.Fatalf("the owner: %q %v %v", pkg, ok, err)
	}
	for _, a := range asked {
		if !strings.Contains(a, "list-units") && !strings.Contains(a, " show ") && !strings.HasPrefix(a, "pacman -Q") {
			t.Errorf("asked something that is not a read: %q", a)
		}
		if !strings.HasPrefix(a, "pacman") && !strings.Contains(a, "--machine=operator@") {
			t.Errorf("an account's manager is asked as that account's: %q", a)
		}
	}
}

func contains(args []string, s string) bool {
	for _, a := range args {
		if a == s {
			return true
		}
	}
	return false
}

func TestNothingIsReadBeforeADeclaration(t *testing.T) {
	r := shanks()
	j := New(r)
	if st, changed := j.Look(context.Background()); st.State != "" || changed {
		t.Fatalf("before a declaration every unit would read as the machine's: %+v", st)
	}
}