package localapi

import (
	"bytes"
	"context"
	"encoding/json"
	"log/slog"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"testing"

	"gitea.dooplex.hu/admin/felhom-agent/internal/proxmox"
)

// R-1008: after a power cut Proxmox keeps the dead vzdump task in `tasks?source=active` (measured on demo-hp
// 2026-10-14: still RUNNING ~30–60 s after the boot). A task whose worker process is gone is dead, not in flight.
// Liveness is Proxmox's own rule (pid + pstart vs /proc/<pid>/stat field 22), never the wall clock: the first version
// compared start time with btime and a clock step after the boot could make a live task look dead (security review
// 2026-10-14). These tests pin the helper, the production controller, three callers end to end; the fourth (the
// controller supervisor) by the structural pin at the bottom.

// A worker: pid 0x1E6EEC = 1994476, pstart 0x1B4A0D = 1788429 (UPID hex fields).
const (
	testPID    = 1994476
	testPStart = 1788429
)

func vz(vmid string) proxmox.TaskStatus {
	return proxmox.TaskStatus{UPID: "UPID:demo-hp:001E6EEC:001B4A0D:6ACF4071:vzdump:" + vmid + ":felhom-agent@pve!agent:",
		Type: "vzdump", ID: vmid, Status: "RUNNING", StartTime: 1791967345}
}

// procFixture writes <dir>/<pid>/stat with the given start ticks (comm with a space and a parenthesis, as real ones can).
func procFixture(t *testing.T, pid int, start int) string {
	return procFixtureState(t, pid, start, "S")
}

func procFixtureState(t *testing.T, pid int, start int, state string) string {
	t.Helper()
	d := t.TempDir()
	// PID 1 is always visible on a real host; procFixtureHidden leaves it out
	if err := os.MkdirAll(filepath.Join(d, "1"), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(d, "1", "stat"), []byte("1 (systemd) S 0 1 1 0 -1 0 0 0 0 0 0 0 0 0 20 0 1 0 2 0 0\n"), 0o644); err != nil {
		t.Fatal(err)
	}
	if pid > 0 {
		p := filepath.Join(d, itoaT(pid))
		if err := os.MkdirAll(p, 0o755); err != nil {
			t.Fatal(err)
		}
		f := []string{itoaT(pid), "(task UPID:x (vzdump))", state}
		for i := 4; i <= 21; i++ {
			f = append(f, "0")
		}
		f = append(f, itoaT(start), "0", "0")
		if err := os.WriteFile(filepath.Join(p, "stat"), []byte(strings.Join(f, " ")+"\n"), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	return d
}

// RED-PROOF: make taskAlive return (true, true) for a missing /proc entry → the dead task runs → fails.
func TestVzdumpInFlight_WorkerGoneIsDead(t *testing.T) {
	running, dead := vzdumpInFlight([]proxmox.TaskStatus{vz("9201")}, 9201, procFixture(t, 0, 0))
	if running || len(dead) != 1 {
		t.Fatalf("a task whose worker is gone must be dead: running=%v dead=%d", running, len(dead))
	}
}

// RED-PROOF: drop the `start == u.PStart` comparison (alive whenever the pid exists) → a reused pid runs → fails.
func TestVzdumpInFlight_ReusedPidIsDead(t *testing.T) {
	if running, _ := vzdumpInFlight([]proxmox.TaskStatus{vz("9201")}, 9201, procFixture(t, testPID, 42)); running {
		t.Fatal("the pid exists but started at another tick: another process, the task is dead")
	}
}

// RED-PROOF: drop the `f[0] != "Z"` test → a zombie worker counts as running → fails.
func TestVzdumpInFlight_ZombieIsDead(t *testing.T) {
	if running, _ := vzdumpInFlight([]proxmox.TaskStatus{vz("9201")}, 9201, procFixtureState(t, testPID, testPStart, "Z")); running {
		t.Fatal("a zombie worker is not running (Proxmox's own rule)")
	}
}

func TestVzdumpInFlight_LiveWorkerRuns(t *testing.T) {
	if running, _ := vzdumpInFlight([]proxmox.TaskStatus{vz("9201")}, 9201, procFixture(t, testPID, testPStart)); !running {
		t.Fatal("the worker lives (same pid, same start tick): in flight")
	}
}

// The reason for the rewrite: the wall clock plays no part. A live task whose list start time lies „before the boot"
// (a clock step after the boot) is still running.
func TestVzdumpInFlight_ClockStepCannotKillALiveTask(t *testing.T) {
	tk := vz("9201")
	tk.StartTime = 1 // absurdly early by the wall clock
	if running, _ := vzdumpInFlight([]proxmox.TaskStatus{tk}, 9201, procFixture(t, testPID, testPStart)); !running {
		t.Fatal("a live worker must count as running whatever its wall-clock start says")
	}
}

// RED-PROOF: make an unparsable UPID or unreadable stat „known dead" → fails.
func TestVzdumpInFlight_DoubtFailsSafe(t *testing.T) {
	bad := vz("9201")
	bad.UPID = "garbage"
	if running, _ := vzdumpInFlight([]proxmox.TaskStatus{bad}, 9201, procFixture(t, 0, 0)); !running {
		t.Fatal("an unparsable UPID must count as running (fail safe)")
	}
	d := procFixture(t, testPID, testPStart)
	if err := os.WriteFile(filepath.Join(d, itoaT(testPID), "stat"), []byte("garbage"), 0o644); err != nil {
		t.Fatal(err)
	}
	if running, _ := vzdumpInFlight([]proxmox.TaskStatus{vz("9201")}, 9201, d); !running {
		t.Fatal("an unparsable stat must count as running (fail safe)")
	}
}

// RED-PROOF: drop the PID-1 visibility check → a hidden /proc makes the live task „gone" → fails.
func TestVzdumpInFlight_HiddenProcFailsSafe(t *testing.T) {
	d := t.TempDir() // nothing visible: not even PID 1 (hidepid / ProtectProc)
	if running, _ := vzdumpInFlight([]proxmox.TaskStatus{vz("9201")}, 9201, d); !running {
		t.Fatal("a /proc that hides other users' processes must count as running (fail safe)")
	}
}

func TestVzdumpInFlight_OtherGuestOrTypeIgnored(t *testing.T) {
	tasks := []proxmox.TaskStatus{vz("9202"), {UPID: vz("9201").UPID, Type: "vzsnapshot", ID: "9201"}}
	if running, dead := vzdumpInFlight(tasks, 9201, procFixture(t, testPID, testPStart)); running || len(dead) != 0 {
		t.Fatalf("other guests' and other types' tasks are not 9201's backup: running=%v dead=%d", running, len(dead))
	}
}

func inflightCtrl(api *fakeStaleLockAPI, runner *recordingRunner, logger *slog.Logger, proc string) *staleLockController {
	c := NewStaleLockController(api, runner, "felhom", logger).(*staleLockController)
	c.procDir = proc
	return c
}

// The production controller answers through the helper, and logs a dead task ONCE.
// RED-PROOF: make BackupRunning ignore the helper (any listed task runs) → fails.
func TestStaleLockController_BackupRunningIgnoresDeadTask(t *testing.T) {
	var buf bytes.Buffer
	api := &fakeStaleLockAPI{tasks: []proxmox.TaskStatus{vz("9201")}}
	c := inflightCtrl(api, &recordingRunner{}, slog.New(slog.NewTextHandler(&buf, nil)), procFixture(t, 0, 0))
	for i := 0; i < 3; i++ {
		if running, err := c.BackupRunning(context.Background(), 9201); err != nil || running {
			t.Fatalf("dead task reported running=%v err=%v", running, err)
		}
	}
	if n := strings.Count(buf.String(), "backup-in-flight: a vzdump task is listed as active but its worker process is gone"); n != 1 {
		t.Fatalf("the dead task must be logged exactly once, got %d", n)
	}
	c.procDir = procFixture(t, testPID, testPStart)
	if running, _ := c.BackupRunning(context.Background(), 9201); !running {
		t.Fatal("a live worker must be running")
	}
}

func fixtureFor(t *testing.T, alive bool) string {
	if alive {
		return procFixture(t, testPID, testPStart)
	}
	return procFixture(t, 0, 0)
}

func poolOf(vmids ...int) proxmox.PoolInfo {
	var p proxmox.PoolInfo
	raw := `{"members":[`
	for i, v := range vmids {
		if i > 0 {
			raw += ","
		}
		raw += `{"vmid":` + itoaT(v) + `,"type":"lxc"}`
	}
	raw += `]}`
	_ = json.Unmarshal([]byte(raw), &p)
	return p
}

// Caller 1 — the startup stale-lock recovery clears the lock a power cut left (the night of 2026-10-14 it said
// „genuinely in-flight — leaving the lock").
func TestCaller_StartupStaleLockClearsAfterPowerCut(t *testing.T) {
	for _, tc := range []struct {
		alive   bool
		cleared bool
	}{{false, true}, {true, false}} {
		api := &fakeStaleLockAPI{tasks: []proxmox.TaskStatus{vz("9201")},
			cfg: map[int]proxmox.GuestConfig{9201: staleCfg("backup", true)}}
		runner := &recordingRunner{}
		s := &Server{staleLock: inflightCtrl(api, runner, nil, fixtureFor(t, tc.alive)), logger: slog.New(slog.NewTextHandler(discardW{}, nil))}
		s.recoverOneStaleLock(context.Background(), proxmox.Guest{VMID: 9201, Status: "running"})
		if runner.unlocked("9201") != tc.cleared {
			t.Fatalf("worker alive=%v: unlocked=%v, want %v", tc.alive, runner.unlocked("9201"), tc.cleared)
		}
	}
}

// Caller 2 — the guest-power watchdog starts a stopped guest despite a dead pre-boot vzdump task.
func TestCaller_GuestPowerStartsGuestAfterPowerCut(t *testing.T) {
	for _, tc := range []struct {
		alive   bool
		started bool
	}{{false, true}, {true, false}} {
		api := &fakeStaleLockAPI{lxc: []proxmox.Guest{{VMID: 9201, Status: "stopped"}}, pool: poolOf(9201),
			tasks: []proxmox.TaskStatus{vz("9201")}, cfg: map[int]proxmox.GuestConfig{9201: staleCfg("", true)}}
		s := gpServer(t, inflightCtrl(api, &recordingRunner{}, nil, fixtureFor(t, tc.alive)), nil)
		s.GuestPowerTick(context.Background())
		if (len(api.started) == 1) != tc.started {
			t.Fatalf("worker alive=%v: started=%v, want %v", tc.alive, api.started, tc.started)
		}
	}
}

// Caller 3 — the household power-off guard does not refuse „backup running" for a dead task.
func TestCaller_PowerOffJobBlockerIgnoresDeadTask(t *testing.T) {
	for _, tc := range []struct {
		alive bool
		want  string
	}{{false, ""}, {true, PowerOffBackup}} {
		rig := newPowerRig(t, 0)
		rig.srv.staleLock = inflightCtrl(&fakeStaleLockAPI{tasks: []proxmox.TaskStatus{vz("9201")}}, &recordingRunner{}, nil, fixtureFor(t, tc.alive))
		if code, _ := rig.srv.jobBlocker(context.Background(), 9201); code != tc.want {
			t.Fatalf("worker alive=%v: jobBlocker=%q, want %q", tc.alive, code, tc.want)
		}
	}
}

// Caller 4 (the supervisor), the R-1006 cleanup (VzdumpInFlight) and the rest — structural pin: every non-test BackupRunning call in this package goes through
// s.staleLock (whose one production implementation is staleLockController, which uses vzdumpInFlight), and no
// other production type implements BackupRunning. If someone adds a second path, this fails.
func TestBackupRunning_AllCallersUseTheOneHelper(t *testing.T) {
	files, _ := filepath.Glob("*.go")
	call := regexp.MustCompile(`([A-Za-z_.]+)\.BackupRunning\(`)
	impl := regexp.MustCompile(`func \([a-z]+ \*?([A-Za-z]+)\) BackupRunning\(`)
	callers := 0
	for _, f := range files {
		if strings.HasSuffix(f, "_test.go") {
			continue
		}
		b, err := os.ReadFile(f)
		if err != nil {
			t.Fatal(err)
		}
		for _, m := range call.FindAllStringSubmatch(string(b), -1) {
			if m[1] != "s.staleLock" {
				t.Errorf("%s: BackupRunning called on %q, not s.staleLock", f, m[1])
			}
			callers++
		}
		for _, m := range impl.FindAllStringSubmatch(string(b), -1) {
			if m[1] != "staleLockController" {
				t.Errorf("%s: a second production BackupRunning on %s", f, m[1])
			}
		}
	}
	if callers != 5 {
		t.Errorf("expected the five known callers (stale-lock, guest-power, power-off, supervisor, the R-1006 cleanup), found %d", callers)
	}
	b, _ := os.ReadFile("stalelock.go")
	if !strings.Contains(string(b), "vzdumpInFlight(tasks, vmid, proc)") {
		t.Error("staleLockController.BackupRunning no longer answers through vzdumpInFlight")
	}
}