package localapi

import (
	"context"
	"io"
	"log/slog"
	"testing"

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

// fakeStaleLock is a scripted StaleLockController: it answers the reads from per-vmid maps and records
// the mutating calls (unlock/delsnapshot/start) so a test can assert the exact recovery sequence.
type fakeStaleLock struct {
	guests  []proxmox.Guest
	lock    map[int]string
	onboot  map[int]bool
	snap    map[int]bool // a dangling vzdump snapshot exists
	running map[int]bool // a vzdump task is genuinely in-flight

	unlocked []int
	delsnap  []int
	started  []int

	lockErr    map[int]error
	runningErr map[int]error
}

func (f *fakeStaleLock) Guests(context.Context) ([]proxmox.Guest, error) { return f.guests, nil }

func (f *fakeStaleLock) Lock(_ context.Context, vmid int) (string, bool, error) {
	if err := f.lockErr[vmid]; err != nil {
		return "", false, err
	}
	return f.lock[vmid], f.onboot[vmid], nil
}

func (f *fakeStaleLock) BackupRunning(_ context.Context, vmid int) (bool, error) {
	if err := f.runningErr[vmid]; err != nil {
		return false, err
	}
	return f.running[vmid], nil
}

func (f *fakeStaleLock) HasVzdumpSnapshot(_ context.Context, vmid int) (bool, error) {
	return f.snap[vmid], nil
}

func (f *fakeStaleLock) Unlock(_ context.Context, vmid int) error {
	f.unlocked = append(f.unlocked, vmid)
	return nil
}

func (f *fakeStaleLock) DeleteVzdumpSnapshot(_ context.Context, vmid int) error {
	f.delsnap = append(f.delsnap, vmid)
	return nil
}

func (f *fakeStaleLock) Start(_ context.Context, vmid int) error {
	f.started = append(f.started, vmid)
	return nil
}

func staleLockServer(f *fakeStaleLock) *Server {
	return &Server{staleLock: f, logger: slog.New(slog.NewTextHandler(io.Discard, nil))}
}

func contains(xs []int, v int) bool {
	for _, x := range xs {
		if x == v {
			return true
		}
	}
	return false
}

// TestStaleLock_RecoversStoppedLockedGuest is the F2-b core: a stopped, onboot guest with a
// snapshot-delete lock + a dangling vzdump snapshot is unlocked, its snapshot deleted, and it is
// started — the exact reboot-during-backup recovery.
func TestStaleLock_RecoversStoppedLockedGuest(t *testing.T) {
	f := &fakeStaleLock{
		guests:  []proxmox.Guest{{VMID: 9201, Status: "stopped"}},
		lock:    map[int]string{9201: "snapshot-delete"},
		onboot:  map[int]bool{9201: true},
		snap:    map[int]bool{9201: true},
		running: map[int]bool{9201: false},
	}
	staleLockServer(f).RecoverStaleLockedGuests(context.Background())

	if !contains(f.unlocked, 9201) {
		t.Fatalf("expected pct unlock for 9201, unlocked=%v", f.unlocked)
	}
	if !contains(f.delsnap, 9201) {
		t.Fatalf("expected dangling vzdump snapshot delete for 9201, delsnap=%v", f.delsnap)
	}
	if !contains(f.started, 9201) {
		t.Fatalf("expected start (onboot, stopped) for 9201, started=%v", f.started)
	}
}

// TestStaleLock_NoLockTouchesNothing is the COMPANION proof: a healthy guest with no lock has NONE of
// the mutating ops invoked — recovery acts only on the stale state.
func TestStaleLock_NoLockTouchesNothing(t *testing.T) {
	f := &fakeStaleLock{
		guests: []proxmox.Guest{{VMID: 9201, Status: "running"}},
		lock:   map[int]string{9201: ""}, // unlocked
		onboot: map[int]bool{9201: true},
	}
	staleLockServer(f).RecoverStaleLockedGuests(context.Background())

	if len(f.unlocked)+len(f.delsnap)+len(f.started) != 0 {
		t.Fatalf("no-lock guest must be untouched; got unlocked=%v delsnap=%v started=%v", f.unlocked, f.delsnap, f.started)
	}
}

// TestStaleLock_NonBackupLockLeftAlone: a non-vzdump lock (e.g. migrate) is NEVER cleared — scope is
// strictly the two backup locks.
func TestStaleLock_NonBackupLockLeftAlone(t *testing.T) {
	f := &fakeStaleLock{
		guests: []proxmox.Guest{{VMID: 9201, Status: "running"}},
		lock:   map[int]string{9201: "migrate"},
		onboot: map[int]bool{9201: true},
	}
	staleLockServer(f).RecoverStaleLockedGuests(context.Background())

	if len(f.unlocked) != 0 {
		t.Fatalf("a migrate lock must not be cleared; unlocked=%v", f.unlocked)
	}
}

// TestStaleLock_OnbootZeroNotStarted: a stale-locked guest with onboot=0 (e.g. the golden) is unlocked
// + snapshot-cleaned but NOT started — a deliberately-stopped guest stays stopped.
func TestStaleLock_OnbootZeroNotStarted(t *testing.T) {
	f := &fakeStaleLock{
		guests: []proxmox.Guest{{VMID: 9100, Status: "stopped"}},
		lock:   map[int]string{9100: "snapshot-delete"},
		onboot: map[int]bool{9100: false},
		snap:   map[int]bool{9100: true},
	}
	staleLockServer(f).RecoverStaleLockedGuests(context.Background())

	if !contains(f.unlocked, 9100) || !contains(f.delsnap, 9100) {
		t.Fatalf("onboot=0 guest should still be unlocked + snapshot-cleaned; unlocked=%v delsnap=%v", f.unlocked, f.delsnap)
	}
	if contains(f.started, 9100) {
		t.Fatalf("onboot=0 guest must NOT be started; started=%v", f.started)
	}
}

// TestStaleLock_DelsnapOnlyWhenSnapshotExists: a stop/suspend-mode interruption (lock but NO dangling
// snapshot) is unlocked + started, but delsnapshot is NOT called.
func TestStaleLock_DelsnapOnlyWhenSnapshotExists(t *testing.T) {
	f := &fakeStaleLock{
		guests: []proxmox.Guest{{VMID: 9201, Status: "stopped"}},
		lock:   map[int]string{9201: "backup"},
		onboot: map[int]bool{9201: true},
		snap:   map[int]bool{9201: false}, // no dangling snapshot
	}
	staleLockServer(f).RecoverStaleLockedGuests(context.Background())

	if !contains(f.unlocked, 9201) || !contains(f.started, 9201) {
		t.Fatalf("expected unlock + start; unlocked=%v started=%v", f.unlocked, f.started)
	}
	if len(f.delsnap) != 0 {
		t.Fatalf("delsnapshot must not run without a dangling snapshot; delsnap=%v", f.delsnap)
	}
}

// TestStaleLock_RunningBackupNotCleared is the INVARIANT guard: a backup lock present WITH a genuinely
// in-flight vzdump must NOT be cleared (clearing a live backup's lock corrupts it).
func TestStaleLock_RunningBackupNotCleared(t *testing.T) {
	f := &fakeStaleLock{
		guests:  []proxmox.Guest{{VMID: 9201, Status: "running"}},
		lock:    map[int]string{9201: "backup"},
		onboot:  map[int]bool{9201: true},
		running: map[int]bool{9201: true}, // a real backup is running
	}
	staleLockServer(f).RecoverStaleLockedGuests(context.Background())

	if len(f.unlocked)+len(f.delsnap)+len(f.started) != 0 {
		t.Fatalf("a live backup's lock must be left alone; unlocked=%v delsnap=%v started=%v", f.unlocked, f.delsnap, f.started)
	}
}

// TestStaleLock_RunningProbeErrorFailsSafe: if the no-backup-running confirmation errors, the lock is
// LEFT (fail-safe) rather than blind-cleared.
func TestStaleLock_RunningProbeErrorFailsSafe(t *testing.T) {
	f := &fakeStaleLock{
		guests:     []proxmox.Guest{{VMID: 9201, Status: "stopped"}},
		lock:       map[int]string{9201: "snapshot-delete"},
		onboot:     map[int]bool{9201: true},
		runningErr: map[int]error{9201: context.DeadlineExceeded},
	}
	staleLockServer(f).RecoverStaleLockedGuests(context.Background())

	if len(f.unlocked) != 0 {
		t.Fatalf("an unconfirmable backup state must fail safe (no unlock); unlocked=%v", f.unlocked)
	}
}

// TestStaleLock_AlreadyRunningNotRestarted: a bare agent restart can find the guest UP behind a stale
// lock — it is unlocked but NOT (re)started.
func TestStaleLock_AlreadyRunningNotRestarted(t *testing.T) {
	f := &fakeStaleLock{
		guests: []proxmox.Guest{{VMID: 9201, Status: "running"}},
		lock:   map[int]string{9201: "snapshot-delete"},
		onboot: map[int]bool{9201: true},
		snap:   map[int]bool{9201: true},
	}
	staleLockServer(f).RecoverStaleLockedGuests(context.Background())

	if !contains(f.unlocked, 9201) {
		t.Fatalf("a running but stale-locked guest should still be unlocked; unlocked=%v", f.unlocked)
	}
	if contains(f.started, 9201) {
		t.Fatalf("an already-running guest must NOT be started; started=%v", f.started)
	}
}

// TestStaleLock_NilControllerNoop: an unwired controller is a safe no-op (the optional-feature contract).
func TestStaleLock_NilControllerNoop(t *testing.T) {
	s := &Server{logger: slog.New(slog.NewTextHandler(io.Discard, nil))}
	s.RecoverStaleLockedGuests(context.Background()) // must not panic
}