package monitor

import (
	"context"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"gitea.dooplex.hu/admin/felhom-controller/internal/config"
	"gitea.dooplex.hu/admin/felhom-controller/internal/notify"
	"gitea.dooplex.hu/admin/felhom-controller/internal/settings"
	"gitea.dooplex.hu/admin/felhom-controller/internal/system"
)

const (
	// probeThreshold is the number of consecutive probe failures before declaring disconnected.
	probeThreshold = 3

	// defaultProbeInterval is the normal probe interval for connected drives.
	defaultProbeInterval = 5 * time.Second

	// disconnectedProbeInterval is the slower probe interval for disconnected drives
	// (checking for UUID reappearance, not I/O probing).
	disconnectedProbeInterval = 30 * time.Second

	// hostFstabPath is where the host's fstab is mounted inside the container.
	hostFstabPath = "/host-fstab"

	// hostDevUUIDPath is where the host's /dev/disk/by-uuid is accessible.
	hostDevUUIDPath = "/host-dev/disk/by-uuid"

	// primaryResticSubpath is the relative path to the primary restic repo under a drive.
	primaryResticSubpath = "backups/primary/restic"
)

// WatchdogStackInfo holds minimal stack info for the watchdog.
type WatchdogStackInfo struct {
	Name string
}

// WatchdogStackProvider provides stack operations needed by the watchdog.
// Defined here to avoid circular imports with the backup package.
type WatchdogStackProvider interface {
	ListDeployedStacks() []WatchdogStackInfo
	GetStackHDDPath(name string) string
	StopStack(name string) error
	StartStack(name string) error
}

// pathProbeState tracks in-memory probe state for a single storage path.
type pathProbeState struct {
	consecutiveFailures int
	lastStatus          string // "connected", "disconnected"
	lastProbeTime       time.Time
	probeInterval       time.Duration
	// Debug counters for summary logging
	probeCount      int
	probeOKCount    int
	lastSummaryTime time.Time
	totalLatency    time.Duration
}

// StorageWatchdog monitors registered storage paths and reacts to disconnection/reconnection.
type StorageWatchdog struct {
	settings      *settings.Settings
	stackProvider WatchdogStackProvider
	notifier      *notify.Notifier
	cfg           *config.Config
	logger        *log.Logger

	// Callbacks to break import cycles — set via SetXxx methods after construction
	alertRefresh  func()
	pushHubReport func()
	unlockRepo    func(ctx context.Context, repoPath string) error

	mu        sync.Mutex
	pathState map[string]*pathProbeState

	// Debug simulation state
	simulatedMu    sync.RWMutex
	simulatedPaths map[string]bool
}

// NewStorageWatchdog creates a new storage watchdog.
func NewStorageWatchdog(
	sett *settings.Settings,
	stackProvider WatchdogStackProvider,
	notifier *notify.Notifier,
	cfg *config.Config,
	logger *log.Logger,
) *StorageWatchdog {
	return &StorageWatchdog{
		settings:       sett,
		stackProvider:  stackProvider,
		notifier:       notifier,
		cfg:            cfg,
		logger:         logger,
		pathState:      make(map[string]*pathProbeState),
		simulatedPaths: make(map[string]bool),
	}
}

// isDebug returns true if the logging level is set to "debug".
func (w *StorageWatchdog) isDebug() bool { return w.cfg.Logging.Level == "debug" }

// SetAlertRefresh sets the callback to trigger alert refresh.
func (w *StorageWatchdog) SetAlertRefresh(fn func()) {
	w.alertRefresh = fn
}

// SetHubReportPusher sets the callback to push an immediate hub report.
func (w *StorageWatchdog) SetHubReportPusher(fn func()) {
	w.pushHubReport = fn
}

// SetRepoUnlocker sets the callback to unlock a restic repo on reconnect.
func (w *StorageWatchdog) SetRepoUnlocker(fn func(ctx context.Context, repoPath string) error) {
	w.unlockRepo = fn
}

// Check probes all registered storage paths and reacts to state changes.
// Called by the scheduler every 5 seconds.
func (w *StorageWatchdog) Check(ctx context.Context) error {
	paths := w.settings.GetStoragePaths()
	if len(paths) == 0 {
		return nil
	}

	for _, sp := range paths {
		select {
		case <-ctx.Done():
			return ctx.Err()
		default:
		}

		state := w.getOrCreateState(sp.Path)

		// Rate-limit per-path probes
		if time.Since(state.lastProbeTime) < state.probeInterval {
			continue
		}
		state.lastProbeTime = time.Now()

		// Skip decommissioned drives entirely — no apps reference them
		if sp.Decommissioned {
			continue
		}

		// Skip simulated-disconnected paths (handled by debug UI)
		if w.isSimulated(sp.Path) {
			continue
		}

		if sp.Disconnected {
			w.handleReconnectCheck(ctx, sp)
		} else {
			w.handleConnectedProbe(sp, state)
		}
	}
	return nil
}

// getOrCreateState returns the in-memory probe state for a path, creating if needed.
func (w *StorageWatchdog) getOrCreateState(path string) *pathProbeState {
	w.mu.Lock()
	defer w.mu.Unlock()
	if s, ok := w.pathState[path]; ok {
		return s
	}
	s := &pathProbeState{
		lastStatus:    "connected",
		probeInterval: defaultProbeInterval,
	}
	w.pathState[path] = s
	return s
}

// handleConnectedProbe probes a connected drive and triggers disconnect if needed.
func (w *StorageWatchdog) handleConnectedProbe(sp settings.StoragePath, state *pathProbeState) {
	probeStart := time.Now()
	result := system.ProbeStoragePath(sp.Path)
	probeLatency := time.Since(probeStart)

	if w.isDebug() {
		state.probeCount++
		state.totalLatency += probeLatency
	}

	if result.Status == system.ProbeConnected {
		if state.consecutiveFailures > 0 {
			w.logger.Printf("[DEBUG] [STORAGE] Probe recovered for %s after %d failures", sp.Path, state.consecutiveFailures)
		}
		state.consecutiveFailures = 0
		state.lastStatus = "connected"
		if w.isDebug() {
			state.probeOKCount++
			// Every 60 probes (~5 minutes at 5s interval): emit summary
			if state.probeCount >= 60 {
				avgLatency := state.totalLatency / time.Duration(state.probeCount)
				w.logger.Printf("[DEBUG] [STORAGE] Storage watchdog: %s — %d/%d probes OK (last 5m, avg %dms)",
					sp.Path, state.probeOKCount, state.probeCount, avgLatency.Milliseconds())
				state.probeCount = 0
				state.probeOKCount = 0
				state.totalLatency = 0
				state.lastSummaryTime = time.Now()
			}
		}
		return
	}

	state.consecutiveFailures++

	// Debug: log immediately on unexpected failure (was connected, now failing)
	if w.isDebug() && state.lastStatus == "connected" {
		w.logger.Printf("[DEBUG] [STORAGE] Storage probe failed for %s (%d/%d before disconnect): %v",
			sp.Path, state.consecutiveFailures, probeThreshold, result.Err)
	}

	w.logger.Printf("[WARN] [STORAGE] Probe failed for %s (%d/%d): %v",
		sp.Path, state.consecutiveFailures, probeThreshold, result.Err)

	if state.consecutiveFailures >= probeThreshold {
		w.handleDisconnect(sp, state, result)
	}
}

// handleDisconnect reacts to a confirmed drive disconnection.
func (w *StorageWatchdog) handleDisconnect(sp settings.StoragePath, state *pathProbeState, probe system.ProbeResult) {
	label := sp.Label
	if label == "" {
		label = sp.Path
	}
	w.logger.Printf("[ERROR] [STORAGE] Drive disconnected: %s (%s)", sp.Path, label)

	// 1. Find and stop affected stacks
	stoppedStacks := w.stopAffectedStacks(sp.Path)

	// 2. Mark disconnected in settings (persists to settings.json)
	if err := w.settings.SetDisconnected(sp.Path, true, stoppedStacks); err != nil {
		w.logger.Printf("[ERROR] [STORAGE] Failed to mark disconnected: %v", err)
	}

	// 3. Lazy unmount stale mount (if probe timed out — mount is likely hanging)
	if probe.Status == system.ProbeTimeout {
		w.lazyUnmount(sp.Path)
	}

	// 4. Update in-memory state
	state.lastStatus = "disconnected"
	state.probeInterval = disconnectedProbeInterval
	state.consecutiveFailures = 0

	// 5. Trigger alert refresh
	if w.alertRefresh != nil {
		w.alertRefresh()
	}

	// 6. Send notification
	w.notifier.NotifyStorageDisconnected(label, stoppedStacks)

	// 7. Push immediate hub report
	if w.pushHubReport != nil {
		go w.pushHubReport()
	}
}

// handleReconnectCheck checks if a disconnected drive has been reconnected.
func (w *StorageWatchdog) handleReconnectCheck(ctx context.Context, sp settings.StoragePath) {
	// Find the UUID for this path from fstab
	// For attach-wizard drives, the UUID is on the raw mount, not the bind mount
	mountPath := sp.Path
	rawPath, isAttachWizard := system.HasFelhomRawMount(hostFstabPath, sp.Path)
	if isAttachWizard {
		mountPath = rawPath
	}

	uuid := system.ParseFstabUUID(hostFstabPath, mountPath)
	if uuid == "" {
		// No UUID in fstab — can't detect reconnection automatically
		return
	}

	if w.isDebug() {
		w.logger.Printf("[DEBUG] [STORAGE] Reconnect check for %s: UUID=%s, mountPath=%s, isAttachWizard=%v",
			sp.Path, uuid, mountPath, isAttachWizard)
	}

	// Check if the UUID block device is present
	uuidPath := filepath.Join(hostDevUUIDPath, uuid)
	if _, err := os.Stat(uuidPath); err != nil {
		return // Drive not reconnected yet
	}

	label := sp.Label
	if label == "" {
		label = sp.Path
	}
	w.logger.Printf("[INFO] [STORAGE] Drive reconnected (UUID found), attempting remount: %s (%s)", sp.Path, label)

	if w.isDebug() {
		w.logger.Printf("[DEBUG] [STORAGE] UUID %s found at %s, mounting %s (raw=%s, attachWizard=%v)",
			uuid, uuidPath, sp.Path, rawPath, isAttachWizard)
	}

	// Attempt remount
	if err := w.remount(sp.Path, rawPath, isAttachWizard); err != nil {
		w.logger.Printf("[ERROR] [STORAGE] Remount failed for %s: %v", sp.Path, err)
		return // Try again next cycle
	}

	// Verify with a probe
	verifyResult := system.ProbeStoragePath(sp.Path)
	if verifyResult.Status != system.ProbeConnected {
		w.logger.Printf("[ERROR] [STORAGE] Post-remount probe failed for %s: %v", sp.Path, verifyResult.Err)
		if w.isDebug() {
			w.logger.Printf("[DEBUG] [STORAGE] Post-mount verification failed for %s: status=%v, err=%v",
				sp.Path, verifyResult.Status, verifyResult.Err)
		}
		return
	}

	if w.isDebug() {
		w.logger.Printf("[DEBUG] [STORAGE] Post-mount verification succeeded for %s", sp.Path)
	}

	w.logger.Printf("[INFO] [STORAGE] Drive successfully remounted: %s (%s)", sp.Path, label)

	// Clean stale restic locks
	w.cleanResticLocks(ctx, sp.Path)

	// Validate stopped stacks — filter to only actually stopped ones
	filteredStacks := w.filterStoppedStacks(sp.StoppedStacks)

	// Clear disconnected but preserve StoppedStacks for the restart UI
	if err := w.settings.SetDisconnected(sp.Path, false, filteredStacks); err != nil {
		w.logger.Printf("[ERROR] [STORAGE] Failed to clear disconnected: %v", err)
	}

	// Update in-memory state
	state := w.getOrCreateState(sp.Path)
	state.lastStatus = "connected"
	state.probeInterval = defaultProbeInterval
	state.consecutiveFailures = 0

	// Trigger alert refresh
	if w.alertRefresh != nil {
		w.alertRefresh()
	}

	// Send notification
	w.notifier.NotifyStorageReconnected(label)

	// Push immediate hub report
	if w.pushHubReport != nil {
		go w.pushHubReport()
	}
}

// stopAffectedStacks stops all deployed stacks whose HDD_PATH matches the disconnected drive.
func (w *StorageWatchdog) stopAffectedStacks(drivePath string) []string {
	if w.stackProvider == nil {
		return nil
	}

	var stopped []string
	cleanDrive := filepath.Clean(drivePath)

	for _, stack := range w.stackProvider.ListDeployedStacks() {
		hddPath := w.stackProvider.GetStackHDDPath(stack.Name)
		if hddPath == "" {
			continue
		}
		cleanHDD := filepath.Clean(hddPath)
		if cleanHDD != cleanDrive && !strings.HasPrefix(cleanHDD, cleanDrive+"/") {
			continue
		}

		// Don't stop protected stacks
		if w.cfg.IsProtectedStack(stack.Name) {
			w.logger.Printf("[WARN] [STORAGE] Skipping protected stack: %s", stack.Name)
			continue
		}

		w.logger.Printf("[INFO] [STORAGE] Stopping stack %s (drive disconnected: %s)", stack.Name, drivePath)
		if err := w.stackProvider.StopStack(stack.Name); err != nil {
			w.logger.Printf("[ERROR] [STORAGE] Failed to stop stack %s: %v", stack.Name, err)
			continue // Don't add to stopped list if stop failed
		}
		stopped = append(stopped, stack.Name)
	}

	if len(stopped) > 0 {
		w.logger.Printf("[INFO] [STORAGE] Stopped %d stack(s) due to drive disconnect: %v", len(stopped), stopped)
	}
	return stopped
}

// lazyUnmount performs a lazy unmount of a path and its raw mount (if attach-wizard).
func (w *StorageWatchdog) lazyUnmount(path string) {
	// For attach-wizard, unmount bind first, then raw
	rawPath, isAttachWizard := system.HasFelhomRawMount(hostFstabPath, path)

	// Unmount the bind/main path
	cmd := exec.Command("umount", "-l", path)
	if out, err := cmd.CombinedOutput(); err != nil {
		w.logger.Printf("[WARN] [STORAGE] umount -l %s: %v (%s)", path, err, strings.TrimSpace(string(out)))
	} else {
		w.logger.Printf("[INFO] [STORAGE] Lazy unmounted: %s", path)
	}

	// Then unmount the raw path if it's an attach-wizard drive
	if isAttachWizard && rawPath != "" {
		cmd = exec.Command("umount", "-l", rawPath)
		if out, err := cmd.CombinedOutput(); err != nil {
			w.logger.Printf("[WARN] [STORAGE] umount -l %s: %v (%s)", rawPath, err, strings.TrimSpace(string(out)))
		} else {
			w.logger.Printf("[INFO] [STORAGE] Lazy unmounted raw: %s", rawPath)
		}
	}
}

// remount attempts to remount a storage path using fstab entries.
func (w *StorageWatchdog) remount(path, rawPath string, isAttachWizard bool) error {
	// Clean any stale mount entries first
	exec.Command("umount", "-l", path).Run()
	if isAttachWizard && rawPath != "" {
		exec.Command("umount", "-l", rawPath).Run()
	}

	if isAttachWizard && rawPath != "" {
		// Mount raw first, then bind
		cmd := exec.Command("mount", "-T", hostFstabPath, rawPath)
		if out, err := cmd.CombinedOutput(); err != nil {
			return fmt.Errorf("mount raw %s: %v (%s)", rawPath, err, strings.TrimSpace(string(out)))
		}
		w.logger.Printf("[INFO] [STORAGE] Mounted raw: %s", rawPath)

		cmd = exec.Command("mount", "-T", hostFstabPath, path)
		if out, err := cmd.CombinedOutput(); err != nil {
			return fmt.Errorf("mount bind %s: %v (%s)", path, err, strings.TrimSpace(string(out)))
		}
		w.logger.Printf("[INFO] [STORAGE] Mounted bind: %s", path)
	} else {
		cmd := exec.Command("mount", "-T", hostFstabPath, path)
		if out, err := cmd.CombinedOutput(); err != nil {
			return fmt.Errorf("mount %s: %v (%s)", path, err, strings.TrimSpace(string(out)))
		}
		w.logger.Printf("[INFO] [STORAGE] Mounted: %s", path)
	}
	return nil
}

// cleanResticLocks runs restic unlock on the primary repo for a drive path.
func (w *StorageWatchdog) cleanResticLocks(ctx context.Context, drivePath string) {
	repoPath := filepath.Join(drivePath, primaryResticSubpath)
	locksDir := filepath.Join(repoPath, "locks")
	entries, err := os.ReadDir(locksDir)
	if err != nil || len(entries) == 0 {
		return // No locks dir or no lock files
	}

	w.logger.Printf("[INFO] [STORAGE] Found %d restic lock file(s) in %s, running unlock", len(entries), repoPath)

	if w.unlockRepo != nil {
		if err := w.unlockRepo(ctx, repoPath); err != nil {
			w.logger.Printf("[WARN] [STORAGE] Restic unlock failed for %s: %v", repoPath, err)
		}
	}
}

// filterStoppedStacks validates that stacks in the list still exist as deployed stacks.
func (w *StorageWatchdog) filterStoppedStacks(stackNames []string) []string {
	if w.stackProvider == nil || len(stackNames) == 0 {
		return nil
	}

	deployed := make(map[string]bool)
	for _, s := range w.stackProvider.ListDeployedStacks() {
		deployed[s.Name] = true
	}

	var result []string
	for _, name := range stackNames {
		if deployed[name] {
			result = append(result, name)
		}
	}
	return result
}

// SafeDisconnect performs a safe disconnect of a storage path.
// Stops affected apps, syncs filesystem, and unmounts the drive.
func (w *StorageWatchdog) SafeDisconnect(ctx context.Context, path string) (stoppedStacks []string, err error) {
	sp := w.findStoragePath(path)
	if sp == nil {
		return nil, fmt.Errorf("storage path %q not found", path)
	}
	if sp.Disconnected {
		return nil, fmt.Errorf("drive already disconnected")
	}
	if sp.Decommissioned {
		return nil, fmt.Errorf("drive is decommissioned — no apps to stop")
	}

	label := sp.Label
	if label == "" {
		label = sp.Path
	}
	w.logger.Printf("[INFO] [STORAGE] Safe disconnect requested: %s (%s)", path, label)

	// 1. Stop affected stacks
	stoppedStacks = w.stopAffectedStacks(path)

	// 2. Sync filesystem
	exec.Command("sync").Run()

	// 3. Unmount
	rawPath, isAttachWizard := system.HasFelhomRawMount(hostFstabPath, path)

	// Unmount bind/main
	cmd := exec.Command("umount", path)
	if out, umountErr := cmd.CombinedOutput(); umountErr != nil {
		// Try lazy unmount as fallback
		w.logger.Printf("[WARN] [STORAGE] umount %s failed, trying lazy: %v", path, umountErr)
		cmd = exec.Command("umount", "-l", path)
		if out, umountErr = cmd.CombinedOutput(); umountErr != nil {
			return stoppedStacks, fmt.Errorf("umount %s failed: %v (%s)", path, umountErr, strings.TrimSpace(string(out)))
		}
	}

	// Unmount raw if attach-wizard
	if isAttachWizard && rawPath != "" {
		cmd = exec.Command("umount", rawPath)
		if out, umountErr := cmd.CombinedOutput(); umountErr != nil {
			cmd = exec.Command("umount", "-l", rawPath)
			if out, umountErr = cmd.CombinedOutput(); umountErr != nil {
				w.logger.Printf("[WARN] [STORAGE] umount raw %s failed: %v (%s)", rawPath, umountErr, strings.TrimSpace(string(out)))
			}
		}
	}

	// 4. Mark disconnected
	if setErr := w.settings.SetDisconnected(path, true, stoppedStacks); setErr != nil {
		w.logger.Printf("[ERROR] [STORAGE] Failed to mark disconnected: %v", setErr)
	}

	// 5. Update in-memory state
	state := w.getOrCreateState(path)
	state.lastStatus = "disconnected"
	state.probeInterval = disconnectedProbeInterval
	state.consecutiveFailures = 0

	// 6. Trigger alert refresh
	if w.alertRefresh != nil {
		w.alertRefresh()
	}

	// 7. Notify and push hub report
	w.notifier.Notify("storage_safe_disconnect", "info",
		fmt.Sprintf("Meghajtó biztonságosan leválasztva: %s", label), "")
	if w.pushHubReport != nil {
		go w.pushHubReport()
	}

	w.logger.Printf("[INFO] [STORAGE] Safe disconnect completed: %s — drive can be removed", path)
	return stoppedStacks, nil
}

// Reconnect attempts to remount a disconnected storage path.
func (w *StorageWatchdog) Reconnect(ctx context.Context, path string) (stoppedStacks []string, err error) {
	sp := w.findStoragePath(path)
	if sp == nil {
		return nil, fmt.Errorf("storage path %q not found", path)
	}
	if !sp.Disconnected {
		return nil, fmt.Errorf("drive is not disconnected")
	}

	label := sp.Label
	if label == "" {
		label = sp.Path
	}

	// Check UUID availability
	mountPath := sp.Path
	rawPath, isAttachWizard := system.HasFelhomRawMount(hostFstabPath, sp.Path)
	if isAttachWizard {
		mountPath = rawPath
	}
	uuid := system.ParseFstabUUID(hostFstabPath, mountPath)
	if uuid != "" {
		uuidPath := filepath.Join(hostDevUUIDPath, uuid)
		if _, statErr := os.Stat(uuidPath); statErr != nil {
			return nil, fmt.Errorf("drive not detected (UUID %s not found) — ensure the drive is physically connected", uuid)
		}
	}

	// Attempt remount
	if mountErr := w.remount(path, rawPath, isAttachWizard); mountErr != nil {
		return nil, fmt.Errorf("mount failed: %w", mountErr)
	}

	// Verify
	verifyResult := system.ProbeStoragePath(path)
	if verifyResult.Status != system.ProbeConnected {
		return nil, fmt.Errorf("mount appeared to succeed but probe failed: %v", verifyResult.Err)
	}

	// Clean restic locks
	w.cleanResticLocks(ctx, path)

	// Validate stopped stacks
	filteredStacks := w.filterStoppedStacks(sp.StoppedStacks)

	// Clear disconnected, preserve stopped stacks for restart UI
	if setErr := w.settings.SetDisconnected(path, false, filteredStacks); setErr != nil {
		w.logger.Printf("[ERROR] [STORAGE] Failed to clear disconnected: %v", setErr)
	}

	// Update in-memory state
	state := w.getOrCreateState(path)
	state.lastStatus = "connected"
	state.probeInterval = defaultProbeInterval
	state.consecutiveFailures = 0

	// Trigger alert refresh
	if w.alertRefresh != nil {
		w.alertRefresh()
	}

	// Notify
	w.notifier.NotifyStorageReconnected(label)
	if w.pushHubReport != nil {
		go w.pushHubReport()
	}

	w.logger.Printf("[INFO] [STORAGE] Reconnect completed: %s", path)
	return filteredStacks, nil
}

// RestartStoppedApps restarts apps that were auto-stopped due to a drive disconnect.
func (w *StorageWatchdog) RestartStoppedApps(path string) (started, failed []string) {
	sp := w.findStoragePath(path)
	if sp == nil || sp.Disconnected {
		return nil, nil
	}

	stacks := w.settings.GetStoppedStacks(path)
	if len(stacks) == 0 {
		return nil, nil
	}

	for _, name := range stacks {
		w.logger.Printf("[INFO] [STORAGE] Starting stack %s (drive reconnected: %s)", name, path)
		if err := w.stackProvider.StartStack(name); err != nil {
			w.logger.Printf("[ERROR] [STORAGE] Failed to start stack %s: %v", name, err)
			failed = append(failed, name)
		} else {
			started = append(started, name)
		}
	}

	// Clear stopped stacks list
	if err := w.settings.ClearStoppedStacks(path); err != nil {
		w.logger.Printf("[ERROR] [STORAGE] Failed to clear stopped stacks: %v", err)
	}

	return started, failed
}

// ── Debug simulation methods ─────────────────────────────────────────

// isSimulated returns true if the path is in simulated-disconnect state.
func (w *StorageWatchdog) isSimulated(path string) bool {
	w.simulatedMu.RLock()
	defer w.simulatedMu.RUnlock()
	return w.simulatedPaths[path]
}

// SimulateDisconnect simulates a drive disconnection without actually unmounting.
// Runs disconnect steps 1,2,4,5,6,7 (skips step 3: lazyUnmount).
// Returns the list of stopped stacks.
func (w *StorageWatchdog) SimulateDisconnect(ctx context.Context, path string) ([]string, error) {
	sp := w.findStoragePath(path)
	if sp == nil {
		return nil, fmt.Errorf("storage path %q not found", path)
	}
	if sp.Disconnected {
		return nil, fmt.Errorf("drive already disconnected")
	}
	if sp.Decommissioned {
		return nil, fmt.Errorf("drive is decommissioned")
	}

	label := sp.Label
	if label == "" {
		label = sp.Path
	}
	w.logger.Printf("[INFO] [STORAGE] [DEBUG-SIM] Simulating disconnect: %s (%s)", path, label)

	// Mark as simulated so the watchdog skips probing this path
	w.simulatedMu.Lock()
	w.simulatedPaths[path] = true
	w.simulatedMu.Unlock()

	// Step 1: Stop affected stacks
	stoppedStacks := w.stopAffectedStacks(path)

	// Step 2: Mark disconnected in settings
	if err := w.settings.SetDisconnected(path, true, stoppedStacks); err != nil {
		w.logger.Printf("[ERROR] [STORAGE] [DEBUG-SIM] Failed to mark disconnected: %v", err)
	}

	// Step 3: SKIPPED (no lazyUnmount — drive stays physically mounted)

	// Step 4: Update in-memory state
	state := w.getOrCreateState(path)
	state.lastStatus = "disconnected"
	state.probeInterval = disconnectedProbeInterval
	state.consecutiveFailures = 0

	// Step 5: Trigger alert refresh
	if w.alertRefresh != nil {
		w.alertRefresh()
	}

	// Step 6: Send notification
	w.notifier.NotifyStorageDisconnected(label, stoppedStacks)

	// Step 7: Push hub report
	if w.pushHubReport != nil {
		go w.pushHubReport()
	}

	w.logger.Printf("[INFO] [STORAGE] [DEBUG-SIM] Disconnect simulated: %s — %d stack(s) stopped", path, len(stoppedStacks))
	return stoppedStacks, nil
}

// SimulateReconnect undoes a simulated disconnection.
func (w *StorageWatchdog) SimulateReconnect(ctx context.Context, path string) error {
	if !w.isSimulated(path) {
		return fmt.Errorf("path %q is not in simulated-disconnect state", path)
	}

	sp := w.findStoragePath(path)
	if sp == nil {
		return fmt.Errorf("storage path %q not found", path)
	}

	label := sp.Label
	if label == "" {
		label = sp.Path
	}
	w.logger.Printf("[INFO] [STORAGE] [DEBUG-SIM] Simulating reconnect: %s (%s)", path, label)

	// Remove from simulated set
	w.simulatedMu.Lock()
	delete(w.simulatedPaths, path)
	w.simulatedMu.Unlock()

	// Verify drive is actually still mounted (it should be since we never unmounted)
	verifyResult := system.ProbeStoragePath(path)
	if verifyResult.Status != system.ProbeConnected {
		return fmt.Errorf("drive probe failed after simulation clear: %v", verifyResult.Err)
	}

	// Clean restic locks
	w.cleanResticLocks(ctx, path)

	// Validate stopped stacks
	filteredStacks := w.filterStoppedStacks(sp.StoppedStacks)

	// Clear disconnected, preserve stopped stacks for restart UI
	if err := w.settings.SetDisconnected(path, false, filteredStacks); err != nil {
		w.logger.Printf("[ERROR] [STORAGE] [DEBUG-SIM] Failed to clear disconnected: %v", err)
	}

	// Update in-memory state
	state := w.getOrCreateState(path)
	state.lastStatus = "connected"
	state.probeInterval = defaultProbeInterval
	state.consecutiveFailures = 0

	// Trigger alert refresh
	if w.alertRefresh != nil {
		w.alertRefresh()
	}

	// Send notification
	w.notifier.NotifyStorageReconnected(label)
	if w.pushHubReport != nil {
		go w.pushHubReport()
	}

	w.logger.Printf("[INFO] [STORAGE] [DEBUG-SIM] Reconnect simulated: %s", path)
	return nil
}

// PathDebugStatus holds per-path probe state for the debug page.
type PathDebugStatus struct {
	Path          string    `json:"path"`
	Label         string    `json:"label"`
	Status        string    `json:"status"`
	Simulated     bool      `json:"simulated"`
	ProbeOK       bool      `json:"probe_ok"`
	DebounceCount int       `json:"debounce_count"`
	DebounceMax   int       `json:"debounce_max"`
	LastProbe     time.Time `json:"last_probe"`
	AvgLatencyMs  float64   `json:"avg_latency_ms"`
	ProbeCount    int       `json:"probe_count"`
	ProbeOKCount  int       `json:"probe_ok_count"`
}

// GetDebugStatus returns per-path probe state for the debug page.
func (w *StorageWatchdog) GetDebugStatus() []PathDebugStatus {
	paths := w.settings.GetStoragePaths()
	result := make([]PathDebugStatus, 0, len(paths))

	w.mu.Lock()
	defer w.mu.Unlock()

	for _, sp := range paths {
		if sp.Decommissioned {
			continue
		}
		ds := PathDebugStatus{
			Path:        sp.Path,
			Label:       sp.Label,
			DebounceMax: probeThreshold,
		}
		if sp.Disconnected {
			ds.Status = "disconnected"
		} else {
			ds.Status = "connected"
		}
		ds.Simulated = w.isSimulatedLocked(sp.Path)

		if state, ok := w.pathState[sp.Path]; ok {
			ds.DebounceCount = state.consecutiveFailures
			ds.LastProbe = state.lastProbeTime
			ds.ProbeOK = state.lastStatus == "connected"
			ds.ProbeCount = state.probeCount
			ds.ProbeOKCount = state.probeOKCount
			if state.probeCount > 0 {
				ds.AvgLatencyMs = float64(state.totalLatency.Milliseconds()) / float64(state.probeCount)
			}
		}
		result = append(result, ds)
	}
	return result
}

// isSimulatedLocked checks simulation state without acquiring simulatedMu
// (caller must hold w.mu or be ok with a racy read for debug display).
func (w *StorageWatchdog) isSimulatedLocked(path string) bool {
	w.simulatedMu.RLock()
	defer w.simulatedMu.RUnlock()
	return w.simulatedPaths[path]
}

// findStoragePath returns the storage path entry for a given path, or nil.
func (w *StorageWatchdog) findStoragePath(path string) *settings.StoragePath {
	for _, sp := range w.settings.GetStoragePaths() {
		if sp.Path == path {
			return &sp
		}
	}
	return nil
}