new flat KV structure

internal/watcher/watcher.go

@@ -13,10 +13,11 @@ import (
 
 // Watcher provides file scanning and event dispatching
 type Watcher struct {
-	config     *config.Config
-	debouncer  *Debouncer
-	dispatcher *Dispatcher
-	filesPath  string
+	config        *config.Config
+	debouncer     *Debouncer
+	dispatcher    *Dispatcher
+	filesPath     string
+	stateRegistry *StateRegistry
 
 	mu          sync.RWMutex
 	eventBuffer []FileEvent
@@ -27,11 +28,12 @@ func NewWatcher(cfg *config.Config, dispatcher *Dispatcher) (*Watcher, error) {
 	debouncer := NewDebouncer(0) // No debouncing for polling-based scanning
 
 	w := &Watcher{
-		config:      cfg,
-		debouncer:   debouncer,
-		dispatcher:  dispatcher,
-		filesPath:   cfg.FilesPath,
-		eventBuffer: make([]FileEvent, 0, 1000),
+		config:        cfg,
+		debouncer:     debouncer,
+		dispatcher:    dispatcher,
+		filesPath:     cfg.FilesPath,
+		stateRegistry: NewStateRegistry(),
+		eventBuffer:   make([]FileEvent, 0, 1000),
 	}
 
 	return w, nil
@@ -110,6 +112,138 @@ func (w *Watcher) ScanDirectory(root string) int {
 	return count
 }
 
+// ScanDirectoryDiff scans a directory and only emits events for differences
+// Returns the count of added, changed, and deleted files
+func (w *Watcher) ScanDirectoryDiff(root string, watcherID string) DiffScanResult {
+	result := DiffScanResult{}
+	state := w.stateRegistry.GetOrCreate(watcherID)
+
+	// Get snapshot of known files
+	knownFiles := state.GetAll()
+	seenFiles := make(map[string]bool)
+
+	filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return nil
+		}
+
+		// Skip directories
+		if info.IsDir() {
+			return nil
+		}
+
+		// Skip hidden files
+		if strings.HasPrefix(filepath.Base(path), ".") {
+			return nil
+		}
+
+		// Get relative path
+		relPath, err := filepath.Rel(w.filesPath, path)
+		if err != nil {
+			relPath = path
+		}
+		relPath = filepath.ToSlash(relPath)
+		seenFiles[relPath] = true
+
+		// Check current file state
+		currentMtime := info.ModTime().UnixNano()
+		currentSize := info.Size()
+
+		prevState := knownFiles[relPath]
+
+		if prevState == nil {
+			// New file - emit add event
+			event := FileEvent{
+				Type:      EventTypeAdd,
+				Path:      relPath,
+				Size:      currentSize,
+				Timestamp: NowMS(),
+			}
+
+			// Compute midhash256
+			if hash, err := ComputeMidHash256(path); err == nil {
+				event.MidHash256 = hash
+			}
+
+			// Dispatch event
+			w.dispatcher.Dispatch(event)
+
+			// Update state
+			state.Set(relPath, &FileState{
+				Size:      currentSize,
+				MtimeNano: currentMtime,
+				MidHash:   event.MidHash256,
+			})
+
+			result.Added++
+		} else if prevState.Size != currentSize || prevState.MtimeNano != currentMtime {
+			// File changed - emit change event
+			event := FileEvent{
+				Type:      EventTypeChange,
+				Path:      relPath,
+				Size:      currentSize,
+				Timestamp: NowMS(),
+			}
+
+			// Compute midhash256
+			if hash, err := ComputeMidHash256(path); err == nil {
+				event.MidHash256 = hash
+			}
+
+			// Dispatch event
+			w.dispatcher.Dispatch(event)
+
+			// Update state
+			state.Set(relPath, &FileState{
+				Size:      currentSize,
+				MtimeNano: currentMtime,
+				MidHash:   event.MidHash256,
+			})
+
+			result.Changed++
+		}
+		// If file exists and hasn't changed, do nothing
+
+		return nil
+	})
+
+	// Check for deleted files (in known but not seen)
+	for relPath := range knownFiles {
+		if !seenFiles[relPath] {
+			// File deleted - emit delete event
+			event := FileEvent{
+				Type:      EventTypeDelete,
+				Path:      relPath,
+				Timestamp: NowMS(),
+			}
+
+			w.dispatcher.Dispatch(event)
+			state.Delete(relPath)
+			result.Deleted++
+		}
+	}
+
+	result.Total = state.Count()
+	return result
+}
+
+// ClearState clears the tracked state for a watcher
+func (w *Watcher) ClearState(watcherID string) {
+	w.stateRegistry.Clear(watcherID)
+}
+
+// ClearEventBuffer clears the in-memory event buffer
+func (w *Watcher) ClearEventBuffer() {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	w.eventBuffer = make([]FileEvent, 0, 1000)
+}
+
+// GetStateRegistry returns the state registry for external access
+func (w *Watcher) GetStateRegistry() *StateRegistry {
+	return w.stateRegistry
+}
+
 // ScanMountPath scans a specific mount path and returns file count
 // This is used by the mount poller to scan individual mounts
 func (w *Watcher) ScanMountPath(mountPath string) (int, error) {