Initial project scaffolding

- main.go: CLI entry point with flag parsing
- gitignore.go: .gitignore loading and parsing
- sync.go: initial sync with manifest tracking
- watcher.go: fsnotify-based file watcher with debouncing
- Dockerfile: multi-stage build for Alpine runtime

1 files changed, 210 insertions, 0 deletions

diff --git a/watcher.go b/watcher.go
new file mode 100644
index 0000000..7b823da
--- /dev/null
+++ b/watcher.go
@@ -0,0 +1,210 @@
+package main
+
+import (
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+	"sync"
+	"time"
+
+	"github.com/fsnotify/fsnotify"
+	ignore "github.com/sabhiram/go-gitignore"
+)
+
+func watch(hostDir, dataDir string, manifest *Manifest, rules *ignore.GitIgnore, dryRun, verbose bool) error {
+	watcher, err := fsnotify.NewWatcher()
+	if err != nil {
+		return err
+	}
+	defer watcher.Close()
+
+	var mu sync.Mutex
+	debounce := make(map[string]*time.Timer)
+
+	if err := addWatchersRecursively(watcher, hostDir, rules); err != nil {
+		return err
+	}
+
+	for {
+		select {
+		case event, ok := <-watcher.Events:
+			if !ok {
+				return nil
+			}
+
+			relPath, err := filepath.Rel(hostDir, event.Name)
+			if err != nil {
+				continue
+			}
+
+			if relPath == ".git" || strings.HasPrefix(relPath, ".git"+string(filepath.Separator)) {
+				continue
+			}
+
+			if rules.MatchesPath(relPath) {
+				continue
+			}
+
+			if verbose {
+				log.Printf("event: %s %s", event.Op, relPath)
+			}
+
+			mu.Lock()
+			if t, exists := debounce[relPath]; exists {
+				t.Stop()
+			}
+			debounce[relPath] = time.AfterFunc(200*time.Millisecond, func() {
+				mu.Lock()
+				delete(debounce, relPath)
+				mu.Unlock()
+				handleEvent(event.Op, hostDir, dataDir, relPath, manifest, rules, dryRun, verbose, watcher)
+			})
+			mu.Unlock()
+
+		case err, ok := <-watcher.Errors:
+			if !ok {
+				return nil
+			}
+			log.Printf("watcher error: %v", err)
+		}
+	}
+}
+
+func handleEvent(op fsnotify.Op, hostDir, dataDir, relPath string, manifest *Manifest, rules *ignore.GitIgnore, dryRun, verbose bool, watcher *fsnotify.Watcher) {
+	destPath := filepath.Join(dataDir, relPath)
+	srcPath := filepath.Join(hostDir, relPath)
+
+	switch {
+	case op&fsnotify.Create != 0:
+		syncCreate(srcPath, destPath, relPath, manifest, dryRun, verbose, watcher)
+
+	case op&fsnotify.Write != 0:
+		syncWrite(srcPath, destPath, relPath, manifest, dryRun, verbose)
+
+	case op&fsnotify.Remove != 0:
+		syncRemove(destPath, relPath, manifest, dryRun, verbose)
+
+	case op&fsnotify.Rename != 0:
+		syncRemove(destPath, relPath, manifest, dryRun, verbose)
+	}
+}
+
+func syncCreate(srcPath, destPath, relPath string, manifest *Manifest, dryRun, verbose bool, watcher *fsnotify.Watcher) {
+	info, err := os.Lstat(srcPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return
+		}
+		log.Printf("error stat %s: %v", relPath, err)
+		return
+	}
+
+	if info.IsDir() {
+		if err := watcher.Add(srcPath); err != nil {
+			log.Printf("error adding watcher for %s: %v", relPath, err)
+		}
+		if dryRun {
+			log.Printf("[dry-run] would create dir: %s", relPath)
+			return
+		}
+		if err := os.MkdirAll(destPath, info.Mode()); err != nil {
+			log.Printf("error creating dir %s: %v", relPath, err)
+		}
+		return
+	}
+
+	linkTarget := ""
+	if info.Mode()&os.ModeSymlink != 0 {
+		linkTarget, _ = os.Readlink(srcPath)
+	}
+
+	meta := FileMeta{
+		Size:    info.Size(),
+		Mode:    info.Mode(),
+		Symlink: linkTarget,
+	}
+	manifest.Files[relPath] = meta
+
+	if dryRun {
+		log.Printf("[dry-run] would sync: %s", relPath)
+		return
+	}
+
+	os.MkdirAll(filepath.Dir(destPath), 0755)
+
+	if linkTarget != "" {
+		if err := os.Symlink(linkTarget, destPath); err != nil {
+			log.Printf("error creating symlink %s: %v", relPath, err)
+		}
+		return
+	}
+
+	if err := copyFile(srcPath, destPath, info.Mode()); err != nil {
+		log.Printf("error copying %s: %v", relPath, err)
+	}
+}
+
+func syncWrite(srcPath, destPath, relPath string, manifest *Manifest, dryRun, verbose bool) {
+	info, err := os.Lstat(srcPath)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return
+		}
+		log.Printf("error stat %s: %v", relPath, err)
+		return
+	}
+
+	meta, exists := manifest.Files[relPath]
+	if exists && meta.Size == info.Size() && meta.Mode == info.Mode() {
+		return
+	}
+
+	manifest.Files[relPath] = FileMeta{
+		Size: info.Size(),
+		Mode: info.Mode(),
+	}
+
+	if dryRun {
+		log.Printf("[dry-run] would update: %s", relPath)
+		return
+	}
+
+	if err := copyFile(srcPath, destPath, info.Mode()); err != nil {
+		log.Printf("error copying %s: %v", relPath, err)
+	}
+}
+
+func syncRemove(destPath, relPath string, manifest *Manifest, dryRun, verbose bool) {
+	delete(manifest.Files, relPath)
+
+	if dryRun {
+		log.Printf("[dry-run] would remove: %s", relPath)
+		return
+	}
+
+	os.Remove(destPath)
+}
+
+func addWatchersRecursively(watcher *fsnotify.Watcher, root string, rules *ignore.GitIgnore) error {
+	return filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		relPath, err := filepath.Rel(root, path)
+		if err != nil {
+			return err
+		}
+
+		if relPath == ".git" || strings.HasPrefix(relPath, ".git"+string(filepath.Separator)) {
+			return filepath.SkipDir
+		}
+
+		if info.IsDir() && !rules.MatchesPath(relPath) {
+			return watcher.Add(path)
+		}
+
+		return nil
+	})
+}