audio_pipeline

watcher/internal/scanner/scanner.go

@@ -0,0 +1,144 @@
+package scanner
+
+import (
+	"fmt"
+	"log/slog"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/oklog/ulid/v2"
+)
+
+var allowedExts = map[string]bool{
+	".mp3": true, ".wav": true, ".m4a": true,
+	".ogg": true, ".flac": true, ".webm": true,
+}
+
+type ClaimedFile struct {
+	TaskID   string
+	FilePath string
+	Filename string
+	Size     int64
+}
+
+type Config struct {
+	StorageRoot   string
+	IncomingDir   string
+	ProcessingDir string
+	FailedDir     string
+	StableWindow  time.Duration
+	StableChecks  int
+}
+
+type Scanner struct {
+	cfg Config
+}
+
+func New(cfg Config) *Scanner {
+	return &Scanner{cfg: cfg}
+}
+
+func (s *Scanner) EnsureDirs() error {
+	for _, dir := range []string{s.cfg.IncomingDir, s.cfg.ProcessingDir, s.cfg.FailedDir} {
+		if err := os.MkdirAll(filepath.Join(s.cfg.StorageRoot, dir), 0o755); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (s *Scanner) ScanOnce() ([]ClaimedFile, error) {
+	incoming := filepath.Join(s.cfg.StorageRoot, s.cfg.IncomingDir)
+	entries, err := os.ReadDir(incoming)
+	if err != nil {
+		if os.IsNotExist(err) {
+			return nil, nil
+		}
+		return nil, err
+	}
+
+	var claimed []ClaimedFile
+	for _, e := range entries {
+		if e.IsDir() {
+			continue
+		}
+		name := e.Name()
+		if strings.HasPrefix(name, ".") || strings.HasSuffix(strings.ToLower(name), ".tmp") {
+			continue
+		}
+		ext := strings.ToLower(filepath.Ext(name))
+		if !allowedExts[ext] {
+			continue
+		}
+		src := filepath.Join(incoming, name)
+		if !s.isStable(src) {
+			continue
+		}
+		cf, err := s.claim(src, name, ext)
+		if err != nil {
+			slog.Warn("claim failed", "file", name, "error", err)
+			continue
+		}
+		claimed = append(claimed, cf)
+	}
+	return claimed, nil
+}
+
+func (s *Scanner) isStable(path string) bool {
+	var lastSize int64 = -1
+	for i := 0; i < s.cfg.StableChecks; i++ {
+		info, err := os.Stat(path)
+		if err != nil {
+			return false
+		}
+		size := info.Size()
+		if lastSize >= 0 && size != lastSize {
+			return false
+		}
+		lastSize = size
+		if i < s.cfg.StableChecks-1 {
+			time.Sleep(s.cfg.StableWindow)
+		}
+	}
+	return true
+}
+
+func (s *Scanner) claim(src, originalName, ext string) (ClaimedFile, error) {
+	info, err := os.Stat(src)
+	if err != nil {
+		return ClaimedFile{}, err
+	}
+	taskID := ulid.Make().String()
+	processing := filepath.Join(s.cfg.StorageRoot, s.cfg.ProcessingDir)
+	dst := filepath.Join(processing, taskID+ext)
+	if err := os.Rename(src, dst); err != nil {
+		return ClaimedFile{}, fmt.Errorf("rename: %w", err)
+	}
+	slog.Info("claimed file", "task_id", taskID, "filename", originalName, "path", dst, "size", info.Size())
+	return ClaimedFile{
+		TaskID:   taskID,
+		FilePath: dst,
+		Filename: originalName,
+		Size:     info.Size(),
+	}, nil
+}
+
+func (s *Scanner) RollbackToIncoming(filePath, originalName string) error {
+	incoming := filepath.Join(s.cfg.StorageRoot, s.cfg.IncomingDir)
+	dst := filepath.Join(incoming, originalName)
+	if err := os.Rename(filePath, dst); err != nil {
+		return s.MoveToFailed(filePath, originalName)
+	}
+	return nil
+}
+
+func (s *Scanner) MoveToFailed(filePath, originalName string) error {
+	failed := filepath.Join(s.cfg.StorageRoot, s.cfg.FailedDir)
+	if err := os.MkdirAll(failed, 0o755); err != nil {
+		return err
+	}
+	dst := filepath.Join(failed, originalName)
+	return os.Rename(filePath, dst)
+}