feat: add file upload workflow

backend/internal/modules/file/service.go

@@ -0,0 +1,76 @@
+package file
+
+import (
+	"context"
+	"errors"
+	"mime/multipart"
+	"strings"
+)
+
+var (
+	ErrDependencyUnavailable = errors.New("dependency unavailable")
+	ErrInvalidFile           = errors.New("invalid file")
+)
+
+const maxUploadSize = 10 * 1024 * 1024
+
+var allowedContentTypes = map[string]bool{
+	"image/jpeg":      true,
+	"image/png":       true,
+	"image/webp":      true,
+	"application/pdf": true,
+}
+
+type Service struct {
+	storage *Storage
+}
+
+func NewService(storage *Storage) *Service {
+	return &Service{storage: storage}
+}
+
+func (s *Service) Upload(req uploadRequest) (*UploadDTO, error) {
+	if s.storage == nil {
+		return nil, ErrDependencyUnavailable
+	}
+	if req.Header == nil || req.Reader == nil || req.Header.Size <= 0 || req.Header.Size > maxUploadSize {
+		return nil, ErrInvalidFile
+	}
+	contentType := req.ContentType
+	if contentType == "" {
+		contentType = req.Header.Header.Get("Content-Type")
+	}
+	if !allowedContentTypes[contentType] {
+		return nil, ErrInvalidFile
+	}
+	scene := normalizeScene(req.Scene)
+	key, err := s.storage.Put(req.Context, scene, req.Header, req.Reader, contentType)
+	if err != nil {
+		return nil, err
+	}
+	return &UploadDTO{
+		ObjectKey:   key,
+		URL:         "/api/files/object?key=" + key,
+		Filename:    req.Header.Filename,
+		ContentType: contentType,
+		Size:        req.Header.Size,
+	}, nil
+}
+
+func normalizeScene(scene string) string {
+	scene = strings.TrimSpace(strings.ToLower(scene))
+	switch scene {
+	case "listing", "handoff", "dispute", "realname", "avatar":
+		return scene
+	default:
+		return "misc"
+	}
+}
+
+type uploadRequest struct {
+	Context     context.Context
+	Scene       string
+	Header      *multipart.FileHeader
+	Reader      multipart.File
+	ContentType string
+}