abstract rest.UploadedFile to allow loading local files

tools/filesystem/file.go

@@ -0,0 +1,135 @@
+package filesystem
+
+import (
+	"fmt"
+	"io"
+	"mime/multipart"
+	"os"
+	"path/filepath"
+	"regexp"
+	"strings"
+
+	"github.com/gabriel-vasile/mimetype"
+	"github.com/pocketbase/pocketbase/tools/inflector"
+	"github.com/pocketbase/pocketbase/tools/security"
+)
+
+// FileReader defines an interface for a file resource reader.
+type FileReader interface {
+	Open() (io.ReadSeekCloser, error)
+}
+
+// File defines a single file [io.ReadSeekCloser] resource.
+//
+// The file could be from a local path, multipipart/formdata header, etc.
+type File struct {
+	Name         string
+	OriginalName string
+	Size         int64
+	Reader       FileReader
+}
+
+// NewFileFromPath creates a new File instance from the provided local file path.
+func NewFileFromPath(path string) (*File, error) {
+	f := &File{}
+
+	info, err := os.Stat(path)
+	if err != nil {
+		return nil, err
+	}
+
+	f.Reader = &PathReader{Path: path}
+	f.Size = info.Size()
+	f.OriginalName = info.Name()
+	f.Name = normalizeName(f.Reader, f.OriginalName)
+
+	return f, nil
+}
+
+// NewFileFromMultipart creates a new File instace from the provided multipart header.
+func NewFileFromMultipart(mh *multipart.FileHeader) (*File, error) {
+	f := &File{}
+
+	f.Reader = &MultipartReader{Header: mh}
+	f.Size = mh.Size
+	f.OriginalName = mh.Filename
+	f.Name = normalizeName(f.Reader, f.OriginalName)
+
+	return f, nil
+}
+
+// -------------------------------------------------------------------
+
+var _ FileReader = (*MultipartReader)(nil)
+
+// MultipartReader defines a [multipart.FileHeader] reader.
+type MultipartReader struct {
+	Header *multipart.FileHeader
+}
+
+// Open implements the [filesystem.FileReader] interface.
+func (r *MultipartReader) Open() (io.ReadSeekCloser, error) {
+	return r.Header.Open()
+}
+
+// -------------------------------------------------------------------
+
+var _ FileReader = (*PathReader)(nil)
+
+type PathReader struct {
+	Path string
+}
+
+// Open implements the [filesystem.FileReader] interface.
+func (r *PathReader) Open() (io.ReadSeekCloser, error) {
+	return os.Open(r.Path)
+}
+
+// -------------------------------------------------------------------
+
+var extInvalidCharsRegex = regexp.MustCompile(`[^\w\.\*\-\+\=\#]+`)
+
+func normalizeName(fr FileReader, name string) string {
+	// extension
+	// ---
+	originalExt := filepath.Ext(name)
+	cleanExt := extInvalidCharsRegex.ReplaceAllString(originalExt, "")
+	if cleanExt == "" {
+		// try to detect the extension from the file content
+		cleanExt, _ = detectExtension(fr)
+	}
+
+	// name
+	// ---
+	cleanName := inflector.Snakecase(strings.TrimSuffix(name, originalExt))
+	if length := len(cleanName); length < 3 {
+		// the name is too short so we concatenate an additional random part
+		cleanName += security.RandomString(10)
+	} else if length > 100 {
+		// keep only the first 100 characters (it is multibyte safe after Snakecase)
+		cleanName = cleanName[:100]
+	}
+
+	return fmt.Sprintf(
+		"%s_%s%s",
+		cleanName,
+		security.RandomString(10), // ensure that there is always a random part
+		cleanExt,
+	)
+}
+
+func detectExtension(fr FileReader) (string, error) {
+	// try to detect the extension from the mime type
+	r, err := fr.Open()
+	if err != nil {
+		return "", err
+	}
+	defer r.Close()
+
+	mt, _ := mimetype.DetectReader(r)
+	if err != nil {
+		return "", err
+	}
+
+	return mt.Extension(), nil
+}