serve files from Storage implementation

1 files changed, 102 insertions, 0 deletions

diff --git a/internal/storage/files/file.go b/internal/storage/files/file.go
new file mode 100644
index 0000000..a71811c
--- /dev/null
+++ b/internal/storage/files/file.go
@@ -0,0 +1,102 @@
+package files
+
+import (
+	"fmt"
+	"hash/fnv"
+	"io"
+	"mime"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"gitlab.com/tozd/go/errors"
+	"go.alanpearce.eu/website/internal/storage"
+)
+
+type File struct {
+	storage.File
+}
+
+var encodings = map[string]string{
+	"br":   ".br",
+	"gzip": ".gz",
+}
+
+func (r *Reader) OpenFile(path string, filename string) (*File, error) {
+	f, err := os.Open(filename)
+	if err != nil {
+		return nil, errors.WithMessage(err, "could not open file for reading")
+	}
+	stat, err := f.Stat()
+	if err != nil {
+		return nil, errors.WithMessage(err, "could not stat file")
+	}
+
+	etag, err := etag(f)
+	if err != nil {
+		return nil, errors.WithMessage(err, "could not calculate etag")
+	}
+
+	file := &File{
+		File: storage.File{
+			Path:         path,
+			ContentType:  mime.TypeByExtension(filepath.Ext(filename)),
+			LastModified: stat.ModTime(),
+			Etag:         etag,
+			Encodings: map[string]io.ReadSeekCloser{
+				"identity": f,
+			},
+		},
+	}
+
+	for enc, suffix := range encodings {
+		_, err := os.Stat(filename + suffix)
+		if err != nil {
+			if errors.Is(err, os.ErrNotExist) {
+				continue
+			}
+
+			return nil, errors.WithMessagef(err, "could not stat file %s", filename+suffix)
+		}
+		file.Encodings[enc], err = os.Open(filename + suffix)
+		if err != nil {
+			return nil, errors.WithMessagef(err, "could not read file %s", filename+suffix)
+		}
+	}
+
+	return file, nil
+}
+
+func etag(f io.Reader) (string, error) {
+	hash := fnv.New64a()
+	if _, err := io.Copy(hash, f); err != nil {
+		return "", errors.WithMessage(err, "could not hash file")
+	}
+
+	return fmt.Sprintf(`W/"%x"`, hash.Sum(nil)), nil
+}
+
+func (f *File) Close() error {
+	var errs []error
+	for _, enc := range f.Encodings {
+		if err := enc.Close(); err != nil {
+			errs = append(errs, err)
+		}
+	}
+
+	return errors.Join(errs...)
+}
+
+func pathNameToFileName(pathname string) string {
+	if strings.HasSuffix(pathname, "/") {
+		pathname = pathname + "index.html"
+	}
+
+	return pathname
+}
+
+func fileNameToPathName(filename string) string {
+	pathname, _ := strings.CutSuffix(filename, "index.html")
+
+	return pathname
+}