fix

internal/biz/media.go

@@ -1,11 +1,13 @@
 package biz
 
 import (
+	"bufio"
 	"context"
 	"crypto/md5"
 	"encoding/hex"
 	"errors"
 	"io"
+	"net/http"
 	"path/filepath"
 	"strings"
 	"time"
@@ -50,9 +52,13 @@ func (uc *MediaUsecase) Upload(ctx context.Context, userID uint, name, mime stri
 		return nil, err
 	}
 	ext := strings.ToLower(filepath.Ext(name))
+	buffered := bufio.NewReader(reader)
+	if header, _ := buffered.Peek(512); len(header) > 0 {
+		mime = http.DetectContentType(header)
+	}
 	key := time.Now().Format("20060102") + "/" + uuid.NewString() + ext
 	hash := md5.New()
-	stored, err := uc.files.Put(ctx, key, io.TeeReader(reader, hash))
+	stored, err := uc.files.Put(ctx, key, io.TeeReader(buffered, hash))
 	if err != nil {
 		return nil, err
 	}