Allow selecting and uploading multiple EPUB files at once

- views/pages.templ: upload input now has "multiple" attribute; page
  title/heading updated to plural ("Bücher hochladen"); templ regenerated
- internal/web/handlers.go: uploadSubmit now reads all files from
  r.MultipartForm.File["book"] instead of a single r.FormFile, saving
  each via a new saveUpload helper; partial failures are reported per
  filename while successfully saved files are kept

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

internal/web/handlers.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"mime/multipart"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -202,19 +203,52 @@ func (h *Handler) uploadSubmit(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	file, header, err := r.FormFile("book")
+	var headers []*multipart.FileHeader
-	if err != nil {
+	if r.MultipartForm != nil {
+		headers = r.MultipartForm.File["book"]
+	}
+	if len(headers) == 0 {
 		render(w, r.Context(), views.UploadPage("Keine Datei ausgewählt."))
 		return
 	}
-	defer file.Close()
 
-	ext := strings.ToLower(filepath.Ext(header.Filename))
+	var errs []string
-	if ext != ".epub" {
+	saved := 0
-		render(w, r.Context(), views.UploadPage("Nur EPUB-Dateien erlaubt."))
+	for _, header := range headers {
+		if msg := h.saveUpload(header); msg != "" {
+			errs = append(errs, fmt.Sprintf("%s: %s", header.Filename, msg))
+		} else {
+			saved++
+		}
+	}
+
+	if len(errs) > 0 {
+		msg := strings.Join(errs, " ")
+		if saved > 0 {
+			msg = fmt.Sprintf("%d von %d Dateien hochgeladen. %s", saved, len(headers), msg)
+		}
+		render(w, r.Context(), views.UploadPage(msg))
 		return
 	}
 
+	http.Redirect(w, r, "/", http.StatusSeeOther)
+}
+
+// saveUpload validates and persists a single uploaded file. It returns a
+// user-facing German error message, or "" on success.
+func (h *Handler) saveUpload(header *multipart.FileHeader) string {
+	ext := strings.ToLower(filepath.Ext(header.Filename))
+	if ext != ".epub" {
+		return "Nur EPUB-Dateien erlaubt."
+	}
+
+	file, err := header.Open()
+	if err != nil {
+		log.Printf("upload: open %q failed: %v", header.Filename, err)
+		return "Datei konnte nicht gelesen werden."
+	}
+	defer file.Close()
+
 	// Sanitize filename: keep only base name, no path components.
 	safeFilename := filepath.Base(header.Filename)
 	destPath := filepath.Join(h.lib.BooksDir(), safeFilename)
@@ -223,28 +257,24 @@ func (h *Handler) uploadSubmit(w http.ResponseWriter, r *http.Request) {
 	cleanBase := filepath.Clean(h.lib.BooksDir())
 	cleanDest := filepath.Clean(destPath)
 	if !strings.HasPrefix(cleanDest, cleanBase+string(filepath.Separator)) {
-		render(w, r.Context(), views.UploadPage("Ungültiger Dateiname."))
+		return "Ungültiger Dateiname."
-		return
 	}
 
 	out, err := os.OpenFile(destPath, os.O_WRONLY|os.O_CREATE|os.O_EXCL, 0o644)
 	if err != nil {
 		if os.IsExist(err) {
-			render(w, r.Context(), views.UploadPage(fmt.Sprintf("Datei '%s' existiert bereits.", safeFilename)))
+			return fmt.Sprintf("Datei '%s' existiert bereits.", safeFilename)
-			return
 		}
 		log.Printf("upload: create %q failed: %v", destPath, err)
-		http.Error(w, "Datei konnte nicht gespeichert werden", http.StatusInternalServerError)
+		return "Datei konnte nicht gespeichert werden."
-		return
 	}
 	defer out.Close()
 
 	if _, err := io.Copy(out, file); err != nil {
 		log.Printf("upload: write %q failed: %v", destPath, err)
 		_ = os.Remove(destPath)
-		http.Error(w, "Upload fehlgeschlagen", http.StatusInternalServerError)
+		return "Upload fehlgeschlagen."
-		return
 	}
 
-	http.Redirect(w, r, "/", http.StatusSeeOther)
+	return ""
 }

views/pages.templ

@@ -69,16 +69,16 @@ templ LoginPage(errMsg string) {
 }
 
 templ UploadPage(errMsg string) {
-  @Layout("Buch hochladen", "/") {
+  @Layout("Bücher hochladen", "/") {
     <section class="page-head">
-      <h2>Buch hochladen</h2>
+      <h2>Bücher hochladen</h2>
     </section>
     if errMsg != "" {
       <p class="error">{ errMsg }</p>
     }
     <form method="post" action="/upload" enctype="multipart/form-data" class="upload-form">
-      <label for="book">EPUB auswählen</label>
+      <label for="book">EPUB(s) auswählen</label>
-      <input id="book" type="file" name="book" accept=".epub" required />
+      <input id="book" type="file" name="book" accept=".epub" multiple required />
       <button type="submit" class="btn">Hochladen</button>
     </form>
   }

views/pages_templ.go

@@ -239,7 +239,7 @@ func UploadPage(errMsg string) templ.Component {
 				}()
 			}
 			ctx = templ.InitializeContext(ctx)
-			templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 14, "<section class=\"page-head\"><h2>Buch hochladen</h2></section>")
+			templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 14, "<section class=\"page-head\"><h2>Bücher hochladen</h2></section>")
 			if templ_7745c5c3_Err != nil {
 				return templ_7745c5c3_Err
 			}
@@ -262,13 +262,13 @@ func UploadPage(errMsg string) templ.Component {
 					return templ_7745c5c3_Err
 				}
 			}
-			templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 17, " <form method=\"post\" action=\"/upload\" enctype=\"multipart/form-data\" class=\"upload-form\"><label for=\"book\">EPUB auswählen</label> <input id=\"book\" type=\"file\" name=\"book\" accept=\".epub\" required> <button type=\"submit\" class=\"btn\">Hochladen</button></form>")
+			templ_7745c5c3_Err = templruntime.WriteString(templ_7745c5c3_Buffer, 17, " <form method=\"post\" action=\"/upload\" enctype=\"multipart/form-data\" class=\"upload-form\"><label for=\"book\">EPUB(s) auswählen</label> <input id=\"book\" type=\"file\" name=\"book\" accept=\".epub\" multiple required> <button type=\"submit\" class=\"btn\">Hochladen</button></form>")
 			if templ_7745c5c3_Err != nil {
 				return templ_7745c5c3_Err
 			}
 			return nil
 		})
-		templ_7745c5c3_Err = Layout("Buch hochladen", "/").Render(templ.WithChildren(ctx, templ_7745c5c3_Var10), templ_7745c5c3_Buffer)
+		templ_7745c5c3_Err = Layout("Bücher hochladen", "/").Render(templ.WithChildren(ctx, templ_7745c5c3_Var10), templ_7745c5c3_Buffer)
 		if templ_7745c5c3_Err != nil {
 			return templ_7745c5c3_Err
 		}