feat: add bulk date management functionality and update admin interface

main.go

@@ -82,6 +82,7 @@ func main() {
 	http.HandleFunc("/api/admin/login", handleAdminLogin)
 	http.HandleFunc("/api/admin/logout", handleAdminLogout)
 	http.HandleFunc("/api/admin/dates", handleAdminDates)
+	http.HandleFunc("/api/admin/dates/bulk", handleAdminBulkDates)
 	http.HandleFunc("/admin", handleAdminPage)
 
 	// Serve static files from webDir directory
@@ -281,6 +282,61 @@ func handleAdminDates(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+func handleAdminBulkDates(w http.ResponseWriter, r *http.Request) {
+	if !isAdminRequest(r) {
+		writeJSON(w, http.StatusUnauthorized, Response{Success: false, Message: "Anmeldung erforderlich."})
+		return
+	}
+	if r.Method != http.MethodPost {
+		http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	var requestedDates []AvailableDate
+	if err := json.NewDecoder(r.Body).Decode(&requestedDates); err != nil {
+		writeJSON(w, http.StatusBadRequest, Response{Success: false, Message: "Ungültige Terminauswahl."})
+		return
+	}
+	seen := make(map[string]bool, len(requestedDates))
+	for _, date := range requestedDates {
+		if !isValidAvailableDate(date) || !isTodayOrFuture(date.Date) || seen[date.Date] {
+			writeJSON(w, http.StatusBadRequest, Response{Success: false, Message: "Bitte wähle gültige, eindeutige Daten ab heute."})
+			return
+		}
+		seen[date.Date] = true
+	}
+	bookedDates, err := getBookedDates()
+	if err != nil {
+		log.Printf("Error reading booked dates: %v", err)
+		http.Error(w, "Booked dates could not be loaded", http.StatusInternalServerError)
+		return
+	}
+	bookedDateSet := make(map[string]bool, len(bookedDates))
+	for _, date := range bookedDates {
+		bookedDateSet[date] = true
+	}
+
+	if err := updateAvailableDates(func(dates []AvailableDate) ([]AvailableDate, error) {
+		preserved := make([]AvailableDate, 0, len(dates)+len(requestedDates))
+		for _, date := range dates {
+			if !isTodayOrFuture(date.Date) || bookedDateSet[date.Date] {
+				preserved = append(preserved, date)
+			}
+		}
+		for _, date := range requestedDates {
+			if !bookedDateSet[date.Date] {
+				preserved = append(preserved, date)
+			}
+		}
+		return preserved, nil
+	}); err != nil {
+		log.Printf("Error saving available dates: %v", err)
+		http.Error(w, "Dates could not be saved", http.StatusInternalServerError)
+		return
+	}
+	writeJSON(w, http.StatusOK, Response{Success: true, Message: "Änderungen gespeichert."})
+}
+
 func getSettingsFilePath() string {
 	path := os.Getenv("SETTINGS_FILE")
 	if path == "" {