feat: Viewport lazy loading and video refresh support

- Add intersection observer hooks for viewport detection
- Lazy load iframes and control video autoplay based on visibility
- Extend refresh button to restart videos from beginning
- Show refresh button for both HTML animations and video content
- Add intelligent feedback messages for mixed media types
- Optimize performance by loading media only when in viewport

frontend/src/components/FilePreview.js

@@ -1,5 +1,6 @@
 import React from 'react';
 import { Spin } from 'antd';
+import { useVideoAutoPlay, useInViewport } from '../utils/viewportUtils';
 
 // Hilfsfunktion für Dateigröße
 export function formatFileSize(bytes) {
@@ -24,6 +25,10 @@ export default function FilePreview({ file, zoom = 1, darkMode = false }) {
   const width = file.width || 300;
   const height = file.height || 200;
 
+  // Viewport-Detection für Videos und iFrames
+  const { containerRef: videoContainerRef, videoRef, isInViewport: videoInViewport } = useVideoAutoPlay();
+  const { ref: iframeRef, isInViewport: iframeInViewport } = useInViewport();
+
   // Wrapper für saubere Skalierung
   const wrapperStyle = {
     display: 'inline-block',
@@ -45,7 +50,7 @@ export default function FilePreview({ file, zoom = 1, darkMode = false }) {
   const renderFileContent = () => {
     if (file.type === 'html') {
       return (
-        <div style={wrapperStyle}>
+        <div style={wrapperStyle} ref={iframeRef}>
           <div style={innerStyle}>
             {!loaded && (
               <div style={{ 
@@ -64,14 +69,34 @@ export default function FilePreview({ file, zoom = 1, darkMode = false }) {
                 <Spin size="large" />
               </div>
             )}
-            <iframe
+            {/* iFrame nur laden wenn im Viewport oder bereits geladen */}
-              src={file.url}
+            {iframeInViewport && (
-              title={file.name}
+              <iframe
-              width={width}
+                src={file.url}
-              height={height}
+                title={file.name}
-              style={{ border: 'none', opacity: loaded ? 1 : 0 }}
+                width={width}
-              onLoad={() => setLoaded(true)}
+                height={height}
-            />
+                style={{ border: 'none', opacity: loaded ? 1 : 0 }}
+                onLoad={() => setLoaded(true)}
+              />
+            )}
+            {/* Placeholder wenn nicht im Viewport */}
+            {!iframeInViewport && (
+              <div style={{
+                width: width,
+                height: height,
+                backgroundColor: darkMode ? '#1f1f1f' : '#f5f5f5',
+                border: `1px solid ${darkMode ? '#404040' : '#d9d9d9'}`,
+                borderRadius: 4,
+                display: 'flex',
+                alignItems: 'center',
+                justifyContent: 'center',
+                color: darkMode ? '#888' : '#666',
+                fontSize: 14
+              }}>
+                HTML Animation
+              </div>
+            )}
           </div>
         </div>
       );
@@ -112,7 +137,7 @@ export default function FilePreview({ file, zoom = 1, darkMode = false }) {
     }
     if (file.type === 'video') {
       return (
-        <div style={wrapperStyle}>
+        <div style={wrapperStyle} ref={videoContainerRef}>
           <div style={innerStyle}>
             {!loaded && (
               <div style={{ 
@@ -132,11 +157,11 @@ export default function FilePreview({ file, zoom = 1, darkMode = false }) {
               </div>
             )}
             <video
+              ref={videoRef}
               src={file.url}
               width={width}
               height={height}
               controls
-              autoPlay
               loop
               muted
               preload="metadata"

frontend/src/utils/adUtils.js

@@ -32,14 +32,17 @@ export const createCopyLinkHandler = (onSuccess) => async (adId, adName) => {
   }
 };
 
-// iFrame Refresh Funktionalität
+// iFrame und Video Refresh Funktionalität
 export const createRefreshAdHandler = (onSuccess, onInfo) => (adId, adName) => {
-  // Finde alle iFrames innerhalb des Ad-Containers
+  // Finde alle iFrames und Videos innerhalb des Ad-Containers
   const adContainer = document.getElementById(adId);
   if (adContainer) {
     const iframes = adContainer.querySelectorAll('iframe');
+    const videos = adContainer.querySelectorAll('video');
     let refreshedCount = 0;
+    let restartedCount = 0;
     
+    // iFrames refreshen (mit Cache-Busting)
     iframes.forEach((iframe) => {
       if (iframe.src) {
         // Füge einen Timestamp als URL-Parameter hinzu, um den Cache zu umgehen
@@ -50,10 +53,31 @@ export const createRefreshAdHandler = (onSuccess, onInfo) => (adId, adName) => {
       }
     });
     
-    if (refreshedCount > 0) {
+    // Videos neu starten
-      onSuccess(`Animation${refreshedCount > 1 ? 'en' : ''} "${adName}" ${refreshedCount > 1 ? 'wurden' : 'wurde'} neu geladen!`);
+    videos.forEach((video) => {
+      if (video.src || video.currentSrc) {
+        video.currentTime = 0; // Zurück zum Start
+        video.play().catch(err => {
+          // Autoplay kann durch Browser-Richtlinien blockiert werden
+          console.log('Video restart prevented:', err);
+        });
+        restartedCount++;
+      }
+    });
+    
+    const totalCount = refreshedCount + restartedCount;
+    if (totalCount > 0) {
+      let message = '';
+      if (refreshedCount > 0 && restartedCount > 0) {
+        message = `${refreshedCount} Animation${refreshedCount > 1 ? 'en' : ''} und ${restartedCount} Video${restartedCount > 1 ? 's' : ''} in "${adName}" ${totalCount > 1 ? 'wurden' : 'wurde'} neu gestartet!`;
+      } else if (refreshedCount > 0) {
+        message = `${refreshedCount} Animation${refreshedCount > 1 ? 'en' : ''} in "${adName}" ${refreshedCount > 1 ? 'wurden' : 'wurde'} neu geladen!`;
+      } else if (restartedCount > 0) {
+        message = `${restartedCount} Video${restartedCount > 1 ? 's' : ''} in "${adName}" ${restartedCount > 1 ? 'wurden' : 'wurde'} neu gestartet!`;
+      }
+      onSuccess(message);
     } else {
-      onInfo(`Keine Animationen in "${adName}" gefunden.`);
+      onInfo(`Keine Animationen oder Videos in "${adName}" gefunden.`);
     }
   }
 };

frontend/src/utils/tabUtils.js

@@ -38,9 +38,9 @@ export const buildTabsFromCategories = (data, zoom, darkMode, handleCopyLink, ha
                             onClick={() => handleCopyLink(adId, ad.name)}
                           />
                         </Tooltip>
-                        {/* Refresh-Button nur bei HTML-Dateien (iFrames) anzeigen */}
+                        {/* Refresh-Button bei HTML-Dateien (iFrames) und Videos anzeigen */}
-                        {Array.isArray(ad.files) && ad.files.some(file => file.type === 'html') && (
+                        {Array.isArray(ad.files) && ad.files.some(file => file.type === 'html' || file.type === 'video') && (
-                          <Tooltip title="Animationen neu laden">
+                          <Tooltip title="Animationen und Videos neu starten">
                             <Button 
                               type="text" 
                               shape="circle" 

frontend/src/utils/viewportUtils.js

@@ -0,0 +1,62 @@
+import { useState, useEffect, useRef } from 'react';
+
+// Custom Hook für Intersection Observer
+export const useInViewport = (options = {}) => {
+  const [isInViewport, setIsInViewport] = useState(false);
+  const [hasBeenInViewport, setHasBeenInViewport] = useState(false);
+  const ref = useRef(null);
+
+  useEffect(() => {
+    const element = ref.current;
+    if (!element) return;
+
+    const observer = new IntersectionObserver(
+      ([entry]) => {
+        const inViewport = entry.isIntersecting;
+        setIsInViewport(inViewport);
+        
+        // Einmal im Viewport gewesen = für immer markiert (für Videos die einmal geladen werden sollen)
+        if (inViewport && !hasBeenInViewport) {
+          setHasBeenInViewport(true);
+        }
+      },
+      {
+        threshold: 0.5, // 50% des Elements müssen sichtbar sein
+        rootMargin: '50px', // 50px Vorlaufbereich
+        ...options
+      }
+    );
+
+    observer.observe(element);
+
+    return () => {
+      observer.unobserve(element);
+    };
+  }, [hasBeenInViewport, options]);
+
+  return { ref, isInViewport, hasBeenInViewport };
+};
+
+// Hook speziell für Videos mit Auto-Play Kontrolle
+export const useVideoAutoPlay = (options = {}) => {
+  const { ref, isInViewport, hasBeenInViewport } = useInViewport(options);
+  const videoRef = useRef(null);
+
+  useEffect(() => {
+    const video = videoRef.current;
+    if (!video) return;
+
+    if (isInViewport) {
+      // Video abspielen wenn im Viewport
+      video.play().catch(err => {
+        // Autoplay kann durch Browser-Richtlinien blockiert werden
+        console.log('Autoplay prevented:', err);
+      });
+    } else {
+      // Video pausieren wenn aus dem Viewport
+      video.pause();
+    }
+  }, [isInViewport]);
+
+  return { containerRef: ref, videoRef, isInViewport, hasBeenInViewport };
+};