Implement cache cleanup for images older than 24 hours and update access time on read

api.js

@@ -29,6 +29,9 @@ function getCachedImage(config) {
     const cachePath = getCachePath(hash);
 
     if (fs.existsSync(cachePath)) {
+        // Update file modification time to mark as recently accessed
+        const now = new Date();
+        fs.utimesSync(cachePath, now, now);
         return fs.readFileSync(cachePath);
     }
 
@@ -41,6 +44,33 @@ function cacheImage(config, imageBuffer) {
     fs.writeFileSync(cachePath, imageBuffer);
 }
 
+function cleanupOldCache() {
+    const ONE_DAY = 24 * 60 * 60 * 1000; // 24 hours in milliseconds
+    const now = Date.now();
+
+    if (!fs.existsSync(CACHE_DIR)) {
+        return;
+    }
+
+    const files = fs.readdirSync(CACHE_DIR);
+
+    let deletedCount = 0;
+    files.forEach(file => {
+        const filePath = path.join(CACHE_DIR, file);
+        const stats = fs.statSync(filePath);
+
+        // Check if file was last modified more than 24 hours ago
+        if (now - stats.mtime.getTime() > ONE_DAY) {
+            fs.unlinkSync(filePath);
+            deletedCount++;
+        }
+    });
+
+    if (deletedCount > 0) {
+        console.log(`Cleaned up ${deletedCount} cached image(s)`);
+    }
+}
+
 function formatTimestamp(epoch) {
     const date = new Date(epoch * 1000);
 
@@ -160,8 +190,17 @@ app.get('/health', (req, res) => {
     res.status(200).json({ status: 'ok' });
 });
 
+// Run cleanup every hour
+setInterval(() => {
+    cleanupOldCache();
+}, 60 * 60 * 1000);
+
+// Run cleanup on startup
+cleanupOldCache();
+
 app.listen(PORT, () => {
     console.log(`Quote generator API running on http://localhost:${PORT}`);
     console.log(`GET:  http://localhost:${PORT}/generate?text=Hello&displayName=Test&username=@test&timestamp=1735574400`);
     console.log(`POST: http://localhost:${PORT}/generate`);
+    console.log(`Cache cleanup runs every hour, images older than 24h are removed`);
 });