Add avatar cache management and cleanup functionality

- Introduced constants for avatar cache limit and cleanup interval.
- Implemented a background cleanup process to manage the avatar cache size, removing the oldest files when the limit is exceeded.
- Updated the AvatarHandler to refresh the modification time of cached avatars for better cache management.

internal/api/constants.go

@@ -1,5 +1,7 @@
 package api
 
+import "time"
+
 const (
 	CompressionLevel = 5
 
@@ -7,4 +9,8 @@ const (
 	PrivacyFile    = "privacy.txt"
 	TermsFile      = "terms.txt"
 	DisclaimerFile = "disclaimer.txt"
+
+	// Avatar Cache
+	AvatarCacheLimit    = 100 * 1024 * 1024 // 100MB
+	AvatarCacheInterval = 1 * time.Hour
 )

internal/api/handlers.go

@@ -83,9 +83,69 @@ func NewServer(token string, initialSoftware []models.Software, statsService *st
 		log.Printf("Warning: failed to create avatar cache directory: %v", err)
 	}
 
+	go s.startAvatarCleanup()
+
 	return s
 }
 
+func (s *Server) startAvatarCleanup() {
+	ticker := time.NewTicker(AvatarCacheInterval)
+	for range ticker.C {
+		s.cleanupAvatarCache()
+	}
+}
+
+func (s *Server) cleanupAvatarCache() {
+	files, err := os.ReadDir(s.avatarCache)
+	if err != nil {
+		return
+	}
+
+	var totalSize int64
+	type fileInfo struct {
+		path string
+		size int64
+		mod  time.Time
+	}
+	var infos []fileInfo
+
+	for _, f := range files {
+		if f.IsDir() {
+			continue
+		}
+		path := filepath.Join(s.avatarCache, f.Name())
+		info, err := f.Info()
+		if err != nil {
+			continue
+		}
+		totalSize += info.Size()
+		infos = append(infos, fileInfo{
+			path: path,
+			size: info.Size(),
+			mod:  info.ModTime(),
+		})
+	}
+
+	if totalSize <= AvatarCacheLimit {
+		return
+	}
+
+	// Sort by modification time (oldest first)
+	sort.Slice(infos, func(i, j int) bool {
+		return infos[i].mod.Before(infos[j].mod)
+	})
+
+	for _, info := range infos {
+		if totalSize <= AvatarCacheLimit {
+			break
+		}
+		if err := os.Remove(info.path); err == nil {
+			totalSize -= info.size
+		}
+	}
+	log.Printf("Avatar cache cleaned up. Current size: %v bytes", totalSize)
+}
+
 func (s *Server) RegisterURL(targetURL string) string {
 	h := sha256.New()
 	h.Write(s.salt)
@@ -304,6 +364,10 @@ func (s *Server) AvatarHandler(w http.ResponseWriter, r *http.Request) {
 
 	cachePath := filepath.Join(s.avatarCache, id)
 	if _, err := os.Stat(cachePath); err == nil {
+		// Update modification time for LRU cleanup
+		now := time.Now()
+		_ = os.Chtimes(cachePath, now, now)
+
 		// Serve from cache
 		w.Header().Set("Cache-Control", "public, max-age=86400")
 		http.ServeFile(w, r, cachePath)