feat: change email, export my data, delete account (with data anonymization)

api/middleware/successRateLimit.go

@@ -0,0 +1,90 @@
+package middleware
+
+import (
+	"RenewCMS/api/pkg/apperr"
+	"net/http"
+	"strconv"
+	"sync"
+	"time"
+)
+
+type successSlots struct {
+	mu     sync.Mutex
+	window time.Duration
+	now    func() time.Time
+	taken  map[string]time.Time
+}
+
+func NewUserSuccessLimiter(window time.Duration) func(http.Handler) http.Handler {
+	return NewUserSuccessLimiterAt(window, time.Now)
+}
+
+func NewUserSuccessLimiterAt(window time.Duration, now func() time.Time) func(http.Handler) http.Handler {
+	slots := &successSlots{window: window, now: now, taken: make(map[string]time.Time)}
+
+	return func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			key := userRateLimitKey(r)
+			claimed, retryAfter, granted := slots.claim(key)
+			if !granted {
+				w.Header().Set("Retry-After", strconv.Itoa(retryAfter))
+				http.Error(w, apperr.TooManyRequestsErrorMessage, http.StatusTooManyRequests)
+				return
+			}
+
+			recorder := &statusRecorder{ResponseWriter: w, status: http.StatusOK}
+			succeeded := false
+			defer func() {
+				if !succeeded {
+					slots.release(key, claimed)
+				}
+			}()
+			next.ServeHTTP(recorder, r)
+			succeeded = recorder.status < http.StatusBadRequest
+		})
+	}
+}
+
+func (s *successSlots) claim(key string) (time.Time, int, bool) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	now := s.now()
+	s.sweepExpired(now)
+	if claimedAt, held := s.taken[key]; held {
+		return time.Time{}, retryAfterSeconds(s.window - now.Sub(claimedAt)), false
+	}
+	s.taken[key] = now
+	return now, 0, true
+}
+
+func (s *successSlots) release(key string, claimedAt time.Time) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if current, held := s.taken[key]; held && current.Equal(claimedAt) {
+		delete(s.taken, key)
+	}
+}
+
+func (s *successSlots) sweepExpired(now time.Time) {
+	for key, claimedAt := range s.taken {
+		if now.Sub(claimedAt) >= s.window {
+			delete(s.taken, key)
+		}
+	}
+}
+
+type statusRecorder struct {
+	http.ResponseWriter
+	status int
+}
+
+func (s *statusRecorder) WriteHeader(status int) {
+	s.status = status
+	s.ResponseWriter.WriteHeader(status)
+}
+
+func (s *statusRecorder) Unwrap() http.ResponseWriter {
+	return s.ResponseWriter
+}