Initial commit: Custom Start Page application with authentication and DynamoDB storage

internal/auth/state_store.go

@@ -0,0 +1,78 @@
+package auth
+
+import (
+	"sync"
+	"time"
+)
+
+// MemoryStateStore is an in-memory implementation of StateStore
+// Note: This is suitable for development but should be replaced with
+// a distributed store (Redis, DynamoDB) for production with multiple servers
+type MemoryStateStore struct {
+	mu     sync.RWMutex
+	states map[string]time.Time
+}
+
+// NewMemoryStateStore creates a new in-memory state store
+func NewMemoryStateStore() *MemoryStateStore {
+	store := &MemoryStateStore{
+		states: make(map[string]time.Time),
+	}
+	
+	// Start cleanup goroutine to remove expired states
+	go store.cleanupExpired()
+	
+	return store
+}
+
+// Set stores a state token with an expiry time
+func (s *MemoryStateStore) Set(state string, expiry time.Time) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	
+	s.states[state] = expiry
+	return nil
+}
+
+// Validate checks if a state token is valid and not expired
+func (s *MemoryStateStore) Validate(state string) (bool, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	
+	expiry, exists := s.states[state]
+	if !exists {
+		return false, nil
+	}
+	
+	if time.Now().After(expiry) {
+		return false, nil
+	}
+	
+	return true, nil
+}
+
+// Delete removes a state token from the store
+func (s *MemoryStateStore) Delete(state string) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	
+	delete(s.states, state)
+	return nil
+}
+
+// cleanupExpired periodically removes expired state tokens
+func (s *MemoryStateStore) cleanupExpired() {
+	ticker := time.NewTicker(5 * time.Minute)
+	defer ticker.Stop()
+	
+	for range ticker.C {
+		s.mu.Lock()
+		now := time.Now()
+		for state, expiry := range s.states {
+			if now.After(expiry) {
+				delete(s.states, state)
+			}
+		}
+		s.mu.Unlock()
+	}
+}