add rate limiting, CSRF, newsletter, auto-checker, /uses and /projects pages

internal/newsletter/newsletter.go

@@ -0,0 +1,111 @@
+// Package newsletter manages email subscriber storage as a flat JSON file.
+package newsletter
+
+import (
+	"encoding/json"
+	"errors"
+	"os"
+	"strings"
+	"sync"
+	"time"
+)
+
+// Subscriber holds a single email subscription.
+type Subscriber struct {
+	Email     string    `json:"email"`
+	CreatedAt time.Time `json:"created_at"`
+}
+
+// Store manages subscribers persisted to a JSON file.
+type Store struct {
+	mu   sync.RWMutex
+	path string
+}
+
+// NewStore returns a Store backed by path, creating the file if needed.
+func NewStore(path string) (*Store, error) {
+	s := &Store{path: path}
+	// Create empty file if it doesn't exist
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		if err := s.save(nil); err != nil {
+			return nil, err
+		}
+	}
+	return s, nil
+}
+
+// All returns all current subscribers.
+func (s *Store) All() ([]Subscriber, error) {
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+	return s.load()
+}
+
+// Add adds an email if it isn't already subscribed. Returns false if duplicate.
+func (s *Store) Add(email string) (bool, error) {
+	email = strings.ToLower(strings.TrimSpace(email))
+	if email == "" {
+		return false, errors.New("email is required")
+	}
+
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	subs, err := s.load()
+	if err != nil {
+		return false, err
+	}
+	for _, sub := range subs {
+		if sub.Email == email {
+			return false, nil // already subscribed
+		}
+	}
+	subs = append(subs, Subscriber{Email: email, CreatedAt: time.Now().UTC()})
+	return true, s.save(subs)
+}
+
+// Remove unsubscribes an email address.
+func (s *Store) Remove(email string) error {
+	email = strings.ToLower(strings.TrimSpace(email))
+
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	subs, err := s.load()
+	if err != nil {
+		return err
+	}
+	filtered := subs[:0]
+	for _, sub := range subs {
+		if sub.Email != email {
+			filtered = append(filtered, sub)
+		}
+	}
+	return s.save(filtered)
+}
+
+func (s *Store) load() ([]Subscriber, error) {
+	raw, err := os.ReadFile(s.path)
+	if err != nil {
+		return nil, err
+	}
+	if len(raw) == 0 {
+		return nil, nil
+	}
+	var subs []Subscriber
+	if err := json.Unmarshal(raw, &subs); err != nil {
+		return nil, err
+	}
+	return subs, nil
+}
+
+func (s *Store) save(subs []Subscriber) error {
+	if subs == nil {
+		subs = []Subscriber{}
+	}
+	raw, err := json.MarshalIndent(subs, "", "  ")
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(s.path, raw, 0600)
+}