Add relay identity management and subscription enhancements.

- Introduced relay identity management for subscriptions and follow-list sync.
- Added `IdentityRequested` function to handle the `identity` subcommand.
- Implemented periodic follow-list synchronization for active subscribers.
- Enhanced payment handling to include payer pubkey and subscription updates.
- Added trial expiry and subscription expiry notifications.

pkg/database/identity.go

@@ -0,0 +1,81 @@
+package database
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/dgraph-io/badger/v4"
+	"lol.mleku.dev/chk"
+	"lol.mleku.dev/log"
+	"next.orly.dev/pkg/crypto/keys"
+	"next.orly.dev/pkg/encoders/hex"
+)
+
+const relayIdentitySecretKey = "relay:identity:sk"
+
+// GetRelayIdentitySecret returns the relay identity secret key bytes if present.
+// If the key is not found, returns (nil, badger.ErrKeyNotFound).
+func (d *D) GetRelayIdentitySecret() (skb []byte, err error) {
+	err = d.DB.View(func(txn *badger.Txn) error {
+		item, err := txn.Get([]byte(relayIdentitySecretKey))
+		if errors.Is(err, badger.ErrKeyNotFound) {
+			return err
+		}
+		if err != nil {
+			return err
+		}
+		return item.Value(func(val []byte) error {
+			// value stored as hex string
+			b, err := hex.Dec(string(val))
+			if err != nil {
+				return err
+			}
+			skb = make([]byte, len(b))
+			copy(skb, b)
+			return nil
+		})
+	})
+	return
+}
+
+// SetRelayIdentitySecret stores the relay identity secret key bytes (expects 32 bytes).
+func (d *D) SetRelayIdentitySecret(skb []byte) (err error) {
+	if len(skb) != 32 {
+		return fmt.Errorf("invalid secret key length: %d", len(skb))
+	}
+	val := []byte(hex.Enc(skb))
+	return d.DB.Update(func(txn *badger.Txn) error {
+		return txn.Set([]byte(relayIdentitySecretKey), val)
+	})
+}
+
+// GetOrCreateRelayIdentitySecret retrieves the existing relay identity secret
+// key or creates and stores a new one if none exists.
+func (d *D) GetOrCreateRelayIdentitySecret() (skb []byte, err error) {
+	// Try get fast path
+	if skb, err = d.GetRelayIdentitySecret(); err == nil && len(skb) == 32 {
+		return skb, nil
+	}
+	if err != nil && !errors.Is(err, badger.ErrKeyNotFound) {
+		return nil, err
+	}
+
+	// Create new key and store atomically
+	var gen []byte
+	if gen, err = keys.GenerateSecretKey(); chk.E(err) {
+		return nil, err
+	}
+	if err = d.SetRelayIdentitySecret(gen); chk.E(err) {
+		return nil, err
+	}
+	log.I.F("generated new relay identity key (pub=%s)", mustPub(gen))
+	return gen, nil
+}
+
+func mustPub(skb []byte) string {
+	pk, err := keys.SecretBytesToPubKeyHex(skb)
+	if err != nil {
+		return ""
+	}
+	return pk
+}

pkg/database/subscriptions.go

@@ -188,3 +188,30 @@ func (d *D) GetPaymentHistory(pubkey []byte) ([]Payment, error) {
 
 	return payments, err
 }
+
+// IsFirstTimeUser checks if a user is logging in for the first time and marks them as seen
+func (d *D) IsFirstTimeUser(pubkey []byte) (bool, error) {
+	key := fmt.Sprintf("firstlogin:%s", hex.EncodeToString(pubkey))
+	
+	isFirstTime := false
+	err := d.DB.Update(
+		func(txn *badger.Txn) error {
+			_, err := txn.Get([]byte(key))
+			if errors.Is(err, badger.ErrKeyNotFound) {
+				// First time - record the login
+				isFirstTime = true
+				now := time.Now()
+				data, err := json.Marshal(map[string]interface{}{
+					"first_login": now,
+				})
+				if err != nil {
+					return err
+				}
+				return txn.Set([]byte(key), data)
+			}
+			return err // Return any other error as-is
+		},
+	)
+	
+	return isFirstTime, err
+}