sdk: setup KVStore.

sdk/kvstore/badger/store.go

@@ -0,0 +1,59 @@
+package badger
+
+import (
+	"github.com/dgraph-io/badger/v4"
+	"github.com/nbd-wtf/go-nostr/sdk/kvstore"
+)
+
+var _ kvstore.KVStore = (*Store)(nil)
+
+type Store struct {
+	db *badger.DB
+}
+
+func NewStore(path string) (*Store, error) {
+	opts := badger.DefaultOptions(path)
+	db, err := badger.Open(opts)
+	if err != nil {
+		return nil, err
+	}
+	return &Store{db: db}, nil
+}
+
+func (s *Store) Get(key []byte) ([]byte, error) {
+	var valCopy []byte
+	err := s.db.View(func(txn *badger.Txn) error {
+		item, err := txn.Get(key)
+		if err == badger.ErrKeyNotFound {
+			return nil
+		}
+		if err != nil {
+			return err
+		}
+		return item.Value(func(val []byte) error {
+			valCopy = make([]byte, len(val))
+			copy(valCopy, val)
+			return nil
+		})
+	})
+	if err != nil {
+		return nil, err
+	}
+	return valCopy, nil
+}
+
+func (s *Store) Set(key []byte, value []byte) error {
+	return s.db.Update(func(txn *badger.Txn) error {
+		return txn.Set(key, value)
+	})
+}
+
+func (s *Store) Delete(key []byte) error {
+	return s.db.Update(func(txn *badger.Txn) error {
+		return txn.Delete(key)
+	})
+}
+
+func (s *Store) Close() error {
+	return s.db.Close()
+}