refactor(api): restructure bolt package (#1981)

* refactor(api): bolt package refactor

* refactor(api): refactor bolt package

api/bolt/version/version.go

@@ -0,0 +1,66 @@
+package version
+
+import (
+	"strconv"
+
+	"github.com/boltdb/bolt"
+	"github.com/portainer/portainer"
+	"github.com/portainer/portainer/bolt/internal"
+)
+
+const (
+	// BucketName represents the name of the bucket where this service stores data.
+	BucketName = "version"
+	versionKey = "DB_VERSION"
+)
+
+// Service represents a service to manage stored versions.
+type Service struct {
+	db *bolt.DB
+}
+
+// NewService creates a new instance of a service.
+func NewService(db *bolt.DB) (*Service, error) {
+	err := internal.CreateBucket(db, BucketName)
+	if err != nil {
+		return nil, err
+	}
+
+	return &Service{
+		db: db,
+	}, nil
+}
+
+// DBVersion retrieves the stored database version.
+func (service *Service) DBVersion() (int, error) {
+	var data []byte
+
+	err := service.db.View(func(tx *bolt.Tx) error {
+		bucket := tx.Bucket([]byte(BucketName))
+
+		value := bucket.Get([]byte(versionKey))
+		if value == nil {
+			return portainer.ErrObjectNotFound
+		}
+
+		data = make([]byte, len(value))
+		copy(data, value)
+
+		return nil
+	})
+	if err != nil {
+		return 0, err
+	}
+
+	return strconv.Atoi(string(data))
+}
+
+// StoreDBVersion store the database version.
+func (service *Service) StoreDBVersion(version int) error {
+	return service.db.Update(func(tx *bolt.Tx) error {
+		bucket := tx.Bucket([]byte(BucketName))
+
+		data := []byte(strconv.Itoa(version))
+		return bucket.Put([]byte(versionKey), data)
+	})
+}