feat: autoencoding and prefixstore

autoencoding/autoencoding.go

@@ -0,0 +1,213 @@
+package autoencoding
+
+import (
+	"encoding/json"
+	"errors"
+	"reflect"
+	"unicode"
+
+	"github.com/plexsysio/gkvstore"
+	"github.com/vmihailenco/msgpack/v5"
+	"google.golang.org/protobuf/proto"
+)
+
+type Encoding int
+
+const (
+	Invalid Encoding = iota
+	JSON
+	MsgPack
+	Protobuf
+)
+
+type ObjectGetter interface {
+	Get() interface{}
+}
+
+type item struct {
+	val       interface{}
+	namespace string
+	id        string
+	encoding  Encoding
+}
+
+type itemWithTimeTracker struct {
+	*item
+	created string
+	updated string
+}
+
+func getEncoding(f reflect.StructField) Encoding {
+	if _, ok := f.Tag.Lookup("protobuf"); ok {
+		return Protobuf
+	}
+	if _, ok := f.Tag.Lookup("json"); ok {
+		return JSON
+	}
+	if _, ok := f.Tag.Lookup("msgpack"); ok {
+		return MsgPack
+	}
+	// If none is provided use JSON as default
+	return JSON
+}
+
+func newItem(val interface{}) (gkvstore.Item, error) {
+	foundId, foundCreated, foundUpdated := false, false, false
+	id, ns, created, updated := "", "", "", ""
+
+	rv := reflect.ValueOf(val)
+	if rv.Kind() != reflect.Ptr && rv.Kind() != reflect.Interface {
+		return nil, errors.New("incorrect value type: use pointer")
+	}
+	t := rv.Elem().Type()
+
+	if t.Name() == "" {
+		return nil, errors.New("incorrect name of type")
+	}
+	ns = t.Name()
+
+	var encoding Encoding
+	// Use first exported field for encoding
+	for i := 0; i < t.NumField(); i++ {
+		if unicode.IsUpper(rune(t.Field(i).Name[0])) {
+			encoding = getEncoding(t.Field(i))
+			break
+		}
+	}
+	if encoding == 0 {
+		return nil, errors.New("no exported field")
+	}
+
+	for i := 0; i < t.NumField(); i++ {
+		field := t.Field(i)
+		tagval, ok := field.Tag.Lookup("aenc")
+		if (field.Name == "ID" || field.Name == "Id") || (ok && tagval == "id") {
+			if foundId {
+				return nil, errors.New("duplicate ID field configured")
+			}
+			if field.Type.Kind() != reflect.String {
+				return nil, errors.New("ID field should be string")
+			}
+			foundId = true
+			id = field.Name
+		}
+		if (field.Name == "Created" || field.Name == "CreatedAt") || (ok && tagval == "created") {
+			if foundCreated {
+				return nil, errors.New("duplicate Created field configured")
+			}
+			if field.Type.Kind() != reflect.Int64 {
+				return nil, errors.New("Created field should be uint64")
+			}
+			foundCreated = true
+			created = field.Name
+		}
+		if (field.Name == "Updated" || field.Name == "UpdatedAt") || (ok && tagval == "updated") {
+			if foundUpdated {
+				return nil, errors.New("duplicate Updated field configured")
+			}
+			if field.Type.Kind() != reflect.Int64 {
+				return nil, errors.New("Updated field should be uint64")
+			}
+			foundUpdated = true
+			updated = field.Name
+		}
+	}
+
+	if !foundId {
+		return nil, errors.New("ID field not configured")
+	}
+
+	if foundCreated && foundUpdated {
+		return &itemWithTimeTracker{
+			item: &item{
+				namespace: ns,
+				id:        id,
+				encoding:  encoding,
+				val:       val,
+			},
+			created: created,
+			updated: updated,
+		}, nil
+	}
+
+	return &item{
+		namespace: ns,
+		id:        id,
+		encoding:  encoding,
+		val:       val,
+	}, nil
+}
+
+func New(val interface{}) (gkvstore.Item, error) {
+	return newItem(val)
+}
+
+func MustNew(val interface{}) gkvstore.Item {
+	it, err := newItem(val)
+	if err != nil {
+		panic(err.Error())
+	}
+	return it
+}
+
+func (i *item) GetNamespace() string {
+	return i.namespace
+}
+
+func (i *item) GetID() string {
+	v := reflect.ValueOf(i.val).Elem()
+	return v.FieldByName(i.id).String()
+}
+
+func (i *item) SetID(id string) {
+	v := reflect.ValueOf(i.val).Elem()
+	v.FieldByName(i.id).SetString(id)
+}
+
+func (i *item) Get() interface{} {
+	return i.val
+}
+
+func (i *item) Marshal() ([]byte, error) {
+	switch i.encoding {
+	case JSON:
+		return json.Marshal(i.val)
+	case MsgPack:
+		return msgpack.Marshal(i.val)
+	case Protobuf:
+		return proto.Marshal(i.val.(proto.Message))
+	}
+	return nil, errors.New("invalid encoding")
+}
+
+func (i *item) Unmarshal(buf []byte) error {
+	switch i.encoding {
+	case JSON:
+		return json.Unmarshal(buf, i.val)
+	case MsgPack:
+		return msgpack.Unmarshal(buf, i.val)
+	case Protobuf:
+		return proto.Unmarshal(buf, i.val.(proto.Message))
+	}
+	return errors.New("invalid encoding")
+}
+
+func (i *itemWithTimeTracker) GetCreated() int64 {
+	v := reflect.ValueOf(i.val).Elem()
+	return v.FieldByName(i.created).Int()
+}
+
+func (i *itemWithTimeTracker) GetUpdated() int64 {
+	v := reflect.ValueOf(i.val).Elem()
+	return v.FieldByName(i.updated).Int()
+}
+
+func (i *itemWithTimeTracker) SetCreated(val int64) {
+	v := reflect.ValueOf(i.val).Elem()
+	v.FieldByName(i.created).SetInt(val)
+}
+
+func (i *itemWithTimeTracker) SetUpdated(val int64) {
+	v := reflect.ValueOf(i.val).Elem()
+	v.FieldByName(i.updated).SetInt(val)
+}