Additions to domain/ and workspace/ chron-note packages

chron-note/internal/domain/event.go

@@ -1 +1,137 @@
 package domain
+
+import (
+	"fmt"
+
+	"git.michelsen.id/phill/chron/chron-note/internal/util"
+)
+
+type EventType uint8
+
+const (
+	EventObjectUpsert EventType = 1
+	EventObjectDelete EventType = 2
+)
+
+const encodingVersion uint8 = 1
+
+type ObjectUpsert struct {
+	ObjectID ObjectID
+	Name     string
+	Tags     []string
+
+	HasBlob bool
+	Blob    BlobID
+}
+
+type ObjectDelete struct {
+	ObjectID ObjectID
+}
+
+type Event struct {
+	Type EventType
+
+	Upsert *ObjectUpsert
+	Delete *ObjectDelete
+}
+
+func EncodeEvent(e Event) ([]byte, error) {
+	enc := util.NewEncoder(nil)
+	enc.U8(encodingVersion)
+	enc.U8(uint8(e.Type))
+
+	switch e.Type {
+	case EventObjectUpsert:
+		if e.Upsert == nil {
+			return nil, ErrInvalidEvent
+		}
+		u := e.Upsert
+
+		var flags uint8
+		if u.HasBlob {
+			flags |= 0x01
+		}
+		enc.U8(flags)
+
+		enc.BytesFixed(u.ObjectID[:])
+		enc.String(u.Name)
+		enc.StringSlice(u.Tags)
+
+		if u.HasBlob {
+			enc.BytesFixed(u.Blob[:])
+		}
+
+	case EventObjectDelete:
+		if e.Delete == nil {
+			return nil, ErrInvalidEvent
+		}
+		enc.BytesFixed(e.Delete.ObjectID[:])
+
+	default:
+		return nil, ErrUnknownEventType
+	}
+
+	if err := enc.Err(); err != nil {
+		return nil, err
+	}
+	return enc.Bytes(), nil
+}
+
+func DecodeEvent(b []byte) (Event, error) {
+	dec := util.NewDecoder(b)
+
+	ver := dec.U8()
+	if dec.Err() != nil {
+		return Event{}, ErrDecode
+	}
+	if ver != encodingVersion {
+		return Event{}, fmt.Errorf("%w: unsupported encoding version %d", ErrDecode, ver)
+	}
+
+	typ := EventType(dec.U8())
+	if dec.Err() != nil {
+		return Event{}, ErrDecode
+	}
+
+	switch typ {
+	case EventObjectUpsert:
+		flags := dec.U8()
+		var objID ObjectID
+		copy(objID[:], dec.BytesFixed(len(objID)))
+
+		name := dec.String()
+		tags := dec.StringSlice()
+
+		hasBlob := (flags & 0x01) != 0
+		var blob BlobID
+		if hasBlob {
+			copy(blob[:], dec.BytesFixed(len(blob)))
+		}
+
+		if dec.Err() != nil {
+			return Event{}, ErrDecode
+		}
+
+		return Event{
+			Type: typ,
+			Upsert: &ObjectUpsert{
+				ObjectID: objID,
+				Name:     NormalizeName(name),
+				Tags:     NormalizeTags(tags),
+				HasBlob:  hasBlob,
+				Blob:     blob,
+			},
+		}, nil
+
+	case EventObjectDelete:
+		var objID ObjectID
+		copy(objID[:], dec.BytesFixed(len(objID)))
+		if dec.Err() != nil {
+			return Event{}, ErrDecode
+		}
+		return Event{Type: typ, Delete: &ObjectDelete{ObjectID: objID}}, nil
+
+	default:
+		return Event{}, ErrUnknownEventType
+	}
+}